The role of natural vegetation strips in sugarcane monocultures: Ant and bird functional diversity responses

Abstract

Simplification of landscapes due to the increase of monocultures negatively impacts biodiversity and its functions. In tropical landscapes that are dominated by sugarcane monocultures, some small natural vegetation patches still exist, yet little is known about their capacity to harbor functional biodiversity that may complement agroecological management of the crop. We compared ant and bird diversity in natural vegetation strips to diversity within sugarcane monocultures at increasing distances from the vegetation strips. We also compared functional groups of ants and birds in order to evaluate the role of vegetation strips in regulating pests of economic importance. During two seasons between 2015 and 2016, we studied 12 sites in the Cauca Valley, Colombia, with both natural vegetation strips and sugarcane monoculture and then sampled ants and birds in natural vegetation strips and at four distances towards the interior of the sugarcane matrix (up to 150 m and 350 m respectively). Species richness of ants and birds differed in vegetation strips and sugarcane matrix with decreases in richness as the distance from vegetation strips increased. Furthermore, predatory functional groups of ants and birds were less abundant in the sugarcane matrix, with important implications for key predation services on key sugarcane pests (e.g., Diatraea spp. – Lepidoptera: crambidae). Our results provide evidence that even in highly modified landscapes dominated by monocultures, the conservation of small patches of natural vegetation favors functional biodiversity. Therefore, maintaining and promoting and natural vegetation strips is especially important in highly industrialized monoculture landscapes in order to promote beneficial biodiversity for ecosystem services without sacrificing production area.