利用地震前后的遥感资料和区域基础数据,结合地震对区域景观生态的破坏特征,分析地震前后景观生态系统过程变化以及不同地震烈度下的景观生态异质性。从景观稳定性和景观异质性出发,运用层次分析法,建立景观生态破坏评价的指标体系,对不同地震烈度下区域景观生态破坏程度进行评价,得出以下结论:(1)地震使大面积林地、耕地和草地破坏,山体滑坡、崩塌严重,裸地、裸岩面积大量增加。在大于Ⅸ级烈度区域,地震后,有林地和耕地面积减少了458.48km2和91.16km2,裸地(岩)面积增加了496.23km2。(2)通过对Ⅸ级以上地震区的景观格局指标分析得出:地震前,区域整体的景观生态的多样性、均匀性、景观破碎度和优势度值均反映出区域的生态系统较为脆弱,地震造成了明显的景观空间异质,加速了生态环境退化。(3)运用层次分析法,从景观稳定性和景观异质性两个方面对不同烈度下景观生态破坏进行评价。得出:Ⅸ、Ⅹ和Ⅺ级地震烈度区域景观生态破坏程度综合值为0.42、0.66和0.80,即中度破坏、重度破坏和极度破坏。根据以上综合分析得出,Ⅷ级地震区域应属于轻微破坏级,建议"5.12"汶川大地震灾害生态环境恢复从建工作应重点考虑Ⅸ级以及Ⅸ级以上区域。

This paper is based on two periods of landscape type maps derived from remote sensed data and basic data,according to the present and characteristics of the landscape ecosystems in regions before and after the 5.12 Wenchuan Earthquake.The paper analyzed the process of change in the landscape ecosystem and heterogeneity in landscape ecology with different earthquake intensity.In order to evaluate the extent of damaged landscape ecology,and by means of Analytical Hierarchy Process(AHP),a synthetically index system from two aspects of landscape-stability and heterogeneity was established.The main results are the following:(1)Large scale of woodland,farmland and grassland were damaged by the Wenchuan Earthquake;landslides and collapses took place,this caused a great number of bare land and bare rock that emerged after the disaster.The change area where earthquake of M≥9 of woodland and farmland reduced by 458.48km2 and 91.16 km2 respectively.The bare land area and bare rock region increased by 496.23km2,and the range ability related to 947.51%.In the Ⅸ level region,relatively lighter influence acts on landscape change,and the variation ranges are all below 2%,the ecosystem is slightly damaged.On the contrary,in the tenth seismic intensity region,damages on the ecosystem are more obvious,and the bare land and bare rock in this region increased by 126.17km2,it is about 7 times contrast to previous status.However,in the eleventh seismic intensity region,where the centre of that hazard earthquake stay,it heavily damaged the ecosystem,and it manifested as obviously change of all vegetation types.The bare land area increased by 334.47km2,for instance,and that is 29.34 times to the earliest situation.All of woodland,grassland and farmland are likewise decreased by 308.04km2,14.36km2.(2)On the analysis of landscape indexes which belong to beyond Ⅸ level region show that the ecosystem is originally fragile.The ecosystem's fragility is reflected by its diversity,homogeneity,fragmentation degree and dominance of local landscape ecosystem.But every target showed that the degeneration of environment and spatial heterogeneity,evidently,after quake.(3)Referring to Sturges' evaluation criterion,the landscape stability and the variability,integrated score of each landscape ecological damage region are 0.42,0.66 and 0.80,separately;and the corresponding destruction can be defined as moderate damage,severe damage and awful damage.In another words,the integrated score of the eighth seismic intensity region should be below 0.4,and should belong to the slightly damaged level.Owning to the overall merit,after-disaster of the'5.12' Wenchuan Earthquake,reconstruction and reconstruction projects should focus mainly on the ninth and above seismic intensity regions.