摘要
根据陕北黄土丘陵区17块不同撂荒年限样地土壤水分的普查和10块样地土壤水分的定位测定,利用多元回归分析和通径分析法研究了植被恢复过程中土壤水分的变化和各植被、土壤因子对土壤水分的作用效应:①农田撂荒后,随着植被的恢复,因群落生物量、植被盖度和土壤有机质等这些对土壤水分有直接作用因子的变化,而间接表现为随着撂荒年限的增加,土壤含水量越来越低,而土壤水分的波动却越来越大;②用地形因子(包括坡度、坡向和海拔)、土壤因子(地表土壤容重和有机质含量)和植被因子(地上生物量和植被盖度)可以较好地对土壤水分做出多元拟合,影响表层土壤水分含量和根系层水分波动的主导因子是植被盖度,而影响深层土壤水分波动的主导因子是地上生物量;③土壤水分两次测定期间深层储水量差值与累积降雨量成显著正相关,说明土壤水分测定下边界存在上渗与下渗运动,而且储水量差值多数为正值,说明是以下渗为主。因此O根据土壤水分来估算群落蒸散时会有正的系统误差。为此论文将深层储水量差值作为补偿调节因子自变量,以提高多元拟合精度。拟合结果说明群落蒸散可由群落生物量、群落盖度、坡度、坡向和土壤表层容重或坚实度来估计。在植被恢复过程中影响群落蒸散的最大因子是群落蒸腾,其次是植被盖度。
In this article,effects of revegetation on soil moisture of old-fields were analyzed using multiregression and path analysis,based on once investigation of 0～300cm soil moisture of 17 sites with different abandonment years,11-times （once measurement of 0～500cm in growth season and ten times of 0～300cm）measurements of 10 sites,each measurement interval in profile is 20cm.The results show that： （1）As the related factors,such as aboveground biomass,vegetation coverage,soil organic matter etc.changed after abandonment,their effects to soil moisture content and fluctuation may vary in different post-abandonment stages.The measurements agree with the above facts,and confirmed that actually in local region,soil moisture content of old-fields tends to decrease,whilst fluctuation,denoted by standard deviation of moisture content,tends to increase after abandonment. （2）Soil moisture content and fluctuation can be estimated by topographic factors （slope gradient,slope facing and altitude）,soil factors （bulk density of topsoil,organic matters） and vegetation factors （aboveground biomass,coverage）,in which contents of top layers and fluctuation in root layers are determined mainly by communities coverage,while the aboveground biomass contributed most to the fluctuation of deeper layers.Both the communities cover and the aboveground biomass act mainly through its relative large positive and direct effect. （3）We found that down flux of soil moisture exists in the 260～300cm layer, deduced from the significant positive relationship between the difference of moisture reserves in 260～300cm and accumulative rainfall.In other words,the 260～300cm in profile is not the critical layer of rainfall compensation and plant usage,in our measurements,rainfall may seep beyond 300cm.This implies that evapotranspiration may be over estimated if calculated from the 0～300cm soil moisture content.So the accumulated leakage calculated by the 280～300cm soil moisture content is used as a supplement adjustor in multiregression to the estimated evapotranspiration.The evapotranspiration can be estimated by vegetation coverage,aboveground biomass,moisture flux in deep layer, slope gradient and direction,and topsoil bulk density.In which the primary influencing factor to communities evapotranspiration is aboveground biomass,vegetation coverage ranks the second.
出处
《自然资源学报》
CSSCI
CSCD
北大核心
2005年第5期669-678,共10页
Journal of Natural Resources
基金
国家自然科学重点基金项目(903020057)
国家自然科学基金项目(40471126)
中国科学院知识创新项目(KZCX01-6)。
关键词
恢复生态
土壤水分
多元分析
撂荒演替
黄土丘陵区
restoration ecology
soil moisture
multivariate analysis
post-abandonment successions
hilly Loess region
