Functional Ecology：不同热起源的植物适应气候变化的能力与叶片氮分配格局和代谢过程有关

森林植物叶片对碳的吸收与释放在全球大气组成平衡中扮演着重要角色，大气组成的变化反过来又影响地球表明温度。各种气候模型一直在试图调整方法以准确计算叶片碳交换在植被－气候模型中的贡献，而准确计算叶片碳交换的关键之处在于确定来自不同热生境（如热带和温带生态系统）的植物表现出的以碳交换为主的一系列叶片属性是否具有本质差异。但在自然生境中，许多热量不同的生态系统通常不仅仅表现在温度不同，可能其他生境变量如水分、养分条件等也会有较大差异。澳州东部广泛分布的从热带到温带的雨林植物正好为这一研究提供了天然条件。

孙书存研究员课题组向双博士在中国科学院公派留学基金等资助下，与澳大利亚国立大学Owen Atkin教授等合作，在澳大利亚昆士兰州、维多利亚州和塔斯马尼亚州选择12个温带物种和13个热带物种进行研究，将来源于当地的植物幼苗种植于水分和养分条件良好的控温25°C（大多数植被模型的模拟温度）的玻璃温室中，在生长期间进行气体交换和相关叶片属性的测定。研究结果发现：温带植物较热带植物呈现出较高的光合速率和呼吸速率；而温带植物较高的气体交换速率与叶片中相应的较高氮含量有关；由于氮是与光合和呼吸作用密切相关的蛋白质和酶代谢的关键营养物质，因而结果也显示温带植物相比于热带植物表现出较强的光的截取和碳的固定能力。这一研究揭示来自不同热起源物种的适应能力是与其内在的氮投资格局以及大气碳交换中植物关键代谢过程的适应能力密切相关的。（生物谷Bioon.com）

生物谷推荐英文摘要：

Functional EcologyDOI: 10.1111/1365-2435.12047

Contrasting leaf trait scaling relationships in tropical and temperate wet forest species

Shuang Xiang1,2, Peter B. Reich3,4, Shucun Sun1, Owen K. Atkin2,*

We investigated whether plants adapted to thermally contrasting environments (e.g. tropical-temperate habitats) exhibit inherent differences in leaf trait scaling relationships.

Thirteen tropical and 12 temperate species (all characteristic of wet forests) were grown in a glasshouse (25/20 °C day/night). A range of leaf traits were quantified, including mass-based leaf nitrogen [N], mass per unit area (LMA), light-saturated photosynthesis (A) and respiration (Rdark).

Average area- and mass-based rates of net CO2 exchange were higher in the temperate species, compared to their tropical counterparts. Average leaf [N] and LMA values were also higher in temperate species than in their tropical counterparts.

The higher LMA in the metabolically more active temperate species was the most striking contrast to the patterns and predictions of the GLOPNET leaf trait data base, and was associated with different elevations (i.e. y-axis intercepts) but not slopes of bivariate trait scaling relationships. As expected, mass-based rates of A and Rdark scaled positively with increasing [N] and negatively with increasing LMA in both tropical and temperate species. No differences were found between temperate and tropical species groups in terms of log-log scaling relationships linking A and Rdark to N. However, at any given LMA, mass-based values of [N], A and Rdark were all higher in the temperate species than in their tropical counterparts.

Underpinning higher A in temperate species was a higher capacity for carboxylation (Vcmax) and RuBP regeneration (Jmax), with Jmax:Vcmax being greater in temperate species.

In conclusion, our results suggest that as a consequence of greater overall N investment as well as greater proportional N investment in metabolic capacity, cool-adapted temperate wet forest species exhibit higher photosynthetic and respiration rates than their warm-adapted tropical counterparts when compared in a common environment.

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