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1.
  • Arnebrant, Kristina, et al. (författare)
  • Effects of different fertilizer treatments on ectomycorrhizal colonization potential in 2 Scots pine forests in Sweden
  • 1992
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 1872-7042 .- 0378-1127. ; 53:1-4, s. 77-89
  • Tidskriftsartikel (refereegranskat)abstract
    • Ectomycorrhizal fungal colonization potential was studied in two low-productivity Scots pine (Pinus sylvestris L.) forests in Sweden treated with different fertilizers. Young Pinus sylvestris seedlings were used as baits for ectomycorrhizal fungi for one growing season and the total ectomycorrhizal colonization level and frequencies of different types were recorded. One of the experimental sites had been fertilized once with 600 kg nitrogen (N) ha-1, either as ammonium nitrate or urea, 13 years previously. At this site no difference in the total number of ectomycorrhizal root tips was found between the different treatments and approximately 70% of all root tips were ectomycorrhizal. The other experimental site had been continuously fertilized for 15 years with a balanced nutrient mixture, applied either daily as a solution (IF treatment), or as solid fertilizers once a year (F treatment). The IF treatment had received 1700 kg N ha-1 and the F treatment 950 kg N ha-1 until our study was conducted. At this site a significant decrease in total ectomycorrhizal infection level was found as an effect of the fertilizer treatment. In the non-fertilized plots, 70% of all root tips were ectomycorrhizal and the corresponding figure for fertilized plots was 55%. At both sites the frequency of one of the eight classified ectomycorrhizal types decreased significantly in all fertilized plots except in the urea treatment.
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2.
  • Engelmark, O., et al. (författare)
  • Ecological effects and management aspects of an exotic tree species : the case of lodgepole pine in Sweden
  • 2001
  • Ingår i: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 141:02-jan, s. 3-13
  • Tidskriftsartikel (refereegranskat)abstract
    • The North American tree Pinus contorta var, latifolia was experimentally introduced in Sweden already in the 1920s, and has been used in Swedish forestry on a large scale since the 1970s. These plantations now cover 565,000 ha, mainly in the northern area. In this paper we summarize and discuss existing ecological knowledge of this species introduction. With regard to longterm sustainability we suggest management means to minimize harmful effects of the introduction on ecosystems. These include aspects of self dispersal, pests, ecosystem and landscape structures, and also ecological processes and biodiversity. We also focus on observed and possible interactions in the ecosystems. As Pinus contorta seeds are disseminated and trees regenerated outside initial plantations, this may have future bearings on biodiversity. We suggest a strategy which takes account of the uncertainty in predicting future ecological effects. The strategy includes areal restrictions and zones without Pinus contorta, but also to set up a monitoring program. Observations of adverse effects from the plantations would then give the possibility to adjust P. contorta management.
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3.
  • Gustafsson, Petter, 1948-, et al. (författare)
  • STRUCTURE AND REGULATION OF PHOTOSYNTHESIS GENES IN PINUS-SYLVESTRIS (SCOTS PINE) AND PINUS-CONTORTA (LODGEPOLE PINE)
  • 1991
  • Ingår i: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 43:3-4, s. 287-300
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure and regulation of one nuclear and one chloroplast gene was studied in Pinus sylvestris (Scots pine) and Pinus contorta (lodgepole pine). cDNA copies of the nuclear located cab genes of Pinus sylvestris, coding for the light-harvesting chlorophyll a/b-binding proteins of photosystem II (LHC-II), were cloned. cab-II genes coding for both types of LHC-II polypeptides, Types 1 and 2, were found. An analysis of the DNA sequences of several different cab-II cDNAs shows that they have a high bias for the nucleotides G and C at the third base positions of the codons, making them more similar to monocot than to dicot genes. Two of the three genes were found to be located within CpG islands. The cab-II genes were found to be expressed in dark-grown seedlings in contrast to what has been found for most angiosperms. The chloroplast genomes of conifers were shown to lack the inverted repeat organization normally found in higher plants, mosses and green algae. The psbA gene, located in the chloroplast genome and coding for the D1 polypeptide in the reaction center of photosystem II, was found to be tandemly duplicated in P. contorta. Cloning and sequence analysis of the two psbA genes and the surrounding regions showed that the duplicated segment is 1.97 kb long and that it ends 19 bp downstream from the psbA stop codon. The corresponding locus of P. sylvestris, which lacks the duplication, was cloned and characterized. A comparison with P. contorta indicates how the duplication/insertion event has occurred. A comparison of third codon position between P. contorta psbA and that of other plants indicated an almost equidistant evolutionary relationship between P. contorta, spinach (or barley) and Marchantia polymorpha.
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4.
  • Hazell, P, et al. (författare)
  • Presence and abundance of four epiphytic bryophytes in relation to density of aspen (Populus tremula) and other stand characteristics
  • 1998
  • Ingår i: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 107:1-3, s. 147-158
  • Tidskriftsartikel (refereegranskat)abstract
    • The influence of the local density of aspen on the presence and abundance of four epiphytic bryophytes was investigated in four mixed forest stands in Central Sweden, each about 30 ha and aged 70-120 yr. Cover of the bryophytes Nyholmiella obtusifolia, Orthotrichum speciosum, Pylaisia polyantha and Radula complanata (the four most frequent aspen-specific epiphytic bryophytes in this region) was recorded on the bark of 155 systematically sampled aspen stems. In circular plots with 10 m radius surrounding each sampled aspen, information on ground vegetation, soil moisture and stand density was collected. In these plots, and also in plots with 5 m and 20 m radius, stem number and diameters of aspen trees were recorded together with an observation of the presence/absence of the four bryophytes. There was no general and consistent relation between aspen density and presence or abundance of the studied bryophytes. Site, host aspen diameter and forest stand structures were more important for the bryophytes. The site factor explained more of the variation than any of the studied variables. All species except N. obtusifolia were favoured by a large diameter of the host tree, and the density of the surrounding forest stand had a positive effect on the cover of Pyl. polyantha and R. complanata. The practical implications of the results are discussed.
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5.
  • Akselsson, Cecilia, et al. (författare)
  • Critical biomass harvesting - Applying a new concept for Swedish forest soils
  • 2018
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 409, s. 67-73
  • Tidskriftsartikel (refereegranskat)abstract
    • The contribution of forest harvesting to base cation losses and soil acidification has increased in recent years in Sweden, as the demand for bioenergy has increased and the sulphur deposition has decreased. Thus, new policy tools are required to evaluate the progress of the recovery from acidification, and as a basis for forest management recommendations. In this study we introduce and test a concept, Critical biomass harvesting. The concept builds on the concept Critical loads, which has been used world-wide for several decades as a bridge between science and policies related to transboundary air pollution and acidification. The basis for the concept is an acidity mass balance, with sources and sinks of acidity. A critical limit defines the highest acceptable acidification status of the water leaving the root zone. Based on the critical limit, the highest allowed biomass harvesting can be calculated, keeping the other parameters constant. In this study the critical limit was set to ANC (Acid Neutralizing Capacity) = 0. Nitrogen was assumed to be affecting acidity only if it leaches from the root zone. The critical biomass harvesting was calculated for almost 12000 National Forest Inventory sites with spruce and pine forest, using the best available data on deposition, weathering and nitrogen leaching. The exceedance of critical biomass harvesting was calculated as the difference between the estimated harvest losses and the critical biomass harvesting. The results were presented as median values in merged catchments in a catchment database, with totally 2079 merged catchments in Sweden. According to the calculations, critical biomass harvesting was exceeded in the southern half of Sweden already at stem harvesting in spruce forests. Whole-tree harvesting expanded the exceedance area, and increased the exceedance levels in southern Sweden. The exceedance in pine forest was lower and affected smaller areas. It was concluded that the concept of critical biomass harvesting can be successfully applied on the same database that has been used for critical load calculations in Sweden, using basically the same approach as has been extensively applied, evaluated and discussed in a critical load context. The results from the calculations in Sweden indicate that whole-tree harvesting, without wood ash recycling, can be expected to further slow down recovery, especially in the most acidified parts of the country, in the southwest.
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6.
  • Akselsson, Cecilia, et al. (författare)
  • Nutrient and carbon budgets in forest soils as decision support in sustainable forest management
  • 2007
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 1872-7042 .- 0378-1127. ; 238:1-3, s. 167-174
  • Tidskriftsartikel (refereegranskat)abstract
    • Knowledge about the nutrient and carbon budgets in forest soils is essential to maintain sustainable production, but also in several environmental issues, such as acidification, eutrophication and climate change. The budgets are strongly influenced by atmospheric deposition as well as forestry. This study demonstrates how budget calculations for nitrogen (N), carbon (C) and base cations (BC) can be used as a basis for policy decisions on a regional level in Sweden. The study was based on existing nutrient and C budget calculations on a regional scale in Sweden. The nutrient budgets have been calculated for each square in a national 5 km x 5 km net by means of mass balances including deposition, harvest losses, leaching, weathering (BC) and fixation (N). Scenarios with different deposition and forestry intensity have been run and illustrated on maps. A simplified C budget has been estimated by multiplying the N accumulation with the C/N ratio in the organic layer, based on the assumption that the C/N ratio in the accumulating organic matter is equal to the ratio in the soil organic matter pool. The budget approaches differ from earlier budget studies since they involve regional high resolution data, combine deposition and forestry scenarios and integrate different environmental aspects. The results indicate that whole-tree harvesting will cause net losses of N and base cations in large parts of Sweden, which means that forestry will not be sustainable unless nutrients are added through compensatory fertilization. To prevent net losses following whole-tree harvesting, compensatory fertilization of base cations would be required in almost the whole country, whereas N fertilization would be needed mainly in the northern half of Sweden. The results further suggest that today's recommendations for N fertilization should be revised in southern Sweden by applying the southwest-northeast gradient of the N budget calculations. The C and N accumulation calculations show that C sequestration in Swedish forest soils is not an effective or sustainable way to decrease the net carbon dioxide emissions. A better way is to apply whole-tree harvesting and use the branches, tops and needles as biofuel replacing fossil fuels. This could reduce the present carbon dioxide emissions from fossil fuels substantially. The study shows that high resolution budget calculations that illuminate different aspects of sustainability in forest ecosystems are important tools for identifying problem areas, investigating different alternatives through scenario analyses and developing new policies. Cooperation with stakeholders increases the probability that the research will be useful. (c) 2006 Elsevier B.V. All fights reserved.
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7.
  • Akselsson, Cecilia, et al. (författare)
  • Regional mapping of nitrogen leaching from clearcuts in southern Sweden
  • 2004
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 1872-7042 .- 0378-1127. ; 202:1-3, s. 235-243
  • Tidskriftsartikel (refereegranskat)abstract
    • Increased nitrogen leaching from forest soils is a potential environmental problem in areas with high nitrogen deposition. In Sweden nitrogen is strongly retained in the forests, and high nitrogen leaching is not common from growing forests. However, soil water measurements on clearcuts along a deposition gradient in Sweden showed a positive correlation between increased concentration of inorganic nitrogen and the deposition. In this paper nitrogen leaching from clearcuts in southern Sweden was modelled on a municipality level, based on this correlation. Modelled deposition was used as input data together with runoff and forest statistics, e.g. clearcut areas from the municipalities. The calculations showed a clear leaching gradient on clearcuts from west (up to 35 kg ha(-1) year(-1)) to east (less than 5 kg ha(-1) year(-1)). This was in accordance with the deposition gradient. The leaching gradient was reinforced by the higher runoff in the west. The results indicated that, in southwestern Sweden with the highest nitrogen deposition, up to 30-40% of the total leaching of nitrogen from forest soils originates from clearcuts. These high amounts of nitrogen leaching from clearcuts in southwestern Sweden have not been included in previous national calculations of nitrogen leaching to surface waters. The contribution of nitrogen from clearcuts to the total nitrogen leaching from all land use classes varies between 1% in the southernmost part where agricultural land is highly dominating, to 11% in the forested central part of southern Sweden. (C) 2004 Elsevier B.V. All rights reserved.
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8.
  • Albaugh, Timothy J, et al. (författare)
  • Do biological expansion factors adequately estimate stand-scale aboveground component biomass for Norway spruce?
  • 2009
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 258:12, s. 2628-2637
  • Tidskriftsartikel (refereegranskat)abstract
    • We developed site specific component (stem, branch, and foliage) biomass functions for two sites in Sweden (64° and 57° North latitude) where four treatments (control, irrigated, fertilized, irrigated plus fertilized) were applied in the existing Norway spruce stands (Picea abies L. Karst.) for 17 years. We tested for site effects in the component biomass equations and compared site specific biomass estimates to those generated using published functions ( Lehtonen et al., 2004 and Wirth et al., 2004). Site effects were significant for all components and indicated it would be unlikely to generate equations that well estimate biomass across the Norway spruce range as implicitly indicated in our efforts to generate species biomass expansion factors. We rejected our hypothesis that the published functions would well estimate component biomass for control plots. The published functions did not compare well with site specific component biomass estimates for the other treatments; both published functions well estimated stem mass up to stem mass of 25 Mg ha−1, beyond which stem mass was overestimated, and both functions over and under estimated foliage and branch mass. Nor did the published functions compare well with each other, with stem, foliage and branch mass estimate differences of 12, 55, −8% and 11, 77, and 59% for the southern and northern sites, respectively, when averaged over all treatments and years. Adding limiting resources through fertilization increased stem, foliage and branch mass 57, 11, 18% and 120, 37, and 69% at the southern and northern sites, respectively, which would increase carbon sequestration and available stemwood and bioenergy materials. We recommend that more effort is spent in process-based modeling to better predict mass at a given site and ultimately provide better estimates of carbon sequestration and bioenergy material production changes.
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9.
  • Aldea, Jorge (författare)
  • Competition and climate influence in the basal area increment models for Mediterranean mixed forests
  • 2022
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 506
  • Tidskriftsartikel (refereegranskat)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.
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10.
  • Aldea, Jorge (författare)
  • Differences in stem radial variation between Pinus pinaster Ait. and Quercus pyrenaica Willd. may release inter-specific competition
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 481
  • Tidskriftsartikel (refereegranskat)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.
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11.
  • Aldea, Jorge, et al. (författare)
  • Evaluation of growth models for mixed forests used in Swedish and Finnish decision support systems
  • 2023
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 529
  • Tidskriftsartikel (refereegranskat)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.
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12.
  • Aldea, Jorge (författare)
  • 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
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 461
  • Tidskriftsartikel (refereegranskat)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.
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13.
  • Aldea, Jorge, et al. (författare)
  • Species stratification and weather conditions drive tree growth in Scots pine and Norway spruce mixed stands along Europe
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 481
  • Tidskriftsartikel (refereegranskat)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.
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14.
  • Aldea, Jorge, et al. (författare)
  • Tree species growth response to climate in mixtures of Quercus robur/ Quercus petraea and Pinus sylvestris across Europe- a dynamic, sensitive equilibrium
  • 2023
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 530
  • Tidskriftsartikel (refereegranskat)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.
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15.
  • Amelia, Tudoran, et al. (författare)
  • Using associational effects of European beech on Norway spruce to mitigate damage by a forest regeneration pest, the pine weevil Hylobius abietis
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 486
  • Tidskriftsartikel (refereegranskat)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.
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16.
  • Andersson, Jon, et al. (författare)
  • Defining stump harvesting retention targets required to maintain saproxylic beetle biodiversity
  • 2016
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 371, s. 90-102
  • Tidskriftsartikel (refereegranskat)abstract
    • Stumps comprise up to 80% of the residual deadwood following clear cutting and are a significant source of biomass for bioenergetic applications. However, stump harvesting may pose significant conservation risks for saproxylic organisms that occur in residual deadwood. To define retention targets for stump harvesting operations, we compared abundance and species richness of saproxylic beetles within individual stumps as well as species accumulation curves in replicated pairs of clear cuts with and without stump harvesting in northern Sweden. Using 20 stands, we sampled 1049 stumps using eclector traps and collected 9821 beetles representing 253 species with known saproxylic biology. Nineteen of these species were red-listed in Sweden. We hypothesized that individual stumps left following stump harvesting would contain higher densities and species richness than in clear cuts without stump removal due to crowding of beetles into increasingly limited habitats. However, we found no difference in density or richness within individual stumps between control clear cuts and stumped stands. We also compared species richness between control and stumped treatments using rarefaction within individual stands and across all stands and found no difference. As with density and richness, beetle composition at the stand-level did not differ between control and stumped stands. Thus, the density of surrounding stumps within a stand had very little effect on beetle assemblages in residual stumps. We estimated the effect of stump harvest on species richness at the stand level by combining all samples and extrapolating a rarefaction curve derived from the landscape-level species pool to an accumulated sample volume of 48 m(3) which corresponds to the total volume of stumps on average-sized clear cuts in Northern Sweden. Using this curve, we compared differences in species richness in average-sized clear cuts with 100% (48 m(3)) and 25% (12 m(3)) stump retention and found that stump harvest resulted in a 26% (95% C.I. 7-41%) loss of species. While the absolute scaling of the landscape-derived rarefaction does not reflect species loss at the stand-level because the combined curve reflects all rare species in the landscape, the relative species loss derived from this curve may serve as credible benchmark for species loss at the stand level following current stump harvesting practices. This benchmark may be further calibrated with additional information on number of singleton species and estimates of maximum species richness. (C) 2016 Elsevier B.V. All rights reserved.
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17.
  • Andersson, Jon, et al. (författare)
  • Long-term effects of stump harvesting and landscape composition on beetle assemblages in the hemiboreal forest of Sweden.
  • 2012
  • Ingår i: Forest Ecology and Management. - Amsterdam : Elsevier. - 0378-1127 .- 1872-7042. ; 271, s. 75-80
  • Tidskriftsartikel (refereegranskat)abstract
    • Studies on the effects of stump harvesting on forest biodiversity are scarce and studies on long-term effects are until now non-existent. We evaluated such long-term effects by sampling beetles at 14 clear-cuts with and 14 clear-cuts without stump harvesting; harvesting had been done 21–28 years before this study. By using window traps, we collected 6429 individuals belonging to 432 species in 55 taxonomic families. To control for potentially confounding effects of among-site variations in landscape setting we also assessed forest age and volume of deciduous trees within the forest surrounding each site. The long-term effects from harvesting on beetle abundance, species richness and species composition was generally small in comparison to the influence of the characteristics of the surrounding forests. The species richness of the beetle family Latridiidae and the functional group fungivores appeared, however, to be negatively affected by the previous stump harvesting, while several other groups showed strong associations to the characteristics of the surrounding forest. We found little support for considerable long-term effects of stump harvesting on beetles flying in the stands. Long-term effects of stump harvesting at the landscape scale accumulated from harvest of many localities may still be severe, and should be the subject of future studies.
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18.
  • Angelstam, Per, et al. (författare)
  • Tradition as asset or burden for transitions from forests as cropping systems to multifunctional forest landscapes: Sweden as a case study
  • 2022
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 505
  • Tidskriftsartikel (refereegranskat)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.
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19.
  • Appiah Mensah, Alex, et al. (författare)
  • Modelling potential yield capacity in conifers using Swedish long-term experiments
  • 2022
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 512
  • Tidskriftsartikel (refereegranskat)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.
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20.
  • Appiah Mensah, Alex, et al. (författare)
  • Taller and slenderer trees in Swedish forests according to data from the National Forest Inventory
  • 2023
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 527
  • Tidskriftsartikel (refereegranskat)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.
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21.
  • Ara, Mostarin, et al. (författare)
  • Pre-commercial thinning in Norway spruce-birch mixed stands can provide abundant forage for ungulates without losing volume production
  • 2022
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 520
  • Tidskriftsartikel (refereegranskat)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.
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22.
  • Ara, Mostarin, et al. (författare)
  • Varying rectangular spacing yields no difference in forest growth and external wood quality in coniferous forest plantations
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 489
  • Tidskriftsartikel (refereegranskat)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.
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23.
  • Aronsson, K. Andreas, et al. (författare)
  • Limnological effects on a first order stream after Wood Ash Application to a boreal forest catchment in Bispgården, Sweden
  • 2008
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 255:1, s. 245-253
  • Tidskriftsartikel (refereegranskat)abstract
    • In Sweden, whole tree harvest is common practice, possibly leading to the depletion of mineral nutrients. Furthermore, the increased use of forestry residues for heat production has caused an increasingly growing amount of by-product consisting of wood ash. Therefore, the Swedish Forest Agency has recommended wood ash application (WAA) to replace the mineral nutrients removed by whole tree harvesting, as well as a means to mitigate the acidification of boreal forests and surface waters. In a multidisciplinary study during 2003-2006 in Bispgarden (Sweden), we have investigated the limnological effects on a first order stream after WAA (conducted in 2004; 3000 kg ha-1) to a 50-ha forested catchment. In general, no significant effects on an annual basis were found for acidification parameters, such as pH, alkalinity and toxic forms of aluminum (Al). There was, however, evidence of an increased pH during the spring flood, accompanied by a simultaneous decrease in the frequency of low pH-values (<5.6). Moreover, alkalinity increased in the years 2005 and 2006 compared to that of 2003, although the increase in 2006 was not statistically different from that in 2005 or 2003. High concentrations of Al repeatedly occurred in the stream, and the WAA did not affect the frequencies of high concentrations of toxic Al forms (>50 μg 1-1). The benthic diatom community did not change as a result of the wood ash treatment and the diatom-based index IPS (Indice de PulluoSensibilité) indicated no nutrient enrichment or organic pollution of the stream water. There were, however, indices of elevated concentrations of potassium (K) in the aquatic moss Fontinalis antipyretica and in leaves from Alder (Alnus incana). We conclude that wood ash treatment of a forested catchment with the dose and form of ash applied in this study did not modify the freshwater ecosystem of a first order stream.
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24.
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25.
  • Axelsson, Petter, et al. (författare)
  • Tolerance and growth responses of populus hybrids and their genetically modified varieties to simulated leaf damage and harvest
  • 2012
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 276, s. 217-223
  • Tidskriftsartikel (refereegranskat)abstract
    • Our results give a strong indication that the growth responses of the GM varieties to leaf damage and harvest were substantially equivalent with their corresponding non-GM varieties. These similarities predict that the effect of damage on production should be alike regardless of if the GM or non-GM products are used. (C) 2012 Elsevier B.V. All rights reserved.
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26.
  • Azizi, Soghra, et al. (författare)
  • Dual inoculations of arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria boost drought resistance and essential oil yield of common myrtle
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 497
  • Tidskriftsartikel (refereegranskat)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.
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27.
  • Backéus, Ingvar, et al. (författare)
  • Tree communities and structural dynamics in miombo (Brachystegia-Julbernardia) woodland, Tanzania
  • 2006
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 230:1-3, s. 171-178
  • Tidskriftsartikel (refereegranskat)abstract
    • Tree vegetation and size structure was sampled in a miombo woodland area in E Tanzania and related to environmental factors, particularly soil and disturbance history. A total of 86 tree species was found. Four plant communities were distinguished through multivariate classification. Community 1 was dominated by Brachystegia boehmii, Brachystegia bussei and Julbernardia globiflora, and community 2 by B. boehmii and Brachystegia spiciformis. Community 1 was found on grey, eroded soil and community 2 on red, residual soil, a fact that opens up possibilities to use soil signals of satellite data for vegetation mapping. Community 3 is heavily disturbed miombo woodland near villages and community 4 was found on more clayey soil where miombo woodland is not expected. At our 42 sampled sites, density ranged from 74 to 1041 individuals ha−1 and basal area from 3.9 to 16.7 m2 ha−1. Regeneration is generally good but large sized trees are less prominent in communities 3 and 4 due to harvesting. With reduced disturbance miombo species may rapidly resume dominance in community 3. A higher than expected representation by the size class 30–40 (−50) cm dbh in community 2 is probably related to disturbance history. Prevalence of certain species (Pseudolachnostylis maprouneifolia, Pterocarpus angolensis and Diplorhynchos condylocarpon) may be related to frequent fires. Selective logging will soon cause extinction of Dalbergia melanoxylon, whereas Pterocarpus angolensis still has good regeneration, possibly because individuals below logging size have a good seed set. A way to get an easy overview of size classes in all species in an area using PCA is discussed.
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28.
  • Bakys, Remigijus (författare)
  • Effects of season and region on sapstain and wood degrade following simulated storm damage in Pinus radiata plantations
  • 2012
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 277, s. 81-89
  • Tidskriftsartikel (refereegranskat)abstract
    • Storms causing windthrow are major natural disturbance events and an unpredictable hazard to forest planning. Knowledge of regional and seasonal climatic effects on sapstain and decay fungi will allow forest managers to minimise losses from wood deterioration during salvage operations. A study was conducted monitoring sapstain in trees that were experimentally felled to simulate storm breakage at up to four times during the year in Pinus radiata plantations across six locations in different climatic zones throughout New Zealand. It was found that drying of sapwood and development of sapstain depended more on the season when the storm occurred, rather than the time since felling. Sapstain appeared almost immediately in stems felled during summer, at some locations reaching more than 20% mean cross-sectional cover inside logs within 3 months, whereas in those felled during winter an initial lag phase during the cooler months preceded a more rapid rise during spring and summer. Rates varied substantially between locations with a tendency for faster deterioration where average temperatures were greater. For trees damaged during winter, it was predicted that a P. radiata butt log with a mid-length diameter of c. 16-23 cm will take from 2 to 8 months, depending on climate, to reach an economic damage benchmark threshold of 10% cross-sectional sapstain cover. However, for storms in spring or summer this period reduces to less than 1 month at warmer locations. Development of sapstain was uniform or increased slightly with height along the felled stem, but was greatest close to the felling cut in the basal section that would normally be removed during log retrieval. The results of this study provide new information about the temporal and regional variation in the dynamics of sapstain fungi that will assist forest managers during timber recovery following storms in regions with similar climates and tree species. (C) 2012 Elsevier B.V. All rights reserved.
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29.
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30.
  • Bandau, Franziska, et al. (författare)
  • European aspen with high compared to low constitutive tannin defenses grow taller in response to anthropogenic nitrogen enrichment
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 487
  • Tidskriftsartikel (refereegranskat)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.
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31.
  • Barbeito, Ignacio (författare)
  • Mixing has limited impacts on the foliar nutrition of European beech and Scots pine trees across Europe
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 479
  • Tidskriftsartikel (refereegranskat)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.
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32.
  • Barbeito, Ignacio, et al. (författare)
  • Regional climate moderately influences species-mixing effect on tree growth-climate relationships and drought resistance for beech and pine across Europe
  • 2022
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 520
  • Tidskriftsartikel (refereegranskat)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.
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33.
  • Barbeito, Ignacio (författare)
  • Trade-offs across densities and mixture proportions in lodgepole pine-hybrid spruce plantations
  • 2021
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 490
  • Tidskriftsartikel (refereegranskat)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.
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34.
  • Berg, Anna, et al. (författare)
  • A century of logging and forestry in a reindeer herding area in northern Sweden
  • 2008
  • Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 256, s. 1009-1020
  • Tidskriftsartikel (refereegranskat)abstract
    • Boreal forest ecosystems are generally highly sensitive to logging and other forestry activities. Thus, commercial forestry has had major effects on the forests and landscape structure in northern Sweden since the middle of the 19th Century, when it rapidly extended across the region. Lichens (which constitute up to 80% of reindeer forage in winter and early spring) have often been amongst the most severely affected ecosystem components. The overall aim of the present study was to analyze how forestry has influenced the potential supply of ground-growing lichens as winter forage for the reindeer in this region over the past ca. 100 years. For this purpose, we analysed changes in forest and stand structure in Scots pine-dominated (Pinus sylvestris L.) reindeer wintering areas in the southern part of the county Norrbotten (covering ca. 58,000 ha) using detailed historical forest inventories and management plans. We found that the amount of the forest types considered potentially good pasture (mainly middleaged and old pine forests) decreased during the first part of the 20th Century. However, the quality of grazing grounds was improved by forestry during this time mainly because selective logging made the forests more open which benefits lichen growth. During the last part of the 20th century forestry impaired the quality of grazing grounds in several ways, e.g. by clear-cutting and intensified use of various silviculturalmeasures. We conclude that ca. 30–50% of the winter grazing grounds have been lost in the study area because of intensive forest management during the last century. The spatially precise historical information about the affects of forestry on lichen pasture provided in this study can be used to direct forest management which will facilitate and promote reindeer herding in the future.
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35.
  • Berg, Björn, et al. (författare)
  • Calcium in decomposing foliar litter – A synthesis for boreal and temperate coniferous forests
  • 2017
  • Ingår i: Forest Ecology and Management. - : Elsevier B.V.. - 0378-1127 .- 1872-7042. ; 403, s. 137-144
  • Tidskriftsartikel (refereegranskat)abstract
    • We have synthesized available data for calcium (Ca) dynamics in decomposing foliar litter of mainly pine (Pinus), spruce (Picea), and birch (Betula) species to determine patterns of Ca concentration with climate in newly shed litter and its dynamics in decomposing litter as well as a possible role for Ca as regards limit values. Initial Ca concentration was negatively related to mean annual precipitation (MAP) with different relationships among genera. A limited data set showed a positive relationship across species (p < 0.05) to extractable Ca in soil. In paired stands, litter of both Norway spruce (Picea abies) and lodgepole pine (Pinus contorta) had higher Ca concentrations than Scots pine (Pinus silvestris), Norway spruce litter even twice as high. Relationships between initial concentrations of Ca and those of other nutrients appeared to be dominated by the positive ones to potassium (K) and magnesium (Mg) and specifically for deciduous litter there was a negative relationship to nitrogen (N). In decomposing litter, Ca concentration followed a negative quadratic (Ca = a + t − t2) function and had a maximum, which was variable. The Ca maximum concentration during decomposition was positively related to initial Ca concentration both within and among species. Separate linear relationships based on species were combined into one, in common for all investigated species and genera (R2 = 0.914, n = 63, p < 0.001). Limit values for decomposition were positively related to maximum Ca concentration at p < 0.05 with separate functions for pine and spruce litter. Calcium net release started directly after the incubation and was linear to accumulated mass loss of litter, giving a slope coefficient for each study. The net release rates were linear to initial Ca concentration both within and across species/genera. All studies combined gave a negative linear relationship (R2 = 0.894, n = 67, p < 0.001).
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36.
  • Berg, Björn, et al. (författare)
  • Decomposition rates in late stages of Scots pine and Norway spruce needle litter: Influence of nutrients and substrate properties over a climate gradient
  • 2022
  • Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 522
  • Tidskriftsartikel (refereegranskat)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.
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37.
  • Berg, Björn, et al. (författare)
  • Late stage pine litter decomposition : Relationship to litter N, Mn, and acid unhydrolyzable residue (AUR) concentrations and climatic factors
  • 2015
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 358, s. 41-47
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this paper is to evaluate relationships between decomposition rates of Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta var. contorta) needle litter in the late stage of decomposition (>30% accumulated mass loss), and the progressively changing concentrations of manganese (Mn), nitrogen (N), and acid unhydrolyzable residue (AUR), as well as mean annual temperature (MAT) and mean annual precipitation (MAP). Using available long-term decomposition studies on pine needle litter in a climate gradient in Sweden, we calculated annual mass loss and related to concentrations of Mn, N, and AUR at the start of each one-year period as well as to MAT and MAP. We investigated these relationships for (i) all data on annual mass loss combined and (ii) annual mass loss for five different decomposition categories as defined by accumulated mass loss. We found highly significant, negative, and dominant relationships between annual mass loss and N (R2=0.39) and AUR (R2=0.39), a slight but significant positive relationship to Mn (R2=0.08) and a significant negative relationship to MAT (R2=0.06). The relationships were dynamic, and changed with accumulated mass loss. The rate-dampening effect of N decreased to be a rate-enhancing effect at c. 60-80% accumulated mass loss. A similar trend was found for AUR, becoming rate-enhancing at 70-80% accumulated mass loss. For Scots pine needle litter the effect of MAT on mass loss decreased with increasing accumulated mass loss and changed to a rate-dampening effect at c. 50-70% accumulated mass loss. Mn showed a stimulating effect on mass loss rate in all categories whereas MAP showed no effect in this mainly boreal climatic gradient. The current approach indicates a method for detailed studies of rate-regulating factors for litter decomposition. 
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38.
  • Berg, Björn, et al. (författare)
  • Manganese in the litter fall-forest floor continuum of boreal and temperate pine and spruce forest ecosystems : a review
  • 2015
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 358, s. 248-260
  • Forskningsöversikt (refereegranskat)abstract
    • We have reviewed the literature on the role of manganese (Mn) in the litter fall-to-humus subsystem. Available data gives a focus on North European coniferous forests. Manganese concentrations in pine (Pinus spp.) foliar litter are highly variable both spatially and temporally within the same litter species and for the genus Pinus we found a range from 0.03 to 3.7mgg-1. Concentrations were related negatively to site mean annual temperature (MAT) and annual actual evapotranspiration (AET) for pine species litter but not for that of Norway spruce (Picea abies) as a single species. Combined data for several species showed a highly significant relationship to MAT.Manganese peroxidase is an Mn-dependent enzyme, found in white-rot fungi, essential for the degradation of lignin and ligninlike compounds. The decomposition rates of lignified litter tissue (late phase) is positively related to the litter’s Mn concentration. Further, the Mn concentration is positively related to the limit value for decomposition - the higher the Mn concentration the smaller the stable litter fraction. Manganese release from decomposing litter appears at least in part to be species related. Thus was release from pine needle litter significantly faster (p<. 0.001) than that from the Mn-richer litter of Norway spruce. Over Northern Europe concentrations of total Mn in mor humus as well as extractable Mn in the mineral soil increase with decreasing MAT and over a climatic gradient the Mn concentrations in Norway spruce mor increase more with decreasing MAT than in a gradient with Scots pine. Higher Mn concentrations in humus appear to decrease its stability and result in a higher release of carbon dioxide (CO2) and dissolved organic carbon (DOC). We conclude that this may explain (i) the lower amount of carbon (C) in mor layers under Norway spruce as compared to Scots pine as well as the higher amount of C in mineral soil under spruce. The increase in nitrogen (N) concentration in humus, following N fertilization resulted in a decrease in that of Mn. We have found four cases - empirical - with negative interaction between Mn and N; (i) in pine foliar litter fall concentrations of Mn decrease with site MAT whereas those of N increase, (ii) in decomposing late-stage litter with N retarding and Mn stimulating decomposition, (iii) for the stable phase, limit values are related negatively to N and positively to Mn, and (iv) Mn concentrations in humus decrease with MAT whereas those of N increase.
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39.
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40.
  • Bergh, Johan, et al. (författare)
  • Long-term responses of Scots pine and Norway spruce stands in Sweden to repeated fertilization and thinning
  • 2014
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 320, s. 118-128
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent investigations have shown that annual wood production in Sweden can be increased by 30 million m(3) per year in a long-term perspective (>50 years) by using new forest management methods such as new tree species or seedling materials. However, to meet the increased demands during the next 20 years, Sweden will have to rely on silvicultural methods available today. Growth in boreal and cold temperate forest is with only few exceptions limited by nutrients availability, primarily nitrogen, and one way to satisfy the increased demands in a short-term perspective is nitrogen fertilization. A set of thinning and fertilization experiments were started in the 1960's in Scots pine and Norway spruce stands over the whole of Sweden representing different soil, moisture and vegetation types. We used data from these experiments to examine the long-term effects of repeated fertilization in thinned stands on growth, stand development, and yield. The 34 Scots pine sites and 13 Norway spruce sites included in our analyses had at least four treatment plots (no thinning, repeated light thinnings, repeated light thinnings with repeated N fertilization, and repeated light thinnings with repeated N + P fertilization). In northern Sweden, 100 kg N ha(-1) and 150 kg N ha(-1) were applied at each fertilization event for Scots pine and Norway spruce stands, respectively. In southern Sweden, 150 kg ha(-1) N was applied in Scots pine stands and 200 kg ha(-1) N in Norway spruce stands. Phosphorus was applied at the rate of 100 kg ha(-1). Several sites also included non-thinned fertilized plots. Pine stands but not spruce stands were responsive (up to 25% more growth depending of the attribute assessed) to repeated fertilization. Surprisingly, the non-thinned pine stands showed strong continuing response to fertilization throughout the 30+ year observation period resulting in higher cumulative volume response than the thinned stands. In thinned stands incremental volume response to fertilization continued but slowly diminished with time indicating that fertilization and thinning effects were less than additive. However, thinning and fertilization effects were additive for diameter growth. Fertilization accelerated stand development with significant shifts in diameter distributions to larger and potentially more valuable trees. Conclusively, repeated nitrogen fertilization is a silvicultural practice that will result in significant and sustained increases in Scots pine production. (C) 2014 Elsevier B.V. All rights reserved.
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41.
  • Bergholm, Johan, et al. (författare)
  • Nitrogen fluxes after clear-cutting. Ground vegetation uptake and stump/root immobilisation reduce N leaching after experimental liming, acidification and N fertilisation
  • 2015
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 342, s. 64-75
  • Tidskriftsartikel (refereegranskat)abstract
    • Clear-cutting often results in a dramatic change in the soil nitrogen (N) balance. This study analysed the fate of inorganic soil N over four years (1992-1995) in a new clear-cut containing three replicate blocks. Treatments comprised control (0), 6000 kg CaCO3 ha(-1) (Ca), 600 kg sulphur powder ha(-1) (S) and 600 kg urea-N ha(-1) (U), applied during 1976-1987 to a Norway spruce (Picea abies) forest. Trees were cut in March 1992, after which stems, tops and branches were removed from the 12 experimental plots. Spruce seedlings were planted in May 1992. Clear-cutting resulted in accumulation of approx. 50 kg inorganic N ha(-1) in the 30 cm deep topsoil of the 0, S and U treatments and 25 kg N ha(-1) in the Ca treatment by October of 1992. During the next two years, the inorganic pools increased (S), stabilised (0 and U) or declined (Ca), but from the end of the third year all inorganic pools decreased. Plant cover gradually increased with dominance of Deschampsia flexuosa. Mean plant N uptake in grasses, forbs and spruce seedlings was estimated at 95 (0), 139 (Ca), 52 (S) and 121 (U) kg N ha(-1) for the four-year period. Nitrogen leaching at 50 cm depth was dominated by NO3-N and culminated during the second (Ca and U) and third (0 and S) years. Cumulative N leaching for the four-year period was lower for U and Ca (28 and 31 kg N ha(-1)) than for 0 and S (53 and 81 kg N ha(-1)), and was inversely correlated with plant N uptake. Nitrogen immobilisation in stumps and root necromass (including spruce and grass roots) was calculated to be 35-45 kg N ha(-1) during this period. The four-year N balance showed 5-17% higher inputs (net mineralisation and deposition) than outputs (plant uptake, leaching, immobilisation in dead stumps/roots and accumulation of inorganic N). Gaseous N losses were not studied, but high pH and high NO3--N formation in the organic layers of the Ca treatment in 1992 might have favoured denitrification, which can partly explain the lower amount of inorganic N remaining in this treatment. A novel finding was that stump and dead root immobilisation of N was quantitatively important. A second novel finding was that lime application, although stimulating nitrification, also stimulated plant N uptake so much that nitrate leaching was reduced in comparison with the control and sulphur treatments. (C) 2015 Elsevier B.V. All rights reserved.
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42.
  • Berglund, Håkan (författare)
  • Dead wood and polypore diversity in natural post-fire succession forests and managed stands - Lessons for biodiversity management in boreal forests
  • 2012
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 286, s. 16-27
  • Tidskriftsartikel (refereegranskat)abstract
    • We tested the extent to which forestry mimics natural stand-replacing fire dynamics, and what factors best explain species richness and assemblages of polyporous fungi in natural northern boreal Picea abies-dominated forests and managed forests which were either clear-cut and planted with pine, or selectively logged. The amount of coarse woody debris (CWD) and diversity of polypores in old-growth forests and in forests at three natural post-fire successional stages (young, middle-aged, old) were compared with managed forests at comparable successional stages. Fire created a high amount of CWD, providing a supply of dead wood for saproxylic species for at least 50-70 y. Dead wood volumes remained high throughout the natural forest succession, exceeding at all stages 18 m(3) ha(-1), the threshold value established in the study for the occurrence of red-listed species. The richness of polypore species was highest on young post-fire sites, and their species composition, including red-listed species, was comparable to that of old-growth forests (>300 y) used as references. The amount of CWD in natural post-fire forests was over two to twenty times higher than that on clear-cut sites, and species diversity on clear-cut sites was considerably lower than on sites undergoing natural succession, with no occurrences of red-listed species. A relatively diverse polypore flora was found in selectively logged forests, likely due to rather a high volume and continuity of spruce CWD. The results indicate a strong but non-linear relationship between total volume of CWD and species richness of polypores, but successional stage and naturalness also explained part of the variation. The species assemblages were influenced most by the decay stage of CWD, tree species composition and naturalness of the site. The results demonstrate the importance of old-growth and young post-fire forests as landscape-level habitats and species pools, especially for red-listed species. We recommend that old-growth spruce forests be preserved whenever possible and that high CWD volumes be generated locally for red-listed species, for example, by prescribed burning. Regeneration forests for spruce, extended rotation periods and the use of logging techniques other than clear-cutting would help in maintaining species diversity in spruce-associated species in boreal forests. (C) 2012 Elsevier B.V. All rights reserved.
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43.
  • Berglund, Håkan (författare)
  • Epiphytic lichen diversity in late-successional Pinus sylvestris forests along local and regional forest utilization gradients in eastern boreal Fennoscandia
  • 2010
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 259, s. 883-892
  • Tidskriftsartikel (refereegranskat)abstract
    • Pinus sylvestris-dominated forests have been heavily utilized across all of boreal Fennoscandia and the remaining natural forests are generally highly fragmented. However, there are considerable local and regional differences in the intensity and duration of past forest utilization. We studied the impact of human forest use on the diversity of epiphytic and epixylic lichens in late-successional Pinus sylvestris-dominated forests by assessing species richness and composition along both local and regional gradients in forest utilization. The effects of local logging intensity were analysed by comparing three types of stands: (i) near-natural, (ii) selectively logged (in the early 20th century) and (iii) managed stands. The effects of regional differences in duration and intensity of past forest use were analysed by comparing stands in two contrasting regions (Hame and Kuhmo-Viena). The species richness of selectively logged stands was as high as that of near-natural stands and significantly higher in these two stand categories than in managed stands. Species richness increased with the density of small understorey Picea, which correlated strongly with decreasing intensity of local forest use and increasing structural complexity of selectively logged and near-natural stands. Stands in the H me region hosted a lower number of species, and were less likely to host many old-growth indicator species than the Kuhmo-Viena region, suggesting that species have been lost from stands in the Hame region due to a longer history of intensive forest use. We conclude that selectively logged stands, along with near-natural stands, are valuable lichen habitats particularly for species confined to old-growth structures such as coarse trees and deadwood. In landscapes where natural forests have become fragmented, the management or restoration of the remaining late-successional Pinus-dominated forests, e.g. through the use of fire, should be carefully planned to avoid adverse effects on lichen species richness. (C) 2009 Elsevier B.V. All rights reserved.
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44.
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45.
  • Bergman, Karl-Olof, et al. (författare)
  • How much and at what scale? Multiscale analyses as decision support for conservation of saproxylic oak beetles
  • 2012
  • Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 265, s. 133-141
  • Tidskriftsartikel (refereegranskat)abstract
    • A key aspect for understanding species distributions is how they respond to habitat factors at different spatial scales. In this study we used a dataset mapping 33,000 large/hollow oaks, habitat for a guild of saproxylic beetles specialised on oaks at an extent of 10,000 km2. A total of 16 oak-dependent saproxylic species, out of 35, showed a clear relationship with substrate density at scales ranging from 52 m to ⩾5200 m. The characteristic scale of response for species richness of oak specialist species was 2284 m. At this scale, there was a tendency for richness to plateau at about 0.15 oaks ha−1, in which case about 250 hollow or large (circumference 310 cm) oaks would be needed in an area of 1600 ha to ensure a rich saproxylic oak fauna. The main general conclusions were: (i) a multi-scale approach is especially valuable to identify the characteristic scale of response; and that assuming a joint, single scale for all species may result in very poor decision support. (ii) The variation in species’ responses to substrate density at different scales means that habitat loss and fragmentation as well as management and restoration may have very different effects upon different species. (iii) Some species respond both to local and landscape scales, indicating that species occurrences in fragmented oak landscapes are affected both by short-term dynamics of the beetles and long term dynamics of the oak substrate. (iv) Maps, useful as decision support, can be constructed based on resource availability (in our case oak density) and characteristic scales.
  •  
46.
  • Bergner, Adam, et al. (författare)
  • Influences of forest type and habitat structure on bird assemblagesof oak (Quercus spp.) and pine (Pinus spp.) stands in southwesternTurkey
  • 2015
  • Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 336, s. 137-147
  • Tidskriftsartikel (refereegranskat)abstract
    • The Mediterranean basin exhibits a multitude of forest habitats affected by former and current exploitation and management. Recent afforestation programs have resulted in an increase in the proportion of coniferous trees, while oak stands, formerly utilized for coppicing and grazing, are abandoned or converted into coniferous plantations. The loss of oak stands might negatively affect birds dependent upon broadleaved forests. Studies confirming or rejecting that statement are scarce, particularly in the eastern part of the region. Using a study area in southwestern Turkey we applied a guild-based approach to investigate how pine and oak stands across a chronosequence differ in their capacity to support forest bird assemblages. Variables describing the vegetation were sampled to characterize the stands and relate bird assemblages to stand structure. Bird abundance and species richness was positively associated with age for both stand types. Richness and diversity was highest in oak stands, while there were no differences in bird abundance between the two forest types. Pine stands supported a different bird species composition compared to oak stands of the same age. Stand age and structure, rather than forest type, held the highest explanatory powers for bird assembly structure. Primary cavity-nesters and ground-nesters were more abundant in oak stands, possibly reflecting differences in stand structure and resource distribution. To support these birds with suitable habitats, oaks stands need conservation. Management practices in pine stands should strive for increasing the amount of old trees and retain vegetation in the understory to benefit breeding birds.
  •  
47.
  • Bergqvist, Göran, et al. (författare)
  • Forage availability and moose winter browsing in forest landscapes
  • 2018
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 419-420, s. 170-178
  • Tidskriftsartikel (refereegranskat)abstract
    • In a large-scale survey, comprising 38 landscapes throughout Sweden, we measured winter forage availability and use by moose within different forest- and land types, and also at three different spatial scales: plot, tract and area.Measured as percent cover of browse species within moose browsing range, young forests contained significantly more browse (16.5 +/- 1.20%: mean +/- SE) compared with older forests (6.7 +/- 0.57%) or non-forest land (5.9 +/- 0.67%). Total cover of browse species increased with increasing mean tree height in forests, and peaked at around 22% when the trees were 3-5 m. The relative consumption was highest in young forests (9.2 +/- 0.98%) compared with non-forest land (7.8 +/- 1.40%) or older forests (5.8 +/- 0.78%). The selection order did not vary much among forest- or land types, with aspen, willows, rowan and oak being the most selected species.A multiple regression, including four independent variables (moose index, cover of Scots pine, cover of other species and temperature sum) explained 45% (young forests), 18% (older forests) and 36% (non-forest land) of the variation in relative consumption. In young forests, moose index and cover of Scots pine accounted for 40 and 44%, respectively, of the explained variation. Model selection, using AICc, further emphasized the importance of moose index and cover of Scots pine, as these variables were included in the most parsimonious models for all forest- and land types.At the tract level, we recorded a proportional relationship between total cover of browse species and absolute consumption, suggesting an ideal free distribution. Taking into account the availability of forage, the degree of browsing and the proportion of each land type in the landscape, we calculated that 44.3% of the total forage consumption occurred in young forests, 42.3% in older forests and 13.4% in non-forest land.Our main conclusions are that moose conform to an ideal free distribution based on availability of forage within the landscape, and that all forest- and land types, not just young forests, are important as sources of browse for moose. Thus, it may be possible to release the browsing pressure on damage-sensitive young forests by increasing the food supply in other forest- and land types. Furthermore, managers needs to consider both the size of the moose population and the amounts of browse in the landscape when deciding on prudent management actions.
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48.
  • Bergsten, Urban (författare)
  • Manipulating overstory density and mineral soil exposure for optimal natural regeneration of Scots pine
  • 2023
  • Ingår i: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 539
  • Tidskriftsartikel (refereegranskat)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.
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49.
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50.
  • Bernhardsson, Carolina, et al. (författare)
  • Present genetic structure is congruent with the common origin of distant Scots pine populations in its Romanian distribution
  • 2016
  • Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 361, s. 131-143
  • Tidskriftsartikel (refereegranskat)abstract
    • Owing to the fact that mitochondrial, chloroplast and nuclear genomes are differently affected by evolutionary forces, the comparative study of all three genomes in combination with paleobotanical evidences allows for a more accurate interpretation of present genetic make-up. In this study, we analyzed the nad1-nad7 mitotype, 14 cpSSR loci and 10 nSSR loci in 13 Romanian Scots pine (Pious sylvestris L.) populations from the Romanian Carpathians and two Hungarian populations. Previous analysis of the macro fossil records supports the presence of Scots pine and Swiss stone pine (Pinus cembra L.) during the glacial period in Hungary and Romania. For a better image into the population structure in the studied area we also included in the data analysis two outgroup populations (north and south of Sweden) of known post glacial origin, which resulted in a more defined genetic structure. Our study reveals that relatively high genetic diversity is preserved at all the Romanian and Hungarian populations, with no distinction among naturally regenerated, managed autochthonous and introduced populations. Furthermore, genetic differentiation analysis fails to distinguish the two introduced populations from the Romanian ones. AMOVA clustering is congruent with the paleobotanical-based evidences of contraction of Scots pine range since the Holocene to its present fragmented distribution. (C) 2015 Elsevier B.V. All rights reserved.
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