Permanent grid studies in bryophyte communities 1. Pattern and dynamics of individual species

Using permanent grids, the bryophyte layer of four Dutch chalk grassland plots have been recorded nine times over a period of nearly three years. Similarly, bryophytes and lichens in 21 plots in various habitats around Barcelona, Spain, have been recorded three or five times over a one-year period. The data have been analyzed for spatial pattern, species dynamics and pattern in dynamics. For analysis of spatial pattern and pattern in dynamics, correlograms of autocorrelation against distance between cells compared were grouped by K-means clustering. Spatial distribution and pattern in increase and decrease tend to be clustered; the scale of clustering varies both within and between species. Species belonging to the same life strategy show similar patterns within each site, but when all sites are considered pattern types correspond better with growth forms than with life strategies. Species dynamics are higher for colonists and particularly annual shuttle species than for perennials. Both spatial pattern and pattern in dynamics in the chalk grassland plots are assumed to be strongly influenced by pattern and dynamics in the phanerogam vegetation. In the Spanish plots from exposed sites, disturbances and soil heterogeneity are thought to be important determinants of pattern. Pattern in the Spanish plots from forest sites seems to reflect mainly inherent growth and mortality characteristics of the species.