| The study of ecological effects in areas is important content in the global change of environment and this is hot issues of the present study at home and abroad. The paper based on the National Natural Science Foundation, choosed Loess Plateau in Guanzhong as the study, using TM、ETM+RS pictures and CASA, USLE mathematical model, on the plant of GIS and RS, research on the spatial and temporal changes of land use change/land coverage change and ecological effects from NPP, the abilities of fixed CO2and released O2, water conservation, and soil conservation. This is the depth and development of sustainable development research on the regional ecological environment, and this is the continuously explore and practice of research methods, and strive to reveal the regional distribution and the spatial different changes.Land use change is the most direct impacts of human actions affecting the changes of global environment. Through evaluating the spatial and temporal changes of ecological effects based on land use change, explore the various effects of human activities on the ecological environment, as well as the response of the ecological environment. The main conclusions in the study were as follows:(1) In the sixth kinds of land use, the cultivated land is the largest share, followed by grassland, forest, construction land, waters, and the proportion of barren land is the smallest. From1985s to2010s, the increasing speed of construction land is the quickest, the area increase as1.60%per year. The reducing area of cultivated land is the most and the total reduction is50132.62hectares in the25years. The reducing speed of barren land is the most and every year reduces2.75%. This shows that the process of urbanization of Loess Plateau in Guanzhong is increasing, the degree of land intensification increasing, and utilization rate of land increasing.(2) The spatial distribution of show that the middle area is lower and the northeast corner and southwest corner area are higher. This is closely related to the spatial distribution of forest land. In the five cities of Guanzhong, Baoji City, Weinan City are relatively high and Tongchuan, Xianyang and Xi’an are low. From1998to2008, NPP and the abilities of fixed CO2and released O2in study area show the overall increasing trend.(3) From the time scale, from1985s to2010s, in the Loess Plateau, the ability of water conservation shows the trend of the first increasing and then reducing. The values are10210.40×104t/hm·a in1985s,10224.38×104t/hm·a in1996s,10237.01×104t/hm·a in2005s,10486.08×104t/hm·a in2010s. From the land-use types, the ability of water conservation shows:forest> grassland> cultivated land. Waters’own nature makes large value on maximal holding water capacity. The ability of water conservation of construction land and barren land are so low.(4) In1985s,1996s,2005s, and2010s, the soil actual erosion in the Loess Plateau as follows:1.295t/hm2·a、1.818t/hm2·a、1.704t/hm2·a、1.339t/hm2·a. Because the slope in the Loess Plateau is less than5°, in fact when the slope is less than8°the soil erosion is very weak, so the soil erosion is small and vegetation service value is low in Loess Plateau. In the study area, high level of soil and water conservation is the southwest, and low level is the central region. From every county in study area, the maximal value of soil conservation is Weibin district in Baoji city and the minimum is Qindu district in Xianyang city in1985s,1996s,2005s,2010s. From1985to2010, the total value of soil and water conservation in the Loess Plateau shows an increasing trend, then reduce.Based on the type of land use, the total value of soil and water conservation as follows:forest> grassland> cultivated land> other types of land.The paper features as follows:(1) The study scale is longer,25years. Smaller study areas make the researchers can be very thorough and meticulous, so the study scale refine to the township level.(2) The evaluation of the land use dynamic degree of the general use can not fully objective and actual perform the land use change in study area, so select the modified model for evaluating the degree of land use change.(3) From time and space scales, conduct a comprehensive evaluation on the ecological effects based on landuse change, and can reflect the change trend on the time scales, but also reflects the spatial differences. According to the change of ecosystem service function, timely adjusts to the implementation in ecosystem conservation, timely and effective manner to protect the ecological environment. |
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