Causes for the unimodal pattern of leaf carbon isotope composition in Abies faxoniana trees growing in a natural forest along an altitudinal gradient
Causes for the unimodal pattern of leaf carbon isotope composition in Abies faxoniana trees growing in a natural forest along an altitudinal gradient
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DOI：
10.1007/s11629-014-3174-2
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发表时间：
2015-01
影响因子：
2.5
通讯作者：
Hong-xia Zhao;B. Duan;Y. Lei
中科院分区：
文献类型：
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作者：
Hong-xia Zhao;B. Duan;Y. Lei
对沿着海拔梯度生长的岷江冷杉（Abies faxonian）叶片形态和生理特征进行了研究，旨在探讨δ 13 C值变化的主要机制。温带半湿润地区植物功能性状表现为单峰型。气孔参数、比叶面积和C/N比随海拔的升高而增加，而C、N和δ 13 C值随海拔的升高而降低。相反，在海拔3000米以上，它们呈现出相反的趋势。结果表明，高海拔植物以降低氮素利用效率（NUE）为代价获得较高的水分利用效率（WUE），而3000 m植物可维持较高的NUE，但WUE较低。NUE和WUE之间的权衡的这种种内差异可以部分地解释植物的水分和养分有效性的海拔分布。我们的研究结果清楚地表明，营养状况和叶片结构之间的功能关系是负责与δ 13 C的海拔变化。比叶面积在调节植物适应性反应中的关键作用为中等海拔种群的生长优势提供了潜在的生理机制。这些适应性反应海拔梯度表明，海拔约3000米a.s.l.是A. faxoniana，允许最旺盛的生长和新陈代谢。这些结果加深了我们对环境和生物变量对δ 13 C动态的各种作用的理解，并为亚高山针叶林管理提供了有用的信息。
Leaf morphological and physiological traits ofAbies faxonianagrowing in a natural forest along an altitudinal gradient were measured with the aim to identify the central mechanism for the marked variation in foliar δ13C determined by an isotope ratio mass spectrometer. There is a unimodal pattern of plant functional traits in these temperate and semi-humid areas. Stomatal parameters, specific leaf area, and C/N ratio increased, whereas C, N and δ13C values decreased with increasing altitude below 3000 m a.s.l.. In contrast, they exhibited opposite trends above 3000 m a.s.l.. Our results demonstrated that high-altitude plants achieve higher water use efficiency (WUE) at the expense of decreasing nitrogen use efficiency (NUE), whereas plants at 3000 m can maintain a relatively higher NUE but a lower WUE. Such intra-specific differences in the trade-off between NUE and WUE may partially explain the altitudinal distribution of the plants in relation to moisture and nutrient availability. Our results clearly indicate that the functional relations between nutritional status and the structure of leaves are responsible for the altitudinal variations associated with δ13C. The pivotal role of specific leaf area in regulating plant adaptive responses provides a potential physiological mechanism for the observed growth advantage of populations occupying the medium altitude. These adaptive responses to altitudinal gradients showed that an altitude of approximately 3000 m a.s.l. is the optimum distribution zone forA. faxoniana, allowing the most vigorous growth and metabolism. These results improve our understanding of the various roles of environmental and biotic variables upon δ13C dynamics and provide useful information for subalpine coniferous forest management.