Sometimes, it isn’t easy staying green.
For some trees, staying green is set to become more of a challenge. Rising temperatures and changing precipitation patterns mean that droughts are likely to become more frequent in some regions. Drought affects the ability of a tree to maintain its leaf turgor – in other words, to avoid wilting – and some plants have been shown to develop certain traits that help them to adapt to drought conditions.
One such trait is Foliar Water Uptake (FWU) – the ability of plants to absorb water directly through the surface of the leaf, as well as through the roots. In the study featured on the cover of New Phytologist 211:2, Cleiton Eller, Aline Lima and Rafael Oliveira examined the ability of trees growing in tropical montane cloud forests to maintain their leaf turgor during drought. Tropical montane cloud forests receive a wide range of rainfall but are known for frequent fog events. Using a range of techniques, including deuterium labelling and a glasshouse experiment, Cleiton and co-authors investigated how reliant a range of tree species were on water obtained through FWU during fog events, for maintaining leaf turgor during drought.
The photo on the cover shows some Araucaria angustifolia (Brazilian pine) trees during one of the frequent fog events that occur in the cloud forest belt, in the Mantiqueria mountain range of Brazil. Like many other tree species, A. angustifolia has a distribution strongly associated with mountainous regions and cloud forests. ‘We believe our results help to explain why these trees are restricted to these sites,’ explained Cleiton. ‘Frequent fog events appear to be essential for some trees (the ones with high foliar water uptake capacity) to maintain leaf turgor during seasonal droughts. We can also infer from our results that these trees species are particularly threatened by reductions in fog events caused by climate change.’
Read the paper: Eller, C. B., Lima, A. L. and Oliveira, R. S. (2016) Cloud forest trees with higher foliar water uptake capacity and anisohydric behavior are more vulnerable to drought and climate change. New Phytologist 211: 489–501. doi: 10.1111/nph.13952
Mike Whitfield (@mgwhitfield)