三峡库区景观格局变化及其影响因素——以重庆市云阳县为例

从20世纪90年代中期至今是三峡库区生态-经济系统与景观格局发生重大变化的一段时期。论文通过对库区重庆市云阳县1994年与2002年遥感影像的解译,分析景观格局的变化,探讨生态建设、城镇化、基础设施建设、生态移民、农业产业结构调整等短时期内高强度的人类活动对该区域景观格局的影响。地形破碎、高差悬殊的山地特点以及在亚热带湿润气候主导下的山地立体气候分异等自然因素造成了景观格局的基本分异;有限的土地资源及其利用与分布状况是控制景观格局变化的主导因子;为保证三峡工程的顺利建设和安全运行而采取一系列生态经济建设活动成为促使景观格局变化的最重要的驱动因素;政治、经济和社会决策对景观格局变化具有重要影响。

Landscape changes and human activities in three gorges reservoir area: the case of Yunyang County

Over the period of Three Gorges Project(TGP),from the middle 1990's up to the present the landscape in three Gorges Reservoir area has been changed enormously.The frangible eco-environment system is being threatened by excessive and careless reclamation in this area.Meanwhile,the economic development level is relatively low.The area is faced with problems such as over-population,less cultivatable land,environment degradation and poor economic conditioin.The conflict between economic growth and the eco-environment conservation is fierce. TGP and other relevant human activities exert various influences on the environment,economy and society in the Three Gorges reservoir areas again.Thus,in this study,we focus on the landscapes which may be subjected to dramatic and irreversible changes and study the major driving force and mechanism.In this study,Yunyang County is used as a case study to understand the complex interactions between human activities and landscape changes.The study area has a special location,and the changes in this area appear as the functions of government,economic and society decision-making.We use landscape indexes to quantify the spatial structure of landscape patterns and explain the observed variation of landscape patterns based on a landscape classification of Landsat TM images of Yunyang County in 1994 and 2002.Results indicate human activities are causing substantial subdivision of plots,which in turn has created a more complex and fragmented landscape in 2002 than in 1994.It is shown that the changes in landscapes are mainly displayed as conversion of sloping field into forestland and grassland,and of cultivated land into construction land,and secondarily as conversion of barren into construction land,of forestland into shrubs and of grassland into forestland.Such changes indicate that the landscapes have indeed experienced several changes over the last few years caused by human impacts.We also outline the impacts of main human activities which have already commenced in recent years,such as reusing cultivated for other purpose,the adjustment of agricultural development,urbanization,infrastructure building and ecological migration.These human activities are playing important roles on the changes of landscapes in this area.We try to assess and predict the positive and negative effects of these human interventions to landscapes.Finally,we consider that the reconcilement between ecological conservation and economical development is the key for the landscape sustainability.In a long run,the landscape ecological restoration and rehabilitation are a vital method for constructing regional ecological security pattern in Three Gorges Reservoir area.