Climatic Response Of Picea Crassifolia Tree-ring Growth In Different Altitudes Of Qilian Mountains

Nowadays regional climate change has become the focus problem when the climate is more and more harsh, and the study of response of ecosystem to global climate change will help people to anticipate and adapt to the changes of future ecological environment. As a key component of terrestrial ecosystems, because the response of plants to global climate change is extremely significant and prominent, so it is of a great significance in the research of the response of plant to climatic change and relationship between plants and climate. With special climate features, plants in high altitude region are more sensitive to climate change than those in other areas, such as low accumulated temperature, low temperature, very short growing season and seasonal drought, and almost without the effect of human activities. Thus, take alpine plants as the research object will be advantageous to study how climate change is affecting plant. Picea crassifolia is the main edificators and is generally located from 2500m to 3200m in the Shady Slope in Qilian Mountains. Qilian Mountains lie in the mid-latitude westerlies, with the striking variation to vertical temperature, thus Picea crassifolia is suitable for this study.Combined with meteorological data of the area in the past 50 years, in this thesis, we study on the correlation between the radial growth of Picea crassifolia species and climate indices, such as average temperature, average maximum temperature, average minimum temperature, precipita-tion, ecological indicators and accumulated temperature from tree-ring of Picea crassifolia at three altitudes (2770m,3100m,3300m) of survey region based on the methods and theories of dendrochronology.Our conclusions are as follows:1. At different elevation, the average amount of annual radial growth is increasingly larger, the sensitivity of trees is lower and lower to environmental change, and the restriction of climatic factors becomes gradually weakened.2. Picea crassifolia at different altitude does not show the same changes to temperature. Tem-perature is the basis of the radial growth of Picea crassifolia, whereas supply of water led to the annual growth. Climatic factors have effects on the inter-annual variation on which are focus: though, at the altitude of 2770m, the precipitation at growing season is the main limited factor, and high temperature at growing season will inhibit the growth of Picea crassifolia; at the altitude of 3100m, the growth of Picea crassifolia will be not restricted by the changing climate; at the altitude of 3300m, higher temperature is helpful to the radial growth of Picea crassifolia.3. Certain temperature has important implications for the growth of Picea crassifolia. Rate of radial growth shows distinct along with the altitudinal gradients, at the altitude of 2770m, shorter accumulated temperature in favor of trees growth at the 3100m and 3300m, however, the longer continuous accumulated temperature is beneficial to radial growth.4. There is difference from responsiveness of radial growth of Picea crassifolia to various climatic indicators at different elevation. It elucidates that not only the synthetic effect of various climatic factors affects the radial growth of Picea crassifolia, but also different environmental and ecological drivers bring about spatiotemporal variability of growth.