| 1. |
- Hahn, Thomas, 1964-, et al.
(författare)
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Specified resilience value of alternative forest management adaptations to storms
- 2021
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 36:7-8, s. 585-597
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Tidskriftsartikel (refereegranskat)abstract
- Resilient ecosystems provide natural insurance value, or resilience value, to the landowner and to society at large. In response to global calls for integrating biodiversity in sector policy and planning, we analysed the specified resilience value by simulating three storm regimes and five management scenarios: Business As Usual/BAU (spruce-dominance), Spruce Monoculture, More Broadleaves, Continuous Cover Forestry (CCF), and No Thinnings. The forest decision support system Heureka RegWise was used to simulate the effects of storms on forest dynamics and Net Present Value (NPV). No Thinnings, CCF and More Broadleaves were more resilient to storms (reduced damage cost) compared to BAU. BAU had the highest NPV only if storms are ignored, a common assumption in today’s forest planning. Given storms, No Thinnings maximises NPV on landscape level. On the 20% most vulnerable plots the NPV was much higher for No Thinnings and slightly higher for CCF and More Broadleaves, compared to BAU. CCF and More Broadleaves also provide nature-based solutions (co-benefits) including public goods. However, forestry adaptations to storms are slow in Sweden, in contrast to e.g. German state forestry which emphasises maximising tree growth and resilience to several stresses and disturbances rather than NPV optimisation.
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| 2. |
- Pretzsch, Hans, et al.
(författare)
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With increasing site quality asymmetric competition and mortality reduces Scots pine (Pinus sylvestris L.) stand structuring across Europe
- 2022
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Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 520
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Tidskriftsartikel (refereegranskat)abstract
- Heterogeneity of structure can increase mechanical stability, stress resistance and resilience, biodiversity and many other functions and services of forest stands. That is why many silvicultural measures aim at enhancing structural diversity. However, the effectiveness and potential of structuring may depend on the site conditions. Here, we revealed how the stand structure is determined by site quality and results from site-dependent partitioning of growth and mortality among the trees. We based our study on 90 mature, even-aged, fully stocked monocultures of Scots pine (Pinus sylvestris L.) sampled in 21 countries along a productivity gradient across Europe. A mini-simulation study further analyzed the site-dependency of the interplay between growth and mortality and the resulting stand structure. The overarching hypothesis was that the stand structure changes with site quality and results from the site-dependent asymmetry of competition and mortality.First, we show that Scots pine stands structure across Europe become more homogeneous with increasing site quality. The coefficient of variation and Gini coefficient of stem diameter and tree height continuously decreased, whereas Stand Density Index and stand basal area increased with site index.Second, we reveal a site-dependency of the growth distribution among the trees and the mortality. With increasing site index, the asymmetry of both competition and growth distribution increased and suggested, at first glance, an increase in stand heterogeneity. However, with increasing site index, mortality eliminates mainly small instead of all-sized trees, cancels the size variation and reduces the structural heterogeneity.Third, we modelled the site-dependent interplay between growth partitioning and mortality. By scenario runs for different site conditions, we can show how the site-dependent structure at the stand level emerges from the asymmetric competition and mortality at the tree level and how the interplay changes with increasing site quality across Europe.Our most interesting finding was that the growth partitioning became more asymmetric and structuring with increasing site quality, but that the mortality eliminated predominantly small trees, reduced their size variation and thus reversed the impact of site quality on the structure. Finally, the reverse effects of mode of growth partitioning and mortality on the stand structure resulted in the highest size variation on poor sites and decreased structural heterogeneity with increasing site quality. Since our results indicate where heterogeneous structures need silviculture interventions and where they emerge naturally, we conclude that these findings may improve system understanding and modelling and guide forest management aiming at structurally rich forests.
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