中文摘要：

为探讨黄土高原退耕还林还草后植被枯落物层的水土保持和水源涵养功能,在黄土丘陵区以多年平均降雨量梯度为样线,从南到北依次选择了7个调查点,研究了黄土丘陵区典型乔木、灌木和草本群落枯落物蓄积量、持水量、吸水速率和有效拦蓄量变化情况.结果表明：（1）各植物群落枯落物蓄积量从南到北逐渐减少,且乔木（440.54～840.07 g/m2）＞灌木（105.94～217.88 g/m2）＞草本（12.23～67.64 g/m2）;（2）从南到北,乔木、灌木和草本枯落物最大持水量分别从3 151.09 g/m2,557.13 g/m2和152.62 g/m2减小到1 710.88 g/m2,290.34 g/m2和44.31 g/m2;而乔木、草本和灌木的最大吸湿比分别为4.57,4.49和3.75,受植被物种的影响枯落物最大吸湿比无显著的空间变化特征;（3）不同植被枯落物吸水速率随时间的变化过程比较相似,在0～0.25 h内吸水速率最大,0.25～0.5 h迅速降低,6h后变化较小,乔木和灌木枯落物持水量6h后基本达到最大持水量,草本群落12 h后达到最大值,24 h时各群落枯落物吸水速率基本为0,持水量达到饱和,枯落物持水量和持水速率受植被类型影响显著,但空间变化规律不明显;（4）枯落物有效拦蓄量表现为乔木（15.79 t/hm2）＞灌木（2.86 t/hm2）＞草本（0.72 t/hm2）,且从南到北呈减小趋势.

英文摘要：

To investigate the effects of plant litter layer on soil and water conservation and hydrologic after Grain for Green project in the Loess Plateau,7survey sites were selected from south to north in the loess hilly region according to the decreasing gradient of average annual rainfall,to study the variation of accumulative amount of plant litters,litter water-holding capacity,water absorption rate and effective interception amount of typical species of arbor,shrub and herb.The result showed that：（1）The litter accumulation of different plant communities decreased from south to north and listed as follows：Arbor（440.54～840.07g/m2）〉shrub（105.94～217.88g/m2）〉herb（12.23～67.64g/m2）.（2）From south to north,the maximum water-holding capacity of arbor,shrubs and herbs litters reduced from 3 151.09g/m2 to 1 710.88g/m2,from557.13g/m2 to 290.34g/m2 and from 152.62g/m2 to 44.31g/m2,respectively.The maximum moisture absorption ratios of arbor,shrub and herb litters were 4.57,4.49 and 3.75,respectively.No significant spatial variation was observed in the maximum absorption ratio of litters because of the influence of plant species.（3）For different plant species,the temporal variation of water absorption rate of litters showed similar trends.Water absorption rate reached the largest level within the initial 0～0.25 hand then decreased rapidly in 0.25～0.5h,while did not show significant variation after 6h.The water-holding capacity of litters almost reached the largest level after 6hfor arbor and shrub vegetation and after 12 hfor herb vegetation.After 24 h,water absorption rate of litters of different vegetation fell to zero and litter waterholding capacity reached the saturated level.Water-holding capacity and water absorption rate of plant litterswere significantly affected by plant species,which did not show significant spatial variation.（4）The effective interception amount of plant litters was 15.79t/hm2 for arbor,2.86t/hm2 for shrub and 0.72t/hm2 for herb,and tended to decrease from s