宁夏河东沙地植被多样性与土壤的关系

Vegetation diversity and its relationship with soil physical and chemical properties in Hedong Sandy Land,Ningxia

明确植被多样性与土壤理化性质的关系是沙地植被保护和荒漠化治理的重要前提。本研究调查了宁夏河东沙地植被群落特征及土壤理化性质,探究了植被与土壤间的关系。结果表明:调查区域有植物15科、34属、41种,其中单种属29属,单属科11科。草本植物占绝对优势,共计36种,占87.80%,仅5种灌木,无乔木。样地物种多样性指数(0.60~1.07)和均匀度指数(0.46~0.63)均较低,而优势度指数较高(0.46~0.68),植被组成较简单,群落优势种较突出。河东沙地主要为碱性土,部分区域为强碱性土,土壤未见明显盐化特征。有机质含量(1.68~2.80 g·kg^(-1))、全氮含量(0.12~0.20 g·kg^(-1))与科尔沁沙地和毛乌素沙地相当,但有效磷含量(0.41~1.85 mg·kg^(-1))仅为科尔沁沙地的20%,表明河东沙地植被可能存在磷限制现象。冗余分析表明,土壤指标能很好地解释河东沙地植被群落特征,第一排序轴的解释率达到75.87%,其中表层土壤全氮、有机质、C∶N总解释率达49.20%,表明表层土壤有机质和氮含量对河东沙地植被形成和分布有重要影响。河东沙地植被盖度与表层土壤水分含量极显著负相关、与土壤养分含量显著负相关,植被高度与表层土壤有机质和全氮含量显著负相关,物种丰富度和多样性指数与土壤养分间显著负相关。

Clarifying the relationship between vegetation diversity and soil physical and chemical properties is the premise for vegetation protection and desertification control in sandy land.Vegetation community characteristic,soil physical and chemical properties and their relationship were studied in the typical area of Hedong Sandy Land in Ningxia.The results showed that there were 41 species,which belongs to 34 genera,15 families.There were 29 genera only have one species and 11 families only have one genus.Herbaceous plants accounted for an absolute advantage,with a total of 36 species,accounting for 87.80%.Only 5 shrubs were recorded and no tree distributed in the study area.The species diversity indices(0.60-1.07)and the evenness indices(0.46-0.68)are both low,while the predominant indices(0.46-0.68)were relatively high,which reflected that the vegetation composition in the studied area was simple and the dominant species have significant impacts on the community characteristics.The soil in this area was mainly alkaline soil,with some area been strongly alkaline soil,but the soil has a low salt content.The soil organic matter content(1.68-2.80 g·kg~(-1))and total nitrogen content(0.12-0.20 g·kg-1)were equivalent to those in Horqin Sandy Land and Maowusu Sandy Land,but the available phosphorus content(0.41-1.85 mg·kg~(-1))had an order of magnitude difference with Horqin.Which indicates that there might have been phosphorus limitation on formation and distribution of vegetation in Hedong Sandy Land.Redundancy analysis(RDA)was applied,and the results showed that soil properties could effectively explain the vegetation community characteristics in Ningdong Sandy Land.The interpretation rate of the first sorting axis reached 75.87%,with a total interpretation rate of 49.20%for total nitrogen,organic matter,and C∶N of surface soil.This showed that surface soil organic matter and nitrogen had important impacts on vegetation formation and distribution in the Hedong Sandy Land.By further analysis,it was found that vegetation coverage has extremely significant negative correlation with surface soil water content and also has significant negative correlation with soil nutrients.The vegetation height has significant negative correlation with surface soil organic matter and total nitrogen content.There was a negative correlation between species richness and species diversity indices and soil nutrients in Hedong Sandy Land.