Rahman, M., Islam,
M., Gebrekirstos, A.
and Bräuning, A.
2020
Disentangling the effects of atmospheric CO2 and climate on intrinsic water-use efficiency in South Asian tropical moist forest trees.
Tree Physiology 40: 904-916
" ... yet another real world example that rising atmospheric CO2 is benefiting vegetation across the globe by helping to improve plant WUE (water use efficiency).
... a mere 15% increase in CO2 was powerful enough to raise the intrinsic water use efficiencies of these tropical forest tree species by 29-46%.
... In nearly all instances ... studies reveal rising CO2 improves plant WUE, typically by reducing plant stomatal apertures, which reduces water lost to the air via transpiration.
... at higher levels of CO2, plants tend to need less water to produce the same (or more) amount of tissue, which portends great benefits for the future of agricultural production, especially in arid and irrigated regions.
... proof of this concept has emerged in studies examining historic trends in the stable carbon isotope ratio (δ13C) of tree rings, which have been utilized to infer long-term changes in intrinsic WUE (iWUE).
Rahman et al. (2020) ... examined tree-ring cores from three moist tropical forest species, Chukrasia tabularis, Toona ciliate and Lagerstroemia speciose, producing an iWUE record spanning the three-decade period 1986-2015.
... iWUE increased by a very respectable
+29% for T. ciliate,
+29% for L. speciose, and
+46% for C. tabularis over the 30-year period.
... statistical analyses revealed the long-term 53 ppm rise in atmospheric CO2 explained nearly all of it (86%), followed by slight influences from temperature and precipitation. ... "
