Effect of farmland shelterbelts on gully erosion in the black soil region of Northeast China

The black soil region of northeast China is one of the most important grain-producing areas in China.Increasingly severe gully erosion in this region has destroyed much farmland and reduced grain production.We analyzed SPOT5 imagery from 2007 and TM imagery from 2008 to describe the distributions of gullies and farmland shelterbelts in Kedong County and to assess the effect of farmland shelterbelts on gully erosion. The imagery revealed 2311 gullies with average density of 418.51 m km-2, indicating very serious gully erosion.With increasing slope gradient there was an inverse trend between gully density and shelterbelt density, indicating that farmland shelterbelts can prevent gully erosion. The defense effect of farmland shelterbelts against gullyerosion varied with distance: for distances<120 m, the defense effect was consistent and very strong; for distances of 120–240 m, a weak linear decrease was found in the defense effect; and for distances>240 m, the defense effect of the shelterbelts was significantly weaker. We recommend an optimal planting density of farmland shelterbelts for the prevention of gully erosion at1100–1300 m km-2.