Study On Calorific Value Seasonal Dynamic Of Major Plant Populations In Different Habitat Of Huangfuchuan Watershed

Green plants turn light into chemical energy in photosynthesis. Study of plant calorific value involves energy utilization, energy conversion and energy flow of plant communities and plant populations, which is foundation of energy ecology. Choosing 11 major plant populations from arsenic rock zone, sandy loess soil zone and sandy soil zone of Huangfuchuan Watershed in warm-temperate typical steppe, the author determines their calorific value, analyses and studies calorific value dynamic of each population, the difference of calorific value of each organ in plant community, the correlation between plant calorific value and nutritional components and climatic factors in the growing season, meanwhile the biomass and energy change of plant community in different succession stages. The result shows that the dynamic curve of calorific value of the 11 major plant populations in Huangfuchuan Watershed during growing season can be divided into 4 types, V-type, wave type, increased type and relatively stable type. Of these, the populations of V-type are in the majority. According to the number of calorific value, the 11 major plants can be divided into 3 types, plant with high calorific value, plant with middle calorific value, plant with low calorific value. Viewing from the life form functional group angle, the calorific value of semishrub is the highest and perennial grass's calorific value is noticeably higher than annual plant's. There is difference in the change of each nutritional organ calorific value of the major plant populations. By different phenophase, the calorific value change of annual plant is much stronger than perennial plant's.In the aspect of plant population energy accumulation of different succession stages in the warm-temperate grassland, the total biomass and total energy of thymus serpyllum community, stipa breviflora + stipa bungeana + artem isia sacronm population and stipa grandis community in unit area are increased from June to August. Reaching the maximum value in August, both of biomass and energy decrease; stipa grandis community is the climax, and the biomass and energy are the highest among the three communities; during middle succession stage, the energy of stipa breviflora + stipa bungeana + artem isia sacronm population is lower. The energy of thymus serpyllum community in the early stage of restoration is the lowest.The calorific value of the major plants aboveground organs in Huangfuchuan Watershed has a significantly positive correlation with its carbohydrate content; it has a significantly positive correlation with crude fat content; it has a significantly correlation with ash content; it has a significantly negative correlation with crude protein content and water content. It indicates, if the ash content is lower, carbohydrate content is higher, and crude fat content is higher, then calorific value is higher.