Species–environment relationships of mosses in New Zealand indigenous forest and shrubland ecosystems

Small and challenging to identify, bryophyte species are often under-represented in large-scale studies of vegetation patterns. Bryophyte occurrence is likely to be influenced by multiple processes and little is known about the relative importance of the different factors across diverse landscapes. Species–environment relationships of 15 common terrestrial moss species in native forests of South and Stewart islands, New Zealand, were examined. Models were developed for each species to test relationships between species distribution and 22 environmental predictors, using Generalised Regression Analysis and Spatial Prediction (GRASP). The New Zealand nationwide vegetation survey LUCAS, although showing several limitations, provided data to investigate factors that may influence bryophyte distribution along large gradients. Combined biotic (primarily total vegetation cover) and abiotic (mean annual temperature and rainfall) effects best contributed to distribution models of all but two moss species. Canopy tree species at a site were also important predictors in the spatial distribution of several individual moss species, possibly through altering the physical environment and resource availability, although both bryophytes and vascular plant species may be influenced independently by the same factors. The study highlights the importance of different factors influencing bryophyte distributions and identifies several factors controlling distributions that require further investigation.