February 4, 2014
Biodiversity Benefits Greatly From Organic Farming
[ Watch the Video: Robotic Biodiversity Thrives On Organic Farms ]
Brett Smith for redOrbit.com - Your Universe Online
The study, being published this week in the Journal of Applied Ecology, traced 30 years of organic farming and found that greater biodiversity compared to conventional farming remains stable over time and shows no signs of decreasing.
“Our study has shown that organic farming, as an alternative to conventional farming, can yield significant long-term benefits for biodiversity,” said study author Sean Tuck, a plant scientist at Oxford University. “Organic methods could go some way towards halting the continued loss of diversity in industrialized nations.”
The study team found that for pollinators like honeybees, the quantity of different species was 50 percent greater on organic farms. However, the researchers noted that their study only looked at “species richness.”
“Species richness tells us how many different species there are but does not say anything about the total number of organisms,” Tuck explained. “There are many ways to study biodiversity and species richness is easy to measure, providing a useful starting point. Broadly speaking, high species richness usually indicates a variety of species with different functions. Taking the example of bees, species richness would tell us how many different species of bee were on each farm but not the total number of bees.”
The scientists looked at data from 94 previous reports on over 180 farm sites dating back to 1989. The scientists reexamined the data using satellite imagery to determine the land use in the area surrounding each farm to see if this had a bearing on species richness.
They found that organic farms had a bigger effect on species richness when surrounding land was more heavily farmed, especially when it was comprised of large tracts of arable land. Arable land is considered land filled with crops that are sown and reaped in the same agricultural year, like wheat or barley.
“We found that the impacts of organic farms on species richness were more pronounced when they were located in intensively-farmed regions," said study author Lindsay Turnbull, of Oxford University's Department of Plant Sciences. “This makes sense because the biodiversity benefits of each organic farm will be diluted in clusters of organic farms compared to an organic 'island' providing rich habitats in a sea of pesticide-covered conventional fields.”
“This effect was weakest in pollinators, which may be because pollinators are likely to visit neighboring farms and could be affected by pesticides there,” Turnbull added.
The effect of organic farming on overall species richness varied noticeably across the data, with the average increase in species richness varying between 26 percent and 43 percent. This variation might be down to a number of factors pertaining to local variation in farming procedures and definitions of “organic.”
“Some conventional farms will intensively spray pesticides and fertilizers whereas others will use mixed methods of crop rotation and organic fertilizers with minimal chemical pesticides,” Turnbull said. “There are also regional differences in farming practices, and the majority of the studies in our data were in developed nations with long histories of farming such as those in Western Europe.”
“There, some wildlife have thrived in extensively managed farmland but are threatened by agricultural intensification,” she added. “However, in developing nations there is often great pressure on the land to provide enough food for local people, resulting in the conversion of natural habitat to farmland. In such cases the benefits of organic farming are less clear, as this may require more land to achieve the same yield as conventional farming.”
“More research is needed on the impact of organic farming in tropical and subtropical regions,” Turnbull concluded. “For example, there are no studies on organic bananas or cocoa beans, two of the most popular organic products found in European supermarkets. At present, we simply cannot say whether buying organic bananas or chocolate has any environmental benefit.”