| In order to explore the impact of land use pattern on land desertification,Based on the data of remote sensing and desertification land subcompartment survey in 2004,2009 and 2014,the spatial and temporal changes of land use pattern and desertification degree pattern in Bashang desertification area were analyzed.The trend of land use and desertification pattern change in Bashang desertification area in the next ten years was predicted by using CA-Markov model.On this basis,the relationship model between desertification change and land use pattern is established by using multiple regression method.Taking Yudaokou as an example,the desertification change is analyzed and predicted by adjusting land use pattern artificially,which provides an operable reference for desertification control on Bashang.The main findings are as follows:(1)The main land types are cultivated land,woodland and grassland.The three land use types account for more than 90% of the total land area;The distribution of cultivated land is zonal,mainly along the contour line in the gentle zone with lower elevation and smaller slope.The whole region is distributed,but concentrated in the central,western and Eastern regions;The distribution of forest land is extremely uneven,with a large degree of dispersion.The distribution area has a higher elevation and a larger slope.In the eastern and central regions,it distributes in patches;The distribution of grassland is scattered,interacting with cultivated land and woodland.It distributes in patches in the central,northern and southwestern regions,and scattered in the central and Western regions;There are obvious changes in land use in the study area.From 2004 to 2014,the land use types showed the changing rules of "two increase,four decrease" and "four increase and two decrease",respectively.In the earlier period,the cultivated land and woodland increased,the grassland,construction land,water area and unused land decreased,and in the later period,the woodland,construction land,water area and unused land increased,while the cultivated land and grassland decreased.From 2004 to 2014,the main land use change transfer in the study area was the mutual transformation of cultivated land,woodland and grassland,and woodland and grassland were the most significant types of land use change.Forestland is mainly transferred to arable land and grassland;grassland is mainly transferred to woodland and arable land;arable land is mainly transferred to woodland and construction land;the transfer of construction land,water area and unused land is not obvious.(2)In terms of cultivated land,there is a slight contraction in the Midwest and Eastern regions,mostly converted into woodland,and the spatial distribution becomes more scattered;the change of woodland is more obvious;the unused land and cultivated land in the eastern region are transformed into woodland,while the cultivated land and grassland in the western region are transformed into woodland;the spatial change of grassland is not obvious,mainly to the surrounding arable land and woodland.From the quantitative point of view,in 2014-2024,the land use types in the study area will show the change rule of "two increases and four decreases",and the change rule is the same as that in 2009-2014.That is,the area of cultivated land and grassland will show a downward trend,while the area of forest land,construction land,water area and unused land will show an increasing trend.(3)The degree of land desertification in the study area was reduced.The area of desertification in the study area is over 50%,and its distribution is relatively concentrated.There are more desertification in the southwest and less desertification in the northeast.Light desertification is the main area;moderate desertification is the second,mainly distributed in the central and western,northwest and northeastern areas;severe and extremely severe desertification is less,scattered in the northwest,central and northeastern areas.From 2004 to 2014,the desertification land in the study area changed significantly,mainly in moderate,severe and extremely severe desertification land.The area of non-desertified land increased gradually;the area of mild desertification increased,but the increase was not obvious;the area of moderate desertification land decreased significantly,and the area of severe and extremely severe desertification land decreased significantly.According to the forecast,the non-desertified land will continue to increase,and the land area of each desertification degree will decrease in varying degrees.(4)The light desertification land in the western region has become scattered and its scope has been slightly reduced;the moderate desertification land has been significantly reduced and changed into light desertification;the change of the heavy and extremely heavy desertification land is not obvious.The moderate desertification land changes obviously in the central region,and the distribution in the non-desertified land decreases obviously;the range of mild desertification land decreases slightly;the severe and extremely severe desertification land decreases slightly.In the eastern region,the land with different desertification degrees showed a decreasing trend,and the land with slight desertification became dispersed;the land with moderate,severe and extremely severe desertification showed a significant contraction trend.(5)A mathematical model of the impact of land use pattern on land desertification was established.The model accuracy and fitting degree are checked,and the fitting degree and model accuracy are higher.Eliminating collinearity by stepwise regression and optimizing model.According to the optimized model,the proportion of arable land,woodland and grassland area and the thickness of soil layer are the main factors affecting the degree of desertification.(6)Taking Yudaokou as an example,its land use status was input into the desertification prediction model,and its desertification status was diagnosed and analyzed.The main land use type affecting desertification is cultivated land,and then the adaptability of cultivated land in this area is analyzed,the land use pattern is adjusted,and the situation of land desertification is improved.The change of desertified land before and after the adjustment is predicted by the model,and some suggestions are put forward for desertification control in this area. |
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