Plants Adapt to Drought But Limits Are Looming, Study Finds

The UA’s Santa Rita Experimental Range is one of the large-scale/long-term study areas that are crucial for this research. Using techniques like repeat photography, inclusion or exclusion of livestock and vegetation surveys since the 1950s, scientists study how ecosystems react to different influences such as climate change and grazing. (Photo: Mitchel McClaran)
The UA’s Santa Rita Experimental Range is one of the large-scale/long-term study areas that are crucial for this research. Using techniques like repeat photography, inclusion or exclusion of livestock and vegetation surveys since the 1950s, scientists study how ecosystems react to different influences such as climate change and grazing. (Photo: Mitchel McClaran)

Scientists with the U.S. Department of Agriculture, or USDA, and their partners have determined that water demand by many plant communities can fluctuate in response to water availability, indicating a capacity for resilience even when changing climate patterns produce periodic droughts or floods.

But their research also suggests that a limit to this resilience ultimately could threaten the survival of these plant communities. Sensitive environments such as the arid grasslands in the Southwestern U.S. already are approaching this limit.

Results from this study were published in the journal Nature by a team of Agricultural Research Service, or ARS, scientists, including three scientists affiliated with the UA. ARS is USDA's chief scientific research agency.

The study was led by UA-affiliated ARS researchers Guillermo Ponce Campos and Susan Moran and an Australian team led by Alfredo Huete from the University of Technology, Sydney.

"We found that plants have a capacity for resilience even in the face of the severe drought over the past decade," said Ponce Campos, the study's lead author. Ponce Campos led the research as part of his doctoral work at the UA and now is a research associate working with Moran.

"From grasslands to forests, plants can tolerate low precipitation, but if drought conditions continue past a certain point, this resilience will fail," said Moran, who graduated from the UA and now is a researcher with the USDA ARS Southwest Watershed Research Center and an adjunct professor in the department of soil, water and environmental science in the UA College of Agriculture and Life Sciences.

Once that limit is reached, water-starved plants lose their ability to take advantage of increased precipitation, even if the drought makes way for wetter conditions, Moran explained.

The researchers conducted their investigation using measurements made during 2000-09 at 29 sites in the United States, Puerto Rico and Australia. This provided data about precipitation patterns in the various types of environments. Globally, the 2000-09 decade ranked as the 10 warmest years of the 130-year (1880-2009) record. The team compared these data with measurements taken from 1975 to 1998 at 14 sites in North America, Central America and South America.

Read the rest of this January 22 UANews article at the link below.

Date released: 
Jan 24 2013
Contact: 
Guillermo Ponce Campos