Field-scale habitat complexity enhances avian conservation and avian-mediated pest-control services in an intensive agricultural crop

摘要

The relationship between on-farm avian conservation measures and the potential provisioning of pest control services by birds is poorly understood in intensive agricultural landscapes, especially in temperate regions. We used an exclusion experiment to test the effects of field- and landscape-scale habitat complexity on avian-provisioned pest-control services and assessed avian abundance and diversity across 32 conventional alfalfa (Medicago sativa) fields in winter and early spring in California. Alfalfa is a key forage crop around the world and is grown on approximately 30 million hectares globally each year. Bird foraging reduced the abundance of the most significant insect pests of alfalfa by over 33%. The presence of complex edge habitat (presence of at least two trees >1.5 m) led to higher avian abundance within fields, which in turn led to reduced pest insect populations at sampling points close to the field edge. Fields with complex edge habitat also harbored nearly three times as many bird species as those with simple edge habitat. The distance from the nearest riparian habitat, a measure of landscape diversity, did not affect bird abundance or diversity in winter alfalfa fields, which may be related to the homogenous landscape in which our study was based. Our results show that relatively simple conservation measures in intensively managed farming landscapes, such as planting small trees along a field edge, can result in increased abundance and diversity of over-wintering birds, with direct benefits to farmers through increased avian-mediated pest-control services. (C) 2016 Elsevier B.V. All rights reserved.