Landscape Pattern Change And Its Driving Force Analysis Of Climate Of Hoh Xil National Nature Reserve

Hoh Xil National Nature Reserve is in the east hinterland of Qinghai-Tibet Plateau, the ecosystem is extremely fragile and has been significantly influenced by global climate change in the past decades. As a consequence, it is very important to study the climate change characteristics and reveal the impact of the climate change on landscape pattern and its dynamic changes in Hoh Xil National Nature Reserve. The climate change characteristics in Hoh Xil National Nature Reserve were analyzed based on local meteorological data from 1970 to 2013. Spatial and temporal landscape pattern were also analyzed by using 3S technology and landscape pattern index based on the remote sensing image data of 1990,2000 and 2013. The relationship between climate change and landscape pattern dynamic was compared by using gray correlation analysis method, which aim to illustrate the driving factors of landscape pattern changes. The 44 years climate data (1970-2013) showed that climate in Hoh Xil presented a trend of warm and wet in general, and precipitation increased significantly at a rate of 20.3 mm/10 years, and annual average temperature increased at a rate of 0.38 ℃/10 years. Meanwhile, the three period of landscape types distribution showed that glaciers and permanent snow, water body, marsh wetland and alpine meadow decreased, while bare land increased significantly, which showing an intensifying trend of simplification and desertification. From 2000 to 2013, however, the landscape in Hoh Xil presented characteristics of diversity and complexity, and part of bare land conversed to water body, alpine meadow, marsh wetland and alpine grassland. Annual average temperature mainly affected glaciers and permanent snow and marsh wetland, and precipitation, potential evapotranspiration and relative humidity were the key driving factors of water body, alpine meadow and alpine grassland. Multiple time scales of climate cumulative effect showed that glaciers and permanent snow, water body and marsh wetland were mostly affected by 11 years climate accumulation, while vegetation was affected more intensely by the short scale of climate change. Alpine meadow area was mainly affected by two years comprehensive climate cumulative effect, and alpine grassland was apparently response to 5 years climate cumulative effect. But it was relatively delayed for alpine grassland compared to alpine meadow in response to cumulative climate change. In conclusion, the landscape pattern changes were significantly influenced by climate in Hoh Xil.