| Rocky desertification is a land degradation in karst regions of the extreme form. Study the dynamic change of desertification situation, analyze the reasons for such changes, and summarize the experiences of desertification control, rocky desertification prevention and control measures for nanning, promote the comprehensive control of rocky desertification provide basic data and scientific basis.This paper reviews the domestic and foreign research present situation and the development trend of rocky desertification and rocky desertification monitoring for the first time in guangxi in 2005 and in 2011 the second rocky desertification monitoring based on the karst areas in nanning city as the research object, using 3S technology and the method of mathematical statistics to nanning city from 2005 to 2011, the dynamic change degree of karst rocky desertification of land, and to study the cause of rocky desertification change analysis. Through the study we found those as follows:(1) The area for the stable Karst land in Nanning was 745496.8 hm2, which was account for 93.6% of Karst land area. The area of sequence succession was 43513.3 hm2, which was account for 5.5% of Karst land area, In addition, the area for reversed succession was 7438.4 hm2, which was account for 0.9% of Karst land area. Thus, Karst land in Nanning was in a stable state in general which showed slightly improvement。(2) Studying the sequent succession of Karst land in autonomous region. The area of by succession of the rocky desertification land for the potential stony desertification was 37602.3 hm2,while by succession for non-stony desertification 2568.3 hm2; by succession of the potential rocky desertification land for the non- stony desertification was 3342.7 hm2,while by succession for the stony desertification was 3189.1 hm2;The situation for reverse succession of Karst land showed that by succession of the non-rocky desertification land for the potential rocky desertification land was 3270.6 hm2,while for the stony desertification was 546.7 hm2。(3) Circumstances of Rocky desertification was analyzed while the result was as follows:Area of stony desertification in 2011 was reduced by 35534.8 hm2 compared with 2005, among them the slightly stony degradation land decreased 3215.3 hm2, moderate rocked desertification land 3152.0 hm2, and the severe stony degradation land 29430.3 hm2, respectively. Extremely severe rocked desertification land increased 262.8 hm2。 In conclusion, Area of rocked desertification was decreased overall and meanwhile there was part of them was deterioration。(4) Analyzing the changing reason for Karst land, it was thought that human governance was the cause for studying sequence succession of Karst land the of the main driving factor in research area, among them the mountain management measures has the most significance, Area of sequence succession of Karst desertification was 29136.3 hm2 due to mountain management measurement which was account for 67.0%. Improper operation such as human factors was cause for disaster factors and reversed succession of Karst land whose area was 1616.4 hm2 and 1479.0 hm2。(5) By building the database of impact factors for changing reason of stony desertification extent and made a correlation analysis, it was indicated that mountain management, artificial afforestation, to facilitate afforestation as well as technical reasons was very relevant with sequence succession of rocked desertification extent, natural repair in addition to engineering construction indicators was relevant with sequence succession of rocked desertification extent, error judgement at early stage, Terrance engineering in addition to young and middle aged forests were all uncorrelated with sequence succession of rocked desertification extent, technical reasons, other reasons as well as catastrophic climate were very correlated with rocked desertification extent, human factors on the rocked desertification degree had a significant impact to reversed cession of rocked desertification extent, for example, destroying forest, excessive logging were had a certain influence however not the main influenced factors。... |
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