焉耆盆地天然植被与地下水关系研究

Research on the Relationship between Natural Vegetation Growth and Groundwater in Yanqi Basin

根据不同水分、盐分梯度,将焉耆盆地分为河畔区、荒漠区和湖畔区。调查不同区天然植被种类、数量、盖度等因子与不同水分、盐分的关系,结果表明：河畔区从第一分水枢纽到开都河下游70 km范围内,土壤水分无明显梯度变化,土壤盐分、地下水矿物质含量则呈明显增加趋势;随盐分梯度变化,乔、灌、草植被盖度与土壤含盐量呈指数关系;适宜植被生长的地下水埋深范围为0.5~2.4 m,当地下水矿物质含量为0.62 g/L时,河畔区植被生长最好。荒漠区（西区、南区、北区）从西北到东南方向,土壤水分、盐分均呈增加趋势;不同盐分条件对植被盖度有明显影响,当土壤含盐量在6~10 g/kg之间时,随土壤含盐量增加,植被覆盖度降低,植被种类明显减少。湖畔区离湖1~3 km范围,随离湖距离增加,土壤水分减小,盐分增大;随土壤含盐量增加,灌、草植被盖度逐渐减小,适宜植被生长的地下水埋深范围为0.5~5.7 m;当地下水矿物质含量0.5 g/L左右时,湖畔区植被生长最佳;地下水矿物质含量3~5 g/L时,盐漠植被仍生长良好。

According to different moisture content and salinity gradient, we divide Yanqi Basin into three areas： river bank area, desert area and lakeside area. We investigated the correlation between natural plant species, amount, cover in different areas and moisture content, and salinity to different degrees. The result indicates that the river bank area from the first water diversion project to the lower reaches of the Kaidu River within 70 km, the soil moisture is not obvious in gradient change, and the soil salinity and the hardness index show an increasing tendency obviously. With the change of the salinity gradient, the arbor, the shrub and the grass vegetation cover degree present an exponential rela- tion with the soil salt content. The suitable depth for vegetation growth is from 0. 5 to 2. 4 m. When the local groundwater hardness index is 0. 62 g/L, vegetation in the river bank area grows best. In desert area （west area, south area, north area） from northwest to southeast, the soil moisture and the salinity show an increasing tendency and different salinity conditions have an obvious influence on the vegetation cover degree. When the soil salt content is less than 3 g/kg, the vegetation cover degree increases with the soil salinity. When soil salt content is in a scope of 6 - 10 g/kg, the vegetation cov- er degree reduces when the soil salt increases, and the plant species reduces obviously. The lakeside area which is in 1 -3 km scope, the soil moisture reduces and the salinity increases with the increase of the distance to the lake. The shrub of the grass cover degree reduces gradually with the increase of the soil salt content, the suitable depth scope for vegetation is 0. 5 -5. 7 m; When the groundwater hardness index is 0. 5 g/L the vegetation grows best, yet as the groundwater hardness index is 3 -5 g/ L, the salt desert vegetation still grows well.