不同土地利用类型下土壤碳酸酐酶剖面分异特征研究

摘要

利用 pH 计法来研究西南岩溶区4类土地利用类型11个样地20 cm、40 cm 和60 cm 土层碳酸酐酶(Carbonic Anhydrase ,CA)的剖面分异特征,并与非岩溶样地进行对比。结果表明：西南岩溶区不同土地利用类型不同土层的 CA 活性存在较大差异。在林地中,40 cm 和60 cm 土层的 CA 活性明显高于20 cm 土层；而在乔灌丛、灌丛和耕地中,土壤 CA 活性表现出60 cm 土层处最高,20 cm 土层处最低,并与弃耕地不同土壤层 CA 活性变化趋势截然相反,这是因为弃耕地受人类活动干扰导致土壤 CA 活性出现逆转。进一步分析还可以看出林地、乔灌丛、灌丛和耕地4种土地利用类型下土壤 CA 活性总体呈现出随植物根系深度增加而增加的变化趋势,从而说明土地利用类型是导致土壤碳酸酐酶剖面产生分异的主要因素,并为进一步研究土壤 CA 在自然界碳酸盐岩风化过程中的作用提供了科学依据。%Carbonic anhydrase (CA)plays an important role in catalyzing the reversible hydration of CO 2 , which connects with chemical weathering (including the carbonate rock dissolution and silicate weathering) in atmospheric CO 2 sink and the mysterious missing sink in carbon cycling.In order to explore the soil CA activity by means of pH method from different types of land use in southwest China karst area,1 1 sampling plots from four different karst ecosystems and 5 sampling plots from non-karst ecosystems as a contrast are selected for the study.The results show that there are larger differences in soil CA activity among different soil layers under different types of land use in southwest China karst area.Under woodland,the soil CA ac-tivity in 40 cm and 60 cm soil layers is higher than that in 20 cm.The soil CA activity under tree-shrub land, shrub land and farmland is the highest in 60 cm soil layer,but the lowest in 20 cm.However,in abandoned field,soil CA activity is the highest in 20 cm soil layer but the lowest in 60 cm.It can be seen that the land use type is the main factor affecting the soil CA activity.The soil CA activity increases with the plant root depth due to the CO 2 increases along with the soil depth. Moreover,karst landform is another important factor that affects the soil CA activity.For example,in the Yaji karst experimental site,the soil CA activity is controlled by the physiognomy character due to the weathering product of carbonate rock and organic matter migration from the bealock and piedmont slope to the karst depression.So,the soil microbe will be assembled,which lead to the soil CA activity in 20 cm lay-er at depression is 0.782 U/g and higher than those at the bealock and piedmont slope.At last,we also need to consider the effect from the change of sample sites.For the future comparison,the samples should be col-lected at the border of the same site.Then,the research can provides a certain theoretical basis for further study on the role of soil CA activity in karst processes.