| Global change is a research hot spot in the geographical fields. With the continuous progress of society, its influence on geographical environment has also been greater, human is faced with a variety of global change brought about by this impact. As the main type of land use, the forest has a direct effect on the stability of the ecological environment, which also relates to economic and social development, and global changes.Loess Plateau is a special geographical unit with dry climate, low and concentrated rainfall, and low vegetation cover. In a long history of the development process, the vegetation has been destroyed, the ecological conditions are very poor, and the ecosystem is very fragile, which seriously affects human's living environment and socio-economic development of this area. Further more, frequent disasters pose a serious threat on the socio-economic development and security of the downstream area of the Yellow River. Huanglong Mountain forest region located in the southeastern Loess Plateau is one of the five forest areas in Shaanxi Province, known as "the Green Pearl of the Loess Plateau, "and also "the lung of Shaanxi. " Therefore, the study that is based on Huanglong county and reveals the character of the forest land in this area, in particular the process of change and development trends, is typical and representative. In addition, this study can provide a theoretical basis for ecological environment construction, industrial restructuring, urbanization, and the formulation and implementation of regional economic policy, which can also be a reference of other similar areas.In this study, the research object is Huanglong county, Landsat TM images in 1990, 2000 and 2008 is the main data source, and in the supports of Erdas9.3 and ArcGIS9.3 software, Huanglong Mountain forest land, especially the recent utilization of it is analyzed. Meanwhile, by using dynamic models of land use, comprehensive analysis of the characteristics and laws of the spatial and temporal changes of land use during the 1990– 2000, 2000 to-2008 and 1990-2008 years, such as the quantitative changes of Huanglong land (forest land) use, the change of the extent of land (forest land) use, the spatial structural changes of land (forest) use, is made. In addition, GIS technology is applied to overlay analysis of data to obtain the land use of this area especially the database of forest area changes. With the aim of sustainable use of regional land, the trend of the changes of land use of Huanglong area is predicted by applying GIS, Markov models and mathematical statistical methods.In this study, the results obtained the following results:(1) Supervised classification results of Landsat TM remote sensing image of 2008 has been verified, and data that is inconsistent with the facts has been modified and updated.(2) During the period from 1990 to 2000, the forest area increased most, up to 246.51km2; arable land and other forest land increased by 36.95 km2 and 12.69 km2, unused land, sparse forest and shrubs decreased by 134.10 km2, 115.59 km2 and 59.06 km2 . The rate of change of land use was as followed: other woodland> water> open forest land> unused> shrub land> Rural Land> woodland> arable land. During 2000-2008, the forest area increased most, up to 180.55 km2; other woodlands increased by 1.48 km2, cultivated land area decreased most by 113.66km2. The rate of change in various land types use was as followed: unused land> arable land> sparse forest land> Rural land> water areas> shrub land> forestland> other woodlands. In the entire period of 1990-2008, the total forest area increased by 427.06 km2, other woodland also increased, and other land use types were reduced. The rate of change in land use was as followed: other woodland> open forest land> unused> water areas> Shrub land> woodland> arable land> urban and rural land. comprehensive land use dynamics is 1.60% in 1990-2000 and 0.94% in 2000-2008.(3) Since 1990, forest recovery process has been significant, forest and other woodlands have been increasing significantly, cultivated land use has changed greatly, which decreased after a increase, however, the unused land decreased sharply. Between 1990 and 2000, the trend of transfer of land use types is not obvious. From 2000 onwards, the main trend is that other types of land use become forest and shrub land, which is mainly caused by returning farmland to forests. Land-use types change towards a more ideal direction.(4) With the use of Markov model to predict the future trends of land use change in the study area, the results showed that: in 16 years after 2008 (2008-2024), the farmland, open forest land, unused land in the study area will reduce fewer and fewer; the area of forest and other woodlands will continue increasing, urban and rural land and water areas also fluctuate, but not obvious. |
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