Which habitat parameters are most important for the persistence of a bryophyte species on patchy, temporary substrates?

Abstract

The effects of changes in habitat parameters important for conservation (abundance and size of habitats and distance between them) on both short-lived fugitive and long-lived resident bryophyte species was studied. Persistence of a species in a system of temporary and patchily distributed habitats was simulated both for stable and fluctuating environments. The values of the parameters in the model were derived from estimates made in two colonist species, Orthodontium lineare and Ptilidium pulcherrimum. Persistence of a resident species is much more enhanced by variable environment that persistence of a fugitive species. Both species are also more often limited with regard to dispersal/establishment in variable environments, especially the resident species. Reducing the habitat parameters (decreased area, fewer localities/substrate patches and increased distance between them) generally results in lower persistence of the species. In variable environments, fugitive species are more sensitive than the resident species to reduction of any of the habitat parameters. Both fugitive and resident species are most sensitive to reduced habitat density (i.e. to increased distance between available patches). Increased isolation of habitat patches is therefore concluded to be the most serious effect of habitat fragmentation.