黄丘区退耕地植被与土壤水分养分的互动效应

对典型黄土丘陵区的延安、安塞和吴旗不同退耕年份植被特征、土壤水分和养分的调查和测定,研究了退耕地植被与土壤水分和养分随时间变异及其互动效应规律。结果表明,退耕初期土壤有较高的水分和养分,在较高的土壤水分和养分支持下,植被指数呈增长趋势,随着耕作施肥活动的停止和植被恢复对土壤水分和养分的消耗,使土壤水分和养分含量降低,土壤水分和养分的变异幅度也较大;从变化趋势看,植被指数和土壤贮水量变化呈相反趋势,植被指数与土壤水分之间的关系比其与土壤养分之间的关系更加密切,表明土壤水分对植被恢复和植被群落演替的作用更加显著;在退耕初期,土壤水分和养分对植被恢复和群落演替的作用要大于植被恢复和群落演替对土壤水分和养分的作用,随着植被群落演替的进行,植被对环境的适应能力不断增强,它们之间的作用关系不断改变,这种相互作用使植被群落以自己的方式改变着土壤水分和养分,并使自己逐步达到稳定。

Reciprocal effects among vegetation, soil moisture and nutrients of cropland to forest and grassland in the Loess Hilly Region

Vegetation,soil moisture and nutrients are the most active factors of landscape and the important contents of evaluation of the conversion of cropland to forest and grassland(CFG).The relationship between them is crucial to ecological research.In the Loess Hilly Region,study of vegetation index,soil moisture and nutrients is required for understanding of landscape ecological processes and vegetation restoration.Relationships between vegetation and soil moisture and nutrients of CFG in the loess hilly region were analyzed in this paper.The results show that vegetation index presented ascending trend in beginning of CFG.Along with the stop of cultivation and fertilization and consumption of soil moisture and nutrient by vegetation,soil moisture and nutrient decreased and showed big changes.The graphs of vegetation index,soil moisture and nutrient showed that the trend of vegetation index was reverse with that of soil moisture.A closer relationship existed between vegetation index and soil moisture.These showed that the soil moisture had a more remarkable effect on vegetation restoration and succession.In beginning of CFG,effect of soil moisture and nutrient on vegetation restoration and succession was more than that of vegetation restoration and succession on soil moisture and nutrient.Meantime,adaptability and stability of vegetation to environment was improved.