Why
elevated carbon dioxide studies?
Global concentrations of
CO2 in the atmosphere are continuously rising as a result of
anthropogenic activity including fossil fuel consumption. Levels
have increased dramatically from preindustrial levels of 270 mmol
mol-1 and are currently rising at a rate of 1-2
mmol mol-1
yr-1. Atmospheric concentrations are expected to
reach 650-700 mmol
mol-1
by the mid to later part of the 21st century (Saxe et
al 1998). The effects of this increase will not only impact
climate, but will certainly impact vegetation patterns as well. These changes
could have serious implications in agriculture and management of forest
resources. The significance of agricultural effects are clear, but
what about natural vegetation? Vegetation is an important sink for
CO2 on a global scale. Forests alone account for up to
70% of terrestrial carbon fixation (Waring and Schlesinger 1985).
Evaporative surfaces provided by vegetation are vital to the processes
of atmospheric humidity and rainfall patterns (Grime 1997). Therefore,
changes in vegetation growth patterns could have substantial effects on
climate as well as the global carbon cycle. The initial effect on
vegetation would be seen at the leaf level, which potentially would lead
to effects in overall physiology and growth. For this reason, many
studies of vegetative effects of rising CO2 have focused on
the physiological effects on single leaves through their stomata (Gunderson
and Wullschleger 1994). This short review focuses on the results
of elevated CO2 studies on plant stomata.
Types of elevated
CO2 experiments
Stomatal
Responses to CO2
VPD
experiments
Conclusions
References