中文摘要：

为探讨区域尺度上枯落物蓄积量的空间分布特征及其影响因素,在黄土丘陵区按照年降水量梯度,从南到北依次选择7个调查样点,对典型乔木群落、灌木群落和草本群落枯落物蓄积量进行了系统调查。结果表明：3种植被群落枯落物蓄积量差异显著（P〈0.05）,且乔木群落（440.5-840.1 g/m^2）〉灌木群落（105.9-217.9 g/m^2）〉草本群落（12.2-67.6 g/m^2）;在坡面尺度上,枯落物蓄积量受地形条件影响显著,乔木群落、灌木群落和草本群落阴坡的枯落物比阳坡分别多14.9%,39.3%和27.5%,且坡下大于坡中、大于坡顶;在区域尺度上,从南到北,枯落物蓄积量表现出减小趋势,乔木、灌木和草本群落分别从808.6、145.1、67.6 g/m^2减少到478.7、118.6、12.2 g/m^2,枯落物蓄积量随年均降水量的增加而增大,且与温度、郁闭度、密度、地上生物量和海拔间存在显著相关关系,拟合的枯落物蓄积量方程效率系数〉0.61,能够较好地模拟黄土丘陵区典型植被枯落物蓄积量。

英文摘要：

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 agroecosystem 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 been changed 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 weresignificant with the litter mass ranked as arbor（ 440. 5 - 840. 1 g / m^2） shrub（ 105. 9 - 217. 9 g /m^2） herb（ 12. 2 - 67. 6 g / m^2）. 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