祁连山不同海拔火绒草叶片生态化学计量特征及其与土壤养分的关系

叶片生态化学计量反映植物生存环境的变化信息,研究不同海拔植物叶片化学计量特征有助于了解植物对环境变化的适应策略.通过对祁连山不同海拔(2400、2600、2800、3000和3200 m)火绒草叶片生态化学计量的研究,探讨了火绒草对环境变化(温度、降水和土壤养分)的响应,并分析其生长的限制性元素.结果表明: 在海拔梯度上,火绒草叶片碳(LC)、氮(LN)、磷(LP)含量分别为401.27、23.99和1.22 g·kg^-1,LC∶LN、LC∶LP、LN∶LP均值分别为16.8、352.5和20.7.LC含量、LC∶LN、LC∶LP和LN∶LP均随海拔升高呈先升后降再升的趋势,并在2600和3000 m处达到最大值和最小值,LP含量则呈相反趋势,而LN含量呈先降后升的趋势,并在2800 m处达到最小值.火绒草LC含量与LN含量不相关,与LP含量呈显著负相关;LN含量除与LP含量呈显著正相关外,与其他化学计量比均无相关关系;LP含量与各化学计量比均呈显著负相关;LC∶LN、LC∶LP和LN∶LP两两呈正相关.土壤总磷和土壤总氮是影响LC及LN的重要因素,而LP仅与土壤总磷呈显著负相关.该区火绒草生长主要受P限制.

Characteristics of Leontopodium leontopodioides leaf stochiometry with altitude and their relationship with soil nutrients in Qilian Mountains,Northwest China

Foliar stoichiometry provides information on the biotic and abiotic changes of environment. We examined the stoichiometric characteristics of plant leaves at different altitudes to understand how plants adapt to environmental changes. Foliar stoichiometry of Leontopodium leontopodioides at various altitudes (2400, 2600, 2800, 3000 and 3200 m) were analyzed in the Qilian Mountains of China. Across the altitude gradient, mean value of leaf carbon content (LC), nitrogen content (LN), and phosphorous content (LP) of L. leontopodioides was 401.27, 23.99 and 1.22 g·kg^-1, respectively. The mean value of LC:LN, LC:LP and LN:LP was 16.8, 352.5 and 20.7, respectively. LC, LC:LN, LC:LP and LN:LP initially increased with increases in altitude, rea-ching the maximum at 2600 m, then decreased, reaching the minimum at 3000 m, and finally increased again. LP exhibited the opposite trend. LN demonstrated an initial decrease with altitude, reaching the minimum at 2800 m, followed by an increase at higher altitudes. LC did not correlate with LN, but was significantly negatively correlated with LP. LN was significantly positively correlated with LP. There was no correlation between LN and any other stoichiometry ratios. LP showed a significantly negative correlation with other stoichiometry ratios. LC:LN, LC:LP, and LN:LP were positively correlated with each other. Both soil total nitrogen and total phosphorus affected LC and LN, whereas LP was significantly negatively correlated with soil total phosphorus. The results suggested that the growth of L. leontopodioides in the study region was mainly limited by P availability.