Correlation mechanism between rocky desertification degrees and slope position factors in karst mountainous area of southeast Yunnan
As a kind of land degradation phenomenon,rocky desertification is one of the main ecological problems in karst areas in Southwest China.The key to the effective control of rocky desertification is to explore the distribution law and influence mechanism of rocky desertification.Taking three typical experimental areas in the karst mountainous area of southeast Yunnan as the research subjects,we extracted rocky desertification degrees and slope position factors as variables,and analyzed the correlation mechanism between these two variables.We also explored the roles of terrain factors such as slope gradients,slope aspects,terrain cutting depths,etc.in the correlation mechanism in order to further clarify the distribution law of different degrees of rocky desertification at different slope positions under the natural conditions as well as under the human interference.This study provides support for the case study on distribution and influence mechanism of rocky desertification in karst mountainous areas,and provides scientific basis for monitoring and restoring the regional ecological environment.The results show as follows:(1)The area of rocky desertification decreased gradually from ridge to valley,mainly distributed in the areas in high slope positions.Accordingly,the area of non-rocky desertification increased gradually.Slight rocky desertification mostly occurs along the ridge and on the uphill slope,while moderate rocky desertification mostly occurs at the ridge,and on the uphill and downhill slopes.The heavy rocky desertification is distributed in a uniform way in each slope position.(2)Slope positions are significantly correlated with degrees of rocky desertification,and directly affect the distribution law of rocky desertification.At the same time,the effect of slope positions on rocky desertification is indirectly enhanced by slope gradients and terrain cutting depths.(3)The correlation mechanism between slope positions and degrees of rocky desertification is demonstrated below.If the area is dominated by natural evolution,slope positions are negatively correlated with degrees of rocky desertification.The higher the slope position is,the greater the slope gradient and the deeper the terrain cutting will be.In this case,the increasing frequency of material migration in the area of high slope position will intensify the degree of rocky desertification.Conversely,the lower the slope position is,the smaller the slope gradient and the terrain cutting will be.In this case,human activities will become more convenient and frequent,which may consume the accumulated materials from the high slope position to the low and intensify the rocky desertification.The implications of research findings indicate that the geomorphic structure of the karst area is relatively complex according to the field investigation,and relevant research should be carried out based on the geographical environment of the study area.Most studies on rocky desertification have been conducted at a large or medium scale such as at a scale of the river basin or of the administrative unit,and the driving factors of different research scales have different influences on the degrees of rocky desertification.In addition,degrees of rocky desertification in different slope positions are significantly different.In the natural distribution,materials are lost along the ridge and accumulate in the valley.In rocky desertification areas,soil and other materials are lost along the ridge,and some remain in the valley.Furthermore,rocky desertification degrees are significantly correlated with slope positions,and the internal correlation mechanisms between rocky desertification degrees and slope positions are different under different intensities of human activity.Human interference is also an important factor affecting the correlation between slope positions and rocky desertification degrees.The research results can provide reference for in-depth analysis of the comprehensive influencing mechanism of rocky desertification degrees in karst mountainous areas,and provide basis for rocky desertification control and ecological restoration in mountainous areas.
rocky desertificationslope positionpath analysisassociation mechanismkarst mountainous area
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