Edge creation and tree dieback influence the patch-tracking metapopulation dynamics of a red-listed epiphytic bryophyte

Abstract

Summary1. Edges in landscapes have an effect on the abundance of many species but the underlying ecological mechanisms are poorly known for most taxonomic groups. One way to gain insight into the mechanisms is to examine how key demographic or metapopulation parameters are affected by proximity to edge. The main objective of this study was to investigate the effects of edge creation through clearcutting on the dynamics of forest species' metapopulations. 2. We used the red-listed epiphytic moss Neckera pennata as a model species. Based on data from repeated surveys of a metapopulation and its host tree network in a hemiboreal forest, we tested the effect of edge creation on key metapopulation parameters: rates of local colonization and extinction, local abundance growth and patch destruction through the fall of host trees. We predicted the long-term consequences of the edge effects using simulations with Bayesian statistical models. We also explored the potential effects of the pathogen Chalara fraxinea causing ash dieback, a tree disease currently spreading in Europe. 3. The colonization probability on host trees unoccupied by the moss increased with increasing connectivity to occupied trees. The growth of local populations on occupied trees decreased with increasing proximity to edge, and with initial local abundance. Stochastic extinctions of the epiphyte from standing trees were very rare and only occurred near the edge; most of the observed extinctions were deterministic due to tree fall. Tree fall decreased with increasing distance from the edge into the forest, and with increasing tree diameter. 4. Under edge conditions, simulations predicted decreases in the total number of host trees, number of occupied host trees, and in the total abundance of the epiphyte over a 30-year period. We suggest that ash dieback increases the tree fall rate and thereby the local extinction rate, leading to increased metapopulation extinction risk. 5. Synthesis and applications. The results show that small protected forest areas such as woodland key habitats may not allow long-term persistence of red-listed epiphytes if they are influenced by edge creation through clearcutting. Delineating uncut buffers of 50-100 m around the protected areas may alleviate such effects.

Indirect effects of hiking trails on the community structure and diversity of trunk-epiphytic bryophytes in an old-growth fir forest

“…Therefore, the existence of the hiking trail promoted the growth of native sun-loving species and resulted in a decrease in shade-tolerant species. Similar results were also reported by Roberge et al (2011). Bates (1998) pointed out that different bryophyte growth forms can reflect distinct habitat moisture levels and the light intensity tolerances of the plants.…”

Epiphyte metapopulation dynamics are explained by species traits, connectivity, and patch dynamics

“…However, if the focal species influences the dynamics of the patches, such as in hostparasite systems, the model needs further extension. Fitted models for joint metapopulation and patch dynamics can be used to project the dynamics into the future, and are useful tools in metapopulation viability analysis for comparing species persistence in scenarios of land use or climate change (e.g., Sna¨ll et al 2009, Roberge et al 2011.…”

Human-sensitive bryophytes retreat into the depth of forest fragments in central European landscape

“…Similarly, the occurrence of hemerophobic bryophyte species continually increased along the entire distance gradient from the forest edge to the interior (0-477 m). This is much greater than the previously reported range of the edge effect for bryophytes, which was only several tens of meters (Hylander 2005;Roberge et al 2011;Löbel et al 2012). However, the maximum distance from the forest edge considered in most previous studies varied only between 40 and 150 m (Hylander 2005;Roberge et al 2011;Löbel et al 2012) which may be too short for Chiloscyphus profundus (52) Pohlia nutans (26) Fissidens taxifolius (16) Pseudoscleropodium purum (9) Ceratodon purpureus (50) Schistidium elegantulum (6) Brachytheciastrum velutinum (205) Hypnum cupressiforme (220) Bryum capillare (136) Brachythecium rutabulum (168) Atrichum undulatum (14) Amblystegium serpens (112) Orthotrichum diaphanum (6) Bryum moravicum (112) Platygyrium repens (13) Orthotrichum affine (28) Orthotrichum anomalum (22) Schistidium crassipilum (17) distance to the forest edge (m)…”

“…However, we have a limited understanding of what range and impact the edge effect has (Łuczaj and Sadowska 1997). A relatively short-distance influence of the forest edge has been observed in bryophyte communities in boreal forests, averaging 10 and 30 m at north and south-facing edges, respectively (Löbel et al 2012) with a maximum of 80 m (Roberge et al 2011).…”