关键词: 全球变暖, 生命周期, 双季稻, 碳足迹

Abstract: Rhododendron chrysanthum is listed as one of the national protected plants at third category in Chinese Plant Red Book. Its population size is very small, being on the verge of extinction. Based on the methods of population static life table, survival curve, and individual amount dynamic prediction, the quantitative characteristics and dynamic trend of R. chrysanthum population at different altitudes of alpine tundra in Changbai Mountain were studied. The results were as follows: (1) The spindleshaped size class structure suggested that R. chrysanthum population exhibited a declined pattern. (2) The growth potential of population decreased gradually with the rising altitude. Under incomplete random disturbance, the growth potential of the population was limited, and the V_pi″ of low altitude was close to 0. (3) The survival curve of population exhibited as the DeeveyⅢ type, which had higher death rate and lethal force with obvious degradation at the higher altitude. (4) After 1, 2, and 4 age classes, the individual number at age class 4 would increase to varying degree. The individual number was supplemented in the later growth stage. (5) The population size of R. chrysanthum was maintained mainly by ramets reproducing from reptant roots. The possible factors leading to the species being endangered might be its biological characteristics and the disturbances from human activities.

Key words: double rice cropping, life cycle assessment, carbon footprint, global warming