Restoration of ecological interactions: the influence of site and landscape factors

Abstract

Restoration has been extensively used in agricultural landscapes as a mitigation measure to reduce biodiversity loss in response to historic habitat destruction. Trophic interactions between insects and plants underpin key ecosystem processes and contribute to system robustness, which is a critical outcome for habitat restoration. We evaluate how restoration age, site size and landscape proximity to similar habitats impact the re-establishment of trophic linkages between empirically measured grassland plant-pollinator (60 sites; 1–76 years) and woodland plant-herbivore networks (60 sites; 13–67 years). In each case, sites were selected along a chronosequence with the goal of maximising variation along these temporal and spatial gradients. For both grassland and woodlands, older and larger sites typically support higher levels of connectance, nestedness and generality of the networks. In contrast, landscape proximity promotes these metrics for woodland webs but has the reverse effect for grassland webs. The similarities show common characteristics of community trophic re-establishment in response to local environmental drivers for these different ecosystems. Focusing on interactions rather than species identity highlights opportunities for targeted policies to restore ecosystem function in wider agricultural landscapes; for example, through increasing site size as well as the need for continuity of older sites.