A Study On The Land Use And Eco-Environmental Effects Based On The RS And GIS In The Agriculture And Pasturage Interlaced Zone Of Northern Shaanxi

Land use /land cover closely correlate to the atmosphere and the biology variety, and directly influence the global change. Therefore, it has been the core of IGBP and IHDP. In this paper, the land use / land cover change(LUCC) of agriculture and pasturage interlaced zone of northern ShaanXi of China in the past 17 years is investigated by taking TM images in 1986,1993 and 2003 as main information source. The information of land use /land cover change is extracted with the help of images from 1986 to 2003 in study area, the method which is used multilevel-layer information extraction by combination principal components analysis(PCA) and supervised classification based on the basis of systemic analysis of spectral characters of representative land use types. Software Arc/Info 9.0, ArcView 3.2, Spss 12.0, Matlab 6.5 and Excel 2003 were employed in the analysis. Then, spatial-tempo of LUCC characters and land use types one another conversion process in study area in recent 17 years was analyzed with the help of GIS. Also, the spatial character of landscape pattern for land use was studied based on method and theory of landscape ecology, tendency of the land use change from 2003 to 2033 was predicted, following the Markov Chain Mode. Driving mechanisms that lead to changing of land use pattern was analyzed using PCA and recursive analysis method, and an indexes system which shows the driving factors effect on land use change agriculture and pasturage interlaced zone of northern ShaanXi was designed according to factors analysis. Through above analysis, the land use impact in the eco-environment in study area was integrative appraised by method of Analytic Hierarchy Process (AHP) and GIS mapping. The study showed:â… . The multilevel-layer class methods can be used to automatic classification for LUCC based on systemic analysis of spectral characters of representative land use type combination principal components analysis (PCA) and supervised classification. With the method, the land use types can be classified automatically with accuracy upwards 84%, and the Kappa Coefficient exceeds 0.77. Study in the area shows that the method is operational and results in a high accuracy in classification, so, it's an effective method for LUCC information extraction.â…¡. Agriculture land is the main land use structure in agriculture and pasturage interlaced zone of northern ShaanXi of China, which area proportion to total area nearly 3/4, the total area of unusable land and civil, industrial and mine land proportion to total area inferior to 1/4. Desert land is the biggest land type in unusable land types, which area proportion to 4/5 for unusable land, and proportion to total area nearly 1/5 as well. Further, the rate of cultivated land, forest land and grass land is 1:1.1:0.9 in 2003, this result obvious showed that the research area is agriculture and pasturage interlaced zone which is give priority to plating and alternation herd.â…¢. The degree of collectivity land use is higher from 1986 to 2003 in agriculture and pasturage interlaced zone of northern ShaanXi of China, that significant changes have taken place. Mostly represent to forest land at a average increasing rate of 25 983.69 hm²Â·a^-1 from 1986 to 2003, the increasing area rooted in grass land, unusable land and cultivated land that were returning cropland to woodland where happened in the southern loess gully and hilly areas and in the northwest sandy area, which was in accordance with the regional environmental characteristics and the land policy"returning farmland to woodland or grassland and rehabilitating desertification". With the rapid developing of city based and economic of the study area, civil, industrial and mine land at a increasing rate of 2 047 hm²Â·a^-1, and the source of increased area is primary cultivated land. As the same time, grass land as a reducing rate of 0.41% per year, the reduced area mostly converted to forest land and desert land. This give us attention, the grassland converted to desert land should be paid to great attention. In the whole, cultivated land, water body, unusable land and desert land fractionation decreased 105 206.36 hm², 471.34 hm², 109 231.35 hm², 206 655.21 hm² in the past 17 years,meanwhile, the multi-degree of spatial distribution for each land use type had distinct reduced. As we monitoring, the reduced area of cultivated land mostly converted to forest land and grassland. The reduced area of water body mostly converted to cultivated land, forest land and unusable land as a result. Also, the desert land had distinct decreased which mostly converted to grassland, forest land and cultivated land by integration rehabilitated where happened in the vicinity of the Mu Us Desert edge.â…£. Based on GIS and theory of landscape ecology, spatial character and process of land use landscape pattern was analyzed in study area from 1986 to 2003. The analysis showed that the characters of landscape structure is obviously, the total number of landscape type patches trended decrease, and the landscape types in space assuming collected distributing. But the comprehensive landscape fragmentation process and landscape diversity are increased and patch shape is dispersed., the whole landscape is conversing from simple to diversified landscape, thanks to the action of coupling of which climate was the inducing and irrational human being activities were aggravating factors lead to these changes. Meanwhile, the distribution centroids of landscape patches were calculated for analyses in 1986, 1993 and 2003. The results showed that within the study area, the distribution centroids of cultivated land landscape patches moved 6 517.6 m towards northeast from 1986 to 2003, the distribution centroids of forest land landscape patches extended 54 094.14 m towards southwester, the distribution centroids of civil, industrial and mine land patches moved 58 543.76 m as the same direction as cultivated land, the centroids of water body patches moved 16 637.57 m and unusable land patches stretched 51 312.03 m towards northeast. The centroids of desert landscape patches moved 11 843.43 m towards northeast also. This indicated that the constant aggravation of the desertification trend in the study area has been basically controlled and tends to be in a relatively stable state. Fortunately, the desertification degree had mitigated evidently for the primary desertified land, because the severe desertification land and heavy degree desertification land area dropped off gradually and changed into moderate desertified land and slight desertified land in the past 17 years. So, the moderate desertified land and slight desertified land had taken in the leading position rather than severe land and heavy degree desertified land, due to their area proportion to total unchanged desertification land area exceed 50%. But slight and moderate land had to faced potential danger that may convert to severe lands due to human activities and droughty climate.â…¤. Average transition probability matrix of land use structure in study area has been offered from its balance tables from 1993 to 2003, we adopted Markov Chain, used field data of 1993 as initialization value to simulate and then test land use structure in 2003, the result is found basic identical to the actual in 2003, showing that the model is efficient and suitable for prediction. Then, use the Markov model to forecast the change of future land structure in 2003, 2013, 2023 and 2033 in study area. The results of calculation using the Markov Chain model indicate that the land use and land cover pattern is changing. Cultivated land, grassland and desert land will keep on decreasing, while the area of civil, industrial and mine land, transportation land and water body will continue to increase. Meanwhile the area of forest land and unusable land will increase continuously between 2003 and 2023, thereafter, the area will decrease relaxedly. It is predicted that by 2033, the cultivated land area is 740 614.75 hm², grassland is 665 803.62 hm², desert land is 556 752.73 hm², civil, industrial and mine land is 104 362.2 hm², transportation land is 35 670.71 hm², water body is 51 018.71 hm², forest land is 217 768.66 hm², and unusable land is 188 131.3 hm². However, both of them will change largely from 2003 to 2013, then, the degree of change will weaken obviously.â…¥. An indexes system which effect on LUCC in agriculture and pasturage interlaced zone of northern ShaanXi was built by using the method of PCA and recursive analysis. Natural factors, human activities and socio-economic were main driving force factors of LUCC together. Through the analysis on specialties, we agreed that climate was an importance factor of natural factors that drove land use /land cover change, governmental policies played a dominant role in land use / land cover change in this region. Population pressure, socio-economic activities and d agricultural and industrial industrialization affected on spatial-temporal shifting of LUCC directly, and drove the landscape pattern change.â…¦. The land use change effect on eco-environment was estimated in study area by calculating the weight of indicators which was estimated by Analytic Hierarchy Process (AHP). The result showed that the integrative ecological index value of the region rose from 3.31 in 1986 to 3.98 in 2003. It is sure that the eco-environment of the whole region has been improved because of measures of ecological restoration, such as sandy rehabilitated, tree planting, soil and water conservation, and so on. However, the integrative ecological remained in a poor state; the service function of ecosystem has degenerated badly. To confirm the main elements of land use types that affect regional eco-environment, we overlap the raster of eco-environment index by GIS mapping with the land use raster, then statistic the pixel frequency of different land use type in eco-environment index raster by summarize zone of arcview 3.2. The result is found that the main land use type and effect on eco-environment are cultivated land, forest land, grassland and desert land.