Cascading effects of canopy mortality drive long-term changes in understorey diversity in temperate old-growth forests of Europe
ID Nagel, Thomas Andrew (Author), ID Iacopetti, Giovanni (Author), ID Javornik, Jernej (Author), ID Rozman, Andrej (Author), ID De Frenne, Pieter (Author), ID Selvi, Federico (Author), ID Verheyen, Kris (Author)

URLURL - Source URL, Visit https://doi.org/10.1111/jvs.12767 This link opens in a new window

Questions: We investigated the influence of protracted mortality of a dominant canopy tree (Abies alba) on long-term understorey dynamics. We ask (a) how tree regeneration and understorey species diversity and composition changed over 32 years; and (b) whether the observed changes were mainly driven by mortality of A. alba. Location: Three old-growth forest reserves dominated by A. alba and Fagus sylvatica in the Dinaric Mountains of Slovenia. Method: Tree layer and understorey regeneration and herbs were surveyed in 147 plots across the three forest reserves in 1983 and 2015. Soils were also sampled in 2015. The study period coincides with a protracted period of increased A. alba mortality in the canopy layer associated with anthropogenic emissions. Results: Between 1983 and 2015, the decline in canopy layer A. alba caused a recruitment pulse of F. sylvatica regeneration to the subcanopy tree layer across the three reserves. These changes were accompanied by a significant decline in plot level herb species richness. A model-based analysis of beta-diversity revealed significant community convergence during the study period, mainly caused by the loss of rare species. Ellenberg values indicate that these changes were mainly driven by loss of understorey light, while an increase in soil pH may have played a role also. Conclusions: This observational study suggests that the long-term decline of A. alba resulted in a cascade of processes - widespread F. sylvatica recruitment that impeded penetration of light to the forest floor, and possibly a change in soil conditions due to the decline of coniferous litter. These changes caused a significant loss of herb diversity and homogenization of the understorey community across the three sites. This study sheds light on the potential cascading consequences triggered by episodes of increased tree mortality resulting from global-change-type drivers.

Keywords:beech, fir decline, forest dieback, forest herbs, foundation species, old-growth, resurveys, semi-permanent plots, tree mortality, understorey vegetation
Typology:1.01 - Original Scientific Article
Organization:BF - Biotechnical Faculty
Publication version:Version of Record
Number of pages:Str. 905-916
Numbering:Vol. 30, iss. 5
PID:20.500.12556/RUL-114159 This link opens in a new window
ISSN on article:1100-9233
DOI:10.1111/jvs.12767 This link opens in a new window
COBISS.SI-ID:5562278 This link opens in a new window
Publication date in RUL:19.02.2020
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Record is a part of a journal

Title:Journal of vegetation science
Shortened title:J. veg. sci.
Publisher:Opulus Press
COBISS.SI-ID:35399937 This link opens in a new window

Secondary language

Keywords:propadanje jelke, umiranje gozdov, gozdna zelišča, pragozd, mortaliteta, podstojna vegetacija

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