| Soil moisture is the main factor that affects the ecological restoration of rocky desertification areas,and it has an important influence on the dissolution and transfer of soil nutrients and solutes,the activities of microorganisms,and the growth and development of plants.The complex geological characteristics of the rocky desertification area have resulted in karst landforms of varying degrees of development and variable climate characteristics even in small areas,which has a particularly great impact on soil moisture.In this study,different levels of rocky desertification(no rocky desertification,latent rocky desertification,mild rocky desertification,moderate rocky desertification,severe rocky desertification)were carried out in the rocky desertification area of the typical rift basin in Jianshui County,Yunnan Province.The method of combining dynamic monitoring and analysis with artificial rainfall control experiments was used to explore the dynamic characteristics of soil water runoff in different rocky desertification karst systems under different rainfall conditions,aiming to reveal the difference in soil water runoff between different degrees of rocky desertification.It provides a reference for the dynamic management of soil moisture in the rocky desertification area of southwest China.The main research conclusions are as follows:(1)The higher the degree of rocky desertification,the more complicated the fluctuation of soil water active level.There is no rocky desertification,potential rocky desertification and mild rocky desertification soil water active layer,sub-active layer and relatively stable layer are complete and orderly,which is convenient for the development of rocky desertification ecological restoration.The level of moderate rocky desertification soil is missing(no relatively stable layer),and the level of water activity in severe rocky desertification soil is chaotic(from active layer to relatively stable layer to sub-active layer),and it is necessary to explore and utilize deeper soil moisture.(2)Within the scope of the experimental design,the maximum water content of the soil during the rainfall process and the rate of infiltration runoff increased with the increase of rainfall intensity and rocky desertification degree.When the rainfall intensity is 30 mm/h,the soil moisture continues to increase,the infiltration process is similar,and the infiltration rate has an obvious rapid growth period,a rapid decline period,a relatively flat period and a stable end period.When the rainfall intensity is 60mm/h,the soil moisture content continues to increase to a stable maximum.The infiltration process of non-rocky desertification and potential rocky desertification are similar,and the runoff rate from light rocky desertification to severe rocky desertification gradually increases.When the rainfall intensity is 90 mm/h,the rocky desertification soil moisture at different depths rapidly increases to a stable maximum value.The moisture change during the infiltration process only has a rapid growth period and a rapid decline period.The runoff rate increases with the degree of rocky desertification.The increase of is a typical stepped increase.(3)The water use efficiency of plants increases with the degree of rocky desertification.The water use efficiency of plants at the leaf level shows the order of severe rocky desertification>moderate rocky desertification>light rocky desertification>potential rocky desertification>no rocky desertification,indicating that as the degree of rocky desertification increases,water use The efficiency is also increasing,and a higher degree of water use efficiency is reached under the rainfall intensity of 60mm/h,indicating that plants may adapt to the increasing degree of rocky desertification and the most frequent rainfall environment by improving water use efficiency. |
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