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Deadwood and tree microhabitat dynamics in unharvested temperate mountain mixed forests: A life-cycle approach to biodiversity monitoring: A life-cycle approach to biodiversity monitoring

Dynamique du bois mort et des microhabitats dans les forêts tempérées mixtes de montagne : une approche du cycle forestier pour les suivis de biodiversité

Abstract : In forest ecosystems, conservation is often considered in the absence of any long-term dynamic perspective, yet dynamic processes extend over hundreds of years. Saproxylic taxa represent about 25% of the species diversity in temperate and boreal forests and they depend on both spatial and temporal continuity in the availability of deadwood and certain tree microhabitats. Our study focused on the dynamics of deadwood and tree microhabitats throughout the silvigenetic cycle in 32 unharvested European mountain mixed forests. Our dataset contained 178 plots classified into one of five forest development phases (regeneration, establishing, growing, culmination and disintegration). We analyzed how the amount and quality of deadwood and microhabitats varied according to the five phases. Contrary to expectations, deadwood and tree microhabitat availability remained more or less stable throughout the silvigenetic cycle, both in quantity and diversity. Furthermore, whether the forests were dominated by broadleaves or conifers, there were no significant differences in terms of deadwood or tree microhabitat dynamics. Pioneer (Betula spp., Salix spp.) and post-pioneer species (Fraxinus exelsior, Sorbus spp., Prunus avium) played an important role throughout the silvigenetic cycle by providing a diversity of deadwood when deadwood from the dominant species (i.e. Abies alba, Fagus sylvatica, Picea abies) was scarce. Understanding the dynamics of deadwood and tree microhabitats may help us provide a model for forest managers who intend to emulate natural forest dynamics and will also improve our understanding of the relationship between forest dynamics and biodiversity conservation.