Jc. Gottschalck et Rr. Gillies, Implications of feedback processes in plant water usage and resulting climate change, J AM WAT RE, 37(2), 2001, pp. 305-314
Citations number
24
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION
Increased carbon dioxide in the atmosphere has the secondary effect on plan
ts of reducing transpiration. The degree of reduction in transpiration has
been studied mostly at the leaf scale and as such, has not taken feedbacks
into account that come into play when the plant canopy or the atmosphere as
a whole is considered. The objective of this paper is to examine the role
of negative feedback processes that act through the dynamics of the canopy
and the atmosphere. This is done through the application of two canopy mode
ls, one of which is later coupled to a full Atmospheric General Circulation
Model (AGCM) called GENESIS. The results suggest that the reduction in tra
nspiration in a double CO2 environment compared to present day will not be
as considerable as the leaf scale experiments suggest - a 7 percent reducti
on compared to 15 to 57 percent when feedbacks are considered. At the regio
nal scale, precipitation patterns appear to be the primary factor in determ
ining evapotranspiration. The implications for agriculture, in terms of wat
er usage, would therefore not seem to be as acute as the leaf scale experim
ents depict. Regarding climate change, there is a suggestion that regional
water usage may vary from present day values in certain areas.