川南坡地不同退耕模式土壤及枯落物持水特性

采用浸泡法对川南坡地退耕成慈竹林、杂交竹林、桤木+慈竹混交林和弃耕地5年后土壤和枯落物持水特性进行了研究。结果表明:坡地退耕后土壤自然含水量(t/hm2)、毛管持水量(t/hm2)和最小持水量(t/hm2)增加,并呈现出慈竹林>杂交竹林>桤木+慈竹混交林>弃耕地>农耕地的变化规律;4种退耕模式枯落物蓄积量(t/hm2)、自然持水量(t/hm2)、最大持水量(t/hm2)、最大拦蓄量(t/hm2)和有效拦蓄量(t/hm2)呈现出慈竹林>杂交竹林>桤木+慈竹混交林>弃耕地的变化规律。枯落物持水量(g/kg)与浸泡时间的关系为Q=alnt+b,吸水速率(g/(kg.h))与浸泡时间关系为V=ktn;在枯落物持水过程中,前2h内枯落物持水作用较强。因此,林下枯落物在降雨过程前期2h对降雨的吸持具有更重要的作用和意义;慈竹林能较好地提高坡地退耕后土壤和枯落物水文生态功能。

Water-holding Characteristics of Soil and Litter in Several Slope Farmlands with Different De-farming Patterns in Southern Sichuan Province of China

The water-holding capacity of soil and litter was studied by the soaking method in slope farmlands in Southern Sichuan of China.Five slope farmlands with different de-farming patterns were selected,including Neosinocalamus affinis plantation(NAP),Bambusa pervariabilis × Dendrocalamopsis oldhami plantation(BDP),Alnus crenastogyne + Neosinocalamus affinis plantation(ANP),abandoned farmland(AFL),and CK.The results showed that,the soil natural water content,capillary water-holding capacity and field water-holding capacity were increased,and followed the order of NAP>BDP>ANP>AFL>CK after 5 years’ de-farming.The litter stock,natural water content,maximum water-holding capacity,maximum interception and modified interception in the four de-farming patterns were also increased and followed the order of NAP>BDP>ANP>AFL.According to the regression,litter water-holding capacity and immerse time showed the relationship of Q=alnt+b,and the relationship is V=ktn between the litter water absorption speed and immerse time.High water-holding capacity and rapid absorption speed were observed at the first 2 h during the process of litter water-holding.Therefore,the results suggested that the first 2 h during rainfall was important to litter water-holding,and the NAP could better enhance the eco-hydrological functions of soil and litter compared with other de-farming patterns.