The research aims to improve the models used by climatologists to predict future climate. Current models, said Barron-Gafford, have mostly relied on plant physiology alone. "In an age that will be defined by our management of water resources, it is important to understand the role that this woody plant encroachment has on our regional ecohydrology."
"The known differences in photosynthetic biochemistry have led the scientific community to expect that grasses should be better adapted to a warming climate because they have evolved to be more efficient with less water in higher temperatures and drier conditions."
The new findings reveal that a plant's structure such as deep roots plays a more important role in how vegetation adapts to a changing environment than leaf physiology.
His research team used a "portable biosphere" to test how plants perform under different environmental conditions and temperatures. The shoebox-sized device can accommodate a leaf or a branch of a living plant and allows the researchers to seal it off from the environment.
The team made its measurements shortly before, during and after the monsoon in the San Pedro Riparian National Conservation Area in Southeastern Arizona.
"With our portable biosphere we can obtain snapshots of plant activity," Barron-Gafford said. "The device allows us to set and control parameters like temperature, light and relative humidity while we measure the carbon dioxide going in and out of the leaf."
He explained that the dry periods before and after the monsoon are different from each other because once the monsoon rains cease, plant metabolism is still running on high.
"Everything is cranking, except the remaining rain water is now deep underground, and we are measuring at a time when the shallow-rooted plants no longer have that pool to dangle their toes in. That is when the str
|Contact: Daniel Stolte|
University of Arizona