Abstract: Alpine grassland wetland is the most important water source region of arid area oasis. Its ecosystem health assessment is crucial for understanding the mechanisms of regional environmental change. The Bayanbulak National Alpine Grassland Nature Reserve in the central part of Tianshan Mountains is the representative alpine grassland wetland ecosystem in the arid area of Eurasia continent. In this paper, “3S” technology and ground reflective spectrumbiomass model were applied to analyze the 2002-2010 MODIS NDVI data, and the ecosystem health status of the Reserve was assessed from the viewpoint of productivity. In the Reserve, the ecosystem health was mainly affected by climate fluctuation. In the process of the ecosystem health changed from average level to the best, the health status of the ecosystem was generally good. The healthy and healthier areas accounted for more than 91% of the total area, and there was no significant difference among different divisions. In the process of ecosystem health changed from average level to the worst, the health status of the ecosystem was overall bad, and the healthy area was less than 40%. There was an obvious heterogeneity among different divisions. The health level of the core area (wetland) was lower than that in the experimental and buffer areas (alpine grassland). The core area (wetland) played an important role in animal husbandry production and biodiversity conservation. Even in the worst year, 48% of the wetland still had a higher productivity than the average level, and the healthier area accounted for more than 18%.

Key words: epikarst, prerequisite, hydrologic properties of source water., shallow soil, rock fracture