Rainfall drives variation in rates of change in intrinsic water use efficiency of tropical forests.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31413322.
- Also identified by DOI 10.1038/s41467-019-11679-8 and PMC identifier 6694106.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Rates of change in intrinsic water use efficiency (W) of trees relative to those in atmospheric [CO<sub>2</sub>] (c<sub>a</sub>) have been mostly assessed via short-term studies (e.g., leaf analysis, flux analysis) and/or step increases in c<sub>a</sub> (e.g., FACE studies). Here we use compiled data for abundances of carbon isotopes in tree stems to show that on decadal scales, rates of change (dW/dc<sub>a</sub>) vary with location and rainfall within the global tropics. For the period 1915-1995, and including corrections for mesophyll conductance and photorespiration, dW/dc<sub>a</sub> for drier tropical forests (receiving ~ 1000 mm rainfall) were at least twice that of the wettest (receiving ~ 4000 mm). The data also empirically confirm theorized roles of tropical forests in changes in atmospheric <sup>13</sup>C/<sup>12</sup>C ratios (the <sup>13</sup>C Suess Effect). Further formal analysis of geographic variation in decade-to-century scale dW/dc<sub>a</sub> will be needed to refine current models that predict increases in carbon uptake by forests without hydrological cost.