武夷山五种竹子叶、枝、秆碳氮磷化学计量对生长阶段和海拔的响应

探究竹子化学计量特征对生长阶段和海拔的响应对于了解其生理生态特征及生长适应策略至关重要。对武夷山沿海拔分布的五种典型竹子叶、枝、秆的碳(C)、氮(N)、磷(P)含量及化学计量内稳态指数(H)进行两个生长阶段的测定。结果显示不论生长阶段的变化，各器官N、P含量的变异系数均显著大于C含量，且秆的N、P含量变异系数要显著大于叶片和竹枝，但不同生长阶段并未改变秆的N∶P (12∶1)。毛竹4月份枝和8月份叶的N、P含量均随海拔增加而降低，而箬竹叶的N、P含量均随海拔增加而增加。海拔和生长阶段的交互作用显著提高了竹秆N含量对生长阶段变化的响应。竹叶N和秆的N、P含量在不同生长阶段具有明显的内稳性调控机制，但竹枝N、P的内稳性特征表现不明显。总而言之，这些结果一方面反映了武夷山五种竹子偏向于选择维持叶N含量的内稳态机制，另一方面调节秆N、P含量的协变来应对海拔和生长阶段变化中养分的利用策略。

Responses of five bamboos leaf, branch and culm stoichiometric to growth stages and elevations in Wuyi Mountain

It is essential to understand the physiological and ecological responses and life-history strategies adjustment by investigating the stoichiometric characteristics of bamboos in different elevation and growth stages. The contents of carbon (C), nitrogen (N), and phosphorus (P) of five bamboos leaf, branch, and culm, as well as the homeostatic index (H) were measured in two growth stages in Wuyi Mountain, respectively. The results show that although the N:P of bamboos branch does not change with different growth stages, the coefficient of variation of N and P content of each organ is significantly larger than that of C. The coefficient of variation of N and P content for culm is significantly larger than leaf and branch. The contents of branch N and P in April and leaf N and P in August of Phyllostachys edulis decrease with the increase of elevation. For Indocalamus tessellatus, the contents of leaves N and P show significantly increased with the elevation. The response of culm N content in bamboos increases considerably due to the interactions between elevation and growth stages. The homeostatic regulation mechanisms of N in leaf, N, and P in culm have been showing at different growth stages, but not for the bamboo branch. In a word, on the one hand, the results indicate that the five bamboos are preferring to maintain the stoichiometric homeostasis mechanism of leaf N. On the other hand, the bamboo adjusting by the content of N and P in culm to cope with the variations on nutrient utilization strategies during the elevation and growth stage changes.