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Biophysical homoeostasis of leaf temperature: A neglected process for vegetation and land-surface modelling

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Title: Biophysical homoeostasis of leaf temperature: A neglected process for vegetation and land-surface modelling
Authors: Dong, N
Prentice, IC
Harrison, SP
Song, QH
Zhang, YP
Item Type: Journal Article
Abstract: 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 (ΔΤ) 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 (ΔΤ) 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 ΔT. 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 ΔT 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 °C range. Daily time courses of ΔT could be approximated by either the PT or the PM model, but JULES tended to underestimate the magnitude of negative ΔT. 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.
Issue Date: 16-Aug-2017
Date of Acceptance: 4-Jun-2017
URI: http://hdl.handle.net/10044/1/54730
DOI: https://dx.doi.org/10.1111/geb.12614
ISSN: 1466-822X
Publisher: Wiley
Start Page: 998
End Page: 1007
Journal / Book Title: Global Ecology and Biogeography
Volume: 26
Issue: 9
Copyright Statement: This is the peer reviewed version of the following article: Dong N, Prentice IC, Harrison SP, Song QH, Zhang YP. Biophysical homoeostasis of leaf temperature: A neglected process for vegetation and land-surface modelling. Global Ecol Biogeogr. 2017;26:998–1007, which has been published in final form at https://dx.doi.org/10.1111/geb.12614.  This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Sponsor/Funder: AXA Research Fund
Funder's Grant Number: AXA Chair Programme in Biosphere and Climate Impacts
Keywords: Science & Technology
Life Sciences & Biomedicine
Physical Sciences
Geography, Physical
Environmental Sciences & Ecology
Physical Geography
boundary-layer conductance
crossover temperature
energy balance
land-surface model
leaf temperature
stomatal conductance
0602 Ecology
0501 Ecological Applications
Publication Status: Published
Appears in Collections:Department of Life Sciences
Faculty of Natural Sciences