Abstract: In order to study the effect of soil available phosphorus content on the physicochemical properties of plants, 32 major forest plants as the research objects include Pinusyunnanensis, Myrica nana and Artemisia dubia Wallich. They are from Kunming, Yuxi and Qujing (include 12 counties, cities or districts) in the central Yunnan region. A total of 346 batches of leaves (stems) of 32 species, 43 batches of branches of 17 species，and corresponding plant root soil were collected as experimental samples. The extract content, ash content, calorific value and soil available phosphorus content were determined, and analyzed the effect of soil available phosphorus content on the physicochemical property of plants, and then studied the effect of soil available phosphorus content on the combustibility of plants. The results showed that: (1) Soil available phosphorus increased leaves extract content and calorific value to a certain extent, and reduced its ash content, but the physicochemical properties of the branches have less response to the soil available phosphorus content than the leaves; (2) The leaves physicochemical properties of Cyclobalanopsis glaucoides, P. armandii,Heteropogon contortus, Lyonia ovalifolia, Artemisia dubia, Illicium simonsii, Acacia dealbata and Cinnamomum glanduliferum responded more sensitively to soil available phosphorus content, and the branches physicochemical properties of Keteleeria evelyniana and Cinnamomum glanduliferum responded more sensitively to soil available phosphorus content, and available phosphorus in soil can significantly increase the extract content and caloric value of branches and leaves (stems) of common plants in central Yunnan, such as Pinus yunnanensis, P. armandii, P. yunnanensis var. pygmaea, Artemisia dubia and Eupatorium adenophorum, and reduce their ash content; (3) Under similar habitat conditions, the soil available phosphorus content and extract content, calorific value are significant positive relationship. Soil available phosphorus can increase the crude fat content and calorific value of plants to a certain extent, and reduce their ash content. This change trend is conducive to the improvement of the combustibility of plants. Based on this, the corresponding measures and suggestions are put forward to strengthen forest fire risk management in central Yunnan.

Key words: combustible physical and chemical properties, soil available phosphorus content, forest plants