Biodiversity on kiwifruit orchards: the importance of shelterbelts.

摘要

The Agricultural Research Group On Sustainability (ARGOS) conducted an ecological survey of 437 shelterbelts on 36 New Zealand kiwifruit orchards in 2004. Species composition and stature of shelter on three orchard types (Organic Hayward, KiwiGreen 'Hayward', and KiwiGreen 'Hort 16A') were compared. Shelterbelts protect fruit and vines from wind damage that would otherwise reduce yield and fruit quality. They also affect the microclimate in orchards and occupy space that could be used for fruit production. Shelterbelts around the perimeter of orchards are more substantive than internal shelterbelts. The predominant shelter species (Cryptomeria japonica, Causurina spp. and Salix spp.) are similar between orchards, but shelterbelts in 'Organic' orchards have a greater diversity of woody incidental species, less accumulation of dense litter beds and more rank grass. Shelterbelts harbour incipient weed threats, but also provide potentially important refuges for maintaining biodiversity on orchards. Some orchardists have removed shelterbelts or replaced them with wind-cloth screens, partly to increase fruit dry matter by reducing shade. There is no evidence that the stature and porosity of shelterbelts differs between Organic and KiwiGreen systems, so shelter is unlikely to be driving differences in mean fruit production, fruit quality and animal diversity and abundance between orchard systems. Observed differences in fruit production and increases in species richness and abundance of animals on Organic orchards therefore probably result from (a) differences in orchard inputs and management, (b) increased plant biodiversity and/or (c) the presence of different micro-habitats on Organic orchards.