摘要:植物叶片碳（C）、氮（N）、磷（P）化学计量学能够反映植物对环境的适应性以及环境变化对植物的影响，是生态化学计量学的热点之一。研究亲缘关系相近物种对环境变化的适应差异对于深入了解植物的化学计量策略具有重要意义，而目前对于亲缘关系相近物种沿海拔梯度各如何变化未获得一致性的结论。因此，本研究在秦岭太白山海拔约1100-2200 m范围内，对槲栎（Quercus aliena）、栓皮栎（Q.variabilis）、锐齿栎（Q.aliena var.acuteserrata）、辽东栎（Q.wutaishansea）这4种栎属树种的叶片C、N、P含量进行测定与分析，考察叶片化学计量特征随海拔的变化趋势，同时量化气候、土壤和地形3种影响因素对其变异规律的解释程度。结果表明：（1）总体来看，4树种叶片C含量随海拔升高先上升后降低，叶片N含量和N：P则表现出随海拔升高而降低的趋势，而叶片C：N随海拔升高而升高。（2）不同树种随海拔的变化趋势不同：槲栎与锐齿栎具有相似性，叶片N、P含量都随海拔升高显著降低，C：N都随海拔升高显著升高；栓皮栎的叶片N含量和C：N与前两者呈现相反趋势；辽东栎叶片C含量随海拔上升而下降，与栓皮栎相同，但其叶片P含量和N：P分别呈现先升高后降低、先降低后升高的曲线变化趋势。（3）叶片不同化学计量特征值受到不同因子的影响。其中，叶片N含量和C：N主要受气候因子影响（解释度为39.91%和36.59%）；叶片C含量主要受土壤因子影响（解释度为25.22%）；叶片P含量、N：P和C：P则主要受到土壤因子和坡度影响（解释度有23.70%-39.83%），且这两个因子的交互效应影响较大（交互效应解释度有16.24%-24.72%）。本研究结果说明：（1）亲缘关系较近的物种在应对环境变化时，也会有不同的变化格局及对应的养分策略，而且这能在一定程度上解释它们的地带性分布规律；（2）地形因子会与土壤因子共同影响植物的化学计量特征，在研究山地森林生态系统时，坡度也是需要考虑的重要影响因子。



Abstract:The carbon (C), nitrogen (N) and phosphorus (P) stoichiometry of plant leaves could reflect the adaptive strategies of plants to environmental changes, which is one of the hot issues in ecological stoichiometry study. Research on the variation in leaf stoichiometry of related species along environmental gradients is significant for in-depth understanding of plants' nutrient strategies. However, the results of changes in leaf stoichiometry along altitude gradients are not consistent in previous studies. In this study, we collected leaves of four Quercus species, including Q. aliena, Q. variabilis, Q. aliena var. acuteserrata, and Q. wutaishansea in Taibai Mountain from 1100 m to 2200 m. Leaf C, N, P concentrations were measured and analyzed to explore the variations along the altitudinal gradient. Meanwhile, we quantified the influences of climate, soil and topographic factors (i.e. the slope of land) on the variations of leaf C, N, P and C ∶ N ∶ P ratio. The results showed that 1) overall, leaf C of the four species increased first and decreased then with the elevation, leaf N and N ∶ P decreased and leaf C ∶ N increased with the elevation. 2) Variations of leaf stoichiometry were different among the four species. Similar to Q. aliena var. acuteserrata, leaf N and P of Q. aliena decreased but C ∶ N increased with the elevation. However, leaf N and C ∶ N of Q. variabilis showed opposite trends. Leaf C of Q. wutaishansea decreased with the elevation, but the variation in leaf P and N ∶ P showed nonlinear trend. Specifically, leaf P of Q. wutaishansea increased first and decreased then along the altitudinal gradient, while the trend of leaf N ∶ P was opposite. 3) The main impact factors for the variations of leaf stoichiometry were different. Leaf N and C ∶ N in leaves were mainly influenced by climatic factors, with 39.91%─36.59% variation explained. Leaf P, N ∶ P and C ∶ P were mainly affected by soil and landform factor (explaining 23.70%─39.83% variation), and influenced by the interaction between them was significant (explaining 16.24%─24.72% variation). The results indicate that: 1) when facing and dealing with environmental change, even closely related species could exhibit different spatial patterns and nutrient strategies, which could explain their zonal distribution to some extent. 2) The topographic factor could affect stoichiometry of plants together with soil factors, and the slope of land is also an important factor which should be considered in leaf stoichiometry studies of mountain forest ecosystem.





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