Reduced pesticide toxicity and increased woody vegetation cover account for enhanced native bird densities in organic orchards

Abstract

Summary 1.Organic farming is often promoted as a solution for counteracting the adverse impacts of agricultural intensification on biodiversity. However, it is unclear whether the biodiversity benefits derived from organic farming require an adoption of organic farming in its entirety (i.e. a systemslevel approach) or whether the benefits derived are because of just a small subset of the associated management practices. 2. Using bird survey data collected from kiwifruit orchards in New Zealand, we assessed whether orchards managed under an organic system support higher bird densities than those under integrated management systems. To determine whether biodiversity gains might also be achieved on non-organic orchards, we tested whether variation among kiwifruit orchards in the amount of (non-crop) woody vegetation cover, density of shelterbelts and toxicity of pesticide applications are better predictors of bird densities than management systems. 3. Composite measures of breeding season densities of all native species and the subset of native insectivores were higher on organic orchards than integrated management orchards. Densities of introduced bird species were comparable among management systems. 4. Pesticide use and habitat composition variables were better predictors of native bird densities than management system, with native bird densities negatively associated with pesticide toxicity ranking and ⁄ or positively associated with woody vegetation cover. 5. Synthesis and applications. A complete conversion to an organic system may not be required to improve biodiversity in agroecosystems. Instead, the transfer of specific land management practices known to benefit biodiversity in organic systems has the potential to enhance biodiversity in other more intensively managed systems (e.g. integrated management). This may be a path towards attaining biodiversity benefits at a larger scale, because such changes may be more straightforward than conversion to an organic system.

Are Organic Standards Sufficient to Ensure Sustainable Agriculture? Lessons From New Zealand’s ARGOS and Sustainability Dashboard Projects

“…This makes them potential "Market Flagship" species for promoting sustainable farming practices and ethical purchasing by consumers (Meadows, 2012). Higher densities of all New Zealand native bird species (insectivores and nectar-feeders) were detected on orchards managed under organic systems, relative to IM orchards (MacLeod et al, 2012). This lends support to the hypothesis that organic farming systems sustain enhanced biodiversity compared to non-organic counterparts (Bengtsson, Ahnstrom & Weibell, 2005;Hole et al, 2005).…”

“…But we go much further to stress that further enhancement of sustainability of organic agriculture depends on finding and then managing the drivers of variation in those important animals and plants and key social-ecological systems processes. For example, pesticide loadings and woody vegetation cover proved to be more influential predictors of native bird densities than 'management systems' on New Zealand kiwifruit orchards: native bird density was lower where more pesticides were applied and higher on orchards with more woody vegetation (MacLeod et al, 2012). The presence of woody vegetation, while not considered in organic standards, provide vital ecological refuges and habitat for native New Zealand biota .…”

Effects of management intensity and orchard features on bird communities in winter

“…As a consequence, these new orchards are heavily sprayed with insecticides and have very few herbaceous plants or hedges. Studies on avifauna in intensive orchards are limited and authors mainly report on the influence of pesticides on the reproductive rate of passerines (e.g., Bouvier et al 2005) or, rarely, on bird diversity (Ro¨sler 2003;Genghini et al 2006;Wiącek and Polak 2008;Bouvier et al 2011;MacLeod et al 2012). Moreover, the relative effects of abandonment, traditional management as well as modern intensive management of orchards on bird and other organism communities is poorly recognized (Tryjanowski et al 2009(Tryjanowski et al , 2011.…”

Optimising survey effort to monitor environmental variables: A case study using New Zealand kiwifruit orchards

“…As a case study, we analysed pilot monitoring data on 13 environmental variables previously identified as relevant for sustainability performance assessment of the New Zealand kiwifruit sector (Carey et al, 2009;MacLeod et al, 2012aMacLeod et al, , 2012b. In broad terms, we showed the power to detect a specified range of trends over an 11-year period in this sector is much higher for 'soil status' variables than for 'agricultural pest' or 'ecosystem composition' ones, with changes in one subset of native bird species (nectar-feeders) requiring a particularly high level of relative survey effort to detect with confidence (Figs.…”

“…From a social perspective, native species are also of particular conservation interest to New Zealand's public, while European consumers of New Zealand's produce may be more concerned about the introduced species that are declining in their native ranges (MacLeod et al, 2008(MacLeod et al, , 2012a(MacLeod et al, , 2012bMeadows, 2012).…”