Publications

Still, Christopher J.; Pau, Stephanie; Edwards, Erika J. (2014). Land surface skin temperature captures thermal environments of C-3 and C-4 grasses. GLOBAL ECOLOGY AND BIOGEOGRAPHY, 23(3), 286-296.

Abstract
AimNumerous studies have documented ecological sorting of C-3 and C-4 grasses along air temperature gradients. However, phylogenetically structured analyses suggest that closely related C-3 and C-4 grasses (in the same PACMAD clade: Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae and Danthonioideae) occur in environments with similar air temperature, challenging our understanding of how the photosynthetic pathway influences grass biogeography. To better understand thermal differences between C-3 and C-4 grass lineages, we analysed the surface radiative temperature as an alternative measure that is more closely aligned with plant microclimate.LocationHawaiian Islands, USA.MethodsWe used the MODIS land surface temperature (LST) product, a satellite-based measurement of radiative temperature. We compared LST with mean annual air temperature (MAT) for locations where C-3 and C-4 grass species were collected. We also utilized other satellite products, like MODIS tree cover, as a proxy for relative habitat openness where these grasses occur.ResultsComparisons of C-3 lineages [in BEP (Bambusoideae, Ehrhartoideae and Pooideae) and PACMAD clades] and C-4 lineages (PACMAD clade only) illustrate the differing thermal environments for each group. C-4 taxa are found in the environments with the highest MAT, followed by C-3 PACMAD species. By contrast, C-3 PACMAD species are found in the environments with the coolest LST, and the LST values for C-3 BEP species are substantially higher than their MAT values. The difference in LST between C-3 and C-4 PACMADs is larger than the difference in MAT between these groups.Main conclusionsThough LST has been used infrequently in ecology and biogeography, it is intimately related to water and energy balance and ecosystem structure, and should more accurately capture plant temperatures and microclimates than MAT. Our results provide support for a pronounced thermal difference in the environments of closely related C-3 and C-4 grass taxa, and show that C-3 PACMADs occur in the coolest and least variable thermal environments, probably due to the greater tree cover of these habitats.

DOI:
10.1111/geb.12121

ISSN:
1466-822X; 1466-8238