Reversal Process And Cause Analysis Of Desertification In Mu Us Sandland

Desertification process is one of the core issues of desert research.It is also a global important environmental and socio-economic issue.The survival and development of mankind is affected by it.The Mu Us Dunefield is the third largest sandy land in the north of China,with special geographical location.Its climate belongs to transition area between the temperate monsoon climate and the temperate continental climate.Vegetation belongs to transition zone between desert steppe and the loess hilly shrub grassland.At the same time,it is also a staggered area between typical agricultural and animal husbandry area in northern China.In addition,it is one of the important energy bases.Therefore,the study of desertification in the Mu Us Dunefield has important ecological and social significance.The main sandy landscape of the Mu Us Dunefield is constituted by fixed dunes and semi-fixed dunes.After the liberation to the late 70s,unreasonable land reclamation and energy development make the desertification of the study area more serious.With the implementation of a series of ecological projects such as three North shelterbelts,returning farmland to forests and so on,the desertification of the Mu Us Dunefield began to reverse.Scholars have carried out a lot of research,but the cause of desertification reversal has not yet been conclusive.For this reason,the process of desertification reversal and its causes are studied in this paper.The purpose of this paper is to provide some scientific reference and theoretical basis in the prevention and control of desertification,the alleviation of contradictions between man and land,and the formulation of relevant policies.Firstly,the remote sensing image(1980a,1990a,1990a,2005a,2010a and 2015a)of the land use/cover type change(LUCC)is interpreted on the basis of 100m grid.The changes of land landscape during the process of desertification in the Mu Us Dunefield were studied,and the variation process of landscape patches was analyzed in detail.Secondly,the climate change around the sand land to start the analysis of natural factors,including temperature,ground temperature,precipitation,relative humidity,sumshine and wind speed and other six climate elements.Finally,based on the case of Shiyaowan Village in the northeastern part of the Mu Us Dunefield,the real data of population change and social economy and sand control policy implementation and effect and residents'satisfaction were analyzed by field investigation and interview forthe changes in Human Factors.The main conclusions of this paper include the following four aspects:(1)Remote sensing interpretation of changes in land use/cover types shows that the landscape area of the Mu Us Dunefield has generally decreased since the late 1970s.The reduction is 86906 hm2.The area of sandy land near the residential area,which is represented by the Shiyaowan village in the northeastern part of the sandy land,is more obvious.The number of plaques in the Mu Us Dunefield and Shiyaowan villages showed aincrease after the first decrease.The change in the average area of the plaques increases first and then decreases.The maximum plaque index showed an increasing trend.The results show that the change of sandy landscape is the first to reduce the area of small sand,followed by large pieces of sand to break smaller.In general,the process of desertification in the Mu Us Dunefield is the overall reversal,but the local development.(2)The analysis of natural factors shows that,since 1960s,the climate of the Mu Us Dunefield has been gradually warmed up,the temperature raises,the relative humidity of the air decreases,the summer precipitation decreases,and the sunshine hours decrease.The change of these factors is not conducive to the desertification of the Mu Us Dunefield.But the wind speed,wind speed from the sand,sand wind frequency,sand transport potential,etc.are showing a downward trend,resulting in the Mu Us Dunefield as a whole a significant decline in sediment transport capacity.Compared with other climatic factors,the weakening of the wind energy environment has a more important contribution.(3)The analysis of human factors shows that,since the implementation of the sand control policy,the village of artificial vegetation increased by 28.52%,sand area decreased by 17.95%,the ecological environment has improved;the support of villagers is very high.At the same time,it also generally reflects the important role of national ecological policy in the process of desertification reversal throughout the Mu Us Dunefield.However,due to the relative concentration of population distribution,population density is far beyond the allowable boundaries,the contradiction between people and land problems still exist.Therefore,when China strengthens the ecological construction to prevent the degradation of artificial vegetation in the process,it also needs to pay attention to the ecological construction process of economic benefits.(4)In general,the reversal of desertification in the Mu Us Dunefield reflects the coupling process between natural factors and human factors.The reversal of desertification is based on the weakening of near-surface wind energy,combined with the implementation of artificial ecological engineering construction which includes a series of policy guidance,the villagers generally support to achieve.