Production land use alters edge response functions in remnant forest invertebrate communities

Context dependence in the effects of landscape matrix structure on habitat patch dynamics is rapidly becoming the modern paradigm for landscape ecology and the study of habitat fragmentation. Most of these studies have focused on the influence of matrix structure on between-patch processes, or the influence of matrix structure on patch-level dynamics, whereas matrix effects on within-patch processes (such as edge effects) have been largely ignored. Here, we tested whether matrix contrast (the difference in vegetation structure and environmental conditions between the habitat patch and the adjacent matrix) alters ''two-sided'' patch-to-matrix edge response functions in invertebrate diversity and community composition across native forest boundaries. In a severely fragmented landscape in southeastern New Zealand, we selected paired native forest-vs.-pasture and native forest-vs.-plantation edge gradients within four catchments. We sampled invertebrates with flight intercept traps at nine distances across each of the patch-to-matrix gradients (giving a total of 72 sampling sites). We show unequivocally that, in historically forested landscapes such as these, conversion from a high-contrast pasture matrix to a low-contrast plantation matrix can mitigate, nullify, or even reverse edge response functions across whole invertebrate orders and across multiple species within diverse beetle assemblages. Variation in adjacent production land use altered the edge response functions for over 80% of all beetle species tested, predominantly through the provision of supplementary habitat in the adjacent forestry matrix, but also through the buffering effect of the plantation matrix compared to the pasture matrix on the relative abundances of some species within native remnants. These findings raise real prospects for active management intervention at the landscape scale, not only to mitigate edge effects on remnant communities, but to simultaneously address both production goals and biodiversity goals in modified landscapes.