Structure, ecology and plant richness patterns in fragmented beech forests

Abstract

Background: Landscape fragmentation constitutes one of the most severe causes of global biodiversity loss. Aims: We studied Fagus sylvatica forests with different levels of fragmentation to address the following question: do fragmented and non-fragmented forests present a similar floristic composition and richness, structural parameters and ecological features? Methods: Vascular plant species were randomly sampled based on a beech forest map classified into three fragmentation levels. We compared overall native and diagnostic species richness patterns of the different fragmentation levels using rarefaction curves and the ratio between diagnostic and all species curves. We also contrasted different fragmentation levels of beech forests, focusing on floristic information, structural parameters, standard ecological features and the distribution of edge and clearing species. Results: Rarefaction analysis showed two opposite trends: the diversity of diagnostic species decreased in fragmented forests as the overall diversity increased. In highly fragmented forests, we found significantly higher values for therophyte and phanerophyte frequencies, light Ellenberg indicator values and edge and clearing species diversity. Conclusions: The integration of floristic analysis, particularly of certain diagnostic groups, with structural and ecological studies is more sensitive and significant than species richness alone, and could offer useful information for forest conservation and management.