Trait-based, spatial, and temporal variation in leaf temperature of tropical trees.

作者：Olivier Jean Leonce Manzi, Maria Wittemann, Myriam Mujawamariya, Aloysie Manishimwe, Jacques Habimana, Mirindi Eric Dusenge, Etienne Zibera, Lasse Tarvainen, Donat Nsabimana, Göran Wallin, Johan Uddling · 年份：2023 · DOI：10.5194/egusphere-egu23-11921 · 研究领域：Species Distribution and Climate Change、Plant Water Relations and Carbon Dynamics、Remote Sensing in Agriculture

Current estimates of temperature effects on plants are usually based on air temperature (Tair), although it is well known that leaf temperature (Tleaf) can deviate considerably from Tair. In some studies, to overcome the problem of Tair often being a poor proxy of Tleaf, measurements of canopy temperature (Tcan) have been used instead. However, Tcan data do not capture the spatial variation in Tleaf among leaves with different thermoregulatory traits. This may be particularly problematic for highly diverse and heterogeneous tropical forest canopies. In this study, we used infrared thermometers to study Tleaf and Tcan in multispecies tropical tree plantations established at three sites along an elevation gradient from 2,400 m a.s.l. (17.1°C mean daytime temperature) to 1,300 m a.s.l. (24.0°C) in Rwanda.  Measurements of chlorophyll fluorescence were also conducted to study the photosynthetic heat tolerance of these species. Our results showed high Tleaf (up to ~50°C) and leaf-to-air temperature differences (ΔTleaf; on average 8-10°C and up to 24°C) of sun-exposed leaves. Both leaf size and stomatal conductance were important traits in controlling Tleaf. The Tleaf (and thus ΔTleaf) of sun-exposed leaves greatly exceeded the simultaneously measured values of Tcan (and ΔTcan). Photosynthetic heat tolerance partially acclimated to increased growth temperature; on average 0.31°C increase in he...