Microtopographic influence on recolonization patterns of forest floor bryophytes following clear-cut logging
(English)Manuscript (preprint) (Other academic)
The extent to which a plant assemblage might recolonize a disturbed system is in general related to the availability of propagule sources and sites with appropriate conditions for establishment. Both of these factors might be sensitive to aspects of spatial heterogeneity. Microtopographic variation may enhance initial resistance by reducing the impact of the disturbance and facilitate establishment of incoming propagules by providing shaded “safe-sites” for establishment. This study explores the influence of microtopographic heterogeneity (caused by variation in surface boulder cover) on the recolonization of closed-canopy forest floor bryophytes using a chronosequence of 75 spruce-dominated forests in south-central Sweden (2-163 years after clear-cutting). We found that high boulder cover did increase survival and subsequent persistence in young forests at the scale of 1000 m2, but that this effect disappeared on a smaller spatial scale (100 m2). At the smaller scale there was a steady accumulation of species over time in both sites with few and many boulders. Furthermore, species accumulation in boulder-poor subplots was not different when surrounded by boulder-rich compared with boulder-poor subplots suggesting short-distance recolonization from boulder-created refugia to be of little importance during the recolonization process. Apparently, boulders function as creators of refugia, but such events seem to be relatively infrequent, which can explain why we were only able to detect such a pattern at larger scales. To conclude it seems like boulders (and probably microtopographic surface structures in general) increase initial resistance to clear-cutting for this bryophyte guild, but that the subsequent recolonization process is more likely to depend on external propagule sources and factors affecting establishment such as microclimate.
boreal forest, boulders, bryophytes, clear-cutting, microtopography, refugia, resistance, scale
Research subject Plant Ecology
IdentifiersURN: urn:nbn:se:su:diva-38898OAI: oai:DiVA.org:su-38898DiVA: diva2:317321