Organic farming is touted as a way to conserve wildlife while still producing food, but some organic farms are more biodiverse than others. This may be because of regional climatic differences.
Tatsuya Amano, now at the University of Cambridge, UK, and his colleagues examined the influence of topography and climate on the diversity of 230 rice fields in Japan with varying levels of pesticide use. The researchers measured the abundance of pest-eating Tetragnatha spiders as a proxy for biodiversity. They modelled the data and found that fields with reduced pesticide use had more spiders, with the greatest abundance in cold or wet areas.
The authors also used their model to predict which regions of Japan might benefit most from organic farming through increasing Tetragnatha numbers.