5 results on '"Hjältén, J."'
Search Results
2. Wing loading and habitat selection in forest beetles: Are red-listed species poorer dispersers or more habitat-specific than common congenerics?
- Author
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Gibb, H., Hjältén, J., Ball, John P., Pettersson, R.B., Landin, J., Alvini, O., and Danell, K.
- Subjects
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HABITAT selection , *BEETLES , *ANIMAL dispersal , *BIOLOGICAL extinction - Abstract
Abstract: Traits such as poor dispersal ability and high habitat specificity are thought to predispose some species to a greater risk of extinction than others. Habitat preferences and morphological features associated with dispersal ability were compared between red-listed species and common congenerics co-occurring in boreal forests in northern Sweden. Measurements of body size, wing loading and wing aspect ratio were used to compare dispersal abilities, while catches from experimental treatments of dead wood were used to compare habitat preferences. We also compared how restricted red-listed species were to particular sites or habitats relative to common species. The red-listed Epuraea longipennis was longer and wider, while Epuraea. deubeli weighed less than common Epuraea species. In contrast to expectations, these red-listed species had a larger wing area (relative to their body mass) and thus a lower wing-loading than congeneric species, suggesting superior dispersal abilities. The red-listed Tachinus elegans possessed intermediate morphological characteristics, compared with common congenerics. However, the relationships between the risk of extinction in fragmented habitats and size and dispersal ability are likely to be scale-dependent, so intermediate or superior dispersal abilities may increase extinction risk at some scales. Red-listed species were not found in fewer sites or habitat types than congenerics so were not more likely to be habitat specialists. However, some red-listed species preferred deeply shaded and Fomitopsis pinicola-inoculated logs, relative to congenerics, suggesting that specificity to these particular microhabitats may be connected with extinction risk. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
3. Restoration strategies in boreal forests: Differing field and ground layer response to ecological restoration by burning and gap cutting.
- Author
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Espinosa del Alba, C., Hjältén, J., and Sjögren, J.
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RESTORATION ecology ,TAIGAS ,PRESCRIBED burning ,SPECIES diversity ,ENVIRONMENTAL degradation ,FOREST fire ecology ,FIRE ecology - Abstract
• Restoration methods, fire and gap cut, mimic boreal forests' natural disturbances. • Prescribed fire resulted in a significant shift in community composition. • Gap cutting did not affect boreal understory vegetation. • Long-term, multiple organism group studies provide a better comprehension of effects of restoration. The boreal biome is one of the largest in the world and its forests have been widely exploited for centuries. Consequently, large areas have suffered ecological simplification and loss of biodiversity. Under the current circumstances passive conservation measures are no longer enough and active restoration techniques need to be developed and assessed to preserve and recover the loss of biodiversity. We evaluated short- and long-term effects of two restoration methods aimed at mimicking natural disturbances on species richness, Shannon Diversity and community composition of vascular plants in the field layer and bryophytes in the ground layer. The experiment consisted of 18 forest stands in northern Sweden; each assigned to a different treatment: prescribed burning, gap cutting and untreated stands left as controls. A before-after control-impact (BACI) study design was applied and data was collected on three occasions: once prior to restoration (2010) and twice post restoration; one year (2012) and eight years after (2019). We analysed the differences in species richness and Shannon Diversity with linear mixed effect models and community composition changes with multivariate methods. Fire treatment caused an initial decline in diversity for both field and ground layer, but in the long-term, field layer surpassed the species richness and Shannon Diversity values found prior to restoration. Ground layer bryophytes species richness and Shannon Diversity remained lower than pre-treatment. Prescribed burning should, therefore, be used with caution in core areas for bryophyte diversity. Community composition in burned stands differed significantly between each time point as well as when compared to other treatments, for both layers. By contrast, we found no significant differences in diversity measures or community composition after gap cutting. The absence of effects from gap cutting suggests that minor changes in canopy cover does not affect the vegetation structure of forest stands. The organism group-specific responses, and temporal variability to restoration, highlight the importance of including more than one organism group, different restoration methodologies, and long-term studies in order to properly assess restoration outcomes at landscape level. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
4. Conservation-oriented forestry and early successional saproxylic beetles: Responses of functional groups to manipulated dead wood substrates
- Author
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Gibb, H., Pettersson, R.B., Hjältén, J., Hilszczański, J., Ball, J.P., Johansson, T., Atlegrim, O., and Danell, K.
- Subjects
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FOREST conservation , *BEETLES , *PROTECTED areas - Abstract
Abstract: New conservation-oriented forestry aims to maintain intact populations of forest organisms by improving the conservation value of managed forests and providing protected areas. We tested the conservation value of treatments of dead wood for assemblages of early successional saproxylic beetles. In nine areas in northern Sweden, we selected one clear-cut, one mature managed forest and one reserve. In 2001–2002, we placed three blocks of spruce logs, each containing control, burned and shaded logs and a high stump (“snag”) at each site. Saproxylic beetles emerging from the dead wood were collected using emergence traps and beetles flying close to it were collected using flight-intercept traps. After one year of exposure, assemblage composition was examined, with respect to nutritionally-defined functional groups, red-listed species and fire-favoured species. Experimental snags were most complementary to control logs, supporting different assemblages of cambium consumers and fungivores and supporting more red-listed individuals. Burned logs supported depauperate assemblages, particularly with respect to cambium consumers, while shading of logs affected assemblages of fungivores, but only on clear-cuts. Despite containing less dead wood, managed forests provided valuable habitat, supporting similar assemblages of saproxylic beetles to reserves. Most functional groups were less abundant on clear-cuts than in older forests, but fire-favoured species were more common on clear-cuts, suggesting that clear-cuts may support assemblages of species associated with natural disturbances, if suitable substrates are available. Utilization of logs by saproxylic beetles changes over time, so long-term monitoring of our experimental logs will determine their lifetime conservation value. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
5. How climate change adaptation and mitigation strategies can threaten or enhance the biodiversity of production forests: Insights from Sweden.
- Author
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Felton, A., Gustafsson, L., Roberge, J.-M., Ranius, T., Hjältén, J., Rudolphi, J., Lindbladh, M., Weslien, J., Rist, L., Brunet, J., and Felton, A.M.
- Subjects
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CLIMATE change , *FOREST management , *FORESTS & forestry , *BIODIVERSITY , *BIOLOGICAL adaptation - Abstract
Anthropogenic climate change is altering the management of production forests. These changes are motivated by the need to adapt to the uncertainties and risks of climate change, and by the need to enlist their carbon storage and sequestration capacity as part of global mitigation efforts. These changes do however raise concerns regarding the potential implications for forest biodiversity. Here we evaluate these concerns by assessing the biodiversity implications of climate change adaptation and mitigation strategies (CCAMS) being implemented in the production forests of Sweden. We do so by identifying biodiversity goals aimed specifically at closing the existing gap between the habitat requirements of forest-dependent species, and the conditions provided by production forests, in terms of tree species composition, forest structures, and spatio-temporal forest patterns. We then use the existing literature to determine whether and by which pathway each CCAMS is likely to bridge or extend this gap. Our results indicate that CCAMS will often come into direct or partial conflict with Swedish biodiversity goals in production forests. Furthermore, some CCAMS which are inconsistent with biodiversity goals, such as logging residue removal, are being implemented more extensively than those which were most consistent with biodiversity goals. We nevertheless challenge the necessity of setting the preservation of forest biodiversity against climate change mitigation and adaptation. We clarify how CCAMS with negative biodiversity implications may still be implemented without adverse outcomes, if coupled with conservation interventions, or combined with other CCAMS deemed complementary in habitat provision. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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