中科院地理科學(xué)與資源研究所拉薩高原生態(tài)試驗站石培禮等在《功能生態(tài)學(xué)》（Functional Ecology）和《基礎(chǔ)與應(yīng)用生態(tài)學(xué)》（Basic and Applied Ecology）上發(fā)表論文“A test of the growth-limitation theory for alpine tree line formation in evergreen and deciduous taxa of the eastern Himalayas”和“End of Season Carbon Supply Status of Woody Species Near the Treeline in Western China”,，從樹線植物碳供給的角度揭示了青藏高原不同功能型高山樹線的形成機理,，對高山樹線的溫度閾值進行了深入探討,。該成果為高山低溫限制樹線樹木生長的“生長受限”理論提供了有力佐證。
石培禮在他主持的3項國家自然科學(xué)基金的資助下,，與瑞士巴塞爾大學(xué)Christian K?rner教授合作對青藏高原云杉屬,、冷杉屬、落葉松屬,、圓柏屬和樺木屬近10個樹種,、4類功能型、目前所知相應(yīng)屬的世界最高樹線海拔樹木的分布格局,、樹木更新與氣候變化關(guān)系及樹線形成的生理生態(tài)機理等方面開展了多年的研究,。青藏高原由于巨大的山體效應(yīng)(Massenerhebungseffect)分布著世界海拔最高的樹線，呈現(xiàn)從東到西海拔逐漸上升的分布格局,，樹線樹種漸次呈現(xiàn)冷杉-落葉松-云杉-圓柏和樺木過渡的替代規(guī)律,。樹線的溫度閾值與世界樹線相近，生長季平均溫度6.5°C左右,，低溫是氣候樹線高度的主要限制因子,。樹線樹木的定居和更新對氣候變化比較敏感，樹線對氣候變暖的響應(yīng)主要表現(xiàn)在樹木更新密度增加和樹木生長受到促進,，而很少表現(xiàn)為樹線海拔的上升,。采用樹線交錯帶樹木組織的非結(jié)構(gòu)碳水化合物(non-structural carbohydrates)為指標(biāo)，揭示了樹線數(shù)據(jù)碳獲取和碳利用狀況,，從機理上闡明了樹線并非光合作用受限制導(dǎo)致的碳源不足,，而是低溫限制了碳源的利用而形成的。這些成果首次對青藏高原不同功能型天然樹線的形成機理進行了系統(tǒng)的闡述,。（來源：中國科學(xué)院地理科學(xué)與資源研究所拉薩高原生態(tài)試驗站）
生物谷推薦原始出處：
Functional Ecology 2008,22,213–220 doi:10.1111/j.1365-2435.2007.01370.x
A test of the growth-limitation theory for alpine tree line formation in evergreen and deciduous taxa of the eastern Himalayas
P.Shi,C.K?rner2and G.Hoch
1Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,
China;and 2Institute of Botany,University of Basel,Sch?nbeinstrasse 6,CH-4056 Basel,Switzerland
Summary
1.Whether the global high elevation tree line phenomenon is associated with a low-temperatureinduced limitation of sink activities(i.e.direct impact on meristems and thus,growth)or by a limitation of the trees’carbon source activities(net photosynthesis)still awaits detailed tests across a range of taxa and regions,especially for deciduous species in a short growing season.
2.Here,we test the sink limitation hypothesis in the highest tree lines of Eurasia at altitudes up to 4700 m.We assessed growth and tissue concentrations of non-structural carbohydrates(NSC)as a measure of the carbon source-sink balance in needles and branchwood of Abies,Juniperus(evergreen),Betula and Larix(deciduous).
3.The mean soil temperature in deep shade(a proxy for mean air temperature)across the growing season at tree line in this region is around 6·6°C,which is consistent with the threshold temperature found at the natural climatic limit of the tree life-form worldwide.Mean tree height and stem diameter decreased significantly towards the upper tree line in all species studied.
4.Air temperature measurements at an inverted tree line site(valley bottom)indicate strong and rapid oscillations between nighttime freezing and mild daytime temperatures during late winter, which apparently eradicate Abies and select for Juniperus,offering potential explanations for the inferiority of Abies also at the upper Tibetan tree line.
5.At none of the four altitudinal transects studied did we observe a significant depletion of NSC (carbon limitation)at tree line.Instead,NSC increased in the majority of cases,suggesting direct (meristematic)low temperature constraints of growth.These results for these highest Eurasian tree lines suggest a common mechanism of alpine tree line formation for evergreen and deciduous species.
Basic and Applied Ecology 7(2006)370—377
End of season carbon supply status of woody species near the treeline in western China
Peili Shia Christian K ornerb,Gunter Hoch
