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Death from drought in tropical forests is triggered by hydraulics not carbon starvation.

Rowland, L; da Costa, A C L; Galbraith, D R; Oliveira, R S; Binks, O J; Oliveira, A A R; Pullen, A M; Doughty, C E; Metcalfe, Dan LU and Vasconcelos, S S, et al. (2015) In Nature 528(7580). p.119-122
Abstract
Drought threatens tropical rainforests over seasonal to decadal timescales, but the drivers of tree mortality following drought remain poorly understood. It has been suggested that reduced availability of non-structural carbohydrates (NSC) critically increases mortality risk through insufficient carbon supply to metabolism ('carbon starvation'). However, little is known about how NSC stores are affected by drought, especially over the long term, and whether they are more important than hydraulic processes in determining drought-induced mortality. Using data from the world's longest-running experimental drought study in tropical rainforest (in the Brazilian Amazon), we test whether carbon starvation or deterioration of the water-conducting... (More)
Drought threatens tropical rainforests over seasonal to decadal timescales, but the drivers of tree mortality following drought remain poorly understood. It has been suggested that reduced availability of non-structural carbohydrates (NSC) critically increases mortality risk through insufficient carbon supply to metabolism ('carbon starvation'). However, little is known about how NSC stores are affected by drought, especially over the long term, and whether they are more important than hydraulic processes in determining drought-induced mortality. Using data from the world's longest-running experimental drought study in tropical rainforest (in the Brazilian Amazon), we test whether carbon starvation or deterioration of the water-conducting pathways from soil to leaf trigger tree mortality. Biomass loss from mortality in the experimentally droughted forest increased substantially after >10 years of reduced soil moisture availability. The mortality signal was dominated by the death of large trees, which were at a much greater risk of hydraulic deterioration than smaller trees. However, we find no evidence that the droughted trees suffered carbon starvation, as their NSC concentrations were similar to those of non-droughted trees, and growth rates did not decline in either living or dying trees. Our results indicate that hydraulics, rather than carbon starvation, triggers tree death from drought in tropical rainforest. (Less)
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Nature
volume
528
issue
7580
pages
119 - 122
publisher
Nature Publishing Group
external identifiers
  • pmid:26595275
  • wos:000365606000060
  • scopus:84949185334
ISSN
0028-0836
DOI
10.1038/nature15539
language
English
LU publication?
yes
id
14c42f1a-4390-422d-87a5-41a5aa383dad (old id 8234862)
date added to LUP
2016-01-26 09:04:56
date last changed
2017-11-12 03:04:58
@article{14c42f1a-4390-422d-87a5-41a5aa383dad,
  abstract     = {Drought threatens tropical rainforests over seasonal to decadal timescales, but the drivers of tree mortality following drought remain poorly understood. It has been suggested that reduced availability of non-structural carbohydrates (NSC) critically increases mortality risk through insufficient carbon supply to metabolism ('carbon starvation'). However, little is known about how NSC stores are affected by drought, especially over the long term, and whether they are more important than hydraulic processes in determining drought-induced mortality. Using data from the world's longest-running experimental drought study in tropical rainforest (in the Brazilian Amazon), we test whether carbon starvation or deterioration of the water-conducting pathways from soil to leaf trigger tree mortality. Biomass loss from mortality in the experimentally droughted forest increased substantially after >10 years of reduced soil moisture availability. The mortality signal was dominated by the death of large trees, which were at a much greater risk of hydraulic deterioration than smaller trees. However, we find no evidence that the droughted trees suffered carbon starvation, as their NSC concentrations were similar to those of non-droughted trees, and growth rates did not decline in either living or dying trees. Our results indicate that hydraulics, rather than carbon starvation, triggers tree death from drought in tropical rainforest.},
  author       = {Rowland, L and da Costa, A C L and Galbraith, D R and Oliveira, R S and Binks, O J and Oliveira, A A R and Pullen, A M and Doughty, C E and Metcalfe, Dan and Vasconcelos, S S and Ferreira, L V and Malhi, Y and Grace, J and Mencuccini, M and Meir, P},
  issn         = {0028-0836},
  language     = {eng},
  number       = {7580},
  pages        = {119--122},
  publisher    = {Nature Publishing Group},
  series       = {Nature},
  title        = {Death from drought in tropical forests is triggered by hydraulics not carbon starvation.},
  url          = {http://dx.doi.org/10.1038/nature15539},
  volume       = {528},
  year         = {2015},
}