Thermodynamic basis for the demarcation of Arctic and alpine treelines.
Thermodynamic basis for the demarcation of Arctic and alpine treelines.
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DOI：
10.1038/s41598-022-16462-2
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发表时间：
2022-07-22
影响因子：
4.6
通讯作者：
Marsh, Philip
中科院分区：
文献类型：
--
作者：
Martin, Meredith Richardson;Kumar, Praveen;Sonnentag, Oliver;Marsh, Philip
在世界各地的高山和北极生态系统的边缘，存在着一个过渡区，超过这个过渡区，树木要么不可行，要么不适宜生存，俗称树线。我们探讨了植被划分背后的热力学基础的可能性，认为生态系统是由热力学热量驱动的开放系统，热力学热量是由植被将热量从地球表面散发到树冠上方的空气中的能力定义的。为了推断森林是否会比现有的生态系统更具有生态优势超越树线，我们构建和检查反事实的情况下，树木存在超越树线，而不是现有的高山草甸或北极苔原。气象数据从意大利阿尔卑斯山，美国落基山脉，和加拿大西部泰加苔原被用来作为强迫模型计算的生态系统工作和温度梯度的网站两侧的每一个树线有和没有树木。模型结果表明，高山地区不支持树线以外的树木，因为它们的存在会导致过度的CO损失和由于温度逆温而延长的积雪期（即，从地球表面到大气层的正温度梯度）。此外，北极和高山地区表现出负功，导致植被散热和温度梯度之间的正反馈，从而延长逆温的持续时间。这些条件表明热力学不可行性与树木存在超越树线的反事实的情况。因此，我们的结论是，除了资源的限制，一个树线是一个生态系统的能力，自组织的热力学可行性促进最有利的植被结构的结果。
At the edge of alpine and Arctic ecosystems all over the world, a transition zone exists beyond which it is either infeasible or unfavorable for trees to exist, colloquially identified as the treeline. We explore the possibility of a thermodynamic basis behind this demarcation in vegetation by considering ecosystems as open systems driven by thermodynamic advantage—defined by vegetation’s ability to dissipate heat from the earth’s surface to the air above the canopy. To deduce whether forests would be more thermodynamically advantageous than existing ecosystems beyond treelines, we construct and examine counterfactual scenarios in which trees exist beyond a treeline instead of the existing alpine meadow or Arctic tundra. Meteorological data from the Italian Alps, United States Rocky Mountains, and Western Canadian Taiga-Tundra are used as forcing for model computation of ecosystem work and temperature gradients at sites on both sides of each treeline with and without trees. Model results indicate that the alpine sites do not support trees beyond the treeline, as their presence would result in excessive CO loss and extended periods of snowpack due to temperature inversions (i.e., positive temperature gradient from the earth surface to the atmosphere). Further, both Arctic and alpine sites exhibit negative work resulting in positive feedback between vegetation heat dissipation and temperature gradient, thereby extending the duration of temperature inversions. These conditions demonstrate thermodynamic infeasibility associated with the counterfactual scenario of trees existing beyond a treeline. Thus, we conclude that, in addition to resource constraints, a treeline is an outcome of an ecosystem’s ability to self-organize towards the most advantageous vegetation structure facilitated by thermodynamic feasibility.
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影响因子：
2
作者：
Grogan, Paul
通讯作者：
Grogan, Paul
影响因子：
6.4
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Krogh, Sebastian A.;Pomeroy, John W.;Marsh, Philip
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