A world-wide study of high altitude treeline temperatures
A world-wide study of high altitude treeline temperatures
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DOI：
10.1111/j.1365-2699.2003.01043.x
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发表时间：
2004-05-01
影响因子：
3.9
通讯作者：
Paulsen, J
中科院分区：
文献类型：
--
作者：
Körner, C;Paulsen, J
在粗略的尺度上，世界山脉的树木线似乎遵循一个共同的等温线，但到目前为止，这方面的证据是间接的。在这里，我们的目标是用事实来支持这一点。位置我们提出了一个数据记录活动的结果，在46个树线网站之间的68度N和42度S。方法我们测量了根区温度与每小时的分辨率超过1-3年每个网站在1996年和2003年之间。高海拔气候树线与季节平均地面温度6.7 ℃（+/-0.8 SD; 2.2 K不同气候带的平均幅度）相关，这是一个令人惊讶的狭窄范围。温带和地中海地区的树木线温度较高（7-8摄氏度），赤道地区的树木线温度较低（5-6摄氏度），亚北极和北方地区的温度较低（6-7摄氏度）。虽然在温暖时期气温高于土壤温度，在寒冷时期气温低于土壤温度，但空气和土壤温度的日平均值几乎相同，在6-7摄氏度，这与全球平均温度在树线上的物理驱动一致。在全球范围内，生长季节的长度、极端温度或热量总和对树线高度没有预测价值。一些地中海（水青冈属）和温带南半球乔木（Nothofagus spp.）和本地树线在夏威夷（Metrosideros）位于相当高的等温线，并代表属特定的边界，而不是生活型树的边界。在季节性气候中，地面温度在冬季（绝对最小值）反映当地积雪，似乎uncritical.Main结论-数据支持的假设，一个共同的热阈值森林生长在高海拔地区，但也反映了温和的区域和大量的分类影响。
Aim At a coarse scale, the treelines of the world's mountains seem to follow a common isotherm, but the evidence for this has been indirect so far. Here we aim at underpinning this with facts.Location We present the results of a data-logging campaign at 46 treeline sites between 68degrees N and 42degrees S.Methods We measured root-zone temperatures with an hourly resolution over 1-3 years per site between 1996 and 2003.Results Disregarding taxon-, landuse- or fire-driven tree limits, high altitude climatic treelines are associated with a seasonal mean ground temperature of 6.7 degreesC (+/-0.8 SD; 2.2 K amplitude of means for different climatic zones), a surprisingly narrow range. Temperatures are higher (7-8 degreesC) in the temperate and Mediterranean zone treelines, and are lower in equatorial treelines (5-6 degreesC) and in the subarctic and boreal zone (6-7 degreesC). While air temperatures are higher than soil temperatures in warm periods, and are lower than soil temperatures in cold periods, daily means of air and soil temperature are almost the same at 6-7 degreesC, a physics driven coincidence with the global mean temperature at treeline. The length of the growing season, thermal extremes or thermal sums have no predictive value for treeline altitude on a global scale. Some Mediterranean (Fagus spp.) and temperate South Hemisphere treelines (Nothofagus spp.) and the native treeline in Hawaii (Metrosideros) are located at substantially higher isotherms and represent genus-specific boundaries rather than boundaries of the life-form tree. In seasonal climates, ground temperatures in winter (absolute minima) reflect local snow pack and seem uncritical.Main conclusions The data support the hypothesis of a common thermal threshold for forest growth at high elevation, but also reflect a moderate region and substantial taxonomic influence.