Effects of organic farming, fencing and vegetation origin on spiders and beetles within shelterbelts on dairy farms

Abstract

Spiders and beetles provide important ecosystem services in agriculture; however, optimum strategies to promote their density and diversity on dairy farms have received little attention. This study aimed to quantify the effects of farming practice (conventional vs. organic), fencing (fenced vs. unfenced) and plant species origin (exotic vs. native) on the abundance and diversity of spiders and beetles within shelterbelts on eight conventional and six organic dairy farms in North Island, New Zealand. Invertebrates were collected from a total of 43 shelterbelts by vacuum suction and beating in January 2008 and 2009. Organic farms and fenced shelterbelts supported 40% and 67% higher densities of spiders than conventional farms and unfenced shelterbelts, respectively. Shelterbelts of native plant species supported higher species richness of native spiders and beetles than shelterbelts of exotic plants. A combination of converting to organic farming, fencing off shelterbelts and planting more native shelterbelts is likely to provide increased ecosystem services and biodiversity conservation on New Zealand dairy farms.