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Northeast Forestry University (2007)

A Study on Desertification Monitoring and the Impact of Settle Grazing in Mu Us Sandland

刘广峰;

Titre : A Study on Desertification Monitoring and the Impact of Settle Grazing in Mu Us Sandland

Auteur : 刘广峰;

Grade : Master’s Theses 2007

Université : Northeast Forestry University

Résumé
As one of the most serious eco-environmental problems at present, desertification hasplagued human’s survival and development. Desertification monitoring and evaluation is a veryimportant content in desertification studies. Desertification is very serious in Mu Us, there arecontroversies on it’s causes. At present, the studies on human disturbance in desertificationregions are still less. In this study, Mu Us sandland was selected as study area, the mainresearch results were as follows:1. The Dimidiate pixel model was established based on vegetation index (NDVI) toextract vegetation coverage in Mu Us sandland, precision validation of the extraction resultswas conducted by employing field survey data, the correlation coefficient between field surveydata and extracted values from the vegetation coverage imagery was 0.92, and the meanprecision was 79.4%. The results show that the dimidiate pixel model based on NDVI can beused in the extraction of vegetation coverage in desertified region.2. With vegetation coverage as indicator, the evaluation of the Mu Us sandland’sdesertification degree in the late 1970s, the late 1980s and early 21st century was conducted.After statistic analysis, the proportion change of water area is 1.5%~1.0%~1.3% ; Theproportion change of shifting sand is 28.7%~33.5%~26.3% ; The proportion change of semi-fixed sand is 39.4%~44.7%~30.3% ; The proportion change of fixed sand is 28.4%~17.4%~34.7% ; The proportion change of farmland is 1.9%~3.5%~7.4%. Generally, Mu Ussandland was in the development stage of desertification during the late 1970s to the late 1980s,in the recovery stage of desertification during the late 1980s to the early 21st century.3. The Mu Us sandland pastoral area’s desertification degree in the late 1980s and early21st century was evaluated. After statistic analysis, water area has small changes ; Theproportion of shifting sand A, shifting sand B, semi-fixed sand A, semi-fixed sand B havedecreased ; The proportion of fixed sand A, fixed sand B, farmland have increased. There hasbeen an overall improvement in the situation of desertification in the early 21st century, butfarmland area has more increased.4. A total of 29131 settlements were derived from the late 1980s ; a total of 63092settlements from the early 21st century, which was more than the late 1980s. Analysis of thedistance from the settlement center for different grazing pressure changes showed, the order ofgrazing pressure size is 300~500m, 100~300m, inner 100 m.5. Dynamic analysis was done to regional 500m settlements around the late 1980s of thepast 10 years. The results showed developed wasteland was more than abandoned farmland,indicating mass farmlands were developed around settlements ; Vegetation restoration of the area was more than vegetation degradation, indicating a reversal of desertification happendaround the settlement of the whole stage.

Mots clés : Remote sensing; Mu Us sandland; Dimidiate pixel model; Vegetation coverage

Présentation (CNKI)

Page publiée le 27 novembre 2017