Colonization of oak plantations by forest plants: effects of regional abundance and habitat fragmentation.

Abstract

AbstractThis study aimed at analysing how colonization of forest plants is affected by source population size and seed dispersal type in recent oak plantations with different degrees of isolation. Colonization was studied in 40 oak (Quercus robur) plantations on former arable fields in the Torup-Skabersjö area, southern Sweden. Twenty-two oak stands in ancient woodland were used as reference areas. Species richness increased linearly with stand age in plantations adjacent to ancient woodland. The oldest adjacent plantations (70-80 years) approached a species richness similar to that of the ancient woodlands. The results indicate that interspecific differences in colonization rates within contiguous forest landscapes are largely determined by the size of local source populations. Species richness of plantations decreased with increasing distance from ancient woodlands. There was no increase of species richness between stands of age 40-80 years in isolated plantations. Species that regularly colonized isolated plantations often had adhesive seeds or were ferns with wind-dispersed spores. In landscapes with highly fragmented forest patches, interspecific differences in the ability of long-distance dispersal seem to control colonization patterns to a large extent.