DOI: 10.5061/dryad.609t7
title: Data from: Land-use intensity and the effects of organic farming on biodiversity: a hierarchical meta-analysis

description: The benefits of organic farming to biodiversity in agricultural landscapes
 continue to be hotly debated, emphasising the importance of precisely
 quantifying the effect of organic vs. conventional farming. We conducted
 an updated hierarchical meta-analysis of studies that compared
 biodiversity under organic and conventional farming methods, measured as
 species richness. We calculated effect sizes for 184 observations garnered
 from 94 studies, and for each study we obtained three standardised
 measures reflecting land-use intensity. We investigated the stability of
 effect sizes through time, publication bias due to the ‘file-drawer’
 problem, and consider whether the current literature is representative of
 global organic farming patterns. On average, organic farming increased
 species richness by about 30%. This result has been robust over the last
 30 years of published studies and shows no sign of diminishing. Organic
 farming had a greater effect on biodiversity as the percentage of the
 landscape consisting of arable fields increased; i.e. it is higher in
 intensively farmed regions. The average effect size and the response to
 agricultural intensification depend on taxonomic group, functional group,
 and crop type. There is some evidence for publication bias in the
 literature; however, our results are robust to its impact. Current studies
 are heavily biased towards Northern and Western Europe and North America,
 while other regions with large areas of organic farming remain poorly
 investigated. Synthesis and recommendations. Our analysis affirms that
 organic farming has large positive effects on biodiversity compared with
 conventional farming, but that the effect size varies with the organism
 group and crop studied, and is greater in landscapes with higher land-use
 intensity. Decisions about where to site organic farms to maximise
 biodiversity will, however, depend on the costs as well as the potential
 benefits. Current studies have been heavily biased towards agricultural
 systems in the developed world. We recommend that future studies pay
 greater attention to other regions, in particular, areas with tropical,
 subtropical and Mediterranean climates, in which very few studies have
 been conducted.
description: Tucketal2013_MetaAnalysisDataData set for the publication associated with this Dryad data package, on a meta-analysis on the effects of organic vs conventional farming on biodiversity. This data set contains data collected from the literature, including data necessary for calculating effect sizes, data on taxa and crop type subgroups among effect sizes, and descriptive data giving context of the studies. The data set also includes data collected from Google Earth on the surrounding landscape complexity and heterogeneity for each effect size. The method used to collect these data are described in the associated publication. The data set CSV file was created using Microsoft Excel 2013. See README for more details and metadata.PublicationAnalysisScriptR code (using R 3.0.1) used for the analysis of the data set for the associated publication. See README for information on how to run the code.