The relative influence of forest loss and fragmentation on insectivorous bats: does the type of matrix matter?

Abstract

Disentangling the relative effects of forest loss versus fragmentation on species distribution and abundance is crucial for adopting efficient biodiversity conservation actions, which could change with the nature of the landscape matrix.

We tested the moderating effect of landscape matrix on insectivorous bats response to forest loss and fragmentation.

We conducted acoustic surveys at forest patches surrounded by either an agricultural-dominated matrix or a pine-dominated matrix. We related bat activity to forest amount and the number of forest patches at multiple spatial scales, and compared their effects between landscape matrices.

Bat activity was associated with both predictors, however their effects varied with the matrix type. In agricultural landscapes, as the amount of forest increased, the activity of Histiotus montanus, Lasiurus cinereus and Tadarida brasiliensis increased, while activity of Myotis chiloensis decreased. Similarly, as fragmentation increased, the activity of Lasiurus varius and M. chiloensis increased, while activity of H. montanus decreased. In production-forest landscapes, only H. montanus decreased its activity with increasing forest amount. In contrast, activity of L. cinereus, M. chiloensis and T. brasiliensis increased with increasing fragmentation. Forest amount was a stronger predictor for agricultural landscapes than for production-forest landscapes, suggesting that low contrast matrices can mitigate the effects of forest loss.

Fragmented landscapes with native forest patches surrounded by a low contrast matrix may support a higher activity of insectivorous bats. Management efforts in fragmented landscapes should aim to decrease the patch-matrix contrast, which will mitigate the effects of forest loss on bats.