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The influence of forest harvesting intensity on species and structural diversity of forests

concluded 06/2019

Project description


Forests produce the greatest part of renewable resources that are needed by a bio-based economy. So far, the long-term impacts caused by an enhanced use of wood are hard to estimate. This could lead for example to a loss of structural diversity. On the other hand, some endangered species in different forest ecosystems require sparse forest structures, which could be supported by a biomass orientated use.

On the basis of the National Forest Inventory (BWI), the relationship between harvesting intensity and biodiversity in forests will be analyzed, because this inventory delivers information about the amount, dimensions and species of the used wood as well as the changes of forest structure, which is used as a surrogate for biodiversity. In a first step independent variables to quantify harvesting intensityand dependent variables for forest structural diversitywill be developed from forest inventory datasets. In the second step the quality and ecological relevance of a structural diversity index will be calibrated against data from intensive forest biodiversity inventories containing information on the relationships between forest structural attributes and species richness and diversity of a large number of taxonomic groups. This information will be obtained from the German Biodiversity Exploratories. In the last step the forest inventory data for the state of Baden-Württemberg (3. National Forest Inventory) will be analysed for the relationships between harvesting intensityand change in structural diversity, which will be derived from successive inventory periods. This analysis will be stratified according to different ecological forest types and possibly forest ownerships and regions. Based on this analysis, recommendations may be developed for appropriate harvesting intensities and for the maintenance of structural diversity through the retention of structural elements such as habitat trees or dead wood in different types of forests.




To analyse influences of harvesting intensities on structural and species diversity of forests, an index had to be developed to quantify forest structural diversity on basis of the second and third National Forest Inventory of Germany for the state of Baden-Württemberg. To allow a comprehensive assessment of structural diversity, this index (FSI = Forest Structure Index) includes 11 different aspects of forest structure. It was calculated for all sampling plots in Baden-Württemberg for two inventories and then aggregated for different types of forests (National Forest Inventories = NFI2002 and NFI2012). Almost all analysed types of forests showed an increase of the FSI for the inventory-period 2002 – 2012. In a second step it was tested, if the FSI and the individual aspects of structural diversity were suitable to assess habitat quality of forest dwelling species. Therefore we analysed how variation of the FSI can explain variation in different taxonomic groups (TGs). This analysis was performed with data of the German Biodiversity Exploratories, providing information on many taxonomic groups (for example birds, bats, different groups of insects, vascular plants, fungi) as well as data on structural diversity of forests in three regions of Germany. The main aim of this step was to analyse the possibility to assess taxonomic diversity by structural elements to describe biodiversity in a comprehensive way. Our results show that the variation in some taxonomic groups (e.g. the group of birds or deadwood fungi) can be explained by the FSI over different types of forests and regions in Germany. In a last step, influences of different harvesting intensities on changes in structural diversity of forests were analysed. Based on these results, theoretical potentials of additionally harvestable woody biomass of different types of forests were derived before a loss of structural diversity sets in. Our results indicate that especially middle-aged, conifer-dominated forest stands can be harvested more intensely before a reduction in structural diversity and biodiversity sets in.



=> see also article on the internet platform: https://www.biooekonomie-bw.de



Supervisors:Prof. Dr. Jürgen Bauhus,  Prof. Dr. Carsten Dormann, Dr. Gerald Kändler
Researcher:Felix Storch
Funding:MWK Baden-Württemberg
Duration:01.11.2014 – 31.12.2017
Partner:Graduate Program „BBW-ForWerts“
Forest Research Station Baden-Württemberg
German Biodiversity Exploratories


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