Abstract:

Based on the 5 phases remote sensing image data of Dongting Lake area in 1995, 2000, 2005, 2010 and 2015, under the support of ArcGIS and Geoda software, this paper used the equivalent factor method, spatial autocorrelation analysis method to estimate the service value of land ecosystem in Dongting Lake area and explore the temporal and spatial changes of land ecosystem service value in the Dongting Lake. The results are shown as follows: (1) The forest area continued to decrease and unused land area increased steadily from 1995 to 2015, cultivated land area kept rising after a large scale reduction in 1995-2000, wetlands area and waters area decreased gradually after a mass increment in 1995-2000, grassland area fluctuated from 1995 to 2015; a great reduction of forest area and significant increment of unused land area dominated the land use changes in this area in recent 20 years. (2) The total service value of land ecosystem in the study area from 2000 to 2015 was declining after the steep increment in 1995-2000, and it decreased by 21.64×10⁸ yuan, or 1.06%, in the past 20 years. The reduction of forest area was the fundamental reason for the decrease of total value of land ecosystem service in Dongting Lake area. The overall increment of wetlands area cut down the reduction margin of land ecosystem service total value. (3) In terms of the change of land ecological service value structure, the other individual ecological service value had been reduced in varying degrees apart from the slight increment of the waste treatment value, and the eco-environment conservation was always the main function of the Dongting Lake area. (4) The spatial autocorrelation of land ecosystem service value distribution was more significant in Dongting Lake area from 1995 to 2015, its high-value and low-value zones tended to be concentrated, and the agglomeration of spatial distribution of land ecosystem service value was enhancing. The spatial distribution pattern of land ecosystem service value changed obviously, the area of high-high value type zones had been reduced in the Yuanjiang River watershed of Changde, but was rapidly extending to Miluojiang River watershed, while low-low value type zones were mainly concentrated in highly concentrated town area in the north, south, west of the Dongting Lake area, and was expanding gradually to form a sheet along the town development axes and important traffic corridors.

Key words: land ecosystem service value, spatio-temporal changes, spatial autocorrelation, Dongting Lake area