Quantifying the landscape-scale recovery of bird communities over time in response to on-farm restoration plantings

Abstract

Restoring wooded vegetation to cleared agricultural landscapes is a global priority. Restoration is a dynamic, long-term process: individual plantings take years to develop specific resources, and the extent and pattern of plantings change through time. A rarely-tested assumption is that, over time, the biota of restored landscapes will converge towards that of unmodified landscapes. To test this, we compared temporal changes in bird communities in agricultural landscapes in which wooded vegetation was dominated either by planted or remnant native vegetation. In 2007 and 2019, we sampled birds within 23 landscapes (each 8 km2) representing gradients in cover (∼1–19 %) of remnant vegetation (n = 9 ‘remnant’ landscapes) and planted vegetation (n = 14 ‘restored’ landscapes). In 2007, remnant landscapes supported ∼20 % more woodland bird species than restored landscapes but by 2019 richness was similar. There was a strong, positive relationship between species richness and wooded vegetation cover in both landscape types; however, for a given vegetation cover, species richness was higher in remnant landscapes only in 2007. Community composition showed increasing convergence over time, but remnant and restored landscapes supported distinct bird communities in both 2007 and 2019. Our results highlight that: 1) restoring vegetation to agricultural landscapes can reverse the loss of bird species accompanying vegetation clearing, but recovery takes time; 2) landscape-scale restoration will benefit from ‘succession planning’; 3) retaining remnant habitats is crucial because their resources are difficult to replicate with restoration; 4) plantings provide complementary resources and so restored landscapes containing remnant habitats will benefit biodiversity beyond those with only replantings.