Nutrient Characteristics And Its Influencing Factors Of P.tabulaeformis Needle In P.tabulaeformis And Q.mongolica Mixed Stand

Nutrient is the material base for plants to grow and sustain life as well as the essential condition to improve the productivity of trees,while stoichiometric and nutrient resorption characteristics can reflect nutrient utilization strategy.To illustrate the nutrient characteristics of the trees in mixed stand and influencing factors relevant,the paper took P.tabuliformis as object to study the difference of stoichiometric and nutrient characteristics of P.tabuliformis needle in mixed stand and pure stand.Effect of associated Q.Mongolica on the stoichiometric and nutrient characteristics of P.tabuliformis needle at different soil nutrient levels was studied by pot test.The results are as following:The DBH and single needle biomass of P.tabuliformis in mixed stand are higher than pure stand;The concentration of organic C,total N,total P,available N,available P,water-soluble Ca and C:N,C:P of soil in P.tabuliformis and Q.mongolica mixed stand are higher than those of pure stand,so that it can be drawn that mixing not only increasing the nutrient concentration of soil but also the decomposition rate of organic matter and the efficiency of P in soil.Through analyzing C,N,P stoichiometric ratio of P.tabuliformis needle,it is indicated that the C:N and C:P of different age of P.tabuliformis needle are higher in mixed stand than those of pure stand,suggesting that mixed stand can improve the nutrient utilization efficiency of P.tabuliformis.Through analyzing nutrient resorption rate of P.tabuliformis needle,the resorption rate of 1-2 and 2-3 P.tabuliformis needle in mixed stand is higher than that of pure stand,the P.tabuliformis in mixed stand can use nutrient more efficiently,and the nutrient of needle in pure stand are absorbed before the needle fall off.The pot test demonstrates that the associated Q.Mongolica is beneficial to shoot growth of P.tabuliformis at different nutrient levels,but only with the low nutrient,associated Q.Mongolica significantly promotes root growth of P.tabuliformis.The increase of the soil nutrient level is conspicuously beneficial to shoot growth of P.tabuliformis,yet it has no significant influence on root growth.As the increase of the soil nutrient level,the C:N、C:P of P.tabuliformis needle decrease,the utilization efficiency of P.tabuliformis decrease,and yet associated Q.Mongolica can increase the efficiency of nutrient utilization.With the increase of soil nutrient level,the N,P,K nutrient resorption of P.tabuliformis shows a trend of decline,in the case of low nutrient conditions,P.tabuliformis sustain growth by increasing the resorption rate;Associated Q.Mongolica only increase the resorption rate of K.In a word,P.tabuliformis and Q.mongolica mixed can promote growth and utilization efficiency of P.tabuliformis.Through pot simulation test,it was proved that both the associated Q.Mongolica and nutrient improvement of soil could promote growth of P.tabuliformis,but only associated Q.Mongolica could improve nutrient utilization efficiency of P.tabuliformis directly.