Geophys. Res. Lett. http://doi.org/q2j (2013)
Agricultural production is expected to double by the year 2050, fuelled by an increase in the area and productivity of croplands. A comparison of plant growth in agricultural and non-agricultural areas suggests that the continued expansion of croplands could diminish carbon storage in terrestrial ecosystems.
W. Kolby Smith of the University of Montana, USA, and colleagues assessed the effect of converting natural ecosystems to agricultural land on global vegetation growth, as measured by net primary production, using crop yield and satellite data. According to their calculations, the total conversion of unmanaged land to agricultural land has reduced net primary production by 7% globally. Reductions in net primary production are apparent in 88% of agricultural areas, with the greatest declines in regions that were formerly tropical forests and savannahs. Only in intensively managed regions of Asia and the industrialized West, primarily Europe and North America, has the conversion to cropland stimulated vegetation growth.
The researchers argue that significant reductions in ecosystem carbon uptake are to be expected unless future agricultural policies take into account the adverse effects of agriculture on ecosystem productivity.