腾格里沙漠东南缘荒漠植被格局与土壤资源的关系

Association Between Vegetation Patterns and Soil Properties on the Southeastern Edge of the Tengger Desert

本文旨在探讨沙漠与草原化荒漠过渡带灌木和草本植物种格局与土壤资源的关系。结果表明:细质土壤与草本和灌木种的盖度、生物量具有高度相关关系;灌木盖度与60～150cm土层含水量呈正相关(P<0.01),但与0～60cm土层含水量、容重、沙粒含量、pH及Si含量呈负相关;草本植物的丰富度、盖度和生物量与表土层的粘粒、粉粒、有机质、全氮和一些微量元素(Rb、V、Ni)含量呈正相关,与深层土壤容重、EC、pH和含水量呈负相关;逐步回归分析结果也表明,土壤含水量和土壤质地与植被分布格局和结构呈显著相关关系;本研究结果也部分地验证了Sala提出的概念模型,但决定植物群落中草本和灌木种组成比例的关键因素是土壤含水量及土壤其它参数,例如土壤养分状况等。

The structure and pattern of plant communities in the transitional zones or ecotones between biomes change most notably. However, little is studied or made known about what are the key soil factors that allow dominant shrubby or herbaceous species from adjacent communities to coexist in the transitional zones, and how these species respond to the changes in the soil conditions. The aim of the present study is to examine the relationship between the distribution patterns of shrub and herb species and the soil structure in the desert and the steppe desert transitional zones. A total of 5 samling belts, each with 100 quadrats, distributing in different sites, were designed to survey the vegetation and to collect the soil samples. The results indicate that fine-texture soil is highly correlated with the percentage of cover and biomass for both shrub and herbaceous species. Shrub cover is found to be positively correlated with soil moisture at 60～150 cm depth (P<0.01), but is negatively correlated with the soil unit weight, sand content, pH value, Si content, and water content in 0～60 cm soil layer. The diversity, extent of coverage, and biomass of herbaceous species are positively correlated with the soil surface content of silt, clay, organic matter, total N, and some microelements such as Rb, V, and Ni, but negatively correlated to deeper soil's unit weight, EC, pH, and water content. The results of stepwise regression analysis show that the soil moisture and texture are highly correlated with the structure and distribution pattern of vegetation. The present study partly supports Sala's conceptual model. However, the key factors that determine the proportion of shrub of herbaceous species in the composition of a plant community are the soil moisture and other parameters such as nutrients and so on.