| 9631. |
- Johansson, Victor, et al.
(författare)
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Long-term landscape scale effects of bioenergy extraction on dead wood-dependent species
- 2016
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 371, s. 103-113
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Tidskriftsartikel (refereegranskat)abstract
- Dead wood is an important resource for biodiversity, which has often decreased due to forest management. There is an increasing interest in extracting woody residues on clear-cuts for bioenergy production, which will further decrease dead wood amounts. Empirical studies show that such extraction decreases habitat availability for many species at a local scale, but no analyses have been made on long-term effects on population sizes and species persistence in whole landscapes. We investigated how theoretical species that differ in dispersal range, habitat specialization, and commonness are affected by different levels of wood extraction intensity. We also investigated the effect of extracting only slash (branches and tops) compared to both slash and stumps, and the spatial location of the extraction. This was done by simulations of dead wood development and species' colonization extinction dynamics based on metapopulation theory. The simulations were run for 200 years in an 11 x 11 km managed forest landscape in Sweden. For all species the predicted population sizes decreased, and for six out of eight species the landscape level extinction risks increased with increasing bioenergy extraction. The negative impacts were larger when including stumps compared to extracting slash only. However, rare species declined more strongly with increasing extraction than the common species. Specialists on coarse sun-exposed wood declined more than generalists when stumps were included in the extraction, while the pattern was the opposite when only extracting slash. The population declines continued for up to 200 years before colonizations and extinctions were in equilibrium, and were generally slower for rare compared to common species. Concentrating the extraction to 50% of the landscape had a positive effect on rare and short dispersing species, which could be assumed to be the most threatened species. Thus, bioenergy extraction is likely to have negative impacts on biodiversity, which are most severe when stumps are extracted at a high intensity throughout the landscape. Even at low levels of stump extraction, species which are already rare and specialized on sun-exposed coarse dead wood may be threatened. Slash extraction has probably less impact, since few species are specialized on fine woody debris. Concentrating the extraction to a subset of forested areas may reduce the negative impact. The apparent direct trade-off between the amount of bioenergy extracted and the remaining amount of dead-wood habitat may require that bioenergy extraction is either limited or further conservation interventions are employed that compensate for anthropogenic habitat loss. (C) 2015 Elsevier B.V. All rights reserved.
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| 9632. |
- Johansson Wensman, Jonas, et al.
(författare)
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Genetic Relationship Between Hard Ticks (Ixodidae) Infesting Cattle from Select Areas of a Wildlife-Livestock Interface Ecosystem at Mikumi National Park, Tanzania
- 2021
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Ingår i: Vector-Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 21, s. 191-199
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Tidskriftsartikel (refereegranskat)abstract
- Background: There has recently been a substantial increase in the number of tick species and tick-borne infectious agents in Tanzania. Owing to their impact on human, livestock, and wild animal health, increased knowledge of ticks is needed. So far, no published data on the genetic relationship between hard tick (Ixodidae) sequences collected from cattle are available in Tanzania.Methods: Ticks from cattle in the wards, which lie at the border of Mikumi National Park, were collected in the dry season, November to December 2019. Morphological identification of ticks was initially performed at the genus level. To identify ticks at the species level, molecular analysis based on the 16S rRNA gene was performed. Evolutionary relationships and genetic distances between ticks were determined using MaximumLikelihood and Kimura 2-parameter methods, respectively.Results: Based on morphology, two genera (Rhipicephalus and Hyalomma) were identified in the 630 adult ticks collected from a total of 252 cattle. Six species (Rhipicephalus microplus, Rhipicephalus evertsi, Hyalomma marginatum, Hyalomma rufipes, Hyalomma truncatum, and Hyalomma turanicum) were confirmed by BLASTn and phylogenetic analyses. Considerable mean and pairwise genetic distances were observed for Rhipicephalus and Hyalomma genera.Conclusion: The presence of different phylogenetic clusters and considerable mean and pairwise genetic distances observed reflect possible biological diversity of hard ticks present in the study area. Considering the value of the cattle in the livelihoods and economies of people and the country, the outcomes of this study will be useful in planning integrated control strategies for ticks and tick-borne diseases in Tanzania.
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| 9633. |
- Johnson, Richard
(författare)
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Spatial congruency of benthic diatom, invertebrate, macrophyte, and fish assemblages in European streams
- 2010
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 20, s. 978-992
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Tidskriftsartikel (refereegranskat)abstract
- Understanding patterns in taxonomic congruency and the importance of environmental variables as drivers of these patterns is a prerequisite for analyzing changes in regional species pools. Here we evaluated the spatial correspondence of benthic diatoms, invertebrates, macrophytes, and fish assemblages in minimally disturbed lowland (n = 38) and mountain (n = 32) streams and, using constrained ordination and variance decomposition, determined how environmental and biological variables related to these patterns. Using different measures of diversity, abundance, and community composition, principal components analysis failed to reveal a single gradient in lowland and mountain streams. This was due to differences in the relationships between individual diversity measures and environmental variables characterizing habitat diversity (number of debris dams, silt and cobble substratum) in lowland streams, and catchment area and oxygen saturation in mountain streams. Despite the low spatial coherence of individual measures, integral multivariate analyses of community structure revealed coherent patterns between taxonomic groups. From 31.0% to 47.7% of the variance in diversity of. sh, invertebrate, and macrophyte assemblages in mountain streams and from 11.9% to 33.7% of the variance in diversity in lowland streams were explained by one or more of the remaining three groups. Partial redundancy analyses showed that composition of other taxonomic groups was generally a better predictor of assemblage diversity than interactions with environmental variables, lending support to the importance of species interactions for spatial coherence. Finally, although we found little support for a single biodiversity gradient, correlations between. sh diversity and macrophyte and invertebrate diversity in mountain streams and between macrophyte diversity and invertebrate and diatom diversity in lowland streams suggest that these two groups (i.e.,. sh in mountain and macrophytes in lowland streams) may function as surrogate indicators for the diversity of other taxonomic groups.
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| 9634. |
- Jonsell, Mats, et al.
(författare)
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Diptera in clear-felling stumps like it dry
- 2019
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 34, s. 673-677
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Tidskriftsartikel (refereegranskat)abstract
- When stumps on clear cuts are harvested for bioenergy, retention of a share of them is recommended to mitigate environmental issues. To maximise benefits for the diversity of saproxylic beetles, retention should be done in dry positions. Saproxylic dipterans are usually thought to be associated with wetter wood substrates. We therefore hypothesised that dipterans would benefit from other recommendations. We tested that by rearing out insects from spruce and birch stumps sampled in clear fellings, and received a material of 866 individuals of 24 Diptera taxa. Among six Diptera species tested statistically, one was associated with dry stumps when comparing within spruce, and the total abundance of dipterans was higher in dry spruce stumps than in wet. No parameter (total species number, species number per stump, total abundances and abundances of individual species) showed a higher value for wet stumps than for dry. We conclude that there are several Diptera species that frequently use stumps, of which a large share was earlier regarded as very rare. For those, our hypothesis was falsified, as the affinities to dry stumps seem similar as for beetles and the same recommendations could be used.
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| 9635. |
- Jonsell, Mats, et al.
(författare)
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Increasing influence of the surrounding landscape on saproxylic beetle communities over 10 years succession in dead wood
- 2019
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 440, s. 267-284
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Tidskriftsartikel (refereegranskat)abstract
- Studies of the spatial scale to which saproxylic beetles respond to the surrounding landscape have generated varied results. We tested how the relationship between beetle fauna and variables describing the landscape changed over ten years of succession. We hypothesized that the relationship to the nearby landscape would be stronger when the wood was in a later successional stage. This is because habitat predictability is higher in the later stages, as they have a longer turnover time of beetle assemblages than early stages. With higher predict. ability of the habitat, theory expect lower dispersal capacity of hosted species, and thereby higher relation to landscape on smaller scale. The saproxylic beetles were sampled on the same wood objects (high stumps) in three time steps over ten years in 20 clear-cuts in south Sweden. In accordance with our expectations, the nearby (< 5 km radius) forest-landscape variables explained more of the species composition of the saproxylic beetles later in the succession. The first- and third-years geographical location (longitude and latitude) were more important and explained, for three different subsets of beetle species, 21%, 4% and 25% of the fauna composition. At this time, the forest-landscape variables explained almost nothing. After ten years the pattern was the opposite, with surrounding forest explaining up to 27% of the variation, and regional factors almost nothing. We showed that this was related to a shift in the species assemblage after ten years, with an increasing share of species associated with more decayed wood. Our results suggest that successional stage of the dead wood helps explain at what scale saproxylic species respond. Several of the surrounding forest variables were associated with biodiversity hotspots, which thus seem to exist also for species associated with abundant wood types. Latersuccessional species are more indicative of hotspots than earlier-successional species.
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| 9636. |
- Jonsson, Bengt-Gunnar, 1963-, et al.
(författare)
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Rapid changes in ground vegetation of mature boreal forests : an analysis of Swedish national forest inventory data
- 2021
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Ingår i: Forests. - : MDPI. - 1999-4907. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- The boreal forest floor vegetation is critical for ecosystem functioning and an important part of forest biodiversity. Given the ongoing global change, knowledge on broad-scale changes in the composition and abundance of different plant species and species groups is hence important for both forest conservation and management. Here, we analyse permanent plot data from the National Forest Inventory (NFI) on changes in the vegetation over a 10-year period in four regions of Sweden. To limit the direct and relatively well-known effects of forest management and associated succession, we only included mature forest stands not influenced by forestry during the 10 years between inventories, and focused on vegetation change mainly related to other factors. Results show strong decrease among many species and species groups. This includes dominant species such as Vaccinimum myrtillus and Deschampsia flexuosa as well as several forest herbs. The only species increasing are some mosses in the southern regions. Our data do not allow for a causal interpretation of the observed patterns. However, the changes probably result from latent succession in combination with climate change and nitrogen deposition, and with time lags complicating the interpretation of their relative importance. Regardless of the cause, the observed changes are on a magnitude that suggest impacts on ecosystem functioning and hence highlight the need for more experimental work.
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| 9637. |
- Jonsson Čabrajić, Anna V, 1978-
(författare)
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Modeling lichen performance in relation to climate : scaling from thalli to landscapes
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lichens can colonize nearly all terrestrial habitats on earth and are functionally important in many ecosystems. Being poikilohydric, their active growth periods are restricted to periods when the thallus is hydrated from atmospheric water sources, such as rain, fog and high relative humidity. Since lichen hydration varies greatly over time lichen growth is therefore more difficult to model compared with, for example vascular plants with more even water supply. I developed two models to predict lichen hydration under field conditions that incorporates the atmospheric water potential (Ψair), derived from air temperature and humidity, only or in combination with species-specific rehydration and desiccation rates. Using Ψair allows the prediction of hydration induced by several water sources. These models were very accurate for epiphytic lichens with a close coupling to atmospheric conditions, but they were less accurate for mat-forming lichens with substantial aerodynamic boundary layers. The hydration model was further developed to include photosynthetic activation for different species, in order to compare their performance under different micro-climatic scenarios. Water balance and activation rate had large effects on lichen activity and were positively related to habitats providing long hydration periods, for example close to streams. To study effects of climate change, a complete model for net carbon gain (photosynthesis minus respiratory losses) was developed for an epiphytic lichen with intricate responses to light, hydration and temperature. Simulation responses in different climate scenarios revealed that projected climate change on a regional scale resulted in varied local scale responses. At the lighter, exposed sites of a forest, the growth responses were positive, but were potentially negative at darker sites with closed canopy. At the local scale, fluctuating hydration, summed irradiance when wet and Chlorophyll a are variables that predict lichen growth. However, at a landscape scale, these variables may be too detailed. We tested this for two terrestrial, mat-forming lichens and developed statistical models for lichen growth in the widest possible climatic gradient in northern Scandinavia, varying in light, temperature and precipitation. Light was the most important factor for high growth at the landscape scale, reaching saturation at a site openness of 40 %, equivalent to a basal tree area of 15 m2 ha -1 in this study. Thereafter, hydration was the next limiting factor, which could be well described by precipitation for one of the species. The simplest predictor was the normal temperature in July, which was negatively correlated with growth. It was apparent that the predictive variables and their power varied at different scales. However, light and hydration are limiting at all scales, particularly by light conditions when lichens are wet. This implies that ensuring that there is sufficient light below the forest canopy is crucial for lichen growth, especially for mat-forming lichens. Hydrophilic lichens may be better preserved in open habitats with long hydration periods. It was shown that models can be powerful and “easy to use” tools to predict lichen responses in various habitats and under different climate scenarios. Models can therefore help to identify suitable habitats with optimal growth conditions, which is very important for the conservation and management of lichens and their habitats.
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| 9638. |
- Jonsson Cabrajic, Anna V, 1978-, et al.
(författare)
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Predicting growth of mat-forming lichens on a landscape scale : comparing models with different complexities
- 2010
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 33:5, s. 949-960
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Tidskriftsartikel (refereegranskat)abstract
- During the 20th century, forestry practices has adversely affected lichen-rich habitats. Mat-forming lichens are important components of the vegetation of boreal and arctic ecosystems and are the main reindeer forage during the winter. To support the long-term management of lichens in such habitats we developed models for predicting the growth of two common species. The lichens were transplanted across northern Scandinavia along a west-east gradient varying in precipitation, temperature and irradiance. Growth was recorded seasonally over 16 months and ranged from −4.8 to 34.6% and −12.7 to 34.7% dry weight change for Cetraria stellaris and Cladina islandica, respectively. Growth was light limited below canopies with more than ca 60% cover and highest at the more humid sites when light levels were optimal. The models were based on various meteorological parameters, irradiance, physiological data and lichen hydration status; the latter was derived from a recently developed lichen hydration model. Our models' abilities to predict growth, both annually and seasonally (i.e. in summer), were evaluated in relation to their complexity and their potential usefulness from a management perspective. One parameter related to irradiance (the logarithm of site openness) was valuable in the prediction of annual growth for both species and could, in combination with precipitation, explain 52% of the variation in annual growth for C. stellaris and, in combination with total wet time and the irradiance received while wet, explain 66% of the variation in annual growth for C. islandica. The best simplified model explained 43% of the variation in annual growth for C. stellaris, using stem basal area and the annual normal temperature, and 24% for C. islandica using basal area alone. It is concluded that ensuring sufficient irradiance below the forest canopy is of crucial importance in the long-term management of mat-forming lichens and that simplified models can be used to identify appropriate habitats.
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| 9639. |
- Jonsson Čabrajić, Anna V, 1978-, et al.
(författare)
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Predicting local responses of epiphytic lichen vegetation to regional climate change scenarios
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In northern Europe, projected climate change indicates annual warming and increased precipitation, especially during winter. The aim of this study was to assess potential responses to this of poikilohydric and epiphytic lichens that are closely coupled to the local atmospheric conditions, and consequently to climate change. Two scenarios, one moderate and another more intense emission scenario (SRES B2 and A2, respectively) for northern Europe, was used to assess regional climate changes. Both scenarios used the combination of projected changes in temperature (T), humidity (RH) and irradiance (I) towards the end of the 21st century. To generate local climate changes we used microclimate time series from 1993-94 of two contrasting habitats, an interior and an open site, and transformed them by superimposing the regional scenarios. We developed a physiological net carbon gain (NCG) model for Platismatia glauca on the responses of photosynthesis and respiration in relation to I, T and water content (WC), which was simulated by a lichen hydration model using RH and T, and growth. Carbon gain and growth was simulated for reference and the two climate local scenarios during one year, and validated against growth for the reference conditions. The growth response was two times higher at the lighter, exposed site compared to the interior site, in agreement with measured growth. However, the responses to climate change were not uniform locally or seasonally, mainly due to the changed patterns of hydration and whether irradiances were limiting or not during the wet periods. At the darker, interior site of the forest, growth was reduced due to climate change but was in contrast equal or increased at the lighter, exposed site. This was caused by a general increased growth during the more humid spring and a reduced or equal growth response during the drier summer and during the wetter, dark winter. The increasingly favored growth conditions at exposed sites will possibly favor lichens that can manage the potentially adverse effects of increased wind exposure at these sites. At darker sites, the lichens will likely be outcompeted by bryophytes that are better adapted to dark and wet conditions. It is thus likely that the realized niche of lichens will be reduced, with a shift in optimum abundance towards more exposed habitats, or even more reduced for pendulous lichens that are hampered by increased wind at the most exposed sites.
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| 9640. |
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