Land Use Change And Ecological Security Assessment In Yellow River Delta

Land use change and ecological security are the hot issues of globl change studies. By landscape ecological theories and technical approaches, study on the relation of regional land use change and ecological security made good use of land resource and optimized ecologyenvironment,that was of guidance significance for regional ecosystem security. This paper took dongying city as study area. On different scales,the changes and ecological security was studied.On city regional scale,based on remote sensing data(Landsat-TM), the change and effect of land use in Dongying city in 1987 and 2007 were analyzed by the methods of transfer matrix,landscape index,ecosystem service valuation; the ecological security in dongying city was studied by the methods of ecological risks index and synthetical index. The paper studied the results as follows:(1) On city regional scale,land use condition was of great change however farmland and construction land were the major of land use types. The proportion of farmland,construction in gross area in 1987 were 23.88%,18.94% and 38.52%,27.60% in 2007,and increasing trend by 14.64%,8.66%;The area of waterbody increased and the area of saline land,grassland,wetland,shoal differently decreased; Using ecosystem service valuation to evaluate the effect of land use change,the results indicated that:The total ecosystem service value reduced from 12.821 billion yuan in 1987 to 11.247 billion yuan in 2007, 1.575 billion yuan (12.28%, compared with the value in 1987) was lost during this period. Spatially and temporally, changes of ecosystem service values of districts varied, where that in Dongying districts showed decreasing trend (26.75%, compared with the value in 1987), and increasing trend by 2.42% in Hekou district, compared with that in 1987. (2)Analysing ecological security condition in dongying city by ecological risks index,the results could be obtained:The regional change of land ecological risks in the counties in dongying city was obvious:the risks index of land ecology was gradually becoming higher from north to south in 1987,that indicated the ecological security condition in north was better than in south,and the reason was that agricultural development,the construction of industrial and mining enterprises,villiage and urban expansion led to decrease of wetland,grassland and increase of construction land.then the ecological risks index in midlands were greater than in other regions in 2007. The ecological risks increased in 2007 than in 1987 except kenli county.The ecological risk index was 0.1866 in dongying district,and increasing trend by 0.0378,compared with the value in 1987,where the ecological security condition deteriorated quickly. The change of ecological security was little in hekou district and guangrao county, where the destructiveness of ecology environment was less and the ecosystem structure was undamaged, and the ecological risks were higher in lijin county than in other regions, and the ecological security condition was better in keli county.On libei scale, based on remote sensing data(Landsat-TM), the change and effect of land use in 1987 and 2007 were analyzed; through the soil sampling and analysis,soil salinization index and heavy mental pollution index influencing on ecological security were studied and ecological security was analysed by synthetic index method. The paper studied the results as follows:(1)The change of land use was obvious in Libei area, and reed bed,grassland,waterbody were still the major land use types. In libei area, reed bed,grassland,waterbody accounted for 24.33%,16.70%,19.17% in 1987 in all and 20.34%,18.87%,15.86% in 2007. The total area of shoal,woodland decreased, which the area of woodland decreased more quickly. Farmland,saline land,grassland manifested more or less increase,wich the area of farmland increased sharply; Using ecosystem service valuation to evaluate the effect of land use change,the results indicated that:The total ecosystem service value reduced from 2.452 billion yuan in 1987 to 2.056 billion yuan in 2007, 0.396 billion yuan (16.16%, compared with the value in 1987) was lost during this period.Reed bed, waterbody were of great contribution to ecology service value, especially reed bed was deterministic impact on ecology service value in libei area.(2) Analysing ecological security condition in dongying city by synthesis index method,the results could be obtained:In Libei area the ecological security index was between 0.027 and 0.82, furthermore the average index was 0.45.The area of safety, previous alarm, middle alarm, heavy alarm level accounted for 19.48%,31.4%,27.57%,21.55% and the area was at previous alarm level.The spatial distribution indicated that the area of ecological safety level was in south in Libei area, that the area of previous alarm level was between outskirts of ecological safety regionin and northeast,that the area of middle alarm,heavy alarm level was mainly in northwest.In this paper,the unit area ecology service value of reed bed might be overvalued in ecology service value method estimating the effect of land use change, but the unit area ecology service value of farmland might be undervalued, and the study of soil ecological security was not thorough.those might be further studied.