The study argues that urbanisation can cause indirect loss of forest, by encouraging agricultural expansion in forested areas
The world may have lost up to 35 million hectares (Mha) forest to urbanisation between 1992 and 2015, claimed a recent study published in the journal Nature. Most of thios loss was due to ‘indirect changes’ — new cropland to make up for existing agriculturral land eaten up by cities.
Up to 22 Mha shrubland could also have been lost, according to the study by Jasper van Vliet of Vrije Universiteit Amsterdam.
“On a global scale, urban land increased from 33.2 to 71.3 Mha between 1992 and 2015, leading to a direct loss of 3.3 Mha of forest and an indirect loss of 17.8-32.4 Mha,” claimed Direct and indirect loss of natural area from urban expansion, published on July 29, 2019.
‘Direct changes’ refer to natural area that was converted into urban land.
Urbanisation also led to a direct loss of 4.6 Mha and an indirect loss of 7-17.4 Mha of shrubland, according to the study that used the European Space Agency’s Climate Change Initiative (ESA CCI) land cover data.
Expansion of agriculture is usually seen as a main driver of forest loss. The study argues that urbanisation can cause indirect loss of forest, by encouraging agricultural expansion in forested areas.
“As urban expansion often takes place in cropland areas, and as cropland expansion often leads to a conversion of natural area, cropland displacement may relate urban expansion to losses of natural area elsewhere,” the study says.
Interestingly, the agriculture clearing of forests caused due to urban expansion into erstwhile agricultural land, is larger than the original area taken over by urbanisation.
“Urban areas are typically located in highly productive cropland areas, whereas new cropland mainly comes at the cost of forest and other natural area,” it says.
Due to this, new agricultural land that was carved out of forests was 139 per cent greater than the area lost to urbanisation.
These agricultural areas were used for growing ‘cereal crops’ such as wheat, maize and rice, but also crops that are often associated with tropical deforestation such as oil palm and soybean.
To counter this process, the study suggests that instead of converting fertile cropland, urban development could be directed towards less productive areas.
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