Data from: Stronger cooling effects of transpiration and morphology of the plants from a hot dry habitat than from a hot wet habitat

1. Leaf temperature exerts an important impact on the microenvironment and
physiological processes of leaves. Plants from different habitats have
different strategies to regulate leaf temperature. The relative importance
of morphology and transpiration for leaf temperature regulation in the hot
habitat is still unclear. 2. We investigated 22 leaf morphological traits,
transpiration, and thermal properties of 38 canopy species of seedlings in
a greenhouse, including 18 dominant species from a hot wet habitat (HW)
and 20 dominant species from a hot dry habitat (HD). To separate the
impact of transpiration and morphology on leaf temperature, we measured
the diurnal courses of leaf temperatures with and without transpiration.
The temperature of a reference leaf beside each individual was measured
simultaneously to render temperatures comparable. 3. Generally, the
species from HD showed lower leaf temperatures than the species from HW
under the same conditions. Both transpiration capacity and cooling effect
of leaf morphology were stronger for the plants from HD. Active
transpiration provides a suitable thermal environment for photosynthesis,
while xeromorphic leaves can dampen heat stress when transpiration is
suppressed. Higher vein density and stomatal pore area index (SPI)
facilitated higher transpiration capacity of the plants from HD.
Meanwhile, shorter leaves and thinner lower epidermis of the plants from
HD were more efficient in heat transfer, although relationships were much
weaker than the synergic effect of all the morphologic traits. 4. Our
results confirmed that transpiration and leaf morphology provided double
insurance for avoiding overheating, particularly for plant from HD. We
emphasize that transpiration is a more effective way to cool leaves than
morphology when water is sufficient, which may be an important adaptation
for plant from HD where rainfall is sporadic. Our results provide further
insight into the relationship between morphology and transpiration for the
regulation of leaf temperature, and the co-evolution of gas exchange and
thermal regulation of leaves.