黄土丘陵区两种典型灌木群落坡面侵蚀泥沙颗粒组成及养分流失的比较

在野外模拟降雨条件下,比较研究了黄土丘陵区柠条(Cnragana korshinkii)和狼牙刺(Sophoraviciifolia)径流小区产流产沙、侵蚀泥沙颗粒组成、比表面积(SSA)及养分流失特征.结果表明,两种灌木群落均能显著减小坡面径流泥沙的流失.产流后流失泥沙黏粒、SSA与养分含量随降雨时间总体呈现降低趋势,其中有机质变化显著,全磷变化不显著.受植被盖度影响,泥沙中黏粒与养分含量均表现为柠条群落>狼牙刺群落>对照裸地.侵蚀泥沙具有富集黏粒和富集养分的特征,富集率随群落盖度增大而增大(柠条>狼牙刺>裸地).不同形态养分富集率不同,其中有机质均在2.5以上,全氮平均富集率为2.13,全磷为1.23.富集率随产流时间呈线性递减.流失泥沙养分含量与黏粒(粒径<0.002 mm)含量及SSA达到极显著的正相关.坡面土壤养分主要以黏粒为载体流失.SSA的变化不仅能体现土壤颗粒组成的变化,而且能够反映土壤养分的变化.

Comparison of Particle Composition and Nutrient Contents in Sediment Between Two Typical Shrub Lands in the Loess Hilly Area

Runoff and sediment yield on plot,eroded sediment composition,specific surface area(SSA),and nutrient loss were investigated under field simulated rainfall for two typical shrubs,Caragana korshinkii.and Sophora viciifolia,in the loess gully area.Results showed that both of shrubs can significantly reduce the loss of runoff and sediment.Clay contents,SSA,and nutrient contents decreased with rainfall duration.The organic matter(OM) contents had significant changes with rainfall duration but total phosphorus(TP) contents did not.Clay and nutrient contents in sediment from the two shrub lands were higher than those from the bare lands(CK),and clay and nutrient contents from the Caragana korshinkii lands were higher than those from the Sophora viciifolia lands,which may be resulted from the influence of vegetation including above-ground and below-ground parts.In addition,sediment could enrich clay and nutrients,and the enrichment ratios increased with vegetation coverage but decreased linearly with runoff time.The enrichment ratios of OM in all the plots were greater than 2.5,while the averaged enrichment ratios of TN and TP were 2.13 and 1.23,respectively.The nutrient contents in sediment correlated positively with the content of clay particles(less than 0.002mm) and the SSA,because soil nutrients are mainly carried by fine particles.The SSA can embody the changes of particle size distribution and soil nutrients.