Scientists from leading UK institutions say organic farms provide greater benefits for a range of wildlife including wild flowers, beetles, spiders, birds and bats than their conventional counterparts.
Scientists from the British Trust for Ornithology (Thetford), the Centre for Ecology & Hydrology and the Wildlife Conservation Research Unit (University of Oxford) have spent five years studying the differences between matched pairs of organic and non-organic cereal-producing farms in lowland England.
The study, published in the Royal Society Journal, showed that organic farming systems provide greater potential for biodiversity than their conventional counterparts, as a result of greater variability in habitats and more wildlife-friendly management practices, which resulted in real biodiversity benefits, particularly for plants.
Dr Lisa Norton of the Centre for Ecology & Hydrology: "Organic farmers try to work with natural processes to increase productivity, using sustainable farming practices."
A huge amount of fieldwork was involved in the study - hedges were measured, beetles, spiders, birds and wildflowers were counted, farmers were questioned and bats were detected. Some of the significant results are:
Organic crops contain almost twice as many types of plant species (85% more).
There were more spiders (17% more), birds (5%) and bats (33%) too but the effects were not as significant as for plants.
There is more grassland within organic farms and higher densities of hedges. Fields are smaller and hedges thicker on organic farms. Organic farmers sow their crops later and cut their hedges less frequently.
Dr Rob Fuller, Director of Habitat Research for the British Trust for Ornithology (BTO), and lead author of the paper said: "Organic farms clearly have positive biodiversity effects for wild flowers. However, if they are to provide benefits on the same scale for species that need more space, like birds, we either need the farms to be larger or for neighbouring farms to be organic too. Currently, less than 3% of English farmland is organic so there is plenty of scope for an increase in area. Such an increase would help to restore biodiversity within agricultural landscapes."
Many previous studies that claim to demonstrate that organic farming benefits biodiversity are poorly designed, limited to one group of animals or plants, or local in scale. In this integrated study, covering 160 farms from Cornwall to Cumbria, the authors have shown that the organic farms supported higher numbers of species and overall abundance across most groups of plants and animals.
Dr Lisa Norton of the Centre for Ecology & Hydrology, who carried out the work on plants and interviewed a large number of the farmers involved in the study, said: "Organic farmers try to work with natural processes to increase productivity, using sustainable farming practices. Increased biodiversity is a happy by-product of this approach.
"For example, hedges on organic farms are kept in good stock-proof condition, as livestock are often an important part of the organic farming system. Typically, these stock-proof hedges are full of native, berry-producing shrubs, which are great for insects and the birds and bats that feed on them."
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