Guanzhong - Tianshui Economic Zone Farmland Ecosystem Service Value Evaluation

The farmland ecosystem is half natural and artificial ecosystems that human use of the environment between farmland and farmland species and biological species among farmland depending on land resource to product food and other agricultural production. It has a dual characteristic of natural and social economy, on the one hand,it continuously provides products such as food, fuel for the human, on the other hand, it also provides many public products that cannot deliver in the market, such as soil conservation, water conservation, environment purification and so on, bringing huge benefits for human beings.Choosing Guanzhong-Tianshui economic zone as the study area, based on the remote sensing images(as TM and ETM+) and light energy utilization rate model, the mathematical model as universal soil loss equation (RUSLE),this paper makes a comprehensive evaluation of a spatial and time evolution of farmland ecosystem service value from net primary productivity, soil conservation, water conservation and environment purification capacity, which not only develops the sustainable development of the regional ecological environment, but also constantly explores and pratices the research methods to try to reveal its regional distribution and space diversity change. In this paper, the main results were as follows:(1) The cultivated land in Guanzhong-Tianshui economic zone area accounts for about44%of the total area, in which about28%is dry land and irrigated land accounts for about17%. Overall, the cultivated land area is reduced, the dry land area showed a decreasing trend, and the irrigated area has a certain increasing trend from1980to2010,. In1980-2000,2000-2005and2000-2010these three periods, the areas of other land use types turn into cultivated land are3682.9km2,3854.4km2,2333.3km2, and the areas of the cultivated land turn into other types are4006.6km2,4178.3km2,2657.2km2,the traslation between cultivated land and grass land is the most,the area is3209.2km2, whitch is mainly because their similar component in ecological system and similar distribution area,followed by woodland. At the beginning of twenty-first Century,many people take economy development as heavy,forest for increasing production,resulting in more woodland and farmland conversion.(2) The guanzhong-tianshui economic zone of farmland ecosystem net primary productivity (NPP), the net primary productivity (NPP) of upland is bigger than the irrigated land from1980to2010.Most urban farmland ecological system of NPP quality increases, the increase between2000and2005is the most, it presents decreasing changes in1980-2000and2000-2010,, but it shows increasing trends in total.(3) From1980to2010, the soil conservation quantity farmland of ecosystem in each district and county of the guanzhong-tianshui economic zone in general show:the first decreases, then increases and reduce, the soil conservation quantity in2010has a certain extent decreasing than1980. And the soil conservation value in dryland is greater than the total irrigated soil conservation value.(4) On the whole, from1980to2010, water conservation quantity of farmland ecosystem shows the trend of the southeast more, northwest less in guanzhong-tianshui economic zone; Water conservation quantity in plain area is far greater than mountainous and hilly region; Interannual change rule is:1980>2010>2000>2005, the trend is the first reduce and then increase; And dryland water conservation quantity showed a trend of decrease, and irrigated land showed the first reduce and then increase.(5)The high value area of farmland ecosystem environment purification in the guanzhong-tianshui economic zone is plain area, low value are mountainous and hilly terrain; And purify the environment value in irrigated land is much higher than the dry land; Overall, purify the environment value of farmland ecosystem spatial distribution in guanzhong-tianshui economic zone is:the central high,the east and the west low, plains high, mountain is low, irrigated land high, dry land low.(6) Seen from space, the guanzhong-tianshui economic zone among present farmland ecosystem in food production is low, around the high spatial pattern; From the time, the guanzhong-tianshui economic zone farmland ecological system of grain production from1980to2010counties showed a trend of growth in the north, the south region increased significantly, change is not obvious in central.(7) From1980to2010, the distribution of farmland ecosystem service value in Guanzhong-Tianshui economic zone is inhomogeneous, the high value location in plain area, the plain area has much cultivated land area and has large irrigated area, the low distribution is in mountain area, in which the cultivated land are most without water, it can only rely on precipitation; From the point of time scales, the farmland ecosystem service value in Guanzhong-Tianshui economic zone present the changing trend of first increased after decreased, the farmland ecosystem service value in Guanzhong-Tianshui economic zone IS in the minimum in2000.In this paper, the features of research:(1) The research area is larger and it has macroscopic value, the scales are to county district, and makes the research more deeply, it has reference value;(2)For exploratory research on ecosystem service value of farmland system, considering the spatial heterogeneity,in this paper, the types of cultivated land is subdivided into upland and irrigated to ensure that the research results more credible;(3) From two aspects of time and space scales,this paper make a assessment to Guanzhong-Tianshui economic zone, it not only can reflect the change trend of the time scale, and can reflect the spatial difference, The implementation can be adjusted timely according to the changes of ecological service function of the ecosystem conservation work,and timely and effectively practise the ecological environment protection.