中科院地理科学与资源研究所拉萨高原生态试验站石培礼等在《功能生态学》（Functional Ecology）和《基础与应用生态学》（Basic and Applied Ecology）上发表论文“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”，从树线植物碳供给的角度揭示了青藏高原不同功能型高山树线的形成机理，对高山树线的温度阈值进行了深入探讨。该成果为高山低温限制树线树木生长的“生长受限”理论提供了有力佐证。
石培礼在他主持的3项国家自然科学基金的资助下，与瑞士巴塞尔大学Christian K?rner教授合作对青藏高原云杉属、冷杉属、落叶松属、圆柏属和桦木属近10个树种、4类功能型、目前所知相应属的世界最高树线海拔树木的分布格局、树木更新与气候变化关系及树线形成的生理生态机理等方面开展了多年的研究。青藏高原由于巨大的山体效应(Massenerhebungseffect)分布着世界海拔最高的树线，呈现从东到西海拔逐渐上升的分布格局，树线树种渐次呈现冷杉-落叶松-云杉-圆柏和桦木过渡的替代规律。树线的温度阈值与世界树线相近，生长季平均温度6.5°C左右，低温是气候树线高度的主要限制因子。树线树木的定居和更新对气候变化比较敏感，树线对气候变暖的响应主要表现在树木更新密度增加和树木生长受到促进，而很少表现为树线海拔的上升。采用树线交错带树木组织的非结构碳水化合物(non-structural carbohydrates)为指标，揭示了树线数据碳获取和碳利用状况，从机理上阐明了树线并非光合作用受限制导致的碳源不足，而是低温限制了碳源的利用而形成的。这些成果首次对青藏高原不同功能型天然树线的形成机理进行了系统的阐述。（来源：中国科学院地理科学与资源研究所拉萨高原生态试验站）
生物谷推荐原始出处：
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
