Habitat Connectivity, Habitat Continuity, and Metapopulations in Dynamic Landscapes

Abstract

Landscape ecology and metapopulation ecology share a common interest in developing measures that describe the structure of heterogeneous landscapes, but the specific aim in metapopulation ecology is to construct measures that help predict the dynamics of species with information about the structure of fragmented landscapes. The amount of habitat that individuals in a metapopulation have access to can be divided into four components, the amount of habitat in the present habitat patch (A i ), the amount of connected habitat in other patches available via migration (Γ i ), the amount of preserved habitat in the present patch after time period Δt(A' i ), and the amount of linked habitat in other patches after time period Δt(Γ' i ). Deterministic threshold conditions for metapopulation persistence in patch networks can be approximated with these quantities. For instance, in a version of the Levins model with extinction risk proportional to the inverse of patch area and colonization probability proportional to patch connectivity, the threshold condition for metapopulation persistence is given by ΓA + Var(Γ A)/ΓA >e/c, where e and c are the species-specific extinction and colonization parameters. I conjecture that with measures A' and Γ' the threshold condition for metapopulation persistence can be extended to dynamic landscapes, in which all or part of population turnover is caused by turnover in the habitat patches themselves. The measures of habitat availability described in this paper can be used to rank dissimilar fragmented landscapes in terms of their capacity to support a viable metapopulation.