Rethinking the conceptual foundations of habitat fragmentation research

The conceptual foundations of habitat fragmentation research have not kept pace with empirical advances in our understanding of species responses to landscape change, nor with theoretical advances in the wider disciplines of ecology. There is now real debate whether explicit recognition of ‘habitat fragmentation’ as an over‐arching conceptual domain will stimulate or hinder further progress toward understanding and mitigating the effects of landscape change. In this paper, we critically challenge the conceptual foundations of the discipline, and attempt to derive an integrated perspective on the best way to advance mechanistic understanding of fragmentation processes. We depict the inherent assumptions underlying the discipline as a ‘conceptual phase space’ of contrasting false dichotomies in fragmentation ‘problem space’. In our opinion, the key determinant of whether ‘habitat fragmentation’ can remain a cohesive framework lies in the concept of ‘interdependence’: 1) interdependence of landscape effects on species and 2) interdependence of species responses to landscape change. If there is non‐trivial interdependence among the various sub‐components of habitat fragmentation, or non‐trivial interdependence among species responses to landscape change, then there will be real heuristic value in ‘habitat fragmentation’ as a single conceptual domain. At present, the current paradigms entrenched in the fragmentation literature are implicitly founded on strict independence of landscape effects (e.g. the debate about the independent effects of habitat loss versus fragmentation per se) and strict independence of species responses (e.g. the individualistic species response models underpinning landscape continuum models), despite compelling evidence for interdependence in both effects and responses to fragmentation. We discuss how strong ‘interdependence’ of effects and responses challenges us to rethink long‐held views, and re‐cast the conceptual foundations of habitat fragmentation in terms of spatial context‐dependence in the effects of multiple interacting spatial components of fragmentation, and community context‐dependence in the responses of multiple interacting species to landscape change.