Seed Removal due to Overland Flow on Abandoned Slopes in the Chinese Hilly Gullied Loess Plateau Region

Theories and empirical evidences suggest that seed removal due to overland flow can result two main spatial outcomes, seed redistribution and seed loss. However, it is not fully understood in some sensitive habitats, such as in abandoned cropland of the Chinese hilly gullied Loess Plateau region. This study evaluates seed redistribution patterns in major micro-sites including eroded, deposited and trap micro-sites, characterizes seed loss by using runoff plot, and explores the effect of vegetation coverage and rainfall on seed loss along three abandoned slopes in the Zhifanggou watershed. Soil seed bank densities in eroded, deposited and trap micro-sites were recorded at 4,482, 7,697 and 5,649 seeds m(-2), respectively. Seed density of loss due to overland flow in 2011 and 2012 were recorded at 52 and 27 seeds m(-2), respectively. Seed loss rate, which was the ratio of seed loss density to the mean density of soil seed banks in the three micro-sites due to soil erosion during the study period was 06%. Seed densities of loss exhibited an exponent relationship with natural erosive rainfalls, and significant correlations were not found between seed loss and vegetation coverage. Therefore, soil erosion resulted in seed redistribution and caused seeds to concentrate in soils or on soil surfaces in trap or deposited micro-sites. Seed loss was affected by erosive rainfall significantly, but it could not cause the loss of large quantities of seeds. Copyright (c) 2016 John Wiley & Sons, Ltd.