Effects of several factors on plant calorific value based on largescale conditions

Calorific value is one of the most important plant properties and is stabe normally. It is an important index on evaluating the plant primary productivity and plant nutrition, and also plays an important role in the process of ecology. In the researches of the plant calorific value, people paid much attention on just single plant species or some plant species grown in particular areas, but few people did some researches on largescales conditions.We collected the published papers about the plant calorific value in PSTP (http: //www. cqvip.com) from 1989 to 2010, classified and summarized the calorific values of 547 plants in 39 plots, which attempted to discuss the effects of plant organ，family，life form, longitude and latitude on plant calorific values based on the largescale conditions.The results showed that the order of calorific value of plants was Arborshrubherbaceous， which did not show a variation tendency with the changes of the plant species and distribution. The calorific values of blades of herbaceous and shrubs were the highest，while those of roots were the lowest. For arbor, the calorific value of shoots was the highest, that of roots was also the lowest. The calorific value of a family which had mainly herbaceous and shrubs was lower than that of the family with most of arbors. The study also indicated that Chenopodiaceae plants had the lowest calorific value; Ericaceae had the highest value. The calorific value of plants also increased with increasing latitude.