Consequences of low mobility in spatially and temporally heterogeneous ecosystems

Summary 1 Spatially explicit landscape models have revealed the importance of spatial arrangement of habitat patches in the behaviour of mobile organisms. Such models fail to account for creation and destruction of habitat, which may interrupt the movement of slowly migrating species such as forest herbs. 2 To explore the interaction of habitat turnover and population migration, we present a dynamic landscape model inhabited by a dispersing species. The landscape is represented as a square lattice in which individual cells may be either habitat or non-habitat, and a hypothetical species may spread among habitat cells. Rate of species spread, habitat frequency and habitat clearance and regeneration are allowed to vary. 3 In static landscapes, the fraction of the landscape occupied by the species is limited by connectivity among habitat patches and rate of population migration. Slow species often cannot reach all available habitat despite the presence of continuous paths to it. 4 In dynamic landscapes, slow-moving species show reduced map-scale frequency and high risk of extinction due to the cumulative effects of habitat patch destruction and the failure to colonize newly created habitat. Such species decline cannot be predicted based on static descriptions of habitat connectivity or migration rate. 5 Fast-moving species may be reduced in dynamic landscapes by the cumulative effect of numerous local isolation events. Fast-moving species may also experience a modest range expansion in low-connectivity landscapes due to the cumulative effects of shortlived patch adjacency. 6 These results suggest a novel mechanism that could account for species impoverishment in fragmented landscapes. They emphasize the importance of maintaining habitat connectivity on a time-scale that accommodates slow-migrating species such as forest herbs.