Ecosystems are often arranged in naturally patchy landscapes with habitat patches linked by dispersal of species in a metacommunity. The size of a metacommunity, or number of patches, is predicted to influence community dynamics and therefore the structure and function of local communities. Bromeliads are neotropical plants which impound water and leaf litter in their leaf rosettes and support an aquatic food webs of microbes, detritivores including aquatic insect larvae and other invertebrates, and insect larvae predators. Bromeliads can live as epiphytic or terrestrial plants, and in some areas like the Ilha do Cardoso in Southeastern Brazil can form a dense ground cover. We used this particular bromeliad system in Brazil to study how the structure of the aquatic communities are affected by the number of interconnected patches in a metacommunity. Effects of decreasing metacommunity size included reduced diversity and evenness of the community, increased stochasticity in community structure, and increased predator to prey ratios. This research is the first test of metacommunity size in a full, naturally patchy food web, and has implications for predicting effects of patch loss in other natural metacommunities.
LeCraw, R.M. and Srivastava, D.S. Metacommunity size and functional diversity in a natural mesocosm landscape. In prep