夏季不同土地利用方式下的溶蚀作用研究——以重庆青木关岩溶槽谷区为例

Karstification under different land-use patterns in summer:A case study in the Qingmuguan karst valley,Chongqing

土壤理化性质会随土地利用方式的不同而产生一系列的变化,从而影响到岩溶作用的方向和强度。通过野外溶蚀试片法,测得重庆青木关典型岩溶槽谷区6种典型土地利用方式下6个测试点夏季绝对溶蚀量和单位面积溶蚀量。结果表明,不同土地利用方式土下溶蚀速率存在显著差异,旱地>退耕林>水田>杉竹混交林>荒草地>竹林。对不同土地利用方式的不同层位溶蚀量进行统计发现:溶蚀速率基本上随深度增加而增大,但差别不大。但同一土地利用方式不同层位之间溶蚀量存在明显差别,差别最大点出现在荒草地,其壤中-20cm处溶蚀量是其表层的4.23倍。另外,各点壤中CO2含量随深度增加而增大,与溶蚀速率的变化总趋势有较好的对应关系。而土壤有机质则均随深度的增加而减少,与溶蚀速率变化总趋势相反,但与地表溶蚀速率基本成正相关。故认为有机质含量对溶蚀速率的作用机制较为复杂。

The direction and intensity of karstification could be deeply affected by soil physical and chemical variations resulted from land cover.Taking Qingmuguan karst valley area,Chongqing as an example,the total corrosion amount and corrosion amount under per unit area in 6 kinds of typical land use patterns in summer are got to study the impact of land covers on karst processes by means of limestone tablet corrosion test in the field.The results show that the corrosion rate under different land use patterns is quite different,generally,the corrosion rate decreases from tilled land,woodland exchanged from tilled land,paddy field,woodland mixed with Chinese fir-bamboo land,fallow land and bamboo land successively.It is also found that the corrosion rate largely increases with depth by means of counting up the corrosion rate at different depth.But there is obvious difference in corrosion rate among different depth under same land use pattern,especially in waste land,with the corrosion rate being 4.23 times higher under-20 cm than on the surface layer.Moreover,the CO2 increases with depth in all spot,which is better related with the regime of corrosion rate.The soil organic matter decreases with depth,which is opposite with the regime of corrosion rate but positively correlated with the corrosion rate on the surface layer.So,it is concluded that the impact of organic matter content on the corrosion rate is quite complicated.