Rainfall Drives Variation in Rates of Change in Intrinsic Water Use Efficiency of Tropical Forests
Abstract
Rates of change in intrinsic water use efficiency (W) relative to those in atmospheric [CO2] (ca) of trees have been mostly assessed via short-term studies (e.g. leaf analysis, flux analysis) and/or step increases in ca(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/dca) vary with location and rainfall within the global tropics. For the period 1915-1995, and including corrections for mesophyll conductance and photorespiration, dW/dcafor drier tropical forests (receiving ~1000 mm rainfall) was at least twice that of the wettest (receiving ~4000 mm). The data also empirically confirm theorized roles of tropical forests in changes in atmospheric 13C/12C ratios (the 13C Suess Effect). Further formal analysis of geographic variation in decade-to-century scale dW/dcawill be needed to refine current models that predict increases in carbon uptake by forests without hydrological cost.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B24D..08A
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES