Biodiversity is the variability of all living organisms -- including animal and plant species -- of the genes of all these organisms, and of the terrestrial, aquatic and marine ecosystems of which they are part.
Biodiversity makes up the structure of the ecosystems and habitats that support essential living resources, including wildlife, fisheries and forests. It helps provide for basic human needs such as food, shelter, and medicine. It composes ecosystems that maintain oxygen in the air, enrich the soil, purify the water, protect against flood and storm damage and regulate climate. Biodiversity also has recreational, cultural, spiritual and aesthetic values. – J Randerson
According to the researchers, organic farming aids biodiversity by using fewer pesticides and inorganic fertilisers, and by adopting wildlife-friendly management of habitats where there are no crops, including strategies such as not weeding close to hedges, and by mixing arable and livestock farming.
Mixed farming particularly benefits some bird species. Lapwings, for example, nest on spring-sown crops, but raise their chicks on pasture. Intensive agriculture has been blamed for the 80% decline in lapwing numbers in England and Wales since the 1960s. One of the reviewed studies from the UK also points to benefits for bats. Foraging activity was up 84% on organic farms and two species, the greater and lesser horseshoe bats, were found only on organic farms.
The studies might even have underestimated the benefits to wildlife, says Phillip Grice of English Nature. Some looked at farms shortly after they turned organic, so wildlife numbers may just have started increasing.
Some argue that farms that adopt a few organic practices, swapping chemical weeding for mechanical, for example, may help wildlife flourish just as much as completely organic farms. And it is possible that farmers who switched to organic farming may have been predisposed towards environmentally friendly methods. So the biodiversity on their farms may have been higher than average before conversion. The current studies are not detailed enough to answer these questions.
Ref: Biological Conservation/ Reed Business Info
