|
Résumé :
|
Lake plankton metacommunities are affected by their surrounding multidimensional landscape. Hence, understanding mechanisms shaping lake plankton communities requires considering not only local or geographical drivers, but also drivers at buffer zone level, indicating fluxes of nutrients and organic compounds. We investigated the effects of local, buffer zone (characterised via remote sensing) and geographical level variables on the phyto- and zooplankton community composition in 100 lakes distributed over five watersheds in Finland. We examined the community variation at two spatial scales using redundancy analysis with variation partitioning. Among watersheds, phyto- and zooplankton showed a small spatial imprint in their metacommunity structure, suggesting weak dispersal limitation. Environmental drivers explained negligible shares of the community variation, indicating weak species sorting. However, within single watersheds, larger fractions of the variation in communities were explained by the effects of multi-scale variables, suggesting that communities may be structured by species sorting and mass effects. Groups of variables exerted a relatively equal influence on the community composition. Including buffer zone variables into models increased the explained community variation by one-third. Due to the unique effects of the buffer zone on plankton composition, remotely sensed buffer zone variables may serve as useful proxies in analyses of lake plankton metacommunities.
|