| Karst rocky desertification in the southwest region,soil and water loss in the Loess Plateau,desertification in the northwest region,they are known as the three major ecological problems in China,which is one of the major ecological problems related to the national economy and the livelihood of mankind.In the Karst area of Guizhou Province,the rocky desertification is a particularly prominent problem.Therefore,study on the historical evolution of the rocky desertification in Karst area of Guizhou has an important role and significance in the prevention and restoration of Karst rocky desertification.In this paper,extracted information of the vegetation coverage in 1995,2005 and 2014 through analyzing the corresponding periods' remote sensing images of Luodian county,Guizhou province by ArcGIS9.3 and Erdas9.2 processing softwares.According to the DEM data,obtained the slope information of the study area.Moreover,obtained the bare rock exposed rate of the study area through combining with the field survey.Further,established the information database of Karst rocky desertification intensity grades atlas.In addition,this paper through analysing the characteristics and rules of the temporal and spatial variation of the rocky desertification in Luodian county during the 19 years,researching the landscape pattern and its intensity grades of rocky desertification,discussing the driving forces which led to the change of rocky desertification intensity grades by the method called grey correlation degree analysis,finally,predicted the change trend of rocky desertification intensity grades in the future of the study area.The main conclusions of this paper are as follows:(1)In terms of the spatial distribution pattern of rocky desertification intensity grades,no obvious rocky desertification,potential rocky desertification and mild rocky desertification are the main components of Karst rocky desertification in Luodian county.On the three periods,the total area of the three intensity grades accounted for the total area of the study area,the lowest proportion was 71.29%.During the 19 years,great changes have taken place among the intensitygrades in the study area: In the variation of the first 10 years,the rocky desertification intensity grades unchanged only accounted for 6.418%;in the variation of the after 9 years,it is only accounted for 0.059%.(2)In terms of the temporal and spatial variation of rocky desertification intensity grades,the rocky desertification in variation from 1995 to 2014 in Luodian county,the main types of mutual conversion between different intensity grades are the three types include moderate rocky desertification transferred to mild rocky desertification,mild rocky desertification transferred to potential rocky desertification and potential rocky desertification transferred to no obvious rocky desertification.These three kinds of transformation accounted for 49.42% of the total transfer area,close to a half of the total transfer area.From 1995 to 2014,in the mass,no obvious rocky desertification,potential rocky desertification and strong rocky desertification showed an increasing trend.Among them,the biggest growth area is no obvious rocky desertification,and the total increase area of no obvious rocky desertification and potential rocky desertification is209.91km2.As well,strong rocky desertification had increased 46.41km2.In summary,from 1995 to 2014,the intensity grades of rocky desertification in Luodian county is gradually variation from higher intensity to lower intensity.It shows that the local ecological environment has been improved.(3)In terms of the landscape pattern of rocky desertification intensity grades atlas,during the period from 1995 to 2005,the reverse transformation of the rocky desertification landscape was controlled.However,during the period from 2005 to 2014,under the influence of artificial activities,the rocky desertification in Luodian county gradually deteriorated,and its landscape diversity and the dominance had decreased.(4)In terms of the slope evolution characteristic analysis of rocky desertification intensity grades atlas,three rocky desertification is mainly concentrated in the slope of 15 degrees to 35 degrees.In which no obvious rocky desertification mainly occurred in the flat slope,flat-gentle slope and the gentle slope areas.Potential rocky desertification and mild rocky desertification mainly occurred in the gentle slope areas.Moderate rocky desertification and strong rocky desertification mainly occurred in the gentle-steep slope areas.(5)Using the Markov model to predict the intensity grades of rocky desertification inLuodian county in 2033,the result shows that,to 2033,area of no obvious rocky desertification,potential rocky desertification showed a growth trend,and the area of mild rocky desertification,moderate rocky desertification and strong rocky desertification showed a gradually decrease trend.The area of rocky desertification in Luodian county still showed an decrease trend.(6)From the analysis of the driving force to the variation of rocky desertification intensity grades atlas,it is concluded that the social and economic driving factors are the key elements that affect the intensity grades of rocky desertification in Luodian county.Through the analysis of grey correlation degree and qualitative analysis,the total population,the agricultural population,the gross output value of grain,and the total output value of agricultural are the important driving factors for the variation of rocky desertification intensity grades in the study area. |
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