Ecological Health Assessment Of Gannan Rangeland Dynamically In Past 13 Years

Based on “Pressure-State-Response”(PSR)model, which is including 3 aspects:pressure, state and response, and 17 indicators has been chosen to build the indicator system to assessment alpine grassland ecosystem health in Gannan. With the application of Analytic Hierarchy Process(AHP) and RS(remote sensing) and GIS(geographical information system) technology, alpine grassland ecosystem health had been assessed from 2001 to 2013. Meanwhile, the spatial and temporal variation characteristics of ecosystem health assessment had been analyzed. The results indicated that:(1) In the health evaluation system of grassland ecosystem, the pressurre layer index is the largest, which is 0.5190, and the second is the response layer is 0.3035, and the state layer is 0.1775(2) From the time scale, in past 13 years(2001-2013), Gannan ecosystem health value change range is 0.1136-0.4658, the standard deviation of ecosystem health index gradually reduced. The level of ecosystem health is declining, and the ecosystem structure tends to be stable. In recent 13 years, the health level of grassland ecosystem in Gannan Prefecture showed a downward trend, which showed that the pressure on the ecological system increased.(3) From the spatial scale, the average value of grassland ecosystem health index in Gannan was between 0.1394-0.3914.Northeast ecosystem health level is relatively low, and the ecosystem health of southwest is higher. Overall, low level of health, lower level of health, moderate health, higher health level, high health level accounted for 3.82%,23.5%,0.82%,53.06% and18.81% respectively.(4) In past 13 years, the deterioration of the region accounted for about 68.01% of the total area, which is larger than improved area in Gannan prefecture. The grassland ecosystem health in Gannan needs to be concerned. It is urgent to take human intervention to restore and rebuild the grassland ecosystem in Gannan.(5) For the accuracy of the evaluation results were verified, the evaluation results and 2006-2013 study area of 132 fixed-point observation points were compared. Test results show that the more than 80% of the sample point and the evaluation result is consistent with, and proves that the evaluation result is credible.