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- Berglund, Håkan, 1967-
(författare)
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Biodiversity in fragmented boreal forests : assessing the past, the present and the future
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of this thesis are to (1) analyze the predictability (indicators) of plant and fungal species diversity in old-growth forests, and (2) assess the history and biodiversity of woodland key habitats (WKHs) and their potential to maintain species diversity in fragmented boreal forest landscapes. Predictability was explored in Granlandet nature reserve, an unexploited landscape composed of discrete old-growth Picea forest patches of varying size isolated by wetland, reflecting conditions of insular biota at stochastic equilibrium. Data from 46 patches (0.2-12 ha) showed that most species were rare. However, species richness and composition patterns exhibited a high degree of predictability, which strengthen the possibility to apply biodiversity indicators in old-growth forest stands. Area was a key factor. The increase in species richness starts to level out at 2-3 ha. Large patches host more Red-list species in their interiors than do small ones, i.e. stand size is an important qualitative aspect of old-growth habitat. Nestedness emerged in relation to area but also in equal-sized plots. Structural complexity and habitat quality were important for species richness and compositional patterns, and small habitats of high quality could harbor many rare species. Monitoring of wood-fungi on downed logs showed that species diversity on downed logs changed over periods of 5-10 years and that the occurrences of annual species were unpredictable. It is suggested that monitoring of species with durable fruit bodies (mainly polypores) is likely to be a feasible approach to obtain comparable data over time.Assessments of biodiversity of WKHs were performed in two areas with contrasting histories of forest exploitation, namely in south boreal and north boreal Sweden. Analyses of the history of 15 south boreal WKHs showed that fire-suppression, selective logging until mid-20th century and abandonment by modern forestry has shaped their forest structure. These WKHs are not untouched forests, they lack key structural components and harbor few Red-list species. Artificial interventions to restore natural processes and patterns are needed to further increase their suitability for threatned species. Modeling analyses of species richness in 32 WKHs in north boreal Sweden, some of which have not been isolated by modern forestry until recently, indicated an excess of crustose lichen species, i.e. WKHs may face delayed species extinctions. By contrast, the results indicate that wood-fungi have tracked the environmental changes. Differences in substrate dynamics between epiphytes on living trees and species growing on decaying logs may explain the diffeence between species groups. The results indicate that population densities of Red-list species were low, which may result in further depletion of species diversity.Continuing species declines and extinctions are likely if not conservation of WKHs are combined with other considerations in th managed forest landscape. Both WKHs and their surroundings must be managed and designed to maintain biodiversity over time. For a successful future conservation of boreal forest biodiversity monitoring of WKHs must be combined with monitoring of refeence areas.
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| 3. |
- Berglund, Håkan, et al.
(författare)
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Nested plant and fungal communities : the importance of area and habitat quality in maximizing species capture in boreal old-growth forests
- 2003
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Ingår i: Biological conservation. - 0006-3207. ; 112:3, s. 319-328
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the distribution of rare species is crucial for species conservation in fragmented habitats. Species communities often exhibit nestedness, i.e. species in species-poor sites comprise a subset of richer ones. Thus, rare species are confined to species-rich sites. We evaluate whether plant and fungal communities in 46 old-growth spruce forest patches (0.17–12 ha) exhibit nestedness. The question whether a single large patch or several small patches capture most species (i.e. the SLOSS-issue) is evaluated in combination with species saturation analyses. All species groups exhibited significant nestedness. Area was generally related to nestedness, i.e. rare species were over-represented in the largest patches. Species saturation analysis indicated that large patches accumulated more Red-list species in patch interiors than small patches. Thus, rare and Red-list species were best captured in large patches. However, nestedness also emerged in equal sized sample plots, i.e. rare species were over-represented in high quality habitats. Thus, small habitats of high quality should not be neglected in a conservation perspective.
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| 4. |
- Berglund, Håkan, et al.
(författare)
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Predictability of plant and fungal species richness of old-growth boreal forest islands
- 2001
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Ingår i: Journal of Vegetation Science. - 1100-9233 .- 1654-1103. ; 12:6, s. 857-866
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Tidskriftsartikel (refereegranskat)abstract
- The fragmentation and deterioration of old-growth forest habitat by modern forestry have become a major threat to species diversity in Fennoscandia. In order to develop a conservation strategy for the remaining diversity it is essential to identify the existing diversity and to develop appropriate conservation and monitoring programs. For these purposes indicators of conservation value for administrative prioritization are required. This study examines the predictability of plant and fungal species richness on two spatial scales on 46 isolated old-growth forest islands (0.17-12 ha) in a forest-wetland mosaic. We explore (1) to what extent area, isolation and stand structure variables can explain the variation in species richness and (2) if richness patterns of individual species groups correlate. Isolation showed no relation to species richness. Area explained 50-70% of the variation in total species richness and was positively related to the density of crustose lichens and Red-list species in island interiors. Stand structure variables explained 28-66% of the residual variation in total species richness after controlling for island size, and 15-73% of the variation in density of species in island interiors. The highest predictability of species richness was found among substrate-specific fungi and Red-list species. Different stand structure variables were found to explain richness in the different species groups, and only among a few species groups species richness correlated. Thus, species richness of one single species group is unlikely to be a good indicator for total biodiversity. The results show that measurements of stand size and stand structure variables may be a strong complementary tool. and sometimes a substitute to extensive species inventories when one aims to estimate and monitor plant and fungal species diversity in old-growth Picea abies forests.
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| 5. |
- Cronberg, Nils, et al.
(författare)
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Mossor
- 2000
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Ingår i: Red list of Swedish species. - 9188506231 ; , s. 93-105
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
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Ecology of woody debris in boreal forest
- 2001
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Today dead trees are not only viewed upon as waste and as potential sources of pest species. Instead they have gained an increased attention as key factors for biodiversity in many ecosystems. This change in focus and concern has sparked intense research activities directed to explore the ecological role of dead trees in forest ecosystems. Focus is directed into three main areas: 1) to understand thepatterns of woody debris availability in relation to forest stand dynamics and effects of forestry, 2) the role of woody debris in nutrient and particularly carbon dynamics in forest ecosystems, and 3) the pattern and biology of the utilization of woody debris for a large number of wood-dependent species. This volume summarises the present knowledge and presents a set of case studies on the role of dead wood in boreal forests. The focus is on Fennoscandian boreal forests.However, the results presented have a wide applicability and thus the volume may serve as a general introduction to the importance of woody debris in forest ecosystems.
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| 8. |
- Edman, Mattias, et al.
(författare)
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Local dispersal sources strongly affect colonization patterns of wood-decaying fungi on experimental spruce logs
- 2004
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 14:3, s. 893-901
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Tidskriftsartikel (refereegranskat)abstract
- Coarse woody debris (CWD) is an important habitat for many species in forest ecosystems. However, forestry has decreased the abundance of CWD so that many wood-dependent species have become threatened. To alleviate this problem, guidelines for a more biodiversity-oriented forestry focus on increasing CWD in managed forests. Unfortunately, how this increase is to be allocated on a landscape scale is not well understood. The present study reports an experiment in which freshly cut logs of varying sizes were placed in stands with contrasting abundance of natural CWD and subsequently varying pools of wood-inhabiting species. The first six years of colonization by wood fungi show that local abundance and composition of the fungal flora strongly influenced colonization. Higher species richness was observed in CWD-rich sites, and several species were more frequent on the experimental logs at CWD-rich sites. The strong within-site effect is interpreted as resulting from high spore deposition from the local species pool. This is supported by spore deposition estimates of Fomitopsis rosea, a red-listed species that only occurred on experimental logs at the CWD-rich sites. F. rosea had a 9-180 times higher spore deposition at the CWD-rich sites compared to the CWD-poor sites. The species richness and composition on small logs differed from that of large logs with higher richness on the latter. The results strongly suggest that restoration efforts would be more efficient if directed toward sites close to CWD-rich sites and that preferably large logs should be created.
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| 9. |
- Edman, Mattias, et al.
(författare)
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Spatial pattern of downed logs and wood-living fungi in an old-growth spruce forest
- 2001
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Ingår i: Journal of Vegetation Science. - 1100-9233 .- 1654-1103. ; 12:5, s. 609-620
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Tidskriftsartikel (refereegranskat)abstract
- Since many wood-living forest species are influenced by the dynamics of coarse woody debris (CWD), information about the spatial pattern of CWD under natural conditions is essential to understand species distributions. In this study we examined the spatial pattern of downed logs and wood-decaying fungi in an old-growth boreal Picea abies forest in northwestern Sweden that is governed by gap-phase dynamics. The spatial pattern of wood-decaying fungi was studied to draw conclusions about species dispersal abilities. A total of 684 logs with a diameter 10 cm were mapped and analysed with Ripley's K-function. The distribution of all logs taken together displayed a significant aggregated pattern up to 45 m. The different decay stages also deviated from random expectations. Fairly fresh logs and logs in the middle decay stage were clumped up to about 25 and 35 m respectively, and late decayed logs aggregated up to 95 m. Logs with diameters from 10-29 cm were aggregated up to 25 m, whereas logs ≥30 cm diameter were randomly distributed. The result suggests that gap-dynamics do have an impact on the spatial pattern of the CWD, creating fine-scale clumping. The random distribution of large logs may result from the slightly regular spacing of large living trees. The spatial patterns of 16 species (n 20) of wood-decaying fungi were analysed with Ripley's K-function. Three patterns were aggregated, for Gloeophyllum sepiarium, Coniophora olivacea and Vesiculomyces citrinus. These results indicate that the distribution of most species at the stand level is generally not influenced by dispersal limitations.
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