Changes of Wetland Ecosystem Service Value in the LhasaRiver Basin of Tibetan Plateau
拉萨河流域湿地生态系统服务功能价值变化

In the context of global changes and human activities, study of changes in the alpinewetland system is becoming increasingly important, particularly in alpine wetland ecosystems. TheLhasa river basin is a political, economic, and cultural center in Tibet, with most swamped meadowand pasture of important value. The wetland ecosystems generally include water field, swampedmeadow, grass marshes, shrub wetland, forest wetland and beach wetland. On the basis of GIStechniques and valuation of ecosystem services methods, dynamic changes in wetlands, and gainsand losses of ecosystem service value were examined in detail in this work using three senses ofremote sensing images. Three types of wetland database for assessment of the ecological valuewere built by visual interpretation. Wetland ecosystem services valuation methods were basedprimarily on market value, carbon tax, alternative cost method, the shadow price method and otherenvironmental and economic methods. Results indicated that from 1976 to 2006, the total area ofwetlands maintained decreasing from 230×103 hm2 to 209×103 hm2, an 8.8% reduction. For the twoperiods 1976-1988 and 1988-2006, the reduction in wetlands accounted for 3.7% and 5.2% of thetotal reduction, respectively. Water field, swamped meadow and grass marshes were found toprogressively reduce, while forest wetland and beach wetland gradually increased. The shrinkingratios of marsh wetlands were relatively higher and the reduction amount of the area of swampymeadow was the largest. During the study period, the total value of wetland ecosystem servicefunctions gradually decreased by 4.12 billion Yuan. In particular, for the first and second periodsunder investigation, the reduction ratio of the value per year was calculated as 0.39% and 0.36%,respectively. The value of ecosystem services for open water, alpine meadow and grass marshesincrementally reduced. However, the value of shrub wetlands seemed to be no change. The value offorest wetland and beach wetland gradually increased. The biggest loss in value was the function ofmaterial production, followed by gas component regulation and climate regulation value. Bycontrast, the hydrologic regulation value, habitat value, recreational value, and environmentalpurification increased slightly. In particular, valuation of ecosystem services methods is diversity,and evaluation using different methods could lead to disparate results. It seems that there is noconsent evaluation method. Compared with the existing research, the annual loss rate of theecological service value in the Lhasa river basin is generally higher than that in the Sanjiang Plain,and lower than the Zoige Plateau.