Quantifying farmland shelterbelt impacts on catchment soil erosion and sediment yield for the black soil region, northeastern China

As one part of the 'Three Norths' forest protection system, dense farmland shelterbelt networks in northeastern China could greatly modify water and sediment flows. In this paper, catchment soil erosion rate and sediment yield (SY) that are impacted by farmland shelterbelts were estimated using WaTEM/SEDEMmodel. The shelterbelts reduced catchment soil erosion andSYto some extent. The mean soil erosion rate and specific sediment yield (SSY; defined as the ratio ofSYto catchment area; t km(-2) yr(-1)) of the 25 reservoir catchments decreased from 351.6 and 93.9 t km(-2) yr(-1)under the supposed scenario without shelterbelts to 331.1 t km(-2) yr(-1)and 86.3% t km(-2) yr(-1)under the current situation with shelterbelts. The sediment trap efficiencies (STEs) varied from 0.01% to 23.6% with an average value of 7.6%. TheSTEs were significantly correlated with shelterbelt density, catchment perimeter, topographic factors,RUSLEP-factor and land use patterns including patch density (PD), patch cohesion index (COHESION), Shannon's diversity index (SHDI) and aggregation index (AI). The multiple regression equation involving factors of catchment's topography and morphology and land use pattern has a satisfactory performance, and mean slope gradient (MSG) andAIexplained most of the variability of shelterbelts'STE. This information can help land managers to better design shelterbelts and to reduce water-derived soil loss at catchment scale.