Dispersal assembly rules in Dutch plant communities?

OZINGA W., BEKKER R., SCHAMINÉE J. & VAN GROENENDAEL J.

Local plant communities can only function within a metacommunity context if they are connected by appropriate dispersal vectors (e.g. wind, running water, free moving large mammals), acting like a dispersal infrastructure for seeds. Habitat fragmentation and changes in the dispersal infrastructure may lead to important constraints for nature conservation and restoration. However, little is known about differences in dispersal between plant species and even less about how this integrates at the community level.

For the quantification of inter-specific differences in dispersal capacity we have compiled a large database with relevant traits for the Dutch flora. The various agents of dispersal differ in their efficiency of seed transport between sites, and we only included dispersal vectors with a relatively high efficiency for long-distance dispersal: water (hydrochory), wind (anemochory), attachment to the fur of large mammals (epizoochory), survival of the digestive tract of large herbivores (endozoochory), and birds (ornithochory). Long-distance dispersal is difficult to quantify. Therefore we largely used indicator parameters (in the sense of Weiher et al. 1999), which are a measure for the potential dispersal capacity for the dispersal agents, e.g. falling velocity for dispersal by wind and floating capacity for dispersal by water.

In this presentation we focus on the integration of species traits at the community level. Therefore we linked the trait database to the Dutch vegetation database with over 350,000 descriptions of local species composition. The resulting dispersal spectra give a functional characterization of plant communities with regard to ‘dispersal syndromes’. We discuss some applications of dispersal spectra. We consider both a theoretical perspective (are there ‘dispersal assembly rules’?) and a more applied perspective (implications for nature policy).