武夷山不同海拔黄山松细根碳、氮、磷化学计量特征对土壤养分的适应

细根的生态化学计量特征承载着植物生存环境的变化信息,从而为探索全球变化对植物内在机制的影响提供理论依据。以江西武夷山国家级自然保护区内五个不同海拔梯度(1200、1400、1600、1800、2000 m)的黄山松为对象,运用挖掘法采样后测定细根C、N、P含量及化学计量比特征,研究不同的海拔下细根对土壤养分变化的适应规律。结果表明:(1)黄山松细根C含量年平均值为(486.27±64.32)mg/g,海拔对其没有显著的影响,与土壤养分之间不存在显著的相关关系。(2)细根N含量年平均值为(9.26±2.09)mg/g,海拔对其没有显著的影响,但与土壤C含量存在显著的正相关关系。(3)细根P含量年平均值为(0.39±0.13)mg/g,与海拔梯度及土壤P含量均存在极显著正相关关系,而与土壤碳氮比呈显著负相关关系。(4)细根氮磷比为26.94±12.51,与海拔梯度、土壤P含量及土壤碳氮比均显著负相关。因此,黄山松细根吸收N是以消耗C为代价;细根P主要受土壤P供应量的限制;武夷山地区N沉降将进一步增加植物的氮磷比,加剧黄山松生长的P限制。

Response of fine root carbon, nitrogen, and phosphorus stoichiometry to soil nutrients in Pinus taiwanensis along an elevation gradient in the Wuyi mountains

The ecological stoichiometric characteristics of fine roots reflect environmental changes. Thus, they provide a theoretical basis to explore the mechanisms of global changes affecting plants. The objective of the present study was to analyze the stoichiometry of Pinus taiwanensis is fine roots inhabiting five different elevation gradients (i.e., 1,200, 1,400, 1,600, 1,800, and 2,000 m) in Wuyishan National Nature Reserve. The fine roots were collected and the carbon (C), nitrogen (N), and phosphorus (P) concentrations and stoichiometric characteristics were analyzed. The results showed that:(1) The annual average C concentration of fine roots was (486.27±64.32) mg/g, and was not significantly affected by elevation. There was no significant correlation between the C concentration of fine roots and soil nutrients; (2) The annual average N concentration of fine roots was (9.26±2.09) mg/g, and was not significantly affected by elevation. But, there was a close correlation between the N concentration of fine roots and C concentration of soils; (3) The annual average P concentration of fine roots was (0.39±0.13) mg/g, which was closely correlated with altitude gradients and soil P contents, but negatively correlated with the soil C:N ratio; (4) The annual average N:P ratio of fine roots was 26.94±12.51, which was negatively correlated with altitude, soil P concentration, and the soil C:N ratio. Therefore, fine roots absorb N at the expense of C, fine root P is primarily limited by soil P supply, which would be further exacerbated by N deposition in the Wuyi Mountains.