Spatial variation of typical plant litters in the Loess Plateau
Luan Lili, Zhang Guanghui, Sun Long, Liu Fa,Wang Hao
1. School of Geography, Beijing Normal University, 100875, Beijing,China;2 Institute of Soil and Water Conservation Chinese Academy of Science & Minister of Water Resources, 712100, Yangling,Shaanxi, China
Abstract：Severe soil and water loss in the Loess Plateau caused by the most highly erodible soil,inappropriate land use and low vegetation cover, pose a great pressure to the sustainability of agro-ecosystem and society and economy. Great efforts have been made to restore vegetation cover to reduce soil and water loss in the Loess Plateau over the past several decades. Consequently, the near soil surface characteristics (e. g. soil properties, biomass production, plant litter, and root system) have beenchanged significantly. Plant litter is effective in reducing soil and water loss by enhancing water infiltration, retarding the velocity of overland flow and increasing the water holding capacity. The weight of accumulated plant litter is of spatial heterogeneity, but so far few studies have been conducted to quantify the distribution of plant litter accumulation among different slope positions and on a regional scale. Therefore, in order to investigate the spatial distribution patterns and influencing factors of weight of accumulated plant litter on a regional scale,seven survey sites were selected from south to north in the Loess Plateau along the decreasing gradient of mean annual precipitation. The mass of accumulated plant litter of typical species of arbor, shrub, and herb among different slope positions were investigated and the influencing factors including mean annual precipitation, mean annual temperature, altitude,aboveground biomass, vegetation density and canopy density were analyzed. The result showed that the differences of the weight of accumulated plant litter among typical species of arbor, shrub, and herb were significant with the litter mass ranked as arbor (440.5~840.1 g/m2) > shrub (105.9~217.9 g/m2)> herb (12.2~67.6 g/m2). The weight of accumulated plant litter was significantly affected by the terrain conditions. The weights of accumulated plant litter of arbor, shrub, and herb communities at the shady slope were 14.9%, 39.3%, and 27.5% more than that at the sunny slope. The weight of accumulated plant litter in the middle slopes was greater than that in the base and the top of the slopes.The weight of accumulated plant litter showed a decreasing trend with the altitude increasing and the accumulated litter fall of arbor, shrubs, and herbs were reduced from 808.6 g/m2, 145.1g/m2, and 67.6g/m2 to 478.7 g/m2, 118.6 g/m2, and 12.2 g/m2, respectively. The weight of accumulated plant litter increased with the mean annual precipitation, and was significantly correlated with the mean annual temperature, canopy density, vegetation density, aboveground biomass and altitude. The fitting equations well predicted the weight of accumulated plant litter of typical plants in the Loess Plateau. The Nash coefficients of the fitting equations were greater than 0.61. The results are helpful to understanding the spatial distribution patterns of accumulated plant litter and its influencing factors and evaluating the soil and water conservation and ecological benefits of vegetation restoration in the Loess Plateau.
2015, Vol. 13 
