The Security Assessment Of Regional Land Ecosystem

Land ecosystem is an open, dynamic, hierarchical, flexible system, including all the living organisms and their physical environment on a particular piece of land. With the rapid economic development of the society and population growth, the land resource has been suffered tremendous pressure, causing lots of land ecological security problems. Therefore, it is significant to assess the security of regional land ecosystem and make a comprehensive and reasonable programme for land use.There are many methods of the security assessment of regional land ecosystem. However, since different methods have different emphases, they could solve some problems as well as bring some new problems. How to scientifically evaluate the security of regional land ecosystem has attracted much attention in recent years. In the research, Wu'an city located in the south of Hebei province is chosen as the target area. The present paper applies the 'composition - structure - function ' model of the evaluation of ecological integrity to the security assessment of land ecosystem. In addition to biodiversity and social disruption, the 'composition - structure - function - society ' with four indicators is established based on landscape ecology and ecosystem service value. The primary contents are presented as follows:(1) The paper introduces the 'land - biodiversity ' index, then establishes a system composition index about biodiversity, assesses the influence of land use on the biodiversity, and finally determines the security level of each unit of biodiversity.(2) According to the connection of structure stability and security of ecosystem, the paper proposes a system structure index based on patch density, diversity, fractal dimension and combination degree index, and evaluates the stability of landscape structure using the theory of landscape ecology.(3) On the basis of ecosystem service value, we develop ecosystem function indicator system, assess the degree of ecosystem outputs and ascertain the security level of ecosystem service value. (4) Combined with the bias correction of social factors, the evaluation system related to the component, structure and function is utilized to assess the security of land ecosystem.