A better understanding of colonization processes is
critical to understanding the general patterns and processes
in plant communities. Grubb (1977) was among the first to challenge the traditional view of nicheassembled
plant communities. By elaborating on the
different processes involved in colonization (the production
of viable diaspores, dispersal in space and time,
germination requirements, establishment of seedlings
and the further development of the immature plant),
Grubb stated that, at the local scale, differential colonization
capacities of plant species are of crucial importance
for the coexistence of large numbers of species with
similar resource requirements. Twenty years later, a growing body of literature confirms Grubb’s thesis. It
has been demonstrated that dispersal is a key factor in
community assembly. Evidence comes from observational
studies (e.g. Hubbell
et al
. 1999), experimental
studies (e.g. Turnbull
et al
. 2000) and mathematical
models (e.g. Tilman 1994).