【摘要】：坡耕地土壤再分布對土壤有機(jī)碳(SOC,soil organic carbon)遷移的作用機(jī)制研究已成為土壤侵蝕學(xué)研究的熱點,然而目前極少有研究關(guān)注地震后生態(tài)脆弱的龍門山地震帶坡耕地土壤侵蝕機(jī)理及其導(dǎo)致的土壤有機(jī)碳再分布規(guī)律。該研究選擇龍門山地震帶內(nèi)(都江堰市)一塊陡坡耕地和一個梯田系列,采用137Cs法和野外調(diào)查,對比分析強(qiáng)震導(dǎo)致田埂垮塌和未受損情況下坡耕地土壤侵蝕空間變化特征和有機(jī)碳運移變化機(jī)理。結(jié)果表明,該區(qū)黃棕壤有效137Cs背景值為1 473 Bq/m2;坡度較小的坡式梯田內(nèi)部上坡表現(xiàn)為侵蝕,下坡表現(xiàn)為沉積,同時,上部梯田的侵蝕速率高于下部梯田,但整個梯田系列凈侵蝕量非常小,這表明梯田之間由于缺乏田埂的保護(hù),水力也起著侵蝕、搬運上坡梯田土壤的作用,但是整個坡式梯田系列可以起到較好的保土作用,同時,坡式梯田內(nèi)部主要以耕作侵蝕為主,是造成梯田上部坡位土壤流失嚴(yán)重的主要原因;陡坡耕地的地形為復(fù)合坡,由于田埂垮塌導(dǎo)致其土壤侵蝕速率顯著高于坡式梯田系列,在整個坡面上,除了坡頂土壤侵蝕速率高之外,下坡坡度變大(曲率較大)的部位土壤侵蝕速率也非常高,同時,土壤沉積也發(fā)生在2個坡位(中下坡坡度較緩的部位和坡腳部位);在梯田系列和陡坡耕地上,SOC與土壤137Cs的空間變化規(guī)律較為一致。研究結(jié)果表明,在龍門山地震帶,質(zhì)量較好的石埂梯田仍然發(fā)揮著較好的土壤保持效果,同時,耕作侵蝕是該區(qū)坡耕地上一種重要的土壤侵蝕形式,在制定相應(yīng)的土壤保持措施時,必須充分考慮耕作侵蝕的作用,才能有效地控制土壤侵蝕,此外,該研究結(jié)果還表明采用137Cs核素示蹤技術(shù)可以比較科學(xué)地解釋該區(qū)域的土壤侵蝕速率和SOC的空間變異規(guī)律。
[Abstract]:The mechanism of soil redistribution on soil organic carbon (SOC,soil organic carbon) migration in sloping farmland has become a hotspot in soil erosion. However, little attention has been paid to the mechanism of soil erosion and the redistribution of soil organic carbon (SOC) in sloping farmland in Longmen Mountain seismic zone. In this study, a steep slope cultivated land and a terraced field in the Longmen Mountain seismic belt (Dujiangyan City) were selected, and 137Cs method and field investigation were used. The spatial variation characteristics of soil erosion and the mechanism of organic carbon transport in sloping farmland caused by strong earthquakes were analyzed. The results showed that the background value of available 137Cs of yellow brown soil was 1 473 Bq/m2;. At the same time, the erosion rate of the upper terrace is higher than that of the lower terrace, but the net erosion amount of the whole terrace series is very small. This indicates that due to the lack of field ridge protection between terraces, water power also plays an erosion role in transporting the upper slope terrace soil, but the whole slope terrace series can play a better role in soil conservation, at the same time, In slope terrace, tillage erosion is the main reason, which is the main cause of soil loss in the upper slope of terrace. The topography of steep slope cultivated land is compound slope. The soil erosion rate is significantly higher than that of slope terrace series due to the collapse of field ridge. In the whole slope, except for the high soil erosion rate at the top of slope, the soil erosion rate of steep slope is higher than that of terrace. The soil erosion rate is also very high in the lower slope where the slope becomes larger (curvature is larger), and the soil deposition also occurs in two slope positions (the middle slope is slower and the slope foot is at the bottom). In terrace and steep slope farmland, the spatial variation of SOC and soil 137Cs is consistent. The results show that in the Longmen Mountain seismic belt, the terraces with good quality still play a better role in soil conservation, and tillage erosion is an important form of soil erosion on sloping farmland in this area. In formulating appropriate soil conservation measures, the role of tillage erosion must be fully taken into account in order to effectively control soil erosion, The results also show that the 137Cs tracer technique can scientifically explain the soil erosion rate and the spatial variation of SOC in the region.
【作者單位】： 綿陽師范學(xué)院生態(tài)安全與保護(hù)四川省重點實驗室;中國科學(xué)院水利部成都山地災(zāi)害與環(huán)境研究所中國科學(xué)院山地災(zāi)害與地表過程重點實驗室;
【基金】：生態(tài)安全與保護(hù)四川省重點實驗室開放基金資助(ESP201303) 國家自然科學(xué)基金(41401313) 四川省應(yīng)用基礎(chǔ)研究計劃項目(2014JY0067)
【分類號】：S157.1

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