广西大青山杉木人工林碳氮磷生态化学计量特征

为研究杉木人工林生态系统植物、凋落物和土壤碳(C)、氮(N)、磷(P)生态化学计量特征的差异和相互关系,以广西大青山杉木密度试验林为研究对象,测定了5种初植密度下杉木人工林针叶、草本、凋落物和土壤的C、N、P含量及其比值。结果表明:针叶的C、N、P含量最高,凋落物次之,土壤最低。C∶N、C∶P表现为凋落物针叶草本土壤,N∶P表现为凋落物草本针叶土壤。其中针叶的N∶P均值为16.69,凋落物C∶N显著高于N发生释放的C∶N的临界值(30)。杉木人工林针叶和草本N、C∶N呈显著负相关关系,针叶和土壤的C∶N、N∶P,草本和凋落物P含量、C∶P均呈显著正相关关系,体现了杉木生态系统内的C、N、P在针叶、草本、凋落物和土壤之间相互转化和循环。南亚热带杉木人工林植物生长受P限制,凋落物分解慢,土壤有机质的矿化作用慢,养分循环能力低,因此在人工林抚育管理中,应保护林下植被,适当施肥,提高土壤肥力,维持杉木林长期生产力。

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.