Effects of Old-fields Successional Revegetation on Soil Moisture in Hilly Loess Region of Northern Shaanxi
Effects of Old-fields Successional Revegetation on Soil Moisture in Hilly Loess Region of Northern Shaanxi
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发表时间：
2005
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通讯作者：
T. Yong
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作者：
T. Yong
本文通过对17个不同撂荒年限、11次退耕地0~300cm土壤水分的一次性调查，采用多元回归和通径分析方法，分析了退耕地对土壤水分的影响（生长季0~ 500 cm测量1次，0~300cm测量10次）10个样点，每个剖面测量间隔20 cm。（1）由于弃耕后地上生物量、植被覆盖度、土壤有机质等相关因子发生了变化，在弃耕后的不同阶段，其对土壤含水量及其波动的影响可能有所不同，实测结果与上述事实相吻合，并证实了在局部地区，实际上老田土壤含水量有下降的趋势，而波动以含水量的标准差表示，在被遗弃后会增加。（2）土壤含水量及其波动可以通过地形因子来估计（坡度、坡面和海拔）、土壤因素（表土容重、有机质）和植被因素（地上生物量、盖度），其中群落盖度主要决定着上层生物量和根层生物量的波动，群落覆盖度和地上生物量主要是通过其相对较大的正向和直接作用，效果(3)We从260 ~ 300cm土层土壤水分储量的差异与累积降雨量的显著正相关关系可以看出，260~300cm土层土壤水分存在向下通量，也就是说，260~300cm土层不是降雨补偿和植物利用的关键层，降雨入渗可能超过300cm，这意味着用0~300cm土壤含水量计算蒸散量可能会高估，因此用280~300cm土壤含水量计算的累积渗漏量可能会大于300cm土壤含水量。以300cm土壤含水量为补充调节因子，利用植被覆盖度、地上生物量、深层水分通量、坡度和坡向等因子，影响群落蒸散的主要因子是地上生物量，其次是植被覆盖度。
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.