The Distribution Pattern Of Carbon, Nitrogen And Phosphorus And The Stoichiometry Characteristics Of Robinia Pseudoacacia Forest

To understand the distribution pattern of carbon、nitrogen and phosphorus and the stoichiometry characteristics of robinia pseudoacacia plantation ecosystem in Locust Plantation, we used the space-temporal exchanging method, and selected three different forest stand age(5-year-old young growth, 17-year-old half-mature forest, 22-year-old mature forest) of masson robinia pseudoacacia in similar site conditions as the objects, and analyzed the concentration of carbon, nitrogen and phosphorus and C: N, C: P and N: P stoichiometry characteristics in the needle leaf, litter,fine roots and soil to explore different ages on leaf, litter, fine roots and soil nutrient content and stoichiometric ratio, and the relationship between them. The results showed that:(1) At different ages in Locust Plantation the concentration of N were significant difference between leaf, litter,fine roots and soil which in order of leaf >fine roots >litter > soil. Total P content in leaves showed the largest followed by the litter,soil and fine roots. The concentration of C which in order of fine roots> leaf>litter > soil. Significant differences among the four; Forest age had significant impact on C, N, P concentrations and w(C):w(N), w(C):w(P)and w(N):w(P) stoichiometry ratios.(2) Overall nitrogen, phosphorus and carbon content in soil are quite different, and with the increase of age and larger forest laws are the same. Mature forest highest performance, lowest middle-aged forest. Show the best locust soil fertility in mature forest, middle-aged forest worst. Leaves N: P was significantly less than 14, indicating that the areas affected by severe restrictions N elements, though, with the increasing age of the forest condition has improved, but in order to improve productivity in the future tending phosphorus fertilizer should be added or introducing nitrogen-fixing leguminous plants. With increasing stand age Litter C, N, P content also increased. Mature forest C: N and C: P maximum, indicating that as age increased locust forest litter on the N, P increase efficiency. Fine root content of nitrogen, phosphorus and P content of leaves were significantly correlated. With different ages robinia pseudoacacia forests fine root P exhibited significantly greater than in the young forest. Thus with increasing stand age the P element in plantations suppression and Stress appearance.(3) Robinia pseudoacacia Plantation C, N, P content and stoichiometry. There are strong correlation between leaf, litter, roots and soil.Show Robinia pseudoacacia plantation ecosystem C, N, P element is constantly traffic and switching between in plant leaves, litter, fine roots and soil.In plant-soil systems stoichiometry between nutrients of each component reflects the robinia pseudoacacia plantation by nutrient restrictions. Comparison with the results of other scholars, we have higher C content, but lower nitrogen and phosphorus content. Therefore, we can take to increase the amount of N, P content of nutrient elements when the forest tending measures.