Growth, demography and carbon relations of Polylepis trees at the world's highest treeline
Growth, demography and carbon relations of Polylepis trees at the world's highest treeline
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DOI：
10.1111/j.1365-2435.2005.01040.x
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发表时间：
2005-12-01
影响因子：
5.2
通讯作者：
Körner, C
中科院分区：
文献类型：
--
作者：
Hoch, G;Körner, C
1.在玻利维亚Nevado Sajama海拔4360 - 4810 m的样带上研究了多鳞草菲利普树的生长、繁殖成功率和非结构性碳库。在265天的生长季节中，树线下平均-10厘米土壤温度为5.4摄氏度，与其他亚热带和热带树木的阈值温度相匹配。超过4400米，Polylepis仅限于温暖和干燥的赤道面斜坡，这表明树木生长的直接热限制。最大树高、年新梢生长量和平均树轮宽度随海拔升高而减小。范围上限附近的树木达到了最大树高3.3米，最大干直径34厘米。最小的树高类占主导地位的人口在所有海拔高度，最高的网站揭示了最高比例的幼苗。树木大小的人口统计学表明，在树苗阶段，当树木出现在接近地面的庇护壁龛树木建立的关键阶段。没有证据表明，耗尽的移动的C存储（糖，淀粉和脂质）被发现在任何组织类型的海拔增加，这表明有限的C投资（增长），而不是C收购（光合作用）在树线。
1. Growth, reproductive success and non-structural carbon pools in Polylepis tarapacana Philippi trees were examined across a transect between 4360 and 4810 m altitude on Nevado Sajama, Bolivia.2. The mean -10-cm soil temperature of 5.4 degrees C under trees at the treeline during the 265-day growing season matched the threshold temperature found at other subtropical and tropical treelines. Beyond 4400 m Polylepis is restricted to the warmer and drier equator-facing slopes, suggesting a direct thermal limitation of tree growth.3. Maximum tree height, annual shoot increment and mean tree-ring width decreased with altitude. Trees near the upper range limit reached a maximum tree height of 3.3 m and a maximum stem diameter of 34 cm.4. The smallest tree-height classes dominated populations at all altitudes, and the uppermost site revealed the highest proportion of seedlings. Tree-size demography indicates a critical phase for tree establishment during the sapling stage, when trees emerge from sheltered niches near the ground.5. No evidence of a depletion of mobile C stores (sugars, starch and lipids) was found in any tissue type with increasing elevation, suggesting a limitation of C investment (growth) rather than C acquisition (photosynthesis) at treeline.