长三角地区1995—2007年生态资产时空变化

Spatial and temporal change in ecological assets in the Yangtze River Delta of China 1995—2007

结合遥感定量反演与经济评价法,利用1995年1 km的AVHRR-NDVI、2000年和2007年250m MODIS-NDVI等遥感数据,模拟与评估长三角1995—2007年生态资产时空变化。结果表明:长三角1995—2007年生态资产总量呈持续下降趋势,由1995年891.39亿元减少到2007年845.54亿元,减少5.14%;各地市生态资产总量总体呈下降趋势,但区域变化差异极其显著;长三角1995—2007年生态资产空间分布呈南高北低格局,空间变化呈南部和北部以轻度增长为主、中部以中度和严重退化为主的变化特征;土地利用变化是导致长三角生态资产减少及空间差异的主导因素,自上而下生态修复工程明显有助于增加区域生态资产。

This paper analyses the characteristics of, and drivers for, spatial and temporal change in the ecological assets in the Yangtze River Delta from 1995 to 2007. The ecological assets are simulated by using remote sensing quantitative retrieval and economic evaluation methods. The remote sensing data sets include NOAA/AVHRR-NDVI at a spatial resolution of lkm in 1995 （February 1995--January 1996）, MODIS／NDVI in 2000 （February 2000--January 2001 ） and 2007 at a resolution of 250m, land use interpreted by using Landsat TM images in 1995, 2000 and 2007 at the scale of 1：100000, and land cover in 1980S and 2005 at the scale of 1：250000. The ecological adjustment coefficient is estimated on the basis of the net primary productivity and vegetation coverage in the region, which are simulated by a modified Carnegie Ames Stanford Approach （CASA） terrestrial carbon model and the Pixel Binary Model, respectively. The results show that the overall amount of ecological assets in the Yangtze River Delta declined by 5.1%, changing from 89.1 billion yuan in 1995 to 84.6 billion yuan in 2007. The ecological assets in the region consist of forest, rivers/lakes and cropland, accounting for 48.0% , 26.7% and 20.5% , respectively. The total amount of ecological assets for each major city in the region presents a decreasing trend, and there is a spatial heterogeneity. The reduction of ecological assets in the cities of Shanghai, Suzhou, Jiaxing, Huzhou, Shaoxing and Ningbo was substantial, at 798,486,441,427 and 403 million yuan, respectively. However the decreased amount and rate of the ecological assets in other cities such as Nanjing, Zhenjiang, Hangzhou and Taizhou were small, at 57,47, 122 and 155 million yuan, respectively. The spatial distribution of ecological assets in the Yangtze River Delta exhibits a declining pattern from the south to the north, increasing slightly in the south and north but decreasing severely in the central area from 1995 to 2007. Such a pattern of change in ecological assets implies that it may reduce the ecological safety in some affected areas, but this will not be an ecological constraint for sustainable development in the Yangtze River Deltaic region as a whole. Land-use change is found to be the dominant factor resulting in the reduction of ecological assets and their dissimilarities in spatial distribution. Change in ecological assets is also mediated by urban expansion, land reformation and reclamation. However the national ecological restoration projects, such as ＇ Grain to Green＇ , ＇ Soil and Water Conservation＇ and ＇ Wetland and Barren Hills Rehabilitation＇ , have played an offsetting role in reversing the downward trend of ecological assets in the Yangtze River Delta. There are some uncertainties for evaluating ecological assets based on remote sensing quantitative retrieval and economic evaluation methods. The uncertainties are mainly influenced by three factors： the evaluation factors for ecological assets and the criteria for evaluation; the spatial resolution of remote sensing data and the precision of applied ecological models ; climate fluctuations and meteorological data with inherent interpolation errors.