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1.	Aldea, Jorge (author) Competition and climate influence in the basal area increment models for Mediterranean mixed forests 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 506 Journal article (peer-reviewed)abstract Competition plays a key role controlling tree growth in mixed forests. Contrary to monocultures, quantifying species mixing influence on tree growth suppose a challenge since the presence of two or more species requires to estimate the degree of intra- and inter-specific competition among trees. Moreover, it is well known that aridity can also influence tree growth, especially in the Mediterranean Basin. In the present context of climate change, it is essential to take into account species mixing and aridity uncertainty in the design of sustainable management guidelines for Mediterranean mixed forests. To achieve that, data from Spanish National Forest Inventory was used in this study to fit new mixed-effects basal area increment (BAI) models for 29 two-species compositions in Spain. A wide range of different competition structures (intra-specific, inter-specific, size-symmetric and sizeasymmetric) and aridity conditions (in terms of the De Martonne Index) were included and tested into the BAI models. Parameter estimations were obtained for all possible species, mixtures and combinations by Maximum Likelihood (ML). Models with all the coefficients being significant (p < 0.05) were first selected. Among these models, we used Akaike Evidence Ratios for selecting the best one by species for each mixture. The best model for each species and mixture was used to analyze the competition and climatic influence on tree growth. Regarding competition influence, a common trend among mixtures was found with higher productivity in mixed than pure stands, suggesting that BAI values may increase with the increment of species diversity. Based on intra and inter-specific competition indexes, competition seemed to be the most representative biological interaction in conifer-conifer mixtures, since neutralism and facilitation may occur more frequently in coniferbroadleaved and broadleaved-broadleaved mixtures. Our findings also suggested that tree growth may be significantly limited by arid conditions, excepting for Pinus halepensis and Pinus pinea. Our rigorous modelling approach successfully uncovered not only possible mixing effect among various species but also help us to understand the effect of aridity on tree growth. Thus, models presented in this study can be used in the design and implementation of management and adaptation guidelines under future climate change scenarios.
2.	Aldea, Jorge (author) Differences in stem radial variation between Pinus pinaster Ait. and Quercus pyrenaica Willd. may release inter-specific competition 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 481 Journal article (peer-reviewed)abstract Species complementarity by morphological and physiological trait differences could cause distinct temporal and spatial use of resources. Accordingly, mixed stands may enhance production, biodiversity and/or provide a better adaptation to future climate conditions. We aim to identify species differences in intra-annual stem radial variation patterns, and to recognize species-specific responses to contrasting weather conditions at key intraannual growth phases. Stem radial variation was recorded from high temporal resolution point dendrometers (2012-2014) installed on twelve dominant maritime pine and Pyrenean oak trees in two mixed stands in central Spain. Species differences in stem radial variation were analyzed by synchrony statistics, intra-annual pattern modelling, and evaluating the dependence of main intra-annual growth phases on climate conditions. Both species showed important differences on intra-annual radial increment pattern despite general stem radial variation synchrony. Radial increment onset was earlier for maritime pine during the spring and rainy autumns. Species-specific responses to weather indicate that stem radial variation increased with autumn temperature in maritime pine, but decreased in Pyrenean oak trees. However, summer vapor pressure deficit may reduce stem radial variation for maritime pine. Therefore, maritime pine would adapt more efficiently to warmer temperatures associated with climate change, although summer water stress may reduce this competitive bonus.
3.	Aldea, Jorge, et al. (author) Evaluation of growth models for mixed forests used in Swedish and Finnish decision support systems 2023 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 529 Journal article (peer-reviewed)abstract Interest in mixed forests is increasing since they could provide higher benefits and positive externalities compared to monocultures, although their management is more complex and silvicultural prescriptions for them are still scarce. Growth simulations are a powerful tool for developing useful guidelines for mixed stands. Heureka and Motti are two decision support systems commonly used for forest management in Sweden and Finland respectively. They were developed mostly with data from pure stands, so how they would perform in mixed stands is currently uncertain. We compiled a large and updated common database of well-replicated experimental research sites and monitoring networks composed by 218 and 1,160 plot-level observations of mixed stands from Sweden and Finland, respectively. We aimed to evaluated the accuracy of Heureka and Motti basal area growth models in those mixed-species stands and to detect any bias in their short-term predictions. Basal area growth simulations (excluding mortality models) were compared to observed stand-level values in a period-wise process with update of the start values in each period. The residual plots were visually examined for different stand mixtures: Norway spruce (Picea abies Karst.)-birch (Betula spp), Scots pine (Pinus sylvestris L.)-birch and Scots pine-Norway spruce. We observed that the basal area growth models in both decision support systems performed quite well for all mixtures regardless of the proportion of species. Motti simulations overestimated growth in Scots pine-Norway spruce mixtures by 0.063 m(2)center dot ha(-1)center dot year(-1) which may be acceptable for practical use. Therefore, we corroborated that both decision support systems can be currently utilized for shortterm forest growth simulation of mixed boreal forests.
4.	Aldea, Jorge (author) Species mixing reduces drought susceptibility of Scots pine (Pinus sylvestris L.) and oak (Quercus robur L., Quercus petraea (Matt.) Liebl.) - Site water supply and fertility modify the mixing effect 2020 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 461 Journal article (peer-reviewed)abstract Tree species mixing has been widely promoted as a promising silvicultural tool for reducing drought stress. However, so far only a limited number of species combinations have been studied in detail, revealing inconsistent results. In this study, we analysed the effect of mixing Scots pine and oak (pedunculate oak and sessile oak) trees on their drought response along a comprehensive ecological gradient across Europe. The objective was to improve our knowledge of general drought response patterns of two fundamental European tree species in mixed versus monospecific stands. We focused on three null hypotheses: (HI) tree drought response does not differ between Scots pine and oak, (HII) tree drought response of Scots pine and oak is not affected by stand composition (mixture versus monoculture) and (HIII) tree drought response of Scots pine and oak in mixtures and monocultures is not modified by tree size or site conditions. To test the hypotheses, we analysed increment cores of Scots pine and oak, sampled in mixed and monospecific stands, covering a wide range of site conditions. We investigated resistance (the ability to maintain growth levels during drought), recovery (the ability to restore a level of growth after drought) and resilience (the capacity to recover to pre-drought growth levels), involving sitespecific drought events that occurred between 1976 and 2015. In monocultures, oak showed a higher resistance and resilience than Scots pine, while recovery was lower. Scots pine in mixed stands exhibited a higher resistance, but also a lower recovery compared with Scots pine in monocultures. Mixing increased the resistance and resilience of oak. Ecological factors such as tree size, site water supply and site fertility were found to have significant effects on the drought response. In the case of Scots pine, resistance was increased by tree size, while recovery was lowered. Resistance of oak increased with site water supply. The observed mixing effect on the tree drought response of Scots pine and oak was in some cases modified by the site conditions studied. Positive mixing effects in terms of resistance and resilience of oak increased with site water supply, while the opposite was found regarding recovery. In contrast, site fertility lessened the positive mixing effect on the resistance of Scots pine. We hypothesise that the observed positive mixing effects under drought mainly result from waterand/or light-related species interactions that improve resource availability and uptake according to temporal and spatial variations in environmental conditions.
5.	Aldea, Jorge, et al. (author) Species stratification and weather conditions drive tree growth in Scots pine and Norway spruce mixed stands along Europe 2021 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 481 Journal article (peer-reviewed)abstract Mixed forests are suggested as a strategic adaptation of forest management to climate change. Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) are tree species of high economic and ecological value for European forestry. Both species coexist naturally in a large part of their distributions but there is a lack of knowledge on the ecological functioning of mixtures of these species and how to manage such stands. This paper analyses these species' intra- and inter-specific competition, including size-symmetric vs. size-asymmetric competition, and explore the effect of weather conditions on tree growth and competition. We studied basal area growth at tree level for Scots pine and Norway spruce in mixed versus pure stands in 22 triplets of fully-stocked plots along a broad range of ecological conditions across Europe. Stand inventory and increment cores provided insights into how species mixing modifies tree growth compared with neighbouring pure stands. Five different competition indices, weather variables and their interactions were included and checked in basal area growth models using a linear mixed model approach. Interspecific size-asymmetric competition strongly influenced growth for both tree species, and was modulated by weather conditions. However, species height stratification in mixed stands resulted in a greater tree basal area growth of Scots pine (10.5 em(2) year(-1)) than in pure stands (9.3 em(2) year(-1)), as this species occupies the upper canopy layer. Scots pine growth depended on temperature and drought, whereas Norway spruce growth was influenced only by drought. Interspecific site-asymmetric competition increased in cold winters for Scots pine, and decreased after a drought year for Norway spruce. Although mixtures of these species may reduce tree size for Norway spruce, our results suggest that this could be offset by faster growth in Scots pine. How inter-specific competition and weather conditions alter tree growth may have strong implications for the management of Scots pine-Norway spruce mixtures along the rotation period into the ongoing climate change scenario.
6.	Aldea, Jorge, et al. (author) Tree species growth response to climate in mixtures of Quercus robur/ Quercus petraea and Pinus sylvestris across Europe- a dynamic, sensitive equilibrium 2023 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 530 Journal article (peer-reviewed)abstract Quercus robur/Quercus petraea and Pinus sylvestris are widely distributed and economically important tree species in Europe co-occurring on mesotrophic, xeric and mesic sites. Increasing dry conditions may reduce their growth, but growth reductions may be modified by mixture, competition and site conditions. The annual diameter growth in monospecific and mixed stands along an ecological gradient with mean annual temperatures ranging from 5.5 degrees C to 11.5 degrees C was investigated in this study. On 36 triplets (108 plots), trees were cored and the year-ring series were cross-dated, resulting in year-ring series of 785 and 804 trees for Q. spp. and P. sylvestris, respec-tively. A generalized additive model with a logarithmic link was fit to the data with random effects for the intercept at the triplet, year and tree level and a random slope for the covariate age for each tree; the Tweedie-distribution was used. The final model explained 87 % of the total variation in diameter increment for both tree species. Significant covariates were age, climate variables (long-term mean, monthly), local competition vari-ables, relative dbh, mixture, stand structure and interactions thereof. Tree growth declined with age and local density and increased with social position. It was positively influenced by mixture and structural diversity (Gini coefficient); mixture effects were significant for P. sylvestris only. The influence of potential evapotranspiration (PET) in spring and autumn on tree growth was positive and non-linear, whereas tree growth sharply decreased with increasing PET in June, which proved to be the most influential month on tree growth along the whole ecological gradient. Interactions of PET with tree social position (relative dbh) were significant in July and September for Q. spp. and in April for P. sylvestris. Interactions of climate with density or mixture were not significant. Climatic effects found agree well with previous results from intra-annual growth studies and indicate that the model captures the causal factors for tree growth well. Furthermore, the interaction between climate and relative dbh might indicate a longer growth duration for trees of higher social classes. Analysis of random effects across time and space showed highly dynamic patterns, with competitive advantages changing annually between species and spatial patterns showing no large-scale trends but pointing to the prevalence of local site factors. In mixed-species stands, the tree species have the same competitivity in the long-term, which is modified by climate each year. Climate warming will shift the competitive advantages, but the direction will be highly site-specific.
7.	Amelia, Tudoran, et al. (author) Using associational effects of European beech on Norway spruce to mitigate damage by a forest regeneration pest, the pine weevil Hylobius abietis 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 486 Journal article (peer-reviewed)abstract Forest regeneration can be compromised by insect damage to newly-planted conifer seedlings, with the pine weevil, Hylobius abietis, being the most economically important pest in Europe. Seedling protection strategies include physical barriers, silvicultural measures and insecticides, while the potential benefits of Associational Effects (AE) have been little explored. Associational Resistance (AR) or Susceptibility (AS) arise when neighbouring plants decrease or increase, respectively, the likelihood and extent of attack on a focal plant. We investigated the potential of European beech, Fagus sylvatica, to mediate AE for Norway spruce, Picea abies, seedlings against pine weevil damage. First, we examined the effects of neighbor identity on damage to P. abies at a small scale, using choice arenas in the lab. Then, in the field, we examined these effects at a larger scale using plots containing only Norway spruce, or both species. We found that P. abies seedlings were attacked and damaged less by weevils when beech was their close neighbor, relative to having another Norway spruce as a neighbor in the lab. Yet, no difference in damage between only spruce and mixed seedling plots was found in the field. Our results indicate that the susceptibility of P. abies to H. abietis can be influenced by neighbor identity, and effects can vary with inter-plant distance. In close proximity, the presence of the non-host F. sylvatica can alter pine weevil feeding behaviour and thus, has the potential to mediate AR. However, these associational effects appear not to provide enhanced seedling protection at a larger scale.
8.	Angelstam, Per, et al. (author) Tradition as asset or burden for transitions from forests as cropping systems to multifunctional forest landscapes: Sweden as a case study 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 505 Journal article (peer-reviewed)abstract Expectations of what forests and woodlands should provide vary among locations, stakeholder groups, and over time. Developing multifunctional forests requires understanding of the dynamic roles of traditions and cultural legacies in social-ecological systems at multiple levels and scales. Implementing policies about multifunctional forests requires a landscape and social-ecological perspective, and recognition of both spatial and temporal features at multiple scales. This study explores the dissemination of even-aged silviculture in central, eastern and northern Europe, and the consequences of choosing different vantage points in social-ecological systems for mapping of barriers, and to identify levers, towards multifunctional forest landscapes. Using a narrative approach, we first summarise the development of even-aged silviculture in four European regions. Next, we focus on Sweden as a keen adopter of even-aged silviculture, and identify levers at three groups of vantage points. They were (1) biosphere with biodiversity as short-hand for composition, structure and function of ecosystems, which support human well-being at multiple scales; (2) society in terms of different levels of stakeholder interactions from local to global, and (3) economy represented by value chain hierarchies and currencies. The emergence of even-aged silviculture >200 years ago formed an expanding frontier from central to northern Europe. Sustained yield wood production and biodiversity conservation encompass different portfolios of ecosystem aspects and spatio-temporal scales. Ignorance and lack of knowledge about these differences enforce their mutual rivalry. An exploratory review of six groups of stakeholders at multiple levels in the traditional industrial forest value chain highlights inequalities in terms of distribution of income and power across different levels of governance. This effectively marginalises other than powerful industrial actors. The distribution of financial results along the value chain is dynamic in space and time, and not all benefits of forest ecosystems can be measured using monetary valuation. There are also other currencies and incentives. A discussion of cultural trajectories in central and eastern European, Russian and Swedish forest management illustrates that forest history patterns repeat themselves. Longitudinal case studies of countries and regions can help foster holistic multi-dimensional and multilevel systems thinking. Application of deep levers of change is likely to require external drivers. A key challenge is to handle the manufacturing of doubt and decay of truth, i.e., the appearance of alternative facts, and the diminishing role of evidence and systems analyses in political and civic discourses. This transition is fuelled by new and rapidly evolving digital arenas.
9.	Appiah Mensah, Alex, et al. (author) Modelling potential yield capacity in conifers using Swedish long-term experiments 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 512 Journal article (peer-reviewed)abstract Information on forest site productivity is a key component to assess the carbon sequestration potential of boreal forests. While site index (SI) is commonly used to indicate forest site productivity, expressions of SI in the form of yield capacity (potential maximum mean annual volume increment) is desirable since volume yield is central to the economic and ecological analyses of a given species and site. This paper assessed the functional relationship between SI and yield capacity on the basis of yield plot data from long-term experiments measured over several decades for Norway spruce (Picea abies), Scots pine (Pinus sylvestris), Lodgepole pine (Pinus contorta) and Larch (Larix decidua and Larix sibirica) in Sweden. Component models of total basal area and volume yield were also developed. SI was determined by existing height development functions using top height and age, whereas functions for stand-level (m2 ha- 1) basal area development were constructed based on age, SI and initial stand density using difference equations and nonlinear mixed-effects models. The relation between volume yield (m3 ha- 1) and top height was adjusted with total basal area production through nonlinear mixed-effects models. Species-specific parametric regression models were used to construct functional relationships between SI and yield capacity. The root mean square errors of the species-specific models ranged from 2 to 6% and 10-18% of the average values for the basal area and volume equations, respectively. For the yield capacity functions, the explained variations (R2) were within 80-96%. We compared our yield capacity functions to earlier functions of the species and significant differences were observed in both lower and higher SI classes, especially, for Scots pine and Norway spruce. The new functions give better prediction of yield capacity in current growing conditions; hence, they could later be used for comparing tree species' production under similar site and management regimes in Sweden.
10.	Appiah Mensah, Alex, et al. (author) Taller and slenderer trees in Swedish forests according to data from the National Forest Inventory 2023 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 527 Journal article (peer-reviewed)abstract Changes over time in annual basal area growth and mean height for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) over the period, 1983-2020 were studied using sample tree data from temporary plots recorded in the Swedish National Forest Inventory. The annual basal area growth was derived from the last measured full ring on increment cores. Using 20 to 60-year-old dominant trees, the mean height and annual basal area growth were examined as functions of tree, stand and site conditions, and trends were assessed mainly using residual analyses over time. A significant increase in mean height at a given age was found for both species, but the annual basal area growth level remained stable over the 38-year period. Currently, at a given age of 50 annual rings at breast height, the mean heights of pines and spruces increased on average by 10.1% (i.e. similar to 2 m), compared to 50 year-old pines and spruces in the 1980s, and the increase was similar in the different regions. The results suggest that trees have become taller and slenderer in Swedish forests. Increasing tree height over time at a given age in Northern Europe has been documented in several reports and many causes have been suggested, such as changed forest management, increasing temperatures and nitrogen deposition. We suggest that elevated CO2 in the air and improved water-use efficiency for the trees might also be strong drivers.
11.	Ara, Mostarin, et al. (author) Pre-commercial thinning in Norway spruce-birch mixed stands can provide abundant forage for ungulates without losing volume production 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 520 Journal article (peer-reviewed)abstract Mixed stands of Norway spruce and birch have the potential to simultaneously produce timber and provide large ungulates with a significant amount of forage during the regeneration phase. While the growth and yield of such mixtures are well studied, little is known about potential trade-offs between timber and forage production and which management techniques are suitable for meeting both goals. In this study, four different pre-commercial thinning (PCT) strategies were used to study the trade-offs between production and available forage for free-ranging ungulates in a Norway spruce-birch mixture. The four PCT strategies were: 1) retaining 2000 birch stems ha(-1) with 2000 Norway spruce ha(-1), 2) removing all birches within a 0.75 m radius around Norway spruce stems, 3) removing all birches and other broadleaves, and 4) no PCT (control). Growth of Norway spruce was higher in the 2000 birch ha(-1) and full removal treatments compared to the untreated control, but these two treatments did not differ from one another in volume production of Norway spruce. We found a negative effect of PCT on forage availability but no effect on ungulate browsing. Therefore, PCT strategies that provide both sufficient birch forage and maximize volume production of Norway spruce can be implemented.
12.	Ara, Mostarin, et al. (author) Varying rectangular spacing yields no difference in forest growth and external wood quality in coniferous forest plantations 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 489 Journal article (peer-reviewed)abstract Historically square or almost square spacing design has been used in plantation forest, as it has been claimed to maximize productivity. In this study, based on field experiments established in the mid-1980s, we tested the effect of square or different rectangular planting designs (2 x 2, 1.33 x 3, 1 x 4, 0.8 x 5, 1.46 x 1.46 x 4 m) on productivity, stand heterogeneity, and external wood properties of three coniferous species: Scots pine, Lodgepole pine, and Norway spruce. Stand production (volume, diameter), external wood properties (ovality, branch thickness, living crown height, height-diameter ratio), and stand heterogeneity (Gini coefficient) were not significantly affected by the different rectangular designs. Based on this evidence, we propose that more flexibility is available than previously thought for rectangular spacing layouts and consequently for the choice of planting spots and machinery operations.
13.	Azizi, Soghra, et al. (author) Dual inoculations of arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria boost drought resistance and essential oil yield of common myrtle 2021 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 497 Journal article (peer-reviewed)abstract Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) are increasingly being used to enhance crop abiotic stress resistance. Common myrtle is an economically important essential oilproducing plant but knowledge about its drought resistance mechanisms and the drought mitigation potential of AMF and PGPR is scant. Here, we investigated the effects of single and dual AMF (Funneliformis mosseae, Rhizophagus irregularis) and PGPR (Pseudomonas fluorescens, P. putida) inoculation on seedling survival, growth, physiology, and biochemical traits under soil water deficit (100%, 60%, and 30% of field capacity). Under severe drought, all inoculations increased survival compared to non-inoculated seedlings. Drought-related growth impairment was more strongly compensated belowground than aboveground, especially in dual-inoculated plants, indicating prioritized resource allocation to roots probably linked to AMF- and PGPR-induced phytohormone changes. Particularly dual inoculation significantly improved leaf physiology, reduced electrolyte leakage, malondialdehyde, and proline concentrations and mitigated oxidative pigment losses under drought through upregulation of the antioxidant defense as evidenced by (non-)enzymatic antioxidant accumulation, including essential oils. Our findings indicate similarly significant AMF- and PGPR-mediated boosts in myrtle drought resistance through enhanced water and nutrient supply and stimulation of the antioxidant defense. Dual inoculations proved most effective and provide a low-cost approach to optimizing myrtle cultivation and restoration programs.
14.	Balvanera, Patricia, et al. (author) Social ecological dynamics of tropical secondary forests 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 496 Research review (peer-reviewed)
15.	Bandau, Franziska, et al. (author) European aspen with high compared to low constitutive tannin defenses grow taller in response to anthropogenic nitrogen enrichment 2021 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 487 Journal article (peer-reviewed)abstract Boreal forests receive nitrogen-(N)-enrichment via atmospheric deposition and industrial fertilization. While it is known that N-enrichment can intensify interactions with natural antagonists, it remains poorly understood how genetic variability in plant defense chemistry can affect biotic interactions and height growth in N-enriched environments. We grew replicates of five low- and high-tannin Populus tremula genotypes, respectively, under three N-treatments (ambient, 15, and 150 kg N ha−1 yr−1). We assessed shoot blight occurrence (i.e. symptoms caused by Venturia fungi) during four growing seasons, and tree height growth during the same period. Damage by Venturia spp. increased with N-addition during all years, likely due to enhanced foliar quality. Low–tannin plants showed higher incidences of Venturia infection than high-tannin plants, regardless of the N-input-level. Height responded to an N-by-tannin-group interaction, which occurred because high-tannin plants grew taller than low-tannin plants at the high N-treatment, but not under the other N-levels. This pattern indicates that innate resource investment into tannin production yields a positive effect on growth under N-enriched conditions. Given that N-deposition is increasing globally, our research suggests that further studies are needed to investigate how N-enrichment interacts with plant defense traits globally. Moreover, our research suggests that N-deposition may provide an advantage for well-defended, high-tannin plants; and further, that genetic diversity in plant defense may be a key mechanism by which plant populations respond to this change.
16.	Barbeito, Ignacio (author) Mixing has limited impacts on the foliar nutrition of European beech and Scots pine trees across Europe 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 479 Journal article (peer-reviewed)abstract Tree species-mixing has been suggested as one option to counteract the adverse effects of global change on tree mineral nutrition, yet the effect of mixing on nutrient availability remains poorly documented.We therefore analyzed the current foliar nutrient (N, P, K, Ca, Mg) quantities and ilr balances (isometric log transformed ratios between elements or groups of elements) for 261 European beech and 248 Scots pine trees from 15 sites, each consisting of one beech-pine mixed stand and the respective monocultures, across a gradient of environmental conditions in Europe. We hypothesized an overall positive effect of mixing on tree foliar nutrient content, and that this mixing effect would be stronger on nutrient-poor sites. Using linear mixed models and multivariate linear regression models, we first tested for the effects of species (beech/pine) and composition (pure/mixed) across all sites; we then investigated whether the species-mixing effect was related to site fertility.The nutrient composition of beech leaves and pine needles differed significantly for all ilr balances. For both species, significant mixing effects were detected for some nutrients and ilr balances; those effects, however, could not be consistently related to contrasted nutrient composition between species. For most nutrients and ilr balances, the mixing effect was influenced by the site nutritional status, but the pattern differed from expectation: absence or minor differences between monocultures and mixtures at the lower end of the chemical fertility gradient, and maximum differences in rich soils.The contrasting foliar nutrient composition of pine and beech trees and the site nutrient status only partly explained the mixing effects on tree mineral nutrition. Our results claim for a better understanding of nutrientrelated mechanisms associated with complementarity and points towards the need to further expand the existing frameworks to account for the multivariate nature of tree nutrition.
17.	Barbeito, Ignacio, et al. (author) Regional climate moderately influences species-mixing effect on tree growth-climate relationships and drought resistance for beech and pine across Europe 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 520 Journal article (peer-reviewed)abstract Increasing species diversity is considered a promising strategy to mitigate the negative impacts of global change on forests. However, the interactions between regional climate conditions and species-mixing effects on climate-growth relationships and drought resistance remain poorly documented.In this study, we investigated the patterns of species-mixing effects over a large gradient of environmental conditions throughout Europe for European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.), two species with contrasted ecological traits. We hypothesized that across large geographical scales, the difference of climate-growth relationships and drought resistance between pure and mixed stands would be dependent on regional climate. We used tree ring chronologies derived from 1143 beech and 1164 pine trees sampled in 30 study sites, each composed of one mixed stand of beech and pine and of the two corresponding pure stands located in similar site conditions. For each site and stand, we used Bootstrapped Correlation Coefficients (BCCs) on standardized chronologies and growth reduction during drought years on raw chronologies to analyze the difference in climate-tree growth relationships and resistance to drought between pure and mixed stands.We found consistent large-scale spatial patterns of climate-growth relationships. Those patterns were similar for both species. With the exception of the driest climates where pure and mixed beech stands tended to display differences in growth correlation with the main climatic drivers, the mixing effects on the BCCs were highly variable, resulting in the lack of a coherent response to mixing. No consistent species-mixing effect on drought resistance was found within and across climate zones. On average, mixing had no significant effect on drought resistance for neither species, yet it increased pine resistance in sites with higher climatic water balance in autumn. Also, beech and pine most often differed in the timing of their drought response within similar sites, irrespective of the regional climate, which might increase the temporal stability of growth in mixed compared to pure stands.Our results showed that the impact of species mixing on tree response to climate did not strongly differ between groups of sites with distinct climate characteristics and climate-growth relationships, indicating the interacting influences of species identity, stand characteristics, drought events characteristics as well as local site conditions.
18.	Barbeito, Ignacio (author) Trade-offs across densities and mixture proportions in lodgepole pine-hybrid spruce plantations 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 490 Journal article (peer-reviewed)abstract Monocultures tend to yield higher total stand volumes and are simple to manage. Yet, mixed species stands may result in similar stand volumes while providing benefits such as mitigating damage from insects and disease. To understand the effects of stand density and species mixture and their interactions on stand yield, tree size and morphology, and damage in monocultures and mixtures, we analyzed a 25-year-old experiment in interior British Columbia, Canada. The lodgepole pine (Pl)-interior hybrid spruce (Sx) experiment included three densities?1000, 1500, and 2000 stems per hectare (SPH)?and five species mixtures?1:0, 3:1, 1:1, 1:3, and 0:1 Pl:Sx. Results 25 years after stand establishment showed that stand volume was significantly larger with an increasing proportion of Pl across all stand densities. Pl had 10% larger diameters in the 1000 SPH than in the 2000 SPH and when mixed with Sx (1:1). Pl had larger crowns in mixtures regardless of density. Mixture proportion did not affect gall rust incidence or stem form in Pl, but reduced attack in Sx by spruce weevil. Our findings suggest that mixing Pl-Sx and high planting density decrease weevil attacks in Sx, which reduce loss in timber quality. Yet, Pl quality may decrease when mixed with Sx, due to larger Pl crowns. These results may be used to improve the implementation of management strategies that decrease trade-offs between yields, desired market tree sizes, and timber loss from pest and pathogens, while making the stands more resilient to further climate change impact.
19.	Becs, Artis, et al. (author) Development of crop trees after different thinning methods in mixed Norway spruce (Picea abies L.) and Birch (Betula spp.) forests in Southern Sweden 2024 In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 566 Journal article (peer-reviewed)abstract In Northern Europe, novel thinning methods of small diameter trees are being tested to promote early competition release in young tree -dense forests at a low cost. These methods involve harvesting the whole aboveground tree biomass in 1 - 2 m wide strips between extraction racks (i.e. strip roads). Before recommending such methods to practical forestry, we need to know how the growth of remaining stand and individual trees perform at different stages of stand rotation to avoid compromising future forest production and the overall economy. Therefore, we analysed data from three Norway spruce dominated experimental sites in Southern Sweden with conventional selective biomass thinning (BT) versus geometrical BT in strips, where trees between extraction racks are cut in 1 - 2 m wide, ca. 10 m long strips (i.e. boom -corridor thinning) including unthinned reference treatment. To assess the thinning effect on the remaining stand, we analysed data from the remaining trees five to six years after thinning. We compared stand properties such as standing volume, diameter, height, basal area, volume increment, basal area increment and damages for different cohorts of the remaining trees. We found that BT in 1 - 2 m wide strips do not affect the growth and yield of the most important crop trees (i.e. the 500 -largest crop trees and the next 400 -largest crop trees) and to some extent protect the remaining stand from damages. Although not statistically significant, we observed that for the cohort of the 500 -largest crop trees, the proportions of new damages were lower in unthinned treatment (4.8 %), and strict BT in 1 - 2 m wide strips (1.7 % and 5.8 % respectively) than in conventional BT (14.4 %) and semi -selective BT in 1 m wide strips (7.9 %). A similar pattern was seen for the next 400 -largest crop trees. Thus, these short-term results suggests that BT in narrow strips of 1 - 2 m can be used in young tree -dense forests in Southern Sweden without compromising the development of the remaining crop trees. However, more long-term research on a broader geographical scale is required before we can fully recommend these novel -thinning methods to forest owners across the Northern Europe on a large scale.
20.	Berg, Björn, et al. (author) Decomposition rates in late stages of Scots pine and Norway spruce needle litter: Influence of nutrients and substrate properties over a climate gradient 2022 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 522 Journal article (peer-reviewed)abstract The aim of this paper is to show different patterns for decomposition of the main mass of needle litter from two boreal and temperate coniferous tree species, both leading to a stabilized fraction of litter. To this purpose we have reviewed information on decomposition patterns in the lignin-dominated (late) stages of two local foliar litter types, namely those of Scots pine (Pinus silvestris) and Norway spruce (Picea abies) from two climatic gradients of equal extension. We have also reviewed factors determining the limit values for both species.Long-term decomposition studies were used to calculate annual mass loss in the lignin-dominated decomposition stage and relate these to mean annual temperature (MAT), mean annual precipitation (MAP) and concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), manganese (Mn) and acid unhydrolyzable residue (gravimetric lignin, AUR).There was no effect of MAT on decomposition of either needle litter type. MAP had a rate-dampening effect on decomposition of Norway spruce litter. There was a rate-stimulating effect of Mn for Norway spruce litter but not for that of Scots pine. In spite of the strong negative effect of AUR and N on decomposition of Scots pine litter there was none at all for that of Norway spruce.Limit values for decomposition were related to the litters’ initial concentrations of N, Mn and AUR and differed between litter types for locally collected, natural litter and for that from experimental litter, the latter having higher N and lower Mn concentrations than the natural litter.We conclude that the two litter types have clear differences as regards rate- regulating factors for decomposition in the late lignin-dominated stage as well as for the stable fraction and suggest two different pathways for their decomposition. This is the first time that different pathways have been suggested for decomposing litter.
21.	Bergsten, Urban (author) Manipulating overstory density and mineral soil exposure for optimal natural regeneration of Scots pine 2023 In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 539 Journal article (peer-reviewed)abstract In northern boreal region the growth of forests is slow, and yield and profit are low, which is why low refor-estation costs are important for profitable forestry. If natural regeneration is successful, expensive artificial forest regeneration (planting or direct seeding) can be avoided. In this study, we look at the impact of overstory density and site preparation on natural regeneration and seedling growth of Scots pine. Study stands were established in different parts of Northern Finland and in each stand following treatments: 50, 150 and 250 trees ha-1 or unthinned control, where the stand density was >= 250 trees ha-1, were randomly allocated to experimental plots. In addition, site preparation (disc trenching, 4000-5000 m ha-1) was carried out on two experimental plots in which tree density was either 50 or 150 trees ha-1. In the experimental stands seedling number, age and growth were monitored for 11 years. Monitoring revealed that the number of seedlings increased with decreasing tree density. Average seedling height growth was very low or even non-existent in the unthinned control and in the densest (250 trees ha-1) treatment, but increased when the density of trees decreased. The highest seedling number and the highest growth were achieved when the tree density was 50 trees ha-1 and the soil was prepared to expose mineral soil. Achieving e.g. 2000 seedlings ha-1, would need about 40% exposition of mineral soil. The required low tree density implies that not only seed supply from seed trees and site preparation is important for regeneration success in northern boreal Scots pine forests but also the reduction of competition by mature trees.
22.	Bishop, Kevin (author) Forest water-use efficiency: Effects of climate change and management on the coupling of carbon and water processes 2023 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 534 Research review (peer-reviewed)abstract Forests are essential in regulating global carbon and water cycles and are critical in mitigating climate change. Water-use efficiency, defined by the ratio of plant productivity per unit water use, is widely used to quantify the interactions between forest carbon and water cycles and could be potentially used to manage the carbon and water tradeoffs of forests under different environmental conditions. This paper reviews the literature on how biophysical variables and management practices affect forest water-use efficiency. We found that water-use ef-ficiency varies greatly with forest type, species, age, environmental conditions, and forest management practices. Climatic stresses (e.g., drought and heatwave) often pose negative effects on forest instantaneous water-use ef-ficiency (WUEins), particularly over a short term. Unexpectedly, plantations and natural forests have no statistical differences in WUEins. In addition, WUEins can be effectively improved by forest thinning. These results have important implications for managing the tradeoffs between carbon sequestration and water yield of forests. Finally, four important knowledge gaps, including species-specific water-use efficiency, long-term forest water -use efficiency dynamics, water-use efficiency responses to forest management, and the integrated effects of human and natural disturbances on plantation water-use efficiency are identified and discussed.
23.	Bishop, Kevin, et al. (author) The effects of forest management on water quality 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 522 Research review (peer-reviewed)abstract Water quality is generally high in watercourses draining forested areas. However, forest management can lead to detrimental effects on water quality and the aquatic environment. Key concerns include diffuse pollution, carbon transport and harmful effects on freshwater ecology.Here, we undertake a review of the effects of a range of forestry activities including cultivation and site preparation, fertilisation and harvesting on water quality.We attempt to summarise the literature across a wide geographical area focusing on empirical studies. Studies report a wide range of water quality impacts after forest operations including sediment delivery, nutrient losses, carbon transport, metal and base cation releases, and changes to acidity and temperature. Spatial and temporal resolution is an important consideration. Changes in water quality at the local scale are often not seen at the catchment level and the effects of operations may be manifest many years after the work was carried out, highlighting the importance of monitoring at an appropriate spatial and temporal scale. The development of best management practices (BMPs) such as the use of buffers, low impact techniques and phased felling have led to significant changes in operational activity, reducing and, in some cases, preventing impacts on water quality. We highlight some of the most effective techniques that can protect water quality from cultivation, drainage, fertiliser and harvesting operations.We also take a forward look to technological, methodological and climatic developments that may alter forest management effects on water quality.
24.	Blasko, Robert, et al. (author) Impacts of tree species identity and species mixing on ecosystem carbon and nitrogen stocks in a boreal forest 2020 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 458 Journal article (peer-reviewed)abstract Forest management practices, such as selection or mixing of particular tree species, may enhance forests' carbon (C) sinks and resilience against climate change. While a majority of research on this subject has focused on aboveground production, far less is known about how these management decisions impact belowground C storage, as well as the C and nitrogen (N) stocks of the whole ecosystem. We used a well-replicated 60-year-old experiment in boreal Sweden comparing monocultures and a mixture of the two dominant coniferous species: Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris (L.), set up at a site that was assessed as equally suitable for the growth of either species. Our aim was to evaluate the species identity and species mixing effects on ecosystem C and N stocks. We measured total standing volume, aboveground tree biomass, fine-root biomass, C and N pools in tree biomass and soil, litterfall inputs, and soil CO2 emissions. Our results show major differences in C allocation and growth patterns between spruce and pine. We found almost twice as high total standing volume and litterfall inputs in the pine stands than in the spruce stands. Higher proportion and amount of needle biomass resulted in larger amounts of N retained in the canopy and smaller accumulation of C and N in the humus in the spruce compared to pine stands. The C sinks in aboveground tree biomass and soil were larger in the pine compared to spruce stands at this site. In addition, a significantly higher soil CO2 efflux rate and fineroot biomass in the spruce compared to pine stands suggested greater tree internal allocation of C belowground to roots and ectomycorrhizal fungi in response to stronger N limitation. We found no significant mixing effect in the mixed stands, given the levels of the measured variables did not exceed levels of the most productive monoculture, with an exception of higher SOC stocks in the deeper (10-20 cm) mineral soil layer in the mixed stands. Our results do not support the idea of higher productivity and C sinks of forest mixtures compared to the best performing monoculture on the given site suggesting that these tree species are not complementary from a forest management perspective. However, in many cases the mixed stands performed equally well as the best monoculture, indicating that management for multi-species stands may not result in any loss in C uptake and storage.
25.	Blomquist, Mimmi, et al. (author) Size matters but is big always better? Effectiveness of urea and Phlebiopsis gigantea as treatment against Heterobasidion on Picea abies stumps of variable size 2020 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 462 Journal article (peer-reviewed)abstract Heterobasidion is a severe threat to coniferous forests in the northern hemisphere. Accurate forest management is needed to safeguard the economic values at stake. In this paper we investigate the efficacy of stump treatment with urea and Phlebiopsis gigantea as control treatment in Norway spruce against airborne Heterobasidion infections. The aim of this study was to examine the infection frequency, i.e. frequency of stumps infected by airborne spores, and efficacy of the stump treatments after performing precommercial thinning and final felling, representing highly variable stump diameters. Today treatment after these cuttings are not standard practice across the world.From a total of 27 Norway spruce stands in the southern and mid-regions of Sweden, five precommercial thinning stands and five final felling stands with infection frequencies higher than an economical threshold for treatment, 20%, were selected. In these stands, the efficacy of stump treatment using urea and P. gigantea against Heterobasidion spp. was assessed on stumps of variable diameter. Wooden discs from stumps were analyzed for airborne infections of Heterobasidion spp. 7-8 weeks after treatment. To evaluate the efficacy of treatments, we used the following three different measurements; infection frequency (proportion of infected stumps), relative infected stump area and number of Heterobasidion colonies per square dm, which were tested using three different statistical models each represented by an efficacy value. Overall, untreated stumps were infected to a higher extent than treated stumps, and most infections were found in untreated stumps from final fellings. Treatment with P. gigantea was more efficient for larger sized stumps than small. In precommercial thinnings, urea performed better and had higher mean efficacy values (92-94%) compared to P. gigantea (59%-72%). In final fellings there were no significant differences between the treatments, both had high efficacy values (urea 95.5-99.8% vs P. gigantea 90-98%).Our findings point at the need for accurate stump treatment after precommercial thinning and final felling, when infection rates are likely to be high. Urea seems to be more effective than the biological control agent P. gigantea in controlling Heterobasidion infections in stumps created in precommercial thinnings. We therefore recommend to use urea in precommercial thinnings if possible. In final fellings either urea or P. gigantea can be used.
26.	Blomquist, Mimmi, et al. (author) The potential of biological control against Heterobasidion root rot is not realized in practical forestry 2023 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 531 Journal article (peer-reviewed)abstract For about 25 years, forest managers in Sweden have been treating stumps following harvesting with Phlebiopsis gigantea, retailed as Rotstop (R) S gel, against spore infections of Heterobasidion, which cause root rot in order to minimize losses in timber production. However, not all forest managers trust the efficacy of stump treatment and this fact has hindered widespread adoption of stump treatment using P. gigantea. In this study, we evaluated stump treatment in the field during commercial thinning operations across 15 sites, by assessing the degree of stump coverage and subsequent infection levels in stump discs. In total, 45 % of all stumps were infected with Heterobasidion spp.. Nineteen percent of all stumps were considered to have full (100 %) coverage by Rotstop (R) S but contractors failed to achieve the manufacturers stipulated minimum coverage (85 %) in approximately 1/3 of all stumps. Using PCR, we could only detect the presence of P. gigantea in 73 % of the tested stumps. Large variation occurred between stump coverage and the recovery of P. gigantea in wood chip samples collected from stump discs across sites. In the worst case, we detected P. gigantea in only three out of ten treated stumps at one site. Despite this discrepancy we saw a clear reduction of the size of Heterobasidion infections on stumps where stump treatment coverage was more than 85 % of the stump surface.Our results suggest that forest operators in Sweden repeatedly fail to either apply a spore solution of P. gigantea or cover enough of the stumps to provide the desired protection. The outcome of such sub-standard application, could further undermine the usage of biological control agents in forestry and limit any potential control against Heterobasidion spp..
27.	Bohlin, Inka, et al. (author) Predicting bilberry and cowberry yields using airborne laser scanning and other auxiliary data combined with National Forest Inventory field plot data 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 502 Journal article (peer-reviewed)abstract The increasing availability of wall-to-wall remote sensing datasets in combination with accurate field data enables the mapping of different ecosystem services more accurately and over larger areas than before. The provision of wild berries is an essential ecosystem service, and berries are the most used non-wood forest products in Nordic countries. The aim of the study was to 1) develop general prediction models for bilberry and cowberry yield based on metrics derived from airborne laser scanning (ALS) data and other existing wall-to-wall data and 2) to identify laser-based structural features of forests that can be linked to locations of the highest berry yields. We used the indirect approach where the correlation between forest structure described by the ALS data and the berry yields are utilized. Berry data collected in the Swedish National Forest Inventory (NFI) 2007–2016 were used for training the models and ALS data from 2009 to 2014 from the national ALS campaign of Sweden. Berry yields were modelled using generalised linear mixed models (GLMMs), and forest structural differences were demonstrated in histograms of presence/absence data. The ALS-based canopy cover was an important variable both in bilberry and cowberry models. Other significant variables were ALS-based height variance, shrub cover, height above sea level, slope, soil wetness and terrain ruggedness, satellite-based species-specific volume and percentage, seasonality of temperature and precipitation and annual precipitation, inventory year, soil type and land use class. In addition, the time difference between the inventory day and the Julian day when berries were expected to be ripe showed a 1.5% decrease for bilberry and a 1.1% decrease for cowberry yield per day during the season. The highest bilberry yield was identified in forests with a canopy cover of 50% and the highest cowberry yield in forests with a canopy cover close to zero. The canopy height of 15 m reflected the highest bilberry yield, whereas a canopy height close to 0 m resulted in the highest cowberry yield. The shrub cover was close to zero both with highest bilberry and cowberry yields. This is the first study combining ALS metrics with other wall-to-wall variables and NFI field data to model bilberry and cowberry yields. Prediction models can be used to produce maps showing the most potential locations for berry picking. Further, the models may, in the future, be imported into forest planning systems to obtain stand-level prognoses of berry yield development under different forest management strategies.
28.	Brodde, Laura, et al. (author) Diplodia sapinea as a contributing factor in the crown dieback of Scots pine (Pinus sylvestris) after a severe drought 2023 In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 549 Journal article (peer-reviewed)abstract The frequency and impact of drought on global ecosystems have increased within the last century, while drought has affected tree health in many regions. Diplodia sapinea is a widespread, opportunistic pathogen infecting most conifers, causing Diplodia tip blight, thriving on hosts impacted by stress such as drought, heat, or mechanical wounding. In summer of 2018, a large-scale drought was recorded all over Europe. In late summer, pine trees all over Gotland showed crown dieback, where necrotic twigs and needles were found, especially in the upper part of the crowns. Symptoms were consistent with a potential outbreak of D. sapinea. Effects of the combination of drought and Diplodia tip blight on mortality or recovery of Scots pine in Nordic conditions are unknown. This study confirmed the presence and potential contribution of D. sapinea in the observed damages of Scots pine. Shoot blight and drought led to crown defoliation which was observed one year post-drought, while trees showed a clear recovery of newly grown shoots within the second year. Severely affected pines (>70% of the upper third of the crown with shoot blight) showed increased mortality. Recovery of the surviving trees was independent of previous dieback levels. Diplodia sapinea was most abundant in twigs with shoot blight of the symptomatic trees compared to healthy-looking twigs from the same trees and asymptomatic trees in affected and healthy pine stands. Sampling on affected and healthy sites showed possible endophytic infections with low abundance within healthy-looking twigs. Spore deposition of D. sapinea was monitored on healthy and affected sites for two consecutive years after crown damages occurred to confirm the presence of the opportunistic pathogen in the affected region. Spore deposition was observed during all seasons and correlated with high precipitation during sampling. Our observations provide insights into the emergence of Diplodia tip blight in the Northern countries and underline the potential impact of D. sapinea on tree health in the course of a changing climate.
29.	Burrows, Ryan M., et al. (author) Interactive effects of light and nutrients on stream algal growth modified by forest management in boreal landscapes 2021 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 492 Journal article (peer-reviewed)abstract Boreal forests account for 30% of the world's total forest cover and in many places are subject to intensive forest management, which often involves complete removal of overstory vegetation by clear-cutting. However, we still do not fully understand how forest management affects aquatic ecosystems in these landscapes. Here we asked how forest management-induced changes in environmental conditions, such as incident light and nutrient availability, affect benthic algal growth and nutrient limitation in boreal headwater streams of northern Sweden. We answered this question using a combination of correlative and experimental approaches across a range of forested streams spanning a gradient of site (e.g. canopy openness and water chemistry) and catchment-level (e.g. age of forest regrowth) parameters, with variation among the study streams influenced by different forest management histories and underlying natural variation. We found that benthic algal growth in these forested streams was largely driven by local interactions between dissolved inorganic nitrogen (N) availability and incident light reaching benthic surfaces. Greater water temperature and shallower depths were also associated with greater algal growth. Although high dissolved organic carbon (DOC) concentrations often play a role in reducing light availability to autotrophs in boreal aquatic systems, it was not an important predictor of algal growth in small forested streams despite a large DOC concentration gradient (5 – 32 mg/L). Results from experimental nutrient additions supported the role of N as a key limiting nutrient, but also revealed both spatial and seasonal factors that modulate the effects of altered nutrient availability. Overall, our results suggest that differences in how light regimes and nutrient loading respond to forest management generate small-scale variation in the controls over stream primary productivity, which likely shift in relative importance at the time scale of a forest rotation (60 to 100 years).
30.	Böhlenius, Henrik, et al. (author) Monitoring and control of forest seedling quality in Europe 2023 In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 546 Journal article (peer-reviewed)abstract The relationship between the quality of forest seedlings and their outplanting survival and growth has long been recognized. Various attributes have been proposed to measure the quality of planted seedlings in forest regeneration projects, ranging from simple morphological traits to more complex physiological and performance attributes, or a combination thereof. However, the utility and meaning of seedling quality attributes can differ significantly among regions, nursery practices, site planting conditions, species and the establishment purpose. Here, forest scientists compiled information using a common agreed questionnaire to provide a review of current practices, experiences, legislation and standards for seedling quality across 23 European countries.Large differences exist in measuring seedling quality across countries. The control of the origin of seed and vegetative material (genetic component of plant quality), and control of pests and diseases are common practices in all countries. Morphological attributes are widely used and mandatory in most cases. However, physiological attributes are hardly used at the operative level and mainly concentrated to Fennoscandia. Quality control legislation and seedling quality standards are less strict in northern European countries where seedling production is high, and quality control relies more on the agreements between producers and local plant material users. In contrast, quality standards are stricter in Southern Europe, especially in the Mediterranean countries.The control of seedling quality based on plantation and reforestation success is uncommon and depends on the conditions of the planting site, the traditional practices and the financial support provided by each country. Overall, European countries do not apply the "target seedling concept" for seedling production except for seed origin. Seedling production in many countries is still driven by traditional "know-how" and much less by scientific knowledge progress, which is not adequately disseminated and transferred to the end-users.Our review highlights the need for greater harmonization of seedling quality practices across Europe and the increased dissemination of scientific knowledge to improve seedling quality in forest regeneration activities.
31.	Castaño Soler, Carles (author) How does forest management affect fungal diversity and community composition? Current knowledge and future perspectives for the conservation of forest fungi 2020 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 457 Research review (peer-reviewed)abstract The influence of forest management on fungal diversity and community composition has been the subject of a wide number of studies over the last two decades. However, the difficulty of studying the complex kingdom of fungi under real forest conditions has led to rather scattered scientific knowledge. Here, we provide the current state of knowledge suggesting future research directions regarding (i) stand structure attributes (age, tree cover, stand density, tree species composition), (ii) management history (managed vs unmanaged), (iii) silvicultural treatments (thinning, clearcutting, shelterwood methods, selective cutting) and (iv) other anthropogenic disturbances (mushroom picking, salvage logging, prescribed burning, fertilization) affecting fungal diversity and community composition. The reviewed studies reported a positive correlation between fungal diversity and stand structure variables such as canopy cover, basal area of the stand and tree species diversity, particularly for mycorrhizal species. Abundance and diversity in size, tree species and decomposition stage of deadwood are reported as positively related to richness of wood-inhabiting fungi. The main findings about the effects of silvicultural practices suggest that the higher is the management intensity the lower is the diversity of ectomycorrhizal and wood-inhabiting species, at least in the short term. We have therefore reported those silvicultural practices which may reduce trade-offs between timber harvesting and fungal diversity conservation. Indeed, fungal diversity can be conserved in managed forests if (i) low impact logging operations are performed; (ii) stand structural complexity and late-successional forest characteristics are enhanced; (iii) deadwood amount and diversity is promoted, (iv) landscape heterogeneity and connectivity is improved or maintained.
32.	Castaño Soler, Carles (author) The influence of forest surroundings on the soil fungal community of black truffle (Tuber melanosporum) plantations 2020 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 469 Journal article (peer-reviewed)abstract Black truffles are a highly valued non-wood forest product. The success of truffle plantations is raising the interest to establish orchards within forest settings. One main concern is that the forest may act as a source of ectomycorrhizal fungi that could displace Tuber melanosporum in plantations and impair truffle production. We studied the effects of host tree distance to the surrounding forest on T. melanosporum development and on the root-associated fungal community. Our research was carried out in a 5-year old holm oak (Quercus ilex) plantation established in an abandoned pasture surrounded by a Q. ilex forest in the Pyrenees. The spatial distribution of different fungal guilds as well as of T. melanosporum mycelium quantity and mating types frequency was correlated with the distance to the forest and the diameter of the trees. We found a higher relative abundance of non-T. melanosporum EcM fungi associated with the trees closer to the forest. Larger root collar diameter trees had greater biomass of T. melanosporum mycelium and whose fungal community was less affected by the distance to the forest. No association between the biomass of T. melanosporum mycelium in the soil and the distance to the forest or the abundance of non-T. melanosporum EcM fungi were observed. Our results indicate that T. melanosporum inoculated oaks planted in areas surrounded by forests may be colonised by other ectomycorrhizal species, and develop a distinct microbial community from those usually established in agricultural lands. Further investigations should be carried out to determine whether a different fungal community may affect truffle production in the future, but to date, truffle mycelium does not seem to be impaired.
33.	Chellaiah, Darshanaa, et al. (author) Are riparian buffers surrounding forestry-impacted streams sufficient to meet key ecological objectives? A Swedish case study 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 499 Journal article (peer-reviewed)abstract In many national guidelines and policies regarding protection of freshwater systems from stressors associated with forestry, riparian buffer width is a commonly prescribed strategy, typically with no other refinements of protection measures. In Sweden, the Strategic Management Objectives (SMOs) were developed to ensure that riparian buffers that are left after harvesting sustain important ecosystem attributes in aquatic systems, referred to as objectives, namely shading, biodiversity, reduction of sedimentation, and provision of deadwood and food. However, little specification is given on threshold targets or how to manage riparian zones to effectively provide these objectives. In this paper, we evaluated whether existing riparian buffers of different widths along small, recently harvested (<8 years) streams were able to provide proxies of these targeted objectives, and further compared harvested streams to counterparts situated in mature unharvested production forests (reference) in northern and southern Sweden. The influence of buffer width varied with objective and geographic location. In both regions, canopy cover (proxy for shading) increased with riparian width, and riparian deadwood was highest in no buffer sites. Organic matter (OM; proxy for food) was highest in the northern no buffer streams, while in the south OM increased with buffer width. All other parameters tested had no relationship to buffer width. These differing responses even in streams subjected to similar land-use and management within a close vicinity and region, suggest that the contemporary strategy of prescribing fixed buffer widths and/or stating objectives without defined guidelines for what constitutes an effective riparian buffer is insufficient given the large variability of stream ecosystems across small spatial scales. More comprehensive consideration synergistically accounting for site-specificity and land mosaic planning are needed to develop functionally effective buffers that can mitigate forestry impacts on stream ecosystems.
34.	Cleary, Michelle, et al. (author) The increasing threat to European forests from the invasive foliar pine pathogen, Lecanosticta acicola 2023 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 536 Journal article (peer-reviewed)abstract European forests are threatened by increasing numbers of invasive pests and pathogens. Over the past century, Lecanosticta acicola, a foliar pathogen predominantly of Pinus spp., has expanded its range globally, and is increasing in impact. Lecanosticta acicola causes brown spot needle blight, resulting in premature defoliation, reduced growth, and mortality in some hosts. Originating from southern regions of North American, it devastated forests in the USA's southern states in the early twentieth century, and in 1942 was discovered in Spain.Derived from Euphresco project 'Brownspotrisk,' this study aimed to establish the current distribution of Lecanosticta species, and assess the risks of L. acicola to European forests. Pathogen reports from the literature, and new/ unpublished survey data were combined into an open-access geo-database (http://www.portaloff orestpathology.com), and used to visualise the pathogen's range, infer its climatic tolerance, and update its host range. Lecanosticta species have now been recorded in 44 countries, mostly in the northern hemisphere. The type species, L. acicola, has increased its range in recent years, and is present in 24 out of the 26 European countries where data were available. Other species of Lecanosticta are largely restricted to Mexico and Central America, and recently Colombia.The geo-database records demonstrate that L. acicola tolerates a wide range of climates across the northern hemisphere, and indicate its potential to colonise Pinus spp. forests across large swathes of the Europe. Pre-liminary analyses suggest L. acicola could affect 62% of global Pinus species area by the end of this century, under climate change predictions.Although its host range appears slightly narrower than the similar Dothistroma species, Lecanosticta species were recorded on 70 host taxa, mostly Pinus spp., but including, Cedrus and Picea spp. Twenty-three, including species of critical ecological, environmental and economic significance in Europe, are highly susceptible to L. acicola, suffering heavy defoliation and sometimes mortality. Variation in apparent susceptibility between reports could reflect variation between regions in the hosts' genetic make-up, but could also reflect the signif-icant variation in L. acicola populations and lineages found across Europe. This study served to highlight sig-nificant gaps in our understanding of the pathogen's behaviour.Lecanosticta acicola has recently been downgraded from an A1 quarantine pest to a regulated non quarantine pathogen, and is now widely distributed across Europe. With a need to consider disease management, this study also explored global BSNB strategies, and used Case Studies to summarise the tactics employed to date in Europe.
35.	Cortés-Calderón, Sofía, et al. (author) Ecosystem services supply and interactions along secondary tropical dry forests succession 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 482 Journal article (peer-reviewed)abstract Secondary forests will likely dominate future tropical landscapes, and the ecosystem services they provide to humanity will be particularly relevant. However, few empirical studies provide quantitative evidence of how the supply of ecosystem services change along secondary forest succession. The need for such information is particularly pressing for tropical dry forests because of their extensive global coverage and a high degree of disturbance. Here we examine the changes in the potential supply of ecosystem services and the interactions among them along secondary tropical dry forest succession for a site on the Mexican Pacific coast. Using data from a chronosequence of twelve sites followed over ten years, we characterized changes in five ecosystem services along a successional gradient from abandoned farmland to old-growth forests: forage, multiple forest resources, microclimate regulation, carbon storage and carbon sequestration. The long-term recovery trajectory for each service was modelled using linear and non-linear mixed models. Interactions among them were examined over different timeframes using Spearman correlations. The results showed rapid non-linear recovery of multiple forest resources provision, microclimate regulation and carbon storage within the first two decades of succession. Carbon sequestration increased slightly over time, while the supply of forage showed no clear trend. The strength of the interactions among pairs of services changed through successional time, being particularly higher in farmlands and old-growth forests. Our findings suggest that adaptive forest management practices that foster the natural regeneration of tropical dry forests are cost-effective mechanisms to recover the supply of critical ecosystem services for local actors by meeting their livelihood needs as well as those for the global community through climate change mitigation. Maintaining tropical dry forest resilience will highly depend on the maintenance of diversity in terms of species and ecosystem services.
36.	Cromsigt, Joris (author) Ungulate-adapted forestry shows promise for alleviating pine browsing damage 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 482 Journal article (peer-reviewed)abstract High densities of ungulates can increase human-wildlife conflicts. Where forestry is an important economy, intensive browsing can lead to browsing damage, resulting in volume losses, poor stand regeneration, and reduced timber quality. The forestry industry thus looks for practical, long-term measures to mitigate browsing damage. We tested the effect of two mitigation measures on moose (Alces alces) browsing behaviour and damage to Scots pine (Pinus sylvetris): (1) ungulate-adapted slash piles (i.e., palatable species only) created during felling to increase short-term food availability and (2) intensified soil scarification to increase long-term food availability (collectively, 'ungulate-adapted forestry'). Our study occurred in southern Norway where we established fixed vegetation and moose faecal pellet plots at varying distances from conventional and ungulate-adapted slash piles and scarified stands. We evaluated the effects of ungulate-adapted slash piles and intensified scarification on the density of undamaged Scots pine, moose bite diameters, browsing pressure, and moose faecal pellet density. To assess the effect of spatial scale, we created 250 m, 500 m, and 1000-m radius buffers centered on each plot. We found that ungulate-adapted logging near our plots increased the density of undamaged pines, as compared to no and conventional logging. We found that logging in general led to smaller bite diameters. We also found that plots near conventional logging had higher browsing pressure, whereas browsing pressure near ungulate-adapted logging was similar to unlogged stands. For scarification, density of undamaged pine increased when the ungulate-adapted stand aged whereas undamaged pine decreased as conventional scarification stands aged. Browsing pressure showed a response at the smallest spatial scale only for ungulate-adapted scarification. Peak moose habitat use near conventional and ungulate-adapted scarified stands differed by stand age and distance from scarification. The overall effects of ungulate-adapted forestry were most pronounced at the smallest spatial scale (250 m). Our results support 'ungulate-adapted' forestry as a practical solution to mitigate browsing damage but uncertainty in some of our estimates suggest further research on the area treated is needed.
37.	Djupstrom, Line B., et al. (author) Density of dispersal sources affects to what extent restored habitat is used: A case study on a red-listed wood-dependent beetle 2024 In: Forest Ecology and Management. - : ELSEVIER. - 0378-1127 .- 1872-7042. ; 555 Journal article (peer-reviewed)abstract When restoring habitats, an important question is whether the spatial distribution of habitat affects its contribution to biodiversity conservation. In Sweden, high-cut stumps are routinely created at forestry operations. By counting the number of exit holes of a red-listed beetle, Peltis grossa, we assessed occurrence, colonisations and extinctions per high-cut stump and beetle density per clear-cut. We found a threshold, at which the form of the relationship between density of the beetle and density of high-cut stumps per clear-cut changes abruptly. The beetle density was considerably higher where the density of high-cut stumps exceeded 4.5 per hectare. Such thresholds can be explained by colonisation-extinction processes. Observed colonisation-extinction dynamics were consistent with metapopulation theory. For instance, there was a positive relationship between colonisation rate and a connectivity measure that considered beetle abundance and distance for each high-cut stump in the surrounding area. However, the relationship disappeared when using a connectivity measure solely based on the distance of the high-cut stumps. The observed threshold implies that P. grossa benefits from aggregating the same total number of created high-cut stumps into fewer clear-cuts. This is because the total area with a density of high-cut stumps exceeding the threshold increases, and this expands the number and size of dispersal sources. Therefore, P. grossa and other species that reveal thresholds in their distribution patterns, are favoured when conservation measures are more spatially aggregated than what is resulting from current Swedish policy.
38.	Domevscik, Matej, et al. (author) Effect of drought and pine weevil damage on mechanically protected Norway spruce seedlings 2024 In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 566 Journal article (peer-reviewed)abstract Pine weevils (Hylobius abietis L.) pose a significant threat to conifer seedlings by feeding on the bark, thus damaging or killing seedlings. Historically, insecticides were used to suppress such damage, but were slowly phased out in Sweden due to environmental and health concerns. This study aimed to assess field performance of an alternative protection method: mechanical coating applied to the stem of planted Norway spruce (Picea abies) seedlings. Field trials were conducted on 14 sites in south Sweden, using four different types of mechanical protection (Cambiguard, Conniflex, Ekovax, Hylonox), standard insecticide (Merit Forest), and ambient control. Seven sites were established in the drought year of 2018 and seven more in 2019. This allowed for additional investigation of the effect of drought on seedling establishment and possible interaction with pine weevil damage. Seedlings were surveyed for survival and height after the first, second and fourth growing season. Results show drought as the main source of damage for seedlings planted in 2018, with no significant effect of insecticide or mechanical protection on survival of seedlings. However, mechanical protections performed equally well as insecticide and positively increased survival by 30 %, compared to untreated, four growing seasons after planting for seedlings planted in 2019. Seedling height was not significantly affected by planting year or any of the treatments, suggesting no adverse effects of coating application. However, a synergistic effect between pine weevil damage and drought was observed, where even low levels of pine weevil damage resulted in high mortality for seedlings planted in 2018, compared to those planted in 2019. Additionally, for seedlings planted in 2019, damage to the top of the stem did not result in significant mortality, until high damage levels were reached (40 % and above). The opposite was found for seedlings planted in a 2018 drought year, where both damage to the top and the bottom of the stem followed a linear response. In conclusion, we show that investigated mechanical protection methods can be considered a viable replacement for insecticides, but our results also highlight the importance of considering multiple environmental stressors such as drought and pest damage on seedling establishment.
39.	Drobyshev, Igor, et al. (author) Did forest fires maintain mixed oak forests in southern Scandinavia? A dendrochronological speculation 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 482 Journal article (peer-reviewed)abstract In northern Europe, a long history of human exploitation effectively eliminated legacies of natural disturbances in mixed oak forests and we currently lack understanding of the role of natural disturbance factors in affecting oak regeneration into the forest canopies. We compiled dendrochronological, observational and paleochronological data from Southern Sweden to discuss the role of forest fires in oak (Quercus spp.) dynamics. We analyzed oak age structure and its growth dynamics in six southern Swedish forests, which experienced fires between 42 and 158 years prior to our sampling. Extending our analysis over longer time frames, we studied the relationship between sediment charcoal and oak pollen in an area of south-eastern Sweden, where oak has been a common canopy species. In three of the study sites, forest fires resulted in increased oak regeneration. Although fires were generally not associated with a wave of growth releases in surviving trees, the mean basal area growth rate of oaks increased by a range of 108% to 176%, following the fires. The overall pattern indicated that historical fires in oak-dominated forests were of low severity, did not kill canopy oaks, and yet provided a window of regeneration opportunities for that species. Post-fire sprouting of oak and an increase in oak seedling densities following modern prescribed fires are consistent with this explanation. Consistent with this conclusion were significant positive correlations between charcoal concentration and the oak pollen percentage in a site in southeastern Sweden. We discuss the co-occurrence of oak and pine in the historical southern Swedish landscape, as a possible analogy to eastern North American oak-pine forests. Modern conservation policies aimed at the preservation of oak in the southern Swedish landscape should consider the use of low severity fires to maintain natural oak regeneration.
40.	Drobyshev, Igor, et al. (author) Marginal imprint of human land use upon fire history in a mire-dominated boreal landscape of the Veps Highland, North-West Russia 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 507 Journal article (peer-reviewed)abstract Dendrochronological reconstructions inform us about historical climate-fire-human interactions, providing a means to calibrate projections of future fire hazard. Most of these reconstructions, however, have been developed in landscapes with a considerable proportion of xeric sites that could potentially inflate our estimates of the historic levels of fire activity. We provide a 420-year long reconstruction of fires in a mire-dominated landscape of the Veps Nature Park, North-West Russia. The area has mostly escaped large-scale forestry operations in the past and is an example of pristine mid-boreal vegetation with a high (approximately 30% for the area studied) proportion of waterlogged areas with ombrotropic mires. The historical fire cycle was 91.4 years (90% confidence intervals, CI 66.2-137.6 years) over the 1580-1720 period, decreasing to 35.9 (CI 28.1-47.6 years) between 1730 and 1770, and then increasing again to 122.7 years (CI 91.0-178.0 years) over the 1780-2000 period. Early season fires dominated over late season fires during the reconstruction period. We documented a higher fire activity period between 1730 and 1780, resulting from the increase in early season fires. This period coincided with one of the largest multi-decadal declines in the reconstructed spring precipitation since 1600 CE, although we found no significant relationship between fire and precipitation over the whole reconstructed period. The nine largest fire years were associated with negative summer precipitation and positive summer temperature anomalies over the study region. Land-use history of the area did not appear to have an effect on historical fire dynamics. Modern (1996-2016) fire records indicate a regional fire cycle of ~ 1300 years, featuring a pronounced pattern with early (April-May) and late (July-September) season fires. The uniform fire cycle in the area since 1780, occurrence of nine largest fire years during years with spring-summer droughts, and low ignition frequencies over the last 420 years (0.005 to 0.037 ignitions per year and km2) suggest that the fire regime of the Veps Highland remained largely natural until the onset of the 20th century.
41.	Drobyshev, Igor (author) Recent decline in sugar maple (Acer saccharum Marsh.) growth extends to the northern parts of its distribution range in eastern Canada 2023 In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 545 Journal article (peer-reviewed)abstract Sugar maple (Acer saccharum Marshall) growth in the species' southern range has been declining since the 1980s, putting at risk a variety of ecosystem services that the species provides. Heatwaves, drought, frosts, acidic deposition, and insect defoliation, all reducing photosynthetic activity, have been suggested to be behind the phenomenon. Because the geographic scope of previous studies on maple growth is limited to the southern temperate biome, it is not currently understood whether the same negative trends and factors affecting growth rates apply to the species in more northern regions of its distribution range. Here we used annual ring-width data of 1675 trees from a network of 21 sites in Quebec and Ontario between 45N and 48N to reconstruct maple growth and to analyze its trends and climatic drivers since 1950 CE. We developed a retrospective tree growth index by employing a Generalized Additive Mixed Model (GAMM) that accounted for tree age and size, terrain altitude, slope, competition and mean site climatology. Our reconstruction suggested considerable geographical variations in maple growth trends, with declining growth being less pronounced in the central portion of the study region. The growth decline persisted at the time of sampling in 2019 and 2020. Maple growth negatively correlated with the summer vapour pressure deficit (VPD) during both the previous and current growth seasons. As the decline in sugar maple growth is observed at the northern limit of its distribution, climate change may not favor the expansion of sugar maples to the north. The observed decline along with increasing VPD will likely have a negative impact on the ecosystem services supported by this species and calls for management adaptation measures.
42.	Dynesius, Mats, et al. (author) Bryophyte species composition at the stand scale (1 ha) – Differences between secondary stands half a century after clear-cutting and older semi-natural boreal forests 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 428 Journal article (peer-reviewed)abstract A growing proportion of the boreal biome consists of managed even-aged secondary forest stands regenerated after clear-cutting. Many disturbance-intolerant species may not be able to recolonize or reach their original abundance in these stands before the next clear-cutting, potentially causing large-scale biodiversity losses. Boreal bryophytes (mosses and liverworts) include many species intolerant to clear-cutting, and at small spatial scales species richness and occupancy has been shown to remain changed in secondary stands half a century after logging. To assess if such persistent changes occur also at the stand scale, we listed and estimated cover of all bryophyte species in 1-ha plots, comparing 14 secondary stands originating from clear-cutting 40–60 years earlier with 14 older semi-natural stands. The large plots also made it possible to assess differences in occupancy and abundance for more bryophyte species than in previous studies. Species composition differed significantly for both mosses and liverworts, but unlike earlier studies, we could not detect any significant difference between stand types in species numbers. Thirteen species were significantly associated with semi-natural stands and the total cover of liverworts was less than half in secondary stands. Secondary stands had significantly fewer species typically occurring under shady conditions and/or mostly growing on “tree substrates” (dead wood and/or bases and stems of living trees). Ordination analysis further emphasized the importance of shade and suitable deadwood substrates; the among-plot variation in bryophyte species composition was related to amount of coarse deadwood as well as to gradients from shady spruce dominated to open pine dominated stands and from polar- to equator-facing slopes. Besides lack of suitable habitat conditions in secondary stands, dispersal limitation may have caused a colonization time lag for some species. The clear importance of stand scale habitat conditions for bryophyte species composition calls for management adaptions to facilitate life boating and/or recolonization by ensuring availability of shade, coarse decomposing logs, and specific deciduous tree species (Populus, Salix, Sorbus) in secondary stands.
43.	Ekholm, Adam, et al. (author) Long-term yield and biodiversity in stands managed with the selection system and the rotation forestry system: A qualitative review 2023 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 537 Research review (peer-reviewed)abstract There is an increasing interest in implementing Continuous Cover Forestry (CCF) as a tool to mitigate negative effects of the traditional rotation forestry system on biodiversity. However, the effects of CCF on forest growth and yield and on biodiversity is still poorly known. In this qualitative review, we compare biodiversity and longterm yield between the selection system, which is a type of CCF practiced in full-storied forests, and the traditional rotation forestry system. We specifically focus on forests dominated by Picea abies, which is a tree species of high economic relevance. Our literature search resulted in 17 publications on stand growth and yield and 21 publications on biodiversity. A majority of simulation studies found a higher long-term yield in the rotation forestry system, but it is challenging to conclude which system is the most productive. The magnitude of the difference in yield between systems, and how it varies across different environmental conditions, remains to be determined. For biodiversity, comparisons of species assemblage and individual species were only made to certain phases of the rotation cycle (recent clearcuts and middle-aged stands). Nevertheless, two aspects can be highlighted: i) the species assemblage in clearcuts differ substantially from stands managed with the selection system. Some of these effects may however be short lasting as examplified by studies on beetle assamblages showing that middle-aged rotation forestry stands become more similar to stands managed with the selection system, ii) the selection system maintains a similar species assemblage as the uncut control during the first years after cutting. In conclusion, management with the selection system may come with a loss in long-term stand yield, but much of the species assemblage is maintained after logging. We recommend future studies to specifically focus on long-term effects on biodiversity - in particular on species of conservation concern. There is also a need to establish a long-term research infrastructure to further develop the field.
44.	Ellison, David (author) Forest restoration and hydrology 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 520 Journal article (peer-reviewed)abstract Forest restoration aims to increase forest cover, structure, function, and/or species composition, and it influences hydrology through the partitioning of precipitation into evapotranspiration and streamflow. This paper provides a conceptual framework for forest restoration and hydrology, reviews the literature on forest hydrology that is relevant to forest restoration, and assesses practical forest restoration approaches, their hydrologic effects, and tradeoffs. The hydrologic effects of three types of forest are assessed: mature and old-growth forests, which often are the reference model for restoration; managed forest plantations, which dominated early efforts for forest restoration; and the early stages of native forest succession, an increasingly popular, ecologically-oriented or nature-based approach to forest restoration. This review indicates that mature and old-growth forests have high evapotranspiration and consistent water yield, provided by moderated peak discharges and sustained low flows, while water yield is low from managed forest plantations, especially during dry periods. The early stages of native forest succession may provide greater water yield and increased low flows compared with managed plantations. Inclusion of native species and natural processes in forest restoration can increase some hydrological benefits relative to other forest restoration approaches. Although forest restoration affects hydrology, few studies examine the hydrologic effects of specific forest restoration practices such as choice of species, silvicultural practices, legacies of past land use, and geographic setting. Forest managers and ecologists can play valuable roles by designing studies that explore the hydrologic effects of forest restoration approaches on time scales relevant to ecological succession and forest management under a changing climate.
45.	Ellison, David (author) Multi-Targeted payment for the balanced management of hydrological and other forest ecosystem services 2022 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 522 Journal article (peer-reviewed)abstract Societal demand for vitally important hydrological and other forest ecosystem services (FES) has been rapidly increasing due to accelerating socioeconomic development and global change. Combined with growing threats of water insecurity, complex forest-water interactions are especially challenging to address given the trade-offs among competing FES (e.g., water yield vs carbon sequestration, or biomass production vs biodiversity conservation). The concept of balanced forest ecosystem service management (BFESM) offers a strategy for optimizing the production of multiple FES to meet societal demand and ensure ecological integrity in ways that harmonize both the synergies and tradeoffs across desired FES and the differing and often conflicting needs and priorities of diverse stakeholders. Better understanding the complex and often nonlinear interactions among different FES and how these vary across spatial and temporal scales and different site contexts is critical to developing BFESM strategies. Moreover, the often sharply contrasting FES needs and priorities of different societal groups or stakeholders must be considered in conjunction with information about FES trade-offs. Policy strategies that introduce compensation mechanisms to account for the public good and non-market nature of many highly valued FES (e.g., clean and plentiful water supply, climate regulation) such as Payments for Ecosystem Services (PES), are increasingly being used to foster FES stewardship, yet transitioning from the conventional single FES towards multi-targeted PES (MTPES) approaches could greatly improve the effectiveness of PES schemes. Here, we present five guiding principles of BFESM and discuss the opportunities and challenges of designing effective MTPES policy frameworks. Building on the strengths of each, we then propose an integrated BFESM-MTPES framework for balancing the biophysical understanding of complex synergies and trade-offs across the target FES with the demands and interests of diverse stakeholders. We then discuss specific tools for developing a decision support framework that better integrates and informs strategies for managing forest-water interactions and other FES to achieve BFESM-MTPES goals based on innovative, science-based approaches. We conclude by highlighting key future research directions.
46.	Espinosa del Alba, Clara, et al. (author) Restoration strategies in boreal forests: Differing field and ground layer response to ecological restoration by burning and gap cutting 2021 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 494 Journal article (peer-reviewed)abstract The boreal biome is one of the largest in the world and its forests have been widely exploited for centuries. Consequently, large areas have suffered ecological simplification and loss of biodiversity. Under the current circumstances passive conservation measures are no longer enough and active restoration techniques need to be developed and assessed to preserve and recover the loss of biodiversity. We evaluated short- and long-term effects of two restoration methods aimed at mimicking natural disturbances on species richness, Shannon Diversity and community composition of vascular plants in the field layer and bryophytes in the ground layer. The experiment consisted of 18 forest stands in northern Sweden; each assigned to a different treatment: prescribed burning, gap cutting and untreated stands left as controls. A before-after control-impact (BACI) study design was applied and data was collected on three occasions: once prior to restoration (2010) and twice post restoration; one year (2012) and eight years after (2019). We analysed the differences in species richness and Shannon Diversity with linear mixed effect models and community composition changes with multivariate methods. Fire treatment caused an initial decline in diversity for both field and ground layer, but in the long-term, field layer surpassed the species richness and Shannon Diversity values found prior to restoration. Ground layer bryophytes species richness and Shannon Diversity remained lower than pre-treatment. Prescribed burning should, therefore, be used with caution in core areas for bryophyte diversity. Community composition in burned stands differed significantly between each time point as well as when compared to other treatments, for both layers. By contrast, we found no significant differences in diversity measures or community composition after gap cutting. The absence of effects from gap cutting suggests that minor changes in canopy cover does not affect the vegetation structure of forest stands. The organism group-specific responses, and temporal variability to restoration, highlight the importance of including more than one organism group, different restoration methodologies, and long-term studies in order to properly assess restoration outcomes at landscape level.
47.	Esseen, Per-Anders, et al. (author) Influence of canopy structure and light on the three-dimensional distribution of the iconic lichen Usnea longissima 2023 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 529 Journal article (peer-reviewed)abstract Forest canopies modify microclimates and create habitats for nonvascular epiphytes, but we need to better understand the mechanisms regulating their vertical and horizontal distributions. Here we examine how canopy structure and light environment influence the 3D distribution of Usnea longissima, the world's longest lichen, and associated with old-growth forests. We quantified forest structure, vertical profile of light (PPFD transmittance fraction), and horizontal as well as vertical distribution of the lichen in a 1 ha plot dominated by Picea abies. The forest had a multi-layered canopy with mortality driven by small-scale gap dynamics. The population size of the lichen had an approximate log-normal distribution with host trees showing strong clustering. The lichen extended up to mid-canopy and had a rather sharp upper limit. Population size increased with DBH and upper limit but did not correlate with basal area. The vertical profile of light was steeper in dead than in live trees, with the lichen occurring in a zone with low-intermediate light. The horizontal distribution was linked to the vertical distribution through short-distance asexual dispersal. The lichen's 3D distribution was shaped by various interacting functional mechanisms. Its absence from the upper canopy was mainly explained by sensitivity to high light when desiccated and limited capacity for upward migration. The population dynamics was driven by source trees hosting large populations in mid-canopy. The lichen's strong association with humid, old-growth forests is explained by narrow niche preferences and dispersal limitation, and not by slow growth. Protection of multi-layered forests with long continuity of tree cover is needed to secure substrates and suitable microclimates for development of viable lichen populations. Our study highlights that the 3D distribution of lichens in forest canopies is driven by forest dynamics, canopy structure, microclimate, and lichen functional traits.
48.	Esseen, Per-Anders, et al. (author) Long-term dynamics of the iconic old-forest lichen Usnea longissima in a protected landscape 2023 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 546 Journal article (peer-reviewed)abstract Long-term data on spatial dynamics of epiphytic lichens associated with old-growth forests are fundamental for understanding how environmental factors drive their extinction and colonization in heterogeneous landscapes. This study focuses on Usnea longissima, a flagship species for biodiversity conservation. By using a long-term data set (37 yr.) of U. longissima in old Picea abies forests in Skuleskogen National Park, Sweden, we examined changes in the number of host trees, population size (sum of thallus length), extinction, colonization, dispersal, and distribution in a protected landscape. We surveyed the lichen in 1984–1985 by applying a line transect inventory and a total population inventory and tagged 355 occupied trees with an aluminium plate buried in the ground. We repeated the survey in 2021 using a metal detector and recorded GPS-position of host trees, tree and lichen population characteristics. We also measured the structure and age (tree-ring data) of the forest to understand how disturbance history influenced lichen populations. Usnea longissima occurred on 66 of the tagged trees and we recorded 141 new host trees. The number of host trees decreased with 41.7% and the population size with 41.9%. One third of the decline was caused by deterministic extinction (treefalls) and two thirds by stochastic extinction on standing trees. The probability of stochastic extinction on live trees decreased with population size in logistic regression. The decline in the sites with largest populations (35–87% loss) was more influenced by limited colonization than extinction. Colonization was highest in humid north-facing hillslopes with multi-layered forests driven by gap dynamics. The lichen was strongly dispersal-limited, with a median effective horizontal dispersal of only 3.8 m in 37 yr., explaining its strong dependence of long continuity of forest cover. The populations were clustered and had substantial local turnover, yet with stable distribution at landscape scale. The tree-ring index, growth releases and gap recruitments indicate extensive harvesting ∼ 1860–1900, but without major disturbances during the last 70–80 yr. Instead, the decline of U. longissima was probably driven by air pollution, climate change (autumn/winter mortality and heatwaves) and denser forests. Our findings highlight that the long-term survival of this lichen may be at risk even in forests having a strong level of protection.
49.	Etzold, Sophia, et al. (author) Nitrogen deposition is the most important environmental driver of growth of pure, even-aged and managed European forests 2020 In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 458 Journal article (peer-reviewed)abstract Changing environmental conditions may substantially interact with site quality and forest stand characteristics, and impact forest growth and carbon sequestration. Understanding the impact of the various drivers of forest growth is therefore critical to predict how forest ecosystems can respond to climate change. We conducted a continental-scale analysis of recent (1995–2010) forest volume increment data (ΔVol, m3 ha−1 yr−1), obtained from ca. 100,000 coniferous and broadleaved trees in 442 even-aged, single-species stands across 23 European countries. We used multivariate statistical approaches, such as mixed effects models and structural equation modelling to investigate how European forest growth respond to changes in 11 predictors, including stand characteristics, climate conditions, air and site quality, as well as their interactions. We found that, despite the large environmental gradients encompassed by the forests examined, stand density and age were key drivers of forest growth. We further detected a positive, in some cases non-linear effect of N deposition, most pronounced for beech forests, with a tipping point at ca. 30 kg N ha−1 yr−1. With the exception of a consistent temperature signal on Norway spruce, climate-related predictors and ground-level ozone showed much less generalized relationships with ΔVol. Our results show that, together with the driving forces exerted by stand density and age, N deposition is at least as important as climate to modulate forest growth at continental scale in Europe, with a potential negative effect at sites with high N deposition.
50.	Fagerberg, Nils, 1972-, et al. (author) Prediction of knot size in uneven-sized Norway spruce stands in Sweden 2023 In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 544 Journal article (peer-reviewed)abstract The size of knots is negatively correlated with bending strength in sawn timber and it is therefore used as a quality grading criterion in national roundwood grading standards. Some standards even use the size of the largest knot as the sole estimate for individual log knottiness. The size of knots is determined by crown horizontal extension, which in turn is dependent on the impact of competing trees. Thus, with knot size models that are competition-dependent, roundwood quality due to knottiness can be simulated for different management al-ternatives. However, these types of models, calibrated on uneven-sized Norway spruce in Fennoscandia, are currently not available. Therefore, the objective of this study is to develop a competition-dependent model framework for prediction of the largest knot size per stem height section, for application within uneven-sized Norway spruce stands. Data from terrestrial laser scanning of an uneven-sized stand in southern Sweden are used to calibrate a modular prediction framework, consisting of interlinked allometric statistical models. Alternative framework sub-models are presented and the preferred model combination can be selected according to context and available input data. The flexible modular format enables further development of separate sub-components for adaptation to growing conditions not covered by the current calibration range.

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Author/Editor: Löf, Magnus (13); Holmström, Emma (12); Aldea, Jorge (8); Nilsson, Urban (7); Barbeito, Ignacio (7); Lundmark, Tomas (6); show more...; Hjältén, Joakim (6); Felton, Annika (6); Bader, Martin K.-F. (5); Nordin, Annika (5); Cromsigt, Joris (5); Appiah Mensah, Alex (5); Lindbladh, Matts (4); Näsholm, Torgny (4); Bergh, Johan (4); Widemo, Fredrik (4); Högberg, Peter (4); Egnell, Gustaf (4); Johansson, Ulf (3); Cleary, Michelle (3); Pettersson, Lars B. (3); Franzén, Markus (3); Gustafsson, Lena (3); Lindström, Åke (3); Petersson, Hans (3); Lindberg, Eva (3); Ruiz-Peinado, Ricard ... (3); del Rio, Miren (3); Pretzsch, Hans (3); Heym, Michael (3); Brazaitis, Gediminas (3); Jansons, Aris (3); Metslaid, Marek (3); Bielak, Kamil (3); Holm, Stig-Olof (3); Nothdurft, Arne (3); Sitko, Roman (3); Singh, Navinder (3); Vesterdal, Lars (3); Schlyter, Fredrik (3); Jonsson, Bengt-Gunna ... (3); Roberge, Jean-Michel (3); Johansson, Victor (3); Kuglerova, Lenka (3); Löfroth, Therese (3); Öquist, Mats (3); Marshall, John (3); Ram, Dafne (3); Caplat, Paul (3); Gundale, Michael (3); show less...

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