石灰岩山地不同生境淡竹的养分特征及其生理适应

目的 石灰岩山地土壤高度异质、养分分布不均,探寻石灰岩山地优势种淡竹（Phyllostachys glauca McClure）养分分配特征及低P适应机制,为喀斯特植被管理和植物资源利用提供理论参考。 方法 通过对赣西北石灰岩山地连续土、半连续土和零星土3种土被生境淡竹林设置样地进行调查,测定并分析淡竹各构件N、P含量。 结果 表明：（1）随着裸岩率增加,土壤全N含量增加,而3种生境的全P含量均较低;（2）淡竹植株N含量随裸岩率上升而增加,在零星土生境下最高;P含量随裸岩率增加而减少,零星土生境植株的N:P大幅上升,P限制加剧,但叶的N:P保持相对稳定;淡竹各构件中N含量随裸岩率增加呈缓慢上升趋势,P含量呈下降趋势且除叶片外其余构件均大幅下降。（3）不同生境淡竹N、P分配格局不同,淡竹各构件的N分配比例在3种生境下没有差异（鞭除外）;半连续土和零星土淡竹叶片P分配比例显著高于连续土,而半连续土竹秆的P分配比例显著低于连续土。 结论 植株N、P含量与土壤N、P供应水平正相关,在土壤N供应充足而P供应匮乏的情况下,淡竹通过减少秆的P分配而提高叶片的分配量,以保证叶片养分需求维持植株正常生长,提高逆境下的适合度。

Nutrient Characteristics and Physiological Adaptation of Phyllostachys glauca at Different Habitats in Limestone Mountains

Objective To study the nutrient distribution and low P adaptive mechanism of Phyllostachys glauca McClure in the soil of limestone mountain which is highly heterogeneous and the nutrient distribution is uneven. Method The N and P contents in leaf, branch, culm, stump, rhizome and root of Ph. glauca were measured and analyzed at different soil habitats (continuous soil, semi-continuous soil, and sporadic soil) in the limestone mountain of northwest Jiangxi Province. Result (1) With the increase of rock coverage, the total N content of soil increased, but the total P content was low in all the three habitats. (2) The N content of Ph. glauca increased with the increase of rock coverage, and reached the highest value in sporadic soil habitat. Conversely, the P content decreased with the increase of rock coverage. The ratio of N:P content of plants increased sharply with the greatest degree of P deficiency in sporadic soil habitat, but the ratio of N:P content of leaf remained relatively stable. With the increase of rock coverage, the N content in each component of Ph. glauca showed a slowly increasing trend, while the P content showed a decreasing trend, and all plant components except leaf decreased significantly. (3) The distribution pattern of N and P changed with the increase of the rock coverage. No difference was observed on the proportion of N among the three habitats (except the rhizome). The P distribution of leaf in semi-continuous soil and sporadic soil was significantly higher than that in continuous soil, but in semi-continuous soil the P distribution proportion of culm was significantly lower than that in continuous soil. Conclusion The N and P content in Ph. glauca are positively correlated to soil N and P supply. In the case of sufficient supply of soil N and insufficient supply of soil P, this bamboo species will enrich the scarce nutrients (P) to leaf by adjusting its interior distribution pattern, and then ensure the photosynthetic needs of leaf to maintain plant growth and improve the adaptability under soil stress.