Local Ecological Communities

A phenomenological community is an identifiable assemblage of organisms in a local habitat patch: a local wetland or mudflat are typical examples. Such communities are typically persistent: membership and abundance stay fairly constant over time. In this paper I discuss whether phenomenological communities are functionally structured, causal systems that play a role in determining the presence and abundance of organisms in a local habitat patch. I argue they are not, if individualist models of community assembly are vindicated; i.e., if the presence of one species is not typically explained by the presence or absence of specific other species. I discuss two alternatives to individualism, and conclude by arguing for a dimensional model of phenomenological communities. The causal salience of a phenomenological community depends on three factors: the extent to which it is internally regulated, the extent to which it has robust boundaries, and the extent to which it has emergent properties. I conclude by using this model to frame a natural research agenda for community ecology.