Abstract
Changes in tree species composition can have strong effects on ecosystem functioning and the services provided by forests. Empirical observations can provide an improved understanding of the drivers of species population dynamics, yet long-term datasets are scarce in natural forests. This study used inventory data of the Swiss forest reserve network to assess tree population dynamics over the past 60 years. Tree status, species and dbh were repeatedly measured between 1956 and 2018 in 211 permanent plots of 34 forest reserves that covered a wide environmental gradient. Differences in species richness and tree density were compared between the first and last inventory. Furthermore, we used generalized linear mixed effect models to estimate the processes of ingrowth and tree mortality of seven abundant species (Abies alba, Acer pseudoplatanus, Fagus sylvatica, Fraxinus excelsior, Picea abies, Pinus sylvestris and Quercus spp.) separately as a function of stand structural attributes and climate. We found a general decline in the density of the dominant species, with a low recruitment of light-demanding species and an increase in species richness, particularly in the colline vegetation zone. Both species-specific ingrowth and tree mortality were influenced by stand density and climate variables. Tree mortality increased with live tree density and increasing temperature. Ingrowth increased with tree density and decreased with higher temperature. Therefore, forest structural properties and climate have a strong influence on species population dynamics, and both are essential for predicting ingrowth and tree mortality in forest ecosystems.
Highlights
Forest succession and the associated changes in tree species composition can lead to changes of important ecosystem services such as carbon cycling, habitat availability and the potential for timber and fuel production (Balmford and Bond, 2005, Millennium Ecosystem Assess ment, 2005)
Empirical observations can provide an improved understanding of the drivers of species population dynamics, yet long-term datasets are scarce in natural forests
Forest structural properties and climate have a strong influence on species pop ulation dynamics, and both are essential for predicting ingrowth and tree mortality in forest ecosystems
Summary
Forest succession and the associated changes in tree species composition can lead to changes of important ecosystem services such as carbon cycling, habitat availability and the potential for timber and fuel production (Balmford and Bond, 2005, Millennium Ecosystem Assess ment, 2005). Long-term inventory datasets in forest reserves are crucial to improve our knowledge on changes in forest structure and demographic rates. Utilizing such datasets allows to examine historical trends in tree pop ulation dynamics and to identify the underlying drivers. This informa tion can improve our understanding of species dynamics and the natural processes that are driving tree regeneration and mortality (Leibundgut, 1959, Brang, 2005). The vast majority of permanent plots are located in managed forests (Forrester, 2019; Cioldi et al, 2010; Torresan et al, 2020), limiting the ability to monitor long-term natural forest dynamics. An increasing number of forest reserves have been established and protected in recent years, the structure and species composition of these forests are still affected by past management, even after many decades (Heiri et al, 2009, Brad shaw et al, 2005)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
