33 results on '"Sjögren, Jörgen"'
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2. “Land-sparing benefits biodiversity while land-sharing benefits ecosystem services”: Stakeholders’ perspectives on biodiversity conservation strategies in boreal forests
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Löfroth, Therese, Merinero, Sonia, Johansson, Johanna, Nordström, Eva-Maria, Sahlström, Emma, Sjögren, Jörgen, and Ranius, Thomas
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- 2024
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3. Correction to: Translocation of deadwood in ecological compensation: A novel way to compensate for habitat loss
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Tranberg, Olov, Hekkala, Anne-Maarit, Lindroos, Ola, Löfroth, Therese, Jönsson, Mari, Sjögren, Jörgen, and Hjältén, Joakim
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- 2024
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4. Short-term effects of continuous cover forestry on forest biomass production and biodiversity: Applying single-tree selection in forests dominated by Picea abies
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Ekholm, Adam, Axelsson, Petter, Hjältén, Joakim, Lundmark, Tomas, and Sjögren, Jörgen
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- 2022
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5. Multi-taxon conservation in northern forest hot-spots: the role of forest characteristics and spatial scales
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Kärvemo, Simon, Jönsson, Mari, Hekkala, Anne-Maarit, Sjögren, Jörgen, and Strengbom, Joachim
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- 2021
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6. An Exotic Tree in a Foreign Country: A Cultural Biography of the Lodgepole Pine in Sweden.
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MÅRALD, ERLAND, JÖNSSON, JIMMY, KARDELL, ÖRJAN, SJÖGREN, JÖRGEN, and TUNLID, ANNA
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LODGEPOLE pine ,ENVIRONMENTALISM ,BIOGRAPHY (Literary form) ,TREES ,VALUES (Ethics) - Abstract
The movement of plants, animals, and microorganisms by humans, consciously or unconsciously, has changed both ecosystems and societies throughout history. This article focuses on one such transformative species, lodgepole pine, and its relocation from northwestern America to northern Sweden in the mid-twentieth century. A cultural biography of the lodgepole pine's existence in Sweden examines how this tree has been linked to different value regimes, which creates a historical pattern. Through so-called 'thinning processes', powerful actors, in both production forestry and the environmental movement, have tried to reduce the importance of the species to a limited meaning and context. At the same time, more arguments, knowledge and changed contexts have made the lodgepole pine a 'thick thing', with superimposed values and meanings. Although the tree has moved far geographically, from one continent to another, its importance has continued to be framed by interacting international, national and local perspectives. The lodgepole pine, however, is not just an inert thing that is determined by cultural discourses. It is a living tree, with its own ability to act and whose life in a foreign land has created a dynamic that crosses the border between nature and culture. [ABSTRACT FROM AUTHOR]
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- 2024
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7. The evolutionary species pool concept does not explain occurrence patterns of dead-wood-dependent organisms: implications for logging residue extraction
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Ranius, Thomas, Hämäläinen, Aino, Sjögren, Jörgen, Hiron, Matthew, Jonason, Dennis, Kubart, Ariana, Schroeder, Martin, Dahlberg, Anders, Thor, Göran, and Jonsell, Mats
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- 2019
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8. Concept Formation and Concept Grounding
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Sjögren, Jörgen and Bennet, Christian
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- 2014
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9. Multi-scale mosaics in top-down pest control by ants from natural coffee forests to plantations
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Stuber, Moritz, Tack, Ayco J. M., Zewdie, Beyene, Mendesil, Esayas, Shimales, Tamiru, Ayalew, Biruk, Nemomissa, Sileshi, Sjögren, Jörgen, Sjogren, Jorgen, Vesterinen, Eero, Wezel, Alexander, and Hylander, Kristoffer
- Subjects
Ecology - Abstract
While top-down control plays an important role in shaping both natural and agricultural food webs, we lack insights into how top-down control effects vary across spatial scales. We used a multi-scale survey of top-down control of coffee pests and diseases by arboreal ants to examine if colony location creates a small-scale mosaic in top-down control around trees and if the strength of that control varies between sites at the landscape scale. We investigated pest and disease levels on coffee shrubs at different distances from shade trees with and without a Crematogaster spp. ant colony in 59 sites along a coffee management intensity gradient in southwestern Ethiopia. Within sites, ants significantly suppressed herbivory and coffee leaf rust at distances less than 10 m from nesting trees. Top-down control varied between sites, with stronger top-down control of free-feeding herbivory near ant colonies at sites with lower management intensity and stronger top-down control of a skeletonizer at sites with higher canopy cover. We conclude that the strength of top-down control by ants is highly heterogeneous across spatial scales, as a consequence of the biology of the predator at the small scale and herbivore density or changes in herbivore-ant interactions at the landscape scale.
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- 2021
10. Tree species identity and composition shape the epiphytic lichen community of structurally simple boreal forests over vast areas
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Klein, Julian, Low, Matthew, Thor, Göran, Sjögren, Jörgen, Lindberg, Eva, and Eggers, Sönke
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Ecological Metrics ,Lichens ,Science ,Plant Science ,Forests ,Ecosystems ,Trees ,Dendrology ,Symbiosis ,Sweden ,Ecology ,Forest Science ,Ecology and Environmental Sciences ,Organisms ,Biology and Life Sciences ,Eukaryota ,Species Diversity ,Biodiversity ,Plants ,Pinus ,Terrestrial Environments ,Lichenology ,Medicine ,Spruces ,Pines ,Research Article - Abstract
Greatly simplified ecosystems are often neglected for biodiversity studies. However, these simplified systems dominate in many regions of the world, and a lack of understanding of what shapes species occurrence in these systems can have consequences for biodiversity and ecosystem services at a massive scale. In Fennoscandia, ~90% of the boreal forest (~21Mha) is structurally simplified with little knowledge of how forest structural elements shape the occurrence and diversity of for example epiphytic lichens in these managed forests. One form of structural simplification is the reduction of the number and frequency of different tree species. As many lichen species have host tree preferences, it is particularly likely that this simplification has a huge effect on the lichen community in managed forests. In a 40-70 years old boreal forest in Sweden, we therefore related the occurrence and richness of all observed epiphytic lichens to the host tree species and beta and gamma lichen diversity at the forest stand level to the stand's tree species composition and stem diameter. Picea abies hosted the highest lichen richness followed by Pinus sylvestris, Quercus robur, Alnus glutinosa, Betula spp., and Populus tremula. However, P. tremula hosted twice as many uncommon species as any of the other tree species. Stand level beta and gamma diversity was twice as high on stands with four compared to one tree species, and was highest when either coniferous or deciduous trees made up 40-50% of the trees. The stem diameter was positively related to lichen richness at the tree and stand level, but negatively to beta diversity. For biodiversity, these findings imply that leaving a few trees of a different species during forest thinning is unlikely as effective as combining life-boat trees for endangered species with an even tree species mixture.
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- 2021
11. A Note on the Relation Between Formal and Informal Proof
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Sjögren, Jörgen
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- 2010
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12. ON EXPLICATING THE CONCEPT THE POWER OF AN ARITHMETICAL THEORY
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Sjögren, Jörgen
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- 2008
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13. An empirical model for forest landscape planning and its financial consequences for landowners.
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Bostedt, Göran, de Jong, Johnny, Ekvall, Hans, Hof, Anouschka R., Sjögren, Jörgen, and Zabel, Astrid
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FINANCIAL planning ,ENVIRONMENTAL protection ,LANDSCAPES ,FOREST productivity ,FOREST landowners ,LANDOWNERS ,FOREST conservation - Abstract
Despite well-formulated goals for environmental protection in the forestry sector, the biodiversity crisis remains. Protected habitats are often small, isolated and lack continuity. We studied forest planning at a landscape scale as a method to increase habitat connectivity, and improve conservation values whilst maintaining high levels of forest production. We assessed the financial impacts of landscape planning for the landowners, and present a fee-fund system to solve unequal burdens among them. As case studies, we used three landscapes along a latitudinal gradient in Sweden. The results demonstrate some variation between the landscapes in terms of the total cost for set asides and large differences in terms of the financial impact per landowner. Our conclusion is that forest landscape planning may be a way forward to improve conservation efforts, but given the variation in financial impacts, we propose to combine landscape planning with economic tools for compensation. [ABSTRACT FROM AUTHOR]
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- 2021
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14. Retention forestry amplifies microclimate buffering in boreal forests.
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Zhang, Shengmin, Sjögren, Jörgen, and Jönsson, Mari
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TAIGAS , *EDGE effects (Ecology) , *FORESTS & forestry , *OLD growth forests , *TREE mortality , *DEAD trees , *LANDSCAPE assessment - Abstract
• We investigated the thermal buffering of forest retention practices. • T max was lower in retention forests than in clear-cuts but higher than in old forests. • Basal area and canopy cover were identified as key factors impacting microclimates. • Preserving tree diversity and standing deadwood enhance stands' thermal buffering. • Lying deadwood related negatively to canopy cover, likely lowering thermal buffering. Retention forestry is increasingly adopted as an alternative to clearcutting practices and involves retaining structural and compositional complexity (e.g., living and dead trees) from preharvest to postharvest. Past studies have examined the role of retention forestry in supporting various ecosystem functions and biodiversity, whilst its microclimate buffering capacity has been largely neglected. We investigated the microclimates and the underlying mechanisms of retention forests relative to clearcuts and old forests in a boreal forest landscape in central Sweden. We found that both air temperature and vapour pressure deficit (VPD) differed significantly between the forest types. Old forests consistently exhibited the most buffered forest microclimates, followed by retention forests, while clearcuts displayed the lowest. Basal area and canopy cover were identified as the key determinants influencing air temperature and VPD across the forest types. Retention practices can also impact a stand's microclimates. Specifically, maintaining diverse tree species had the potential to lower the stand's maximum temperature, given its positive association with canopy cover. Large volumes of lying deadwood were found to be negatively correlated with both basal area and canopy cover, likely contributing to increased maximum temperatures. Furthermore, standing deadwood directly lowered the maximum temperature within forest stands. Finally, edge effects were observed in the retention forests, with south-facing edges experiencing significantly higher maximum temperature and VPD compared to north-facing edges and forest interiors. These south-facing edge effects were positively associated with the difference in lying deadwood volumes between forest edges and interiors. Our findings support the positive influence of retention practices on a stand's microclimate buffering, achieved through preserving diverse tree species, standing deadwood, and implementing measures to prevent severe wind-induced tree mortality, particularly in south-facing edges (e.g. creating south-facing buffer zones). Forest managers and policy makers can utilize these results to minimize the climate-change impacts on below-canopy biodiversity and functioning. [ABSTRACT FROM AUTHOR]
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- 2024
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15. Boreal forest fertilization leads to functional homogenization of ground beetle assemblages.
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Rodríguez, Antonio, Hekkala, Anne‐Maarit, Sjögren, Jörgen, Strengbom, Joachim, and Löfroth, Therese
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GROUND beetles ,TAIGAS ,FOREST biodiversity ,TREE farms ,CARBON sequestration ,BODY composition - Abstract
Intensive fertilization of young spruce forest plantations (i.e. 'nutrient optimization') has the potential to meet increasing demands for carbon sequestration and biomass production from boreal forests. However, its effects on biodiversity, other than the homogenization of ground‐layer plant communities, are widely unknown.We sampled ground beetles (Coleoptera: Carabidae) in young spruce forest plantations of southern Sweden, within a large‐scale, replicated ecological experiment initiated in 2012, where half of the forest stands were fertilized every second year. We assessed multi‐scale effects of forest fertilization on ground beetle diversity and community assembly, 4 years after commencement of the experiment.We found that nutrient optimization had negative effects on ground beetle diversity at multiple spatial scales, despite having negligible effects on species richness. At the local scale, ground beetle species had lower variation in body size at fertilized sites, resulting in within‐site functional homogenization. At the landscape scale, fertilized sites, with higher basal area and lower bilberry cover, filtered carabid traits composition to larger body sizes, generalist predators and summer breeding species.Synthesis and applications. Fertilization of young spruce plantations is a strong filter for ground beetle assemblages, leading to functionally homogeneous communities in the short term, without changes in species richness. The large‐scale functional impoverishment of carabid communities because of fertilization may have negative consequences on system resilience and on ecosystem service provision by this functionally diverse group. Large‐scale establishment of nutrient optimization threatens ground beetle diversity in young conifer plantations, underlining the risks of introducing more intensive management schemes in already heavily managed forest landscapes. [ABSTRACT FROM AUTHOR]
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- 2021
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16. A struggling collaborative process – revisiting the woodland key habitat concept in Swedish forests.
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Bjärstig, Therese, Sandström, Camilla, Sjögren, Jörgen, Soneson, Johan, and Nordin, Annika
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FORESTS & forestry ,HABITATS ,BUDGET process ,CONCEPTS - Abstract
The term woodland key habitat (WKH) was launched in Sweden in 1990. Definitions for the concept have changed over the years, and today the WKH concept and its application are issues of debate in Sweden. Consequently, the Swedish Forestry Agency (SFA) initiated a collaborative process including forest stakeholders with the purpose to clarify the application and develop the inventory methodology of WKH. We have studied, by means of interviews and observations, participant perceptions of how endogenous and exogenous factors affect the collaborative process. During our research, we identified three game changers: the pause in WKH registration in northwestern Sweden that caused several participants to drop out of the process; budget allocations for new nationwide WKH inventories that put the process on hold; and formal instructions from the government that came nine months later and essentially re-initiated the collaborative process. Altogether, this not only affected the participants' abilities, understanding and willingness to participate, but also the overall legitimacy of the process – indicating the difficulty of conducting policy development in collaborative form, especially when it is highly politicized since it impact on the participants' anticipation of the process and its end results. [ABSTRACT FROM AUTHOR]
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- 2019
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17. Reinventory of permanent plots show that kelo lichens face an extinction debt.
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Larsson Ekström, Albin, Sjögren, Jörgen, Djupström, Line Boberg, Thor, Göran, and Löfroth, Therese
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LICHENS , *PRESCRIBED burning , *WOOD , *ENDANGERED species , *SPECIES diversity - Abstract
Intensive forestry has led to landscape level deficits of important substrates such as deadwood and its associated biodiversity. Several taxa face extinction debts due to continuous declines and lack of regeneration of important habitats. Deadwood-dependent lichens are of great conservation concern due to a general lack of deadwood and due to their slow establishment, especially of rare species. In a field restoration experiment in central Sweden, we studied deadwood-dependent lichens for eight years, their association to different types of deadwood and their response to environmental change caused by variable retention forestry, deadwood enrichment and prescribed burning. Prescribed burning and site preparation caused depauperate lichen species assemblages throughout the study period but retention felling did not majorly affect lichen species assemblages. We found that lichen species were nested along deadwood qualities and deadwood created in the experiment only hosted a subset of lichen species found on kelo wood. Despite large reductions of kelo wood with lichen occurrences over the study period, overall species richness did not decrease. The fact that a large part of the lichen community occur only on kelo wood and that kelo wood is not regenerated implies that lichens associated with kelo wood face an extinction debt. In order to avoid local extinctions of deadwood-dependent lichens, site preparation and prescribed burning should be avoided in areas rich in high quality deadwood. There is urgent need to start creating new kelo wood through reoccurring fires in order to halt the impending extinction debt. • Kelo wood supports overall lichen biodiversity. • Lichens face an extinction debt due to the scarcity of kelo wood. • Prescribed burning and site preparation causes depauperate lichen communities. [ABSTRACT FROM AUTHOR]
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- 2023
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18. Semi-domesticated reindeer avoid winter habitats with exotic tree species Pinus contorta.
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Horstkotte, Tim, Sandström, Per, Neumann, Wiebke, Skarin, Anna, Adler, Sven, Roos, Ulrika, and Sjögren, Jörgen
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INTRODUCED species ,LODGEPOLE pine ,HOME range (Animal geography) ,EPIPHYTIC lichens ,REINDEER ,HABITAT selection ,FOREST soils ,SOIL invertebrates - Abstract
• Semi-domestic reindeer avoid stands of the exotic tree species Pinus contorta. • Terricolous lichens as winter forage are less abundant in stands of P. contorta. • P. contorta is planted mainly on soils where terricolous lichens could thrive. • These effects reduce grazing grounds in addition to other cumulative impacts. The introduction of exotic tree species can have profound effects on the native environment, including habitat use and movement patterns of animals, as well as becoming a management challenge for other land users. Here, we used GPS data from reindeer (Rangifer tarandus) and remote sensing measurements of lichen cover and soil moisture to assess the effects of the exotic lodgepole pine (Pinus contorta) on reindeer husbandry by the Indigenous Sámi in northern Sweden. We used locational data from 67 reindeer for three winters to analyze their habitat selection at the second-order selection (placement of home range in the landscape) and third-order selection (selection of sites within the home range) in relation to land cover class, terricolous lichen cover as measure of winter forage abundance, topographic features, and distance to roads. We also analyzed remotely sensed abundance of lichens in different forest types, and the association between these forest types and soil moisture as measure of suitability as lichen habitat. Compared to native P. sylvestris , we found that reindeer avoided stands with P. contorta where trees were higher than three meters. If P. contorta was the dominant tree species, reindeer were 60 % less likely to select these stands compared to stands with P. sylvestris , and 40 % less likely if P. contorta was less dominant at both orders of selection. We also found that reindeer selected areas with higher lichen cover. Lichen cover was lower in P. contorta stands compared to stands of the native P. sylvestris , even though P. contorta occurred mainly on dry soils usually favorable for terricolous lichens. We conclude that planting P. contorta on soils suitable for terricolous lichens is likely to reduce forage availability for reindeer and turn habitats earlier preferred by reindeer into avoided habitat, resulting in an overall reduction of winter grazing grounds. The effects of stands with P. contorta , albeit covering a comparatively small percentage of the reindeer husbandry area, need to be seen in context with generally declining terricolous lichen abundance due to land uses like forestry and other cumulative effects by external pressures on reindeer husbandry. [ABSTRACT FROM AUTHOR]
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- 2023
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19. Concept Formation in Mathematics
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Sjögren, Jörgen
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Explication, Power of arithmetical theories, Formal Proof, Informal proof, Indispensability, Mathematical Realism - Abstract
This thesis consists of three overlapping parts, where the first one centers around the possibility of defining a measure of the power of arithmetical theories. In this part a partial measure of the power of arithmetical theories is constructed, where ''power'' is understood as capability to prove theorems. It is also shown that other suggestions in the literature for such a measure do not satisfy natural conditions on a measure. In the second part a theory of concept formation in mathematics is developed. This is inspired by Aristotle's conception of mathematical objects as abstractions, and it uses Carnap's method of explication as a means to formulate these abstractions in an ontologically neutral way. Finally, in the third part some problems of philosophy of mathematics are discussed. In the light of this idea of concept formation it is discussed how the relation between formal and informal proof can be understood, how mathematical theories are tested, how to characterize mathematics, and some questions about realism and indispensability.
- Published
- 2011
20. Long-term yield and biodiversity in stands managed with the selection system and the rotation forestry system: A qualitative review.
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Ekholm, Adam, Lundqvist, Lars, Petter Axelsson, E., Egnell, Gustaf, Hjältén, Joakim, Lundmark, Tomas, and Sjögren, Jörgen
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FORESTS & forestry ,BIODIVERSITY ,ROTATIONAL motion ,MIDDLE-aged persons ,FOREST productivity ,WILDLIFE conservation ,MIDDLE-aged women - Abstract
• Continuous Cover Forestry is highly debated. • We reviewed long-term yield and biodiversity between two silviculture systems. • Comparative studies between silviculture systems are inconclusive. • Species sensitive to clearcutting may benefit from Continuous Cover Forestry. • More long-term experiments are needed, especially on conservation species. There is an increasing interest in implementing Continuous Cover Forestry (CCF) as a tool to mitigate negative effects of the traditional rotation forestry system on biodiversity. However, the effects of CCF on forest growth and yield and on biodiversity is still poorly known. In this qualitative review, we compare biodiversity and long-term yield between the selection system, which is a type of CCF practiced in full-storied forests, and the traditional rotation forestry system. We specifically focus on forests dominated by Picea abies , which is a tree species of high economic relevance. Our literature search resulted in 17 publications on stand growth and yield and 21 publications on biodiversity. A majority of simulation studies found a higher long-term yield in the rotation forestry system, but it is challenging to conclude which system is the most productive. The magnitude of the difference in yield between systems, and how it varies across different environmental conditions, remains to be determined. For biodiversity, comparisons of species assemblage and individual species were only made to certain phases of the rotation cycle (recent clearcuts and middle-aged stands). Nevertheless, two aspects can be highlighted: i) the species assemblage in clearcuts differ substantially from stands managed with the selection system. Some of these effects may however be short lasting as examplified by studies on beetle assamblages showing that middle-aged rotation forestry stands become more similar to stands managed with the selection system, ii) the selection system maintains a similar species assemblage as the uncut control during the first years after cutting. In conclusion, management with the selection system may come with a loss in long-term stand yield, but much of the species assemblage is maintained after logging. We recommend future studies to specifically focus on long-term effects on biodiversity – in particular on species of conservation concern. There is also a need to establish a long-term research infrastructure to further develop the field. [ABSTRACT FROM AUTHOR]
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- 2023
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21. Flow-on effects of an introduced tree species: Lodgepole pine plantation affects function and performance of boreal ants.
- Author
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Löfroth, Therese, Andersson, Jon, Roberge, Jean-Michel, and Sjögren, Jörgen
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INTRODUCED species ,LODGEPOLE pine ,FIRE ants ,ANTS ,STAPHYLINIDAE ,DEAD trees ,TYPHA latifolia - Abstract
• Pinus contorta constitutes less favorable habitat for ants than P. sylvestris. • Ant species richness and ant foraging activity was lower in P. contorta stands. • Competition release did not compensate for lower habitat quality in P. contorta stands. • Introduced tree species impact epigaeic assemblages. Increased demand on forests to produce renewable biomass have accelerated the use of non-native tree species in forestry worldwide, often with negative effects on native biodiversity. In Sweden, the North American lodgepole pine (Pinus contorta Douglas ex. Loudon var. latifolia) was introduced already in the 1970's. Even though the species now covers large areas, effects on native flora and fauna have not been thoroughly evaluated. In this study, we used a large-scale field experiment with 30 paired P. contorta and P. sylvestris stands in central and northern Sweden to study the effects of P. contorta plantation on the abundance and activity of red wood ants of the Formica rufa -group, density and species richness of other ant species, as well as possible effects on the abundance of the specialized ant predator Pella humeralis. We collected epigaeic insects with pit fall traps, surveyed wood ant mound density and volume, and monitored ant activity on trees in all stands. Our analyses revealed a trend with higher mound density in P. sylvestris compared with P. contorta stands, although wood ant worker catch did not differ between the pine species. However, red wood ant activity was significantly higher in P. sylvestris stands, suggesting that P. contorta is not a preferred tree species for the tending of aphids for honeydew. Total ant species richness as well as the catch of Camponotus herculeanus and Myrmica ruginodis were higher in P. sylvestris stands, suggesting that they constitute a more favorable habitat for ants. Ant species richness was negatively influenced by wood ants in P. sylvestris stands only. A similar pattern was shown for C. herculeanus. Myrmica ruginodis was more abundant in P. sylvestris stands only if no thinning had been applied. Wood ant catch was positively correlated with catch of the specialized predatory rove beetle Pella humeralis showing that there is a strong interaction between the predatory beetle and wood ants. Our results suggest that P. contorta plantations impact both red wood ants and associated species and although competition from wood ants is more pronounced in P. sylvestris stands they still constitute a more favorable habitat for most ant species. Thus, large scale plantation of the non-native but closely related P. contorta may negatively impact epigaeic assemblages, a pattern that is not compensated by released competition by dominant red wood ants. [ABSTRACT FROM AUTHOR]
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- 2022
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22. Short-term experimental support for bird diversity retention measures during thinning in European boreal forests.
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Klein, Julian, Low, Matthew, Sjögren, Jörgen, and Eggers, Sönke
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BIRD diversity ,TAIGAS ,SUSTAINABLE forestry ,GREAT tit ,FOREST thinning ,BIRDHOUSES ,BIRD populations - Abstract
• Experiment: conventional thinning reduced bird diversity in Swedish boreal forest. • Understory retention and complete retention plots could retain bird diversity. • The willow tit (Poecile montanus) was especially negatively affected. • Novel BACI indicators for evaluating experiments and Bayesian MSOM were used. • A long-term evaluation of the post thinning development is needed. Current levels of forestry expansion in boreal forests threaten to radically reduce biodiversity. For many forest-dwelling species the threat is not simply because the forest is used for biomass production, but rather how it is used. Retention forestry practices aim to limit impacts on biodiversity during the final felling stage of a forestry cycle. However, the efficiency of such methods in retaining biodiversity have rarely been studied for intermediate forestry stages (e.g., forest thinning) with experimental approaches entirely absent from boreal forests. Therefore, we conducted a before-after control-impact experiment in Sweden to investigate the short-term response in occurrence of individual bird species, guilds, and population trend groups (positive, stable, or negative population trend), as well as the response in nest box occupancy and in the reproductive success of Parus major to three different thinning treatments. The three treatments were i) conventional thinning at the plot and stand scale, (ii) understory retention thinning, where at least 250 spruces with live branches below 2 m above ground are retained per hectare, and (iii) complete retention plots, where the forest was not thinned on ∼1 ha plots within conventionally thinned forest stands. We found that conventional forest thinning was likely the cause for observed declines in bird occurrence, with ∼20% of the species showing clear negative responses. Our results indicate that understory retention thinning with double the retention level as previously suggested and combining conventional thinning with complete retention plots, could largely alleviate the short term negative effects of conventional thinning. This was the case for all guilds, population trend groups and individual bird species, except for Poecile montanus , which responded negatively to complete retention. Among the birds occupying the nest boxes, only Cyanistes caeruleus responded to any of the treatments, with higher nest box occupancy upon understory retention thinning. No thinning treatment affected reproductive success in P. major. Our results clearly show that thinning practices that retain the diversity of forest-dwelling birds are possible. Hence, this study provides a crucial puzzle piece towards more sustainable forestry practices in the boreal region. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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23. Antifungal compounds from cultures of dairy propionibacteria type strains.
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Lind, Helena, Sjögren, Jörgen, Gohil, Suresh, Kenne, Lennart, Schnürer, Johan, and Broberg, Anders
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- *
ANTIFUNGAL agents , *PROPIONIBACTERIUM , *GRAM-positive bacteria , *CYCLIC peptides , *HIGH performance liquid chromatography , *MICROBIOLOGY - Abstract
Antifungal compounds from cultures of five type strains of dairy propionibacteria, as well as from the cultivation medium, were studied. Cell-free supernatants and medium were fractionated by C18 solid phase extraction. The aqueous 95% acetonitrile fractions were analyzed by GC-MS or subjected to reversed-phase HPLC, to identify, quantify or isolate antifungal substances. The resulting HPLC fractions were screened for antifungal activity against the mold Aspergillus fumigatus and the yeast Rhodotorula mucilaginosa. Active fractions were further separated by HPLC and the structures of the compounds were determined by spectroscopic and chromatographic methods. All five strains produced 3-phenyllactic acid, at concentrations ranging from 1.0 μg mL−1 ( Propionibacterium freudenreichii ssp. shermanii) to 15.1 μg mL−1 ( Propionibacterium thoenii), and atl/d -ratios ranging from 2 : 3 ( Propionibacterium acidipropionici) to 9 : 1 ( Propionibacterium freudenreichii). A number of active compounds found in cultures of propionibacteria were also present in noninoculated growth medium: two antifungal diketopiperazines, cyclo(l-Phe-l-Pro) and cyclo(l-Ile-l-Pro), and seven antifungal linear peptides. Three of the linear peptides corresponded to sequences found in the medium component casein, suggesting their origin from this component, whereas the diketopiperazines were suggested to be formed from medium peptides by heat treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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24. Antifungal 3-Hydroxy Fatty Acids from Lactobacillus plantarum MiLAB 14.
- Author
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Sjögren, Jörgen, Magnusson, Jesper, Broberg, Anders, Schnürer, Johan, and Kenne, Lennart
- Subjects
- *
LACTOBACILLUS plantarum , *FATTY acids - Abstract
We report the identification and chemical characterization of four antifungal substances, 3-(R)-hydroxydecanoic acid, 3-hydroxy-5-cis-dodecenoic acid, 3-(R)-hydroxydodecanoic acid and 3-(R)-hydroxytetradecanoic acid, from Lactobacillus plantarum MiLAB 14. The concentrations of the 3-hydroxy fatty acids in the supernatant followed the bacterial growth. Racemic mixtures of the saturated 3-hydroxy fatty acids showed antifungal activity against different molds and yeasts with MICs between 10 and 100 µg ml[sup -1]. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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25. Broad and complex antifungal activity among environmental isolates of lactic acid bacteria
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Magnusson, Jesper, Ström, Katrin, Roos, Stefan, Sjögren, Jörgen, and Schnürer, Johan
- Subjects
LACTIC acid bacteria ,ANTIFUNGAL agents - Abstract
More than 1200 isolates of lactic acid bacteria isolated from different environments were screened for antifungal activity in a dual-culture agar plate assay. Approximately 10% of the isolates showed inhibitory activity and 4% showed strong activity against the indicator mould Aspergillus fumigatus. The antifungal spectra for 37 isolates with strong activity and five isolates with low or no activity were determined. Several of the strains showed strong inhibitory activity against the moulds A. fumigatus, Aspergillus nidulans, Penicillium commune and Fusarium sporotrichioides, and also against the yeast Rhodotorula mucilaginosa. Penicillium roqueforti and the yeasts Pichia anomala and Kluyveromyces marxianus were not inhibited. Several isolates showed reduced antifungal activity after storage and handling. The majority of the fungal inhibitory isolates were identified by 16S rDNA sequencing as Lactobacillus coryniformis. Lactobacillus plantarum and Pediococcus pentosaceus were also frequently identified among the active isolates. The degree of fungal inhibition was not only related to production of lactic or acetic acid. In addition, antifungal cyclic dipeptides were identified after HPLC separation and several other active fractions were found suggesting a highly complex nature of the antifungal activity. [Copyright &y& Elsevier]
- Published
- 2003
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26. Lactobacillus plantarum MiLAB 393 Produces the Antifungal Cyclic Dipeptides Cyclo(L-Phe-L-Pro) and Cyclo(L-Phe-trans-4-OH-L-Pro) and 3-Phenyllactic Acid.
- Author
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Ström, Katrin, Sjögren, Jörgen, Broberg, Anders, and Schnürer, Johan
- Subjects
- *
LACTOBACILLUS plantarum , *MICROBIOLOGY - Abstract
We have isolated a Lactobacillus plantarum strain (MiLAB 393) from grass silage that produces broadspectrum antifungal compounds, active against food- and feed-borne filamentous fungi and yeasts in a dualculture agar plate assay. Fusarium sporotrichioides and Aspergillus fumigatus were the most sensitive among the molds, and Kluyveromyces marxianus was the most sensitive yeast species. No inhibitory activity could be detected against the mold Penicillium roqueforti or the yeast Zygosaccharomyces bailii. An isolation procedure, employing a microtiter well spore germination bioassay, was devised to isolate active compounds from culture filtrate. Cell-free supernatant was fractionated on a C[sub 18] SPE column, and the 95% aqueous acetonitrile fraction was further separated on a preparative HPLC C[sub 18] column. Fractions active in the bioassay were then fractionated on a porous graphitic carbon column. The structures of the antifungal compounds cyclo(L-PheL-Pro), cyclo(L-Phe-trans-4-OH-L-Pro) and 3-phenyllactic acid (L/D isomer ratio, 9:1), were determined by nuclear magnetic resonance spectroscopy, mass spectrometry, and gas chromatography. MIC values against A. fumigatus and P. roqueforti were 20 mg ml[sup -1] for cyclo(L-Phe-L-Pro) and 7.5 mg ml[sup -1] for phenyllactic acid. Combinations of the antifungal compounds revealed weak synergistic effects. The production of the antifungal cyclic dipeptides cyclo(L-Phe-L-Pro) and cyclo(L-Phe-trans-4-OH-L-Pro) by lactic acid bacteria is reported here for the first time. [ABSTRACT FROM AUTHOR]
- Published
- 2002
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27. Moving towards multi-layered, mixed-species forests in riparian buffers will enhance their long-term function in boreal landscapes.
- Author
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Maher Hasselquist, Eliza, Kuglerová, Lenka, Sjögren, Jörgen, Hjältén, Joakim, Ring, Eva, Sponseller, Ryan A., Andersson, Elisabet, Lundström, Johanna, Mancheva, Irina, Nordin, Annika, and Laudon, Hjalmar
- Subjects
RIPARIAN forests ,FOREST management ,DECIDUOUS forests ,BUFFER zones (Ecosystem management) ,RIPARIAN areas ,STREAM function ,AQUATIC biodiversity ,FOREST biodiversity - Abstract
• Forest management has promoted conifers and altered stream and riparian function. • We suggest delineating and managing riparian buffers throughout the rotation cycle. • Make multi-layered, mixed-species forests with more deciduous species the goal. • Riparian zones will provide functions throughout the rotation, not just at final-felling. Riparian buffers are the primary tool in forest management for protecting the habitat structure and function of streams. They help protect against biogeochemical perturbation, filter sediments and nutrients, prevent erosion, contribute food to aquatic organisms, regulate light and hence water temperature, contribute deadwood, and preserve biodiversity. However, in production forests of Sweden and Finland, many headwater streams have been straightened, ditched, and/or channelized, resulting in altered hydrology and reduced natural disturbance by floods, which in turn affects important riparian functions. Furthermore, in even-aged management systems as practiced in much of Fennoscandia, understory trees have usually been cleared right up to the stream's edge during thinning operations, especially around small, headwater streams. Fire suppression has further favored succession towards shade tolerant species. In the regions within Fennoscandia that have experienced this combination of intensive management and lack of natural disturbance, riparian zones are now dominated by single-storied, native Norway spruce. When the adjacent forest is cut, thin (5 - 15m) conifer-dominated riparian buffers are typically left. These buffers do not provide the protection and subsidies, in terms of leaf litter quality, needed to maintain water quality or support riparian or aquatic biodiversity. Based on a literature review, we found compelling evidence that the ecological benefits of multi-layered, mixed-species riparian forest with a large component of broadleaved species are higher than what is now commonly found in the managed stands of Fennoscandia. To improve the functionality of riparian zones, and hence the protection of streams in managed forest landscapes, we present some basic principles that could be used to enhance the ecological function of these interfaces. These management actions should be prioritized on streams and streamside stands that have been affected by simplification either through forest management or hydrological modification. Key to these principles is the planning and managing of buffer zones as early as possible in the rotation to ensure improved function throughout the rotation cycle and not only at final felling. This is well in line with EU and national legislation which can be interpreted as requiring landscape planning at all forest ages to meet biodiversity and other environmental goals. However, it is still rare that planning for conservation is done other than at the final felling stage. Implementing this new strategy is likely to have long-term positive effects and improve the protection of surface waters from negative forestry effects and a history of fire suppression. By following these suggested management principles, there will be a longer time period with high function and greater future management flexibility in addition to the benefits provided by leaving riparian buffers at the final felling stage. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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28. A Spatially Explicit Decision Support System for Assessment of Tree Stump Harvest Using Biodiversity and Economic Criteria.
- Author
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Jönsson, Mari, Sjögren, Jörgen, Hannrup, Björn, Larsolle, Anders, Mörtberg, Ulla, Nordström, Maria, Olsson, Bengt A., and Strömgren, Monika
- Abstract
Stump harvesting is predicted to increase with future increasing demands for renewable energy. This may affect deadwood affiliate biodiversity negatively, given that stumps constitute a large proportion of the coarse deadwood in young managed forests. Spatial decision support for evaluating the integrated effects on biodiversity and production of stump harvesting is needed. We developed a spatially explicit decision support system (called MapStump-DSS), for assessment of tree stump harvesting using biodiversity and economic criteria together with different scenarios for biodiversity conservation and bioenergy market prices. Two novel key aspects of the MAPStump-DSS is that it (1) merges and utilizes georeferenced stump-level data (e.g., tree species and diameter) directly from the harvester with stand data that are increasingly available to forest managers and (2) is flexible toward incorporating both quantitative and qualitative criteria based on emerging knowledge (here biodiversity criteria) or underlying societal drivers and end-user preferences. We tested the MAPStump-DSS on a 45 ha study forest, utilizing harvester data on characteristics and geographical positions for >26,000 stumps. The MAPStump-DSS produced relevant spatially explicit information on the biodiversity and economic values of individual stumps, where amounts of "conflict stumps" (with both high biodiversity and economical value) increased with bioenergy price levels and strengthened biodiversity conservation measures. The MAPStump-DSS can be applied in practice for any forest site, allowing the user to examine the spatial distribution of stumps and to obtain summaries for whole forest stands. Information depicted by the MAPStump-DSS includes amounts, characteristics, biodiversity values and costs of stumps in relation to different scenarios, which also allow the user to explore and optimize biodiversity and economy trade-offs prior to stump harvest. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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29. What is good for birds is not always good for lichens: Interactions between forest structure and species richness in managed boreal forests.
- Author
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Klein, Julian, Thor, Göran, Low, Matthew, Sjögren, Jörgen, Lindberg, Eva, and Eggers, Sönke
- Subjects
SPECIES diversity ,TAIGA ecology ,TAIGAS ,FOREST thinning ,EPIPHYTIC lichens ,FOREST density - Abstract
• How forest thinning affects biodiversity in boreal regions is largely unknown. • The vertical distribution and density of forest was measured with LiDAR. • Optimal vegetation density distributions were identified for lichens and birds. • Across taxa richness is highest if the forest is dense below 3 m and open above 3 m. • Clear and implementable management recommendations are given to practitioners. Forestry in the boreal region increasingly replaces natural disturbances in shaping biodiversity. Large-scale removal of small diameter trees (thinning), is ubiquitous in northern European forestry, yet an understanding of how it relates to biodiversity across taxa is lacking. To address this, we examined how two forest structural elements, commonly impacted by forest thinning (i.e. vegetation density in the understory and overstory), are correlated with the species richness of forest-dwelling birds and epiphytic lichens. These taxa were chosen because they likely have opposing habitat demands: epiphytic lichens potentially benefitting from more light in open forests, and birds benefitting from structurally complex forests for foraging, nesting and cover. We used remote sensing tools, already applied in forestry planning, to see if management recommendations could be found that balance the needs of both taxonomic groups within the same forests. Our results show that richness in epiphytic lichens and forest-dwelling birds is not correlated and that a high species richness (~15 birds & ~40 epiphytic lichens) in both taxa is only predicted in the same stand under a specific vertical distribution and density of the forest's vegetation: this occurs when the vegetation above 3 m is open (to promote epiphytic lichen richness) and below 3 m is dense (to promote bird richness). Dense vegetation up to 7 m above ground has a diverging effect on forest birds (positive) and epiphytic lichens (negative). A larger stem diameter further increases species richness in both taxa. Our study provides results that are directly implementable in forestry planning over large areas with the help of remote sensing tools (LiDAR). [ABSTRACT FROM AUTHOR]
- Published
- 2020
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30. Deadwood manipulation and type determine assemblage composition of saproxylic beetles and fungi after a decade.
- Author
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Larsson Ekström, Albin, Djupström, Line Boberg, Hjältén, Joakim, Sjögren, Jörgen, Jönsson, Mari, and Löfroth, Therese
- Subjects
- *
FOREST restoration , *BIOTIC communities , *FOREST conservation , *FOREST management , *TAIGAS , *DEAD trees , *SCOTS pine - Abstract
The biodiversity crisis calls for immediate restoration of deteriorated and rare habitat. Due to fire suppression and intensive forest management, boreal pine forests of high conservation value are exceptionally rare. Despite decades of restoration research in boreal forests, relatively few studies have evaluated multi-taxon biodiversity response of restoration measures in pine forests. In a Scots pine experiment, we investigated biodiversity patterns of wood-inhabiting fungi and beetles a decade after restoration (prescribed burning and deadwood creation) and forest management (harvest with varying retention). We found that fungi and beetles develop differently and have distinct preferences in deadwood originating from restoration. Standing deadwood supported more species for beetles and lying deadwood for fungi and for both taxa, standing and lying deadwood harboured different species assemblages. Burned deadwood displayed less variable assemblages than unburned deadwood for both organism groups. We found that, after a decade, deadwood type and not harvest with different retention levels better explained diversity patterns of wood-inhabiting beetles and fungi in pine forests. Pine forests are naturally prone to recurring disturbances creating open light conditions. Pine-associated species are therefore likely resistant to disturbance as long as a variety of deadwood resources are present. To accommodate multiple taxa, a variety of substrate and environment types is required. Beetles benefit from standing deadwood while fungi benefit from lying deadwood. To support assemblages with both rapid and slow turnover rates, a combination of recurring restoration and leaving restored stands in the adjacent landscapes is required. • Substrate type was more influential than retention level for saproxylic biodiversity. • Logs host more fungal species than snags. • Snags host more beetle species than logs. • Deadwood types hosted different saproxylic assemblages. • Different deadwood types and decay stages are needed to support saproxylic biodiversity. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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31. Habitat heterogeneity is a good predictor of boreal forest biodiversity.
- Author
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Hekkala, Anne-Maarit, Jönsson, Mari, Kärvemo, Simon, Strengbom, Joachim, and Sjögren, Jörgen
- Subjects
- *
TAIGAS , *HABITATS , *FOREST biodiversity , *FORESTS & forestry , *SPECIES diversity , *SUSTAINABLE forestry , *TREE age - Abstract
[Display omitted] • Habitat heterogeneity and resource amount and quality were tested as indicators. • Habitat heterogeneity predicts the richness of species of conservation concern. • Dead wood and tree age predict the richness of red-listed species. • Thresholds for habitat heterogeneity score and deadwood were calculated. • Habitat heterogeneity score is useful tool in practical forestry and conservation. Reliable assessment measures are crucial for tracking changes in biodiversity and for evaluating the state of biodiversity. Two of the main drivers of biodiversity are habitat heterogeneity and resource amount. These drivers are used as proxies of biodiversity but assessing both is costly, limiting their practical use. To test which of the drivers best predicts the number and abundance of sessile species of conservation concern (including macrofungi, lichens, bryophytes, and vascular plants), we assessed forest stand heterogeneity using a method developed in Sweden ('Habitat Heterogeneity Score HHS'), and quantified the resource amount and quality of ecologically important structural variables (deadwood volume, basal area of living trees, proportion of broadleaved trees, and the age of the oldest tree in the stand). We conducted the assessments in 77 boreal conifer-dominated forest stands in two regions of Sweden. Despite some group-specific organism differences, HHS was the best predictor of both number and abundance of all species of conservation concern, regardless of the region. Further, HHS was the best predictor of red-listed species number and abundance in the southern region, while a model including the volume of deadwood and the age of the oldest tree performed best in the northern region. Deadwood (CWD) volume was the single best resource amount predictor of the number and abundance of species of conservation concern, emphasizing the critical role that dead trees have for biodiversity. In addition, we calculated threshold values for deadwood volume and HHS depicting the level above which the number of red-listed species is significantly higher, and found this value to be higher in the southern region (22.4 m3 ha−1 deadwood and a HSS value of 17) than in the north (20.0 m3 ha−1 and 16). These values can be used as guidance when identifying coniferous forests with high enough qualities to support red-listed species. To conclude, the method of assessing habitat heterogeneity presented in this study is a practical and reliable way to identify forests of high biological diversity, and can therefore be part of the toolbox for sustainable forestry in boreal forests. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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32. Tree species identity and composition shape the epiphytic lichen community of structurally simple boreal forests over vast areas.
- Author
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Klein J, Low M, Thor G, Sjögren J, Lindberg E, and Eggers S
- Subjects
- Biodiversity, Lichens classification, Lichens physiology, Pinus, Sweden, Symbiosis, Forests, Lichens growth & development
- Abstract
Greatly simplified ecosystems are often neglected for biodiversity studies. However, these simplified systems dominate in many regions of the world, and a lack of understanding of what shapes species occurrence in these systems can have consequences for biodiversity and ecosystem services at a massive scale. In Fennoscandia, ~90% of the boreal forest (~21Mha) is structurally simplified with little knowledge of how forest structural elements shape the occurrence and diversity of for example epiphytic lichens in these managed forests. One form of structural simplification is the reduction of the number and frequency of different tree species. As many lichen species have host tree preferences, it is particularly likely that this simplification has a huge effect on the lichen community in managed forests. In a 40-70 years old boreal forest in Sweden, we therefore related the occurrence and richness of all observed epiphytic lichens to the host tree species and beta and gamma lichen diversity at the forest stand level to the stand's tree species composition and stem diameter. Picea abies hosted the highest lichen richness followed by Pinus sylvestris, Quercus robur, Alnus glutinosa, Betula spp., and Populus tremula. However, P. tremula hosted twice as many uncommon species as any of the other tree species. Stand level beta and gamma diversity was twice as high on stands with four compared to one tree species, and was highest when either coniferous or deciduous trees made up 40-50% of the trees. The stem diameter was positively related to lichen richness at the tree and stand level, but negatively to beta diversity. For biodiversity, these findings imply that leaving a few trees of a different species during forest thinning is unlikely as effective as combining life-boat trees for endangered species with an even tree species mixture., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2021
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33. Multi-scale mosaics in top-down pest control by ants from natural coffee forests to plantations.
- Author
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Stüber M, Tack AJM, Zewdie B, Mendesil E, Shimales T, Ayalew B, Nemomissa S, Sjögren J, Vesterinen E, Wezel A, and Hylander K
- Subjects
- Herbivory, Pest Control, Trees, Coffee, Forests
- Abstract
While top-down control plays an important role in shaping both natural and agricultural food webs, we lack insights into how top-down control effects vary across spatial scales. We used a multi-scale survey of top-down control of coffee pests and diseases by arboreal ants to examine if colony location creates a small-scale mosaic in top-down control around trees and if the strength of that control varies between sites at the landscape scale. We investigated pest and disease levels on coffee shrubs at different distances from shade trees with and without a Crematogaster spp. ant colony in 59 sites along a coffee management intensity gradient in southwestern Ethiopia. Within sites, ants significantly suppressed herbivory and coffee leaf rust at distances less than 10 m from nesting trees. Top-down control varied between sites, with stronger top-down control of free-feeding herbivory near ant colonies at sites with lower management intensity and stronger top-down control of a skeletonizer at sites with higher canopy cover. We conclude that the strength of top-down control by ants is highly heterogeneous across spatial scales, as a consequence of the biology of the predator at the small scale and herbivore density or changes in herbivore-ant interactions at the landscape scale., (© 2021 The Authors. Ecology published by Wiley Periodicals LLC on behalf of Ecological Society of America.)
- Published
- 2021
- Full Text
- View/download PDF
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