Spatial And Temporal Differences In Ecological Effects Of Land Change In Yinchuan Basin

Assessing the ecological effect in Yinchuan Basin, we can have a good understanding in its land cover change characteristics, we use ecological effect assessment to analysis and quantify the land cover ecological effect as a way to find the structural and functional changes of ecosystem produced by human activities. Thus we can provide a reference for the development of land policies. The method promotes not only the further research in region ecological environment but also further innovation in research method. Yinchuan Basin is the important industrial and agricultural production bases in the upstream areas of Yellow River Basin. as the economy continues to develop in Yinchuan basin, land cover changes have become increasingly prominent. The bad situation makes it worse to the environment. Economic benefits drive the decrease in arable area, forestland area and water area. All this problems trigger a serious threat to human social-economic sustainable development. We, based on different spatial scale, analyze the temporal-spatial differentiation of land use and ecological effect. Firstly, this paper gets the land use data by interpreting the remote sensing images including 1993,2000,2007 and 2014. and then analyzes the land cover changes, the dynamic degree, structural changes and variation of center gravity. Secondly, after calculating the quality of NPP, carbon fixation and oxygen release, water holding capacity and sand break, we use them to analysis the dynamic changes in ecological services. Finally, the values of ecological services were estimated by emergy evaluation method in the form of currency. Besides, we analyses the synergism and tradeoff among these ecological services. And study how Heat Island Effect affects the value of ecological services. the main conclusions are as follows:(1) During 1993-2014, the construction land, sand and gobi area of Yinchuan Basin expand rapidly while dry land plains, grassland with medium-low coverage and lake areas decrease shapely. The single dynamic degree of construction land, lake and arable land is in the peek and the comprehensive dynamic degree is 0.765, up to the peek during 2007-2014.(2) The proportion of the arable land and lower coverage grassland decrease slightly while the proportion of construction land, lower coverage grassland and shrub forest land increase rapidly. the others remains unchangeable. The center of arable land moves to northwest while construction land, grassland and forest land shift from north to southeast. construction land expands when arable land reduces. And the opposite is true.(3) The main grain producer of Yinchuan Basin distribute along the Yellow River. As the arable land is decreasing, the high grain producer features small-lager.(4) The areable land account for a large part to NPP, and grassland, shrub forest and sparse land account for the other parts. The average of NPP in Yinchuan Basin shows from the latitude perspective, the high value lies in the south and the north, the lower lies in the medium. And from the latitude perspective, the average of NPP shows the west is larger than the east. the water retention from the farmland is the main source water retention of NPP. the per unit area of water-holding capacity in every area and county vary from the large to the small. the per unit of wind-break and sand-fixation capacity is decreasing slowly while the total is increasing, meaning the ecological environment is becoming sound.(5) The ecological services value is increasing at the annual speed of 2.7% in every area, and the most significant area is in the middle part of Yinchuan Basin.(6) The ecological service function in yinchuan basin between food production and extreme there is a trade-off relations hip NPP; Windbreak and sand-fixation, water and extreme balance relationship in the food production;NPP and windbreak and sand-fixation,collaborative relationship in the water;Water and windbreak and sand-fixation collaborative relationship.The innovation points In this paper:(1) As the Yinchuan basin belongs to the typical area in arid areas and a new analysis method. dry climate and the eastern monsoon climate staggered under the influence of land change of ecological effect research is less in Yinchuan Basin; And orthogonal polynomial least squares fitting curve to study the synergy and trade-off between ecosystem service function, it is to use the principle of indirect that balancing model and the related formula are deduced in detailwith minimal residual sum of squares of orthogonal distance as criterion,its take into account both the dependent variable and independent variable of error, it can be in the measured data under the condition of less can better guarantee the accuracy.(2) This paper discusses the current hot issues --the influence of heat island effect on the ecological service value.(3) This study when choosing evaluation model based on the actual correctionto make it closer to the actual situation in the study area.