| Yunnan Province is located in the southwest border and is the ecological security barrier in Southwest China.However,rocky desertification ranks second in China,which has become a serious ecological and environmental problem in Yunnan and seriously hindered the social and economic development of rocky desertification areas.Therefore,the analysis of long-term temporal and spatial evolution characteristics of rocky desertification in karst areas of Yunnan Province and the quantitative disclosure of the impact mechanism of natural factors and human activities on the development of rocky desertification in the study area are the important basis and basis for the formulation of rocky desertification control measures in Yunnan Province.Based on this,taking the karst area of Yunnan as the research object,the Landsat TM/oli remote sensing images in 2000,2005,2010,2015 and 2020 are selected as the basic data to extract the rocky desertification information.This paper analyzes the temporal and spatial evolution characteristics of rocky desertification in the study area in the past 20 years from the current situation,evolution mode,area transfer matrix,evolution rate and evolution direction of rocky desertification,and quantitatively explores the driving factors of rocky desertification.The conclusions are as follows:（1）From 2000 to 2020,the Rocky Desertification in Yunnan karst area showed an evolutionary trend of increasing first and then decreasing.On the whole,the rocky desertification area is decreasing,but it is still increasing in some areas.In terms of time,the rocky desertification areas in the five periods are 24720.61 km~2,29584.21 km~2,28060.22 km~2,23477.85 km~2 and 20927.39 km~2 respectively.During the period from 2000 to 2005,the deterioration of rocky desertification occurred.During the period from 2005 to 2020,due to the continuous strengthening of governance,the deterioration of rocky desertification was curbed and gradually reduced;In each karst division,in the past 20 years,the Rocky Desertification in the karst areas of central,Southeast and West Yunnan has been improved.The Rocky Desertification in the karst areas of northeast and Northwest Yunnan is more complex.Affected by human activities and inadequate control measures,the overall area has increased,and the form of rocky desertification is more severe.In the later stage,the control should be strengthened.Spatially,the areas with serious rocky desertification are mainly distributed in Qiubei County and Yanshan County in the southeast of Yunnan and Shilin County,Luliang County,Fuyuan County and Zhanyi District in the karst area in the middle of Yunnan.The karst area in the northeast of Yunnan is concentrated along the Jinsha River Canyon.（2）The evolution of rocky desertification in the karst area of Yunnan has the characteristics of rapid and complex,and there is a phenomenon of good governance and deterioration.The evolution patterns of the two stages from 2000 to 2010 and2020 to 2020 are relatively similar,mainly in the univariate way,accounting for33.45%and 34.66%of all evolution ways,respectively,followed by the gradual change way and the least reversal way.;In the area transfer matrix of rocky desertification,the main source and destination of each rocky desertification type are mainly adjacent types,and the rocky desertification in some areas has a sudden change from no rocky desertification to extremely strong rocky desertification.Low-grade rocky desertification has a large amount of change in transfer;among the four stages of single-grade evolution rates,the fastest evolution rates are rocky desertification with strong and extreme strength.（3）The forward and reverse evolution of rocky desertification occurred at the same time in the past 20 years,and the overall improvement area was larger than the deterioration,but the deterioration was obvious in some areas.The change direction of each period is mainly concentrated in the first level of improvement and the first level of deterioration;spatially,the central and western Yunnan have improved significantly in the past 20 years,and the deterioration is mainly distributed in the karst area of northeast Yunnan,which is widely distributed and has a high degree of deterioration;the central part of southeast Yunnan has deteriorated.The grades are higher and the distribution is contiguous;the deterioration in northwest Yunnan is mainly distributed in strips along the canyon.（4）The driving factors and rocky desertification in 2020 are selected for spatial superposition analysis.The results show that in different lithology,rocky desertification is mainly distributed in carbonate rock with clastic rock and continuous limestone;Among the land use types,rocky desertification is mainly distributed on cultivated land and grassland;On the slope,rocky desertification is mainly distributed in the range of 8~15°and 15~25°;There is no positive correlation between population density and rocky desertification distribution.Rocky desertification is mainly distributed in the range of 100~200 people/km~2 and 0~100people/km~2;In the first output value,the distribution of rocky desertification is the most in the range of more than 4 billion.It shows that the Rocky Desertification in the karst area of Yunnan is mainly distributed in the areas dominated by the primary industry and fragile karst environment,with a certain slope of cultivated land and grassland.（5）The driving factors of rocky desertification in karst areas of Yunnan Province were explored based on geographic detectors.The result is;Among the single factors,slope（q=0.1565）,rock properties（q=0.1557）and land use（q=0.1238）are the main driving factors for the formation of rocky desertification in Yunnan karst area,and the contribution rates of the first output value（q=0.0033）and population density（q=0.0029）are relatively small;Among the interactive factors,when the slope and land use factor（q=0.2228）,land use and rock properties（q=0.1839）work together,the occurrence of rocky desertification is exacerbated.The highest incidence of rocky desertification in land use of all grades of slope is in the range of 8~15°,15~25°and greater than 25°,and the largest distribution of rocky desertification area in each slope range is cultivated land,followed by grassland,It shows that agricultural activities on sloping farmland and grassland in karst area can easily lead to rocky desertification. |
PDF Full Text Request