Study Of The Relationship Between Compositions Of Plant Stable-carbon-isotope And Environmental Factors Using GIS-based Methods In Western China

The in-use of plant carbon isotope in ecology, agriculture and bio-geo-chemical was emerged and developed after mass spectrometry technology generated at 50s of last century. After tens of year's striving, now it has made a great progress. Plant-carbon-isotope plays an important role in ecological restoration and sustainable development. It based on the response of the environmental impact factors. So the study of the modern progress of the relationship between plant-carbon-isotope and environmental factors is the base of the two parts. Because most environmental factors can't be measured by direct, the study has been affected. Fortunately, the powerful data modeling and progressing functions of GIS technology gives us a way to solve this problem.Using GIS based-methods, the data of growing season environmental factors in the western China has been simulated and extracted, such as precipitation, temperature, air press and sunshine. Then the relationship of plant-carbon-isotope and environmental factors has been analyzed. And thus the affect of the environment to the plant-carbon-isotope has been realized.The process of environment factors interpolations shows that, because of the affection of growing season duration, the spatial variability features are notable. After the analysis of five years observation data, it has been concluded that growing season duration has the most stable spatial variability features, with air press standing behind it. The features of precipitation and average air temperature are changing significantly, presenting that they are both affected by some non-structural factors. Multiple-regression can be used for growing season duration and air press'study-zone-fitting. While for precipitation and air temperature, they have to use some integrated approaches.Based on the interpolation maps, the data of environment factors at plant sampling sites from 2000 to 2004 were got. Using spatial analysis tools, also the statistical functions of SPSS, we studied and anglicized the relationship of plant stable-carbon-isotope and environmental factors. The result shows that, in the semi-arid regions of northwest China, due to the role of water stress, precipitation acts the most relevant, followed by temperature and air pressure, and sunshine hours have the weakest action. Precipitation and atmospheric pressure is negatively correlated with plantδ13C. But the other two factors are positively correlated. Generally, when precipitation increase 100mm,δ13C be negative 0.1‰～0.3‰; when air press increase 100hPa,δ13C be negative 1‰; when growing season-air temperature increase 10℃,δ13C be positive about 0.19‰; And when sunshine hours increase 100h,δ13C be positive about 0.2%o. However, it also shows that other factors, such as growing and nutrition forms of the plant do the work.