Organic Farming does not rely on pesticides and other agricultural chemicals. As a result it is not poisoning plants and animals that live on the farm. Organic farming also encourages a diverse ecosystem to develop soil fertility and encourages natural predators that can then keep pest species in check. Many studies have shown that overall there is a greater variety of plant and animal species on organic farms compared to conventional farms, with soil living organisms, birds and butterflies being usually seen as the groups that benefit the most. A Finnish study in 2007 also indicated that converting to organic farming can help to re-establish species that had been lost during the period as a conventional farm.
You can read more on the Wildlife Page of the Soil Association website, which also includes a link to a long study done on the issue of Biodiversity and Organics.
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