Stoichiometry of carbon, nitrogen, and phosphorus of Chinese fir plantations in Daqing Mountain, Guangxi

The main objective of this study is to understand the relationship of nutrient elements and stoichiometry characteristics of carbon, nitrogen, and phosphorus in needle, herb, litter and soil of mature Chinese fir plantation ecosystem. The study was conducted at Daqingshan forest farm, the contents of C, total N, and total P in needle, herb, litter, and soil(10-100 cm soil layers) of Cunninghamia lanceolata(Lamb.) Hook. The mature plantation under five different planting densities were measured. The C∶N, C∶P, and N∶P ratios were estimated. The results indicated that C, N and P contents followed the order of older needle > litter > soil. The rank of the C∶N, C∶P was litter > needle > herb > soil, and the rank of the N∶P was litter > herb > needles >soil. The ratio of N∶P of needle was 16.69. The C∶N radio of litter was significantly higher than the critical value of C∶N released by N(30). There was a significantly negative correlation between needle and herb N, C∶N. The radios of N∶P and C∶P between needle and soil, as well as P content and C∶P between herb and litter showed a significantly positive correlation. It indicated that the C, N, and P in the Chinese fir ecosystem were transformed and recycled among needle, herb, litter, and soil. We found that the growth of the Chinese fir plantation in the south subtropical zone was limited by P. The decomposition of litter and mineralization of organic matter were slow. The nutrient cycling ability was low. Therefore, it is necessary to protect undergrowth vegetation, apply fertilizer appropriately, improve soil fertility, and maintain the long-term productivity of the Chinese fir plantation.