Temporal And Spatial Variation Characteristics Of Ecosystem Service Value (ESV) Of Ningwu County

This paper selected Ningwu County the source of Fenhe as the study area. Using GIS and remote sensing to analyse the temporal and spatial variation of land use and cover change (LUCC) of the study area. Based on the relevant formulas, evaluating the process、 trend and degree of the land use changes in spatial and temporal scales during 1990,2000 and 2010. Using the ESV(ecosystem service value) formula advanced by Costanza and referring to "Chinese ecosystem service value unit area of different ecosystem types", analysed the temporal and spatial variation of ESV in the study area. The followings are the conclusions of this paper:(1) The main land use types in the study area were woodland and grassland, separately accounted for 36.7% and 40.4% across the area. During the study period, the area of grassland, farmland and water body all decreased, especially the water area (43.4%); meanwhile the area of construction land, unused land and woodland increased, the first two increased more obviously (separately200.4% and 74.3%), mainly in the northeast and southeast districts. The whole study area was in unbalanced situation and one-way transformed frequently, and the construction land was in extremely unbalanced situation. The integrated net change rate increased significantly with time.(2) LUD in the study area increased with times, and the extent in the first 10 years was larger. The relatively high land use degree units mainly distributed in the low altitude region of the northeast to southwest direction in the study area. During the study period, units that almost with no LUD changes mainly distributed in the southeast and west parts of the study area. Conversely, LUD in the northeast and southwest districts changed greatly.(3) Woodland made the most contribution (63.7%) to ESV in the study area, followed by grassland (23.3%), farmland (11.0%), water body (1.9%), construction land (0.06%) and unused land (0.01%). The ESV dropped from 21.79×108 yuan in 1990 to 21.45×108 yuan in 2010 with an extent of 1.6%, indicating a significant decreasing trend; ESV in the low altitude regions in the northeast and middle of the study area reduced largely, and decreased or increased slightly in the other regions.(4) The ecosystem service value of soil formation and protection was the highest, followed by biodiversity conservation, and food production was the smallest. During the study period, every ecosystem service value did not change significantly, only raw material value increased, the rest types decreased and the waste disposal value dropped most largely. The total value presented an accelerating decrease trend.(5) The values of different ecosystem services in the northeast of the study area dropped significantly. In the southeast, food production values decreased or unchanged, waste disposal values almost unchanged, and the others increased or unchanged. In the southwest, food production and waste disposal values increased, and the rest types changed more variously.(6) It was the gas regulation that had the largest relative change rate, raw materials value followed, entertainment and culture was the smallest. It showed that the change range of woodland which effects the gas regulation greatly was the largest. And the relative change rate of different ecosystem service values in the northeast was larger than the rest districts, conversely, in the west.The decrease of grassland and water body caused by warming and drying climate in Shanxi province in the past decades, overgrazing and the increase of construction land were the main reasons for the decrease of ESV in. the study area.