Biophysical homoeostasis of leaf temperature: A neglected process for vegetation and land-surface modelling
Biophysical homoeostasis of leaf temperature: A neglected process for vegetation and land-surface modelling
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DOI：
10.1111/geb.12614
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发表时间：
2017-09-01
影响因子：
6.4
通讯作者：
Zhang, Y. P.
中科院分区：
文献类型：
--
作者：
Dong, N.;Prentice, I. C.;Zhang, Y. P.
目的：树叶和空气的温度很少相等，但是许多植被模型假定它们是相等的。陆地表面模型可以计算冠层温度，但效果如何还不得而知。我们鼓励考虑将叶片和冠层对空气的温差(T)作为陆地表面建模的基准，以及植物和生态系统功能的重要特征。地理位置：中国西南部热带地区。时间：2013年。主要分类群研究：热带树木。方法：我们利用热带干燥林地的野外测量数据和热带季节性森林的连续监测数据来说明叶片和冠层对空气温差（δ T）的日循环。利用Priestley-Taylor （PT）和Penman-Monteith （PM）蒸散发方法对Delta t的解释和预测提供了深入的见解。现场测量结果还与根据现场条件设置的联合英国陆地环境模拟器（JULES）获得的陆地表面模型结果进行了比较。结果：δ T遵循一致的日循环，夜间负值（归因于负净辐射）在早晨变为正值，达到平台期，当气温超过24-29摄氏度范围内的“交叉”时再次变为负值。δ T的日时间变化可以用PT或PM模型来近似，但JULES倾向于低估负δ T的大小。主要结论：水分充足的叶片通过被动的生物物理机制部分缓冲了气温变化的影响。这对于优化叶片功能很可能是重要的，陆地表面和植被模型应该以重现它为目标。
Aim: Leaf and air temperatures are seldom equal, but many vegetation models assume that they are. Land-surface models calculate canopy temperatures, but how well they do so is unknown. We encourage consideration of the leaf-and canopy-to-air temperature difference (Delta T) as a benchmark for land-surface modelling and an important feature of plant and ecosystem function.Location: Tropical SW China.Time period: 2013.Major Taxa studies: Tropical trees.Methods: We illustrate diurnal cycles of leaf-and canopy-to-air temperature difference (Delta T) with field measurements in a tropical dry woodland and with continuous monitoring data in a tropical seasonal forest. The Priestley-Taylor (PT) and Penman-Monteith (PM) approaches to evapotranspiration are used to provide insights into the interpretation and prediction of Delta T. Field measurements are also compared with land-surface model results obtained with the Joint U.K. Land Environment Simulator (JULES) set up for the conditions of the site.Results: The Delta T followed a consistent diurnal cycle, with negative values at night (attributable to negative net radiation) becoming positive in the morning, reaching a plateau and becoming negative again when air temperature exceeded a 'crossover' in the 24-29 degrees C range. Daily time courses of Delta T could be approximated by either the PT or the PM model, but JULES tended to underestimate the magnitude of negative Delta T.Main conclusions: Leaves with adequate water supply are partly buffered against air-temperature variations, through a passive biophysical mechanism. This is likely to be important for optimal leaf function, and land-surface and vegetation models should aim to reproduce it.