Application of a New Method of Wetland Vulnerability Assessment to the Lhasa River Basin
拉萨河流域湿地脆弱性评价

Wetland vulnerability assessment is the frontier of wetland science, and the basis for wetland protection and restoration. However, since the biological components of wetlands are not sufficiently accounted for in existing methods of vulnerability assessment, the results of assessment are usually inaccurate and unreliable. In this paper, we use ecological sensitivity, human disturbance and biological integrity and develop a new index system for vulnerability assessment for wetlands of the Lhasa River Basin. Based on biological integrity theory and field data, questionnaires, meteorological observation and statistics, this represents a new approach to wetland vulnerability assessment. Sixteen indexes of biological integrity including mesophyte and xerophytes, species and diversity of birds, species of alien and native fishes, are introduced with indexes reflecting sensitivity and human activity. A wetland vulnerability assessment with multi-scale analysis was conducted for the main wetlands in the area (Lalu wetland in Lhasa city, Jama wetland in Mozhugongka county, Tanggaguo wetland and Chabalang wetland in Qushui country). We found that the vulnerability levels (R) of Lalu wetland, Jama wetland, Tanggaguo wetland and Chabalang wetland are 3.6767, 3.7337,1.9138,2.1757 at the village scale,2.7058, 3.5844,2.8329,2.8461 at the township scale, and 3.5962,3.5923,2.9239,2.9371 at a county-scale, respectively. Village is the best administrative scale for analyzing wetland vulnerability in the Lhasa River basin. The origins of vulnerability are different among wetlands. The vulnerability of Lalu wetland and Jama wetland originates from grazing and climate; due to less anthropogenic disturbance in Tanggaguo wetland and Chabalang wetland climate plays a dominant role in their vulnerability. Biological integrity is a significant aspect of wetland vulnerability whereby greater biological integrity means less vulnerable wetlands. Plants, fishes and birds are major biological communities and indicator species of wetlands, and their diversities are an expression of wetland vulnerability. Therefore, introducing indexes representing biological community characteristics into assessment criteria is a methodological improvement for wetland vulnerability assessment which can help to amend assessment results, understand the components and origins of vulnerability, and improve corresponding technological measures in protecting and restoring wetlands in the Lhasa River Basin.