Ecological Stoichiometry Characteristics Of Castanopsis Hystrix And Atula Alnoides In South Subtropical Area Of China

Ecological stoichiometry is one of the hot research fields of ecology in recent years. It was reported rarely about the artificial forest of ecological stoichiometry studies. In this study, Castanopsis hystrix and Atula alnoides were choiced as the research object in the Experimental of Tropical Forestry, Chinese Academy of Forestry which lied in Pingxiang city. It was designed to evaluate the nutritional status of plants and its relationship with soil nutrients, analysis of the impact of plant growth limiting factors for Castanopsis hystrix and Betula alnoides. It may provide a theoretical basis through the determination of different organs of plant and soil nutrient content, comparison among different organs and organ with soil ecological stoichiometry characteristics for sustainable management of artificial forest. The conclusions are as follows:(1) N, P of organs content in Castanopsis hystrix and Betula alnoides is in the order as:leaves> root> branches> trunk; C content of the order was leaves> trunk> branches> root; Ca, Mg content of the order were branches> leaves> root> trunk; K content was distributed regularly.(2) C content of leaf in Castanopsis hystrix and Betula alnoides was higher than the global average level and the Loess Plateau of China, the Pearl River Delta in blades; P content of leaf was less than global level and the Chinese region of the blade content.(3) C, N of leaf in Castanopsis hystrix and Betula alnoides were not a significantly negative correlation; C and P were not significantly correlated; N and P were extremely significantly positive correlation.(4) C:P, C:N of Castanopsis hystrix and Betula alnoides were in the order as:branches> root> trunk>leaves, N:P of the order was root> leaves> trunk> branches. In addition to N:P of branches, N:P of Castanopsis hystrix were less than Betula alnoides, and each organ C:P were greater than those of Betula alnoides. The stoichiometric ratio in two branches was C:P> C:N> N:P. The stoichiometric ratio of leaves in two tree species was not certain regularity.(5) C:P of leaves and branches in Castanopsis hystrix was significantly positive correlation; C:P of leaves and branches in Betula alnoides was a very significantly positive correlation. C:P of fine roots and trunks in Castanopsis hystrix and Betula alnoides were significantly positive correlation. C:N and N: P of leaf in two species had no significant differences.(6) C, N content of soil from the surface to bottom was gradually decreasing in Castanopsis hystrix and Betula alnoides forest, P content of layer in the soil had no obvious change. C, P content of each layer in Betula alnoides plots were higher than Castanopsis hystrix, N content of the soil were less than Castanopsis hystrix. (7) C content of leaf and soil in Castanopsis hystrix and Betula alnoides was significantly positive correlation, P content was negative correlation. C:N of leaves and soil in Castanopsis hystrix were lower than those of Betula alnoides. C:N, C:P of two kinds of forest soil were lower than the national average.(8) Nutrient of fine root was higher than nutrient of soil in two species. C:N, C:P and N:P of fine-root were significantly greater than those of soil in the two trees. No obvious correlation was in the fine roots and soil nutrient content and stoichiometric ratio.