Agriculture and biodiversity are becoming increasingly hard to reconcile with the growing world population. It has been estimated that food production may need to double by 2050 to feed the global population. A concept that first appeared in 2005 attempts to address this problem. Should land be spared or shared. Land sharing entails ecosystems or landscapes being used for both agriculture and biodiversity simultaneously by utilising less intensive agriculture methods. Examples are seen in Europe where the Common Agricultural Policy (CAP) rewards farmers implementing strategies to help animals, birds and plants that share their land, by protecting hedgerows, leaving some trees and strips for flowers and beetles. Land sparing turns this idea on its head; rather than integrating agriculture and biodiversity contemporarily, some areas are farmed using intensive methods and other areas are left for biodiversity to flourish. However, which method is better for biodiversity is unclear.
Professor Balmford argues that land sparing and land sharing methods favour different sets of species. Wide ranging generalist species (such as sparrows) will flourish under land sharing systems whereas more specialist species (for example crossbills) would do better under land sparing.
600 species of birds and trees across farmland and natural habitats in northern India and southwest Ghana were examined by Cambridge University’s Ben Phalan and his colleagues. It was found that land sparing works best, especially for the most threatened species. The same amount of food was produced in all their scenarios, but land sharing harmed wildlife more. However, how feasible is land sparing as the global population balloons? For land sparing to be effective appropriate policies should be enforced to ensure gains in production from intensification on pre-existing farmland are actually translated into increases in the area of natural habitat being protected.
However, Charles Godfrey, at Oxford University, points out that in the Mediterranean region has a rich biodiversity that has existed for thousands of years in an agricultural setting. It is important to note, however, that what may be considered biological diverse or rich in this area may be actually poor in contrast to times before agriculture took place.
In a study in Proceedings of the Royal Society B, researchers at the University of California, Berkeley, reported an average of 40 percent greater diversity of plants, invertebrates, and vertebrates at farms with low-intensity management practices than at farms with higher-intensity practices. In particular, low-intensity farms had 92 percent greater plant diversity and 21 percent greater invertebrate diversity than high-intensity farms. Vertebrates showed no significant difference between high- and low-intensity farms. Furthermore, invertebrates can help to stabilise soil structure, increase nutrient availability and can act as pest controllers. Land sharing has the additional advantage of potentially creating greater levels of ecological connectivity across agricultural landscapes, facilitating the dispersal and migration of species. This is important for maintaining the resilience of wild populations and facilitating range shifts in response to climate change. The major disadvantage of land sharing is that it is generally associated with decreases in agricultural yield, necessitating further conversion of unmodified habitats.
Ultimately, the land sharing vs land sparing debate is ongoing. With the food crisis and the possibility of an anthropological 6th mass extinction it is more crucial then ever to have some consensus.