Cropland expansion the culprit in biodiversity loss, says study
Rapid cropland expansion is the main cause of biodiversity loss in tropical countries, a study by UNEP's (the UN Environment Programme) World Conservation Monitoring Centre and the Cambridge Conservation Initiative has found.
The study, published in PLOS ONE last month (9 January), highlights maize and soybean as the most expansive crops and as the main drivers of biodiversity loss in tropical regions. Other crops that pose a major threat to habitats and wildlife are beans, cassava, cowpea, groundnut, millet, oil palm, rice, sorghum, sugarcane and wheat, the study says.
It estimates that cropland in tropical countries expanded by 48,000 square kilometres per year from 1999 to 2008, with Brazil, Ethiopia, Indonesia, Nigeria and Sudan experiencing the greatest expansion.
Stuart H. M. Butchart, a UNEP researcher and one of the authors of the study, tells SciDev.Net: "Unsustainable agriculture is the most significant threat to biodiversity, but conservationists have not previously paid much attention to quantifying which particular crops have caused the greatest problems, nor which ones may do so in the future. This [study] starts to address this issue".
One example of crop expansion cited in the study that has quickened the rate of species extinction is the Mega Rice Project in Kalimantan, Indonesia. Vast tracts of peat swamps were drained starting from the late 1990s in misguided attempts to turn them into rice plantations.
More than one million hectares, an area about a third the size of Belgium, have been converted for rice production, threatening the survival of Borneo's last orangutans.
Similarly, peat and forest areas gave way to oil palm in Indonesia and Malaysia while soybean expansion have also replaced habitats of particularly high biodiversity value in the Brazilian Cerrado savanna. Expanding maize cultivation also threatens the dry forests of Madagascar.
Krystof Obidzinski, a scientist at the Centre for International Forestry Research, in Bogor, Indonesia, says that large-scale land acquisition is proceeding apace in countries like Indonesia — with economic benefits dominating the agenda while environmental impacts appear to be underestimated.
If the pace of expansion continues, the report warns, it could derail progress towards meeting the Aichi Biodiversity Targets, a set of 20, time-bound measurable targets aimed at halting global biodiversity loss by the middle of the century.
Butchart believes there should be a system in place so that consumers can make informed choices about the food they buy and how sustainably they have been produced. Such a system could reduce and minimise impacts of agriculture on biodiversity.
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Cropland image via Shutterstock.