Fragmentation impacts may be mixed for conservation but generally bad for restoration

Abstract

The influence of fragmentation per se on biodiversity is hotly debated, with evidence of negative, neutral, or even positive effects after controlling for habitat amount. Principles from this debate are often used to inform biodiversity conservation in remnant habitat fragments but are rarely considered in a restoration context. Habitat restoration is essential to work alongside conservation and reverse biodiversity declines. Although restored habitats vary along a similar fragmentation gradient to remnant patches, the importance of different processes likely varies. Communities in remnant patches are largely determined by existing populations, while communities in restored patches are shaped by colonization from nearby populations. We illustrate how fragmentation per se can have variable outcomes for biodiversity depending on whether habitat is conserved or restored. The fragmentation debate, in its current form, has limited application for restoration ecology, and we emphasize the need for ecologists and conservationists to consider the directionality of the fragmentation process.