Janssen, Thomas;
Fleischer, Katrin;
Luyssaert, Sebastiaan;
Naudts, Kim;
Dolman, Han
Drought resistance increases from the individual to the ecosystem level in highly diverse Neotropical rainforest: a meta-analysis of leaf, tree and ecosystem responses to drought
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Media type:
E-Article
Title:
Drought resistance increases from the individual to the ecosystem level in highly diverse Neotropical rainforest: a meta-analysis of leaf, tree and ecosystem responses to drought
Description:
<jats:p>Abstract. The effects of future warming and drying on tropical
forest functioning remain largely unresolved. Here, we conduct a
meta-analysis of observed drought responses in Neotropical humid forests,
focusing on carbon and water exchange. Measures of leaf-, tree- and ecosystem-scale performance were retrieved from 145 published studies conducted across
232 sites in Neotropical forests. Differentiating between seasonal and
episodic drought, we find that (1) during seasonal drought the increase in
atmospheric evaporative demand and a decrease in soil matric potential
result in a decline in leaf water potential, stomatal conductance, leaf
photosynthesis and stem diameter growth while leaf litterfall and leaf
flushing increase. (2) During episodic drought, we observe a further decline
in stomatal conductance, photosynthesis, stem growth and, in contrast to
seasonal drought, a decline also in daily tree transpiration. Responses of
ecosystem-scale processes, productivity and evapotranspiration are of a
smaller magnitude and often not significant. Furthermore, we find that the
magnitude and direction of a drought-induced change in photosynthesis,
stomatal conductance and transpiration reported in a study is correlated to
study-averaged wood density. Although wood density is often not functionally
related to plant hydraulic properties, we find that it is a good proxy for
hydraulic behaviour and can be used to predict leaf- and tree-scale responses
to drought. We present new insights into the functioning of tropical forest
in response to drought and present novel relationships between wood density
and tropical-tree responses to drought.
</jats:p>