刨花楠叶片碳氮磷化学计量比与个体大小的关系

以9和13年生刨花楠为对象，分析叶片碳氮磷含量与林木胸径的关系，研究林木叶片碳氮磷化学计量特征在个体大小及林龄间的变化规律.结果表明： 利用实生苗所营造的刨花楠人工林，个体分化随年龄增大而明显；两刨花楠人工林林木叶片C、N、P含量及C∶N均存在显著差异，但二者叶片C∶P及N∶P差异不显著；9 年生林木叶片平均C、N、P含量及N∶P均低于13年生林木，但叶片C∶N、C∶P高于13年生林木；同一林龄中，不同个体大小之间叶片的N、P含量及化学计量特征均存在显著差异；9年生刨花楠不同个体叶片N、P含量及其化学计量特征与胸径呈显著线性相关，13年生不同个体林木叶片N、P含量及C∶P、N∶P与胸径呈显著抛物线关系，而C∶N与胸径呈显著线性相关；9年生刨花楠叶片N、P转移率高于13年生，叶片N、P在生长季与非生长季的养分转移策略因不同生长阶段和生长环境而产生差异.

Characteristics of leaf carbon,nitrogen and phosphorus stoichiometry in relation to plant size of Machilus pauhoi.

To explore the effects of stand age on variation patterns of leaf C, N, P stoichiometric characteristics of Machilus pauhoi, two stands, i.e., 9 and 13 years old, were selected. The relationships between leaf nutrient contents (C, N and P) and diameters at breast height (DBH) of individual plants were analyzed. The data revealed that the individual variations of seedlings in M. pauhoi stands were strengthened with the stand development. The stand age had significant effects on leaf C, N, P contents and C：N ratio but not on C：P and N：P ratios. Specifically, the mean values of leaf C, N, P contents and N：P ratio in the 9-year-old stand were lower than those in the 13-year-old stand, whereas, inverse pattern of C：N and C：P ratios were found in the two stands. Furthermore, leaf N and P stoichiometry varied significantly within the stand. Specifically, leaf N and P contents, as well as their stoichiometric ratios, linearly correlated with DBH in the 9-year-old stand. On the contrary, leaf N and P stoichiometry showed quadratic correlation in 13-year-old stand (except leaf C：N which linearly correlated with DBH). Lastly, nutrient transfer rates of leaf N and P in the 9-year-old stand were higher than that in 13-year-old stand, and the discrepancies of leaf nutrient transfer strategy between growing and non-growing seasons were caused by the different growth phases and environmental conditions.