森林植物葉片對碳的吸收與釋放在全球大氣組成平衡中扮演著重要角色，大氣組成的變化反過來又影響地球表明溫度。各種氣候模型一直在試圖調(diào)整方法以準確計算葉片碳交換在植被－氣候模型中的貢獻,，而準確計算葉片碳交換的關(guān)鍵之處在于確定來自不同熱生境（如熱帶和溫帶生態(tài)系統(tǒng)）的植物表現(xiàn)出的以碳交換為主的一系列葉片屬性是否具有本質(zhì)差異,。但在自然生境中,，許多熱量不同的生態(tài)系統(tǒng)通常不僅僅表現(xiàn)在溫度不同,，可能其他生境變量如水分、養(yǎng)分條件等也會有較大差異,。澳州東部廣泛分布的從熱帶到溫帶的雨林植物正好為這一研究提供了天然條件,。
孫書存研究員課題組向雙博士在中國科學院公派留學基金等資助下，與澳大利亞國立大學Owen Atkin教授等合作,，在澳大利亞昆士蘭州,、維多利亞州和塔斯馬尼亞州選擇12個溫帶物種和13個熱帶物種進行研究，將來源于當?shù)氐闹参镉酌绶N植于水分和養(yǎng)分條件良好的控溫25°C（大多數(shù)植被模型的模擬溫度）的玻璃溫室中,，在生長期間進行氣體交換和相關(guān)葉片屬性的測定,。研究結(jié)果發(fā)現(xiàn)：溫帶植物較熱帶植物呈現(xiàn)出較高的光合速率和呼吸速率；而溫帶植物較高的氣體交換速率與葉片中相應的較高氮含量有關(guān),；由于氮是與光合和呼吸作用密切相關(guān)的蛋白質(zhì)和酶代謝的關(guān)鍵營養(yǎng)物質(zhì),，因而結(jié)果也顯示溫帶植物相比于熱帶植物表現(xiàn)出較強的光的截取和碳的固定能力。這一研究揭示來自不同熱起源物種的適應能力是與其內(nèi)在的氮投資格局以及大氣碳交換中植物關(guān)鍵代謝過程的適應能力密切相關(guān)的,。（生物谷Bioon.com）
生物谷推薦英文摘要：
Functional Ecology DOI: 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.
