宁夏盐池沙地土壤水分条件与植被分布格局

以宁夏盐池沙地为对象,研究了沙地水分条件与植被分布格局的关系。通过对2002年和2003年样地调查数据的分析,运用烘干法和L 520型中子仪对不同坡位的土壤水分含量进行测定,研究结果表明,有植被覆盖地段的30 cm和60 cm土层的土壤含水量比裸地低约10%,其变化幅度也由于植物不同生长阶段耗水量的不同而比裸地剧烈,特别是植物根系密集的30 cm土层。土壤含水量的高低决定了该区域的植物种类。选择的10块样地中,只有耐旱能力很强的苦豆子生长在含水量较少的沙丘顶部,主要伴生种只有沙蓬和赖草,赖草、沙蒿、猫头刺和柠条6块样地均分布在水分条件相对较好的沙平地,主要伴生种有10种。土壤含水量与地表植被相互作用、相互制约,沙地的水分条件决定了植被分布的格局。

The Relationship between the Soil Water Condition and Vegetation Distribution Pattern in Yanchi

The relationship between the water condition of sandy soil and the pattern of vegetation distribution in Yanchi is sandy area was studied.Investigation data obtained during 2002 and 2003 were analyzed,and the contents of soil moisture in different slope positions were measured by oven drying methods of neutron water analyzer(L520).The results showed that in the soil layers of 30~60 cm,the contents of the soil moisture in the land with the vegetation cover were 10% lower than those without vegetation.The range of variation of soil moisture in the former was greater than those in the later due to different water consumptions of the plants in different growing stages,especially in the soil layer of 30 cm where the dense root systems concentrated.The types of vegetation were also determined by the contens of soil moisture.Among 10 sampling plots selected,only Sophora alopecuroides, a plant with strong drought resistance grown on the top of the dune,only two accompanying species,such as Salsola ruthenica and Leymus secalinus occurred.Plant species such as Leymus secalinus,Artmisia desertorum,Oxytropis aciphylla and Caragana microphylla all grown in 6 relatively flat sampling plots with better water conditions,and the types of accompanying plant were also over 10.It is conculuded that interactive relationship exists between the content of soil moisture and vegetaion cover.The pattern of vegetation distribution is determined by the conditions of soil moisture.