Arizona researchers study effects of droughts on rain forests

Eighty international research scientists are using the University of Arizona’s Biosphere 2 to study climate change and its effects on the ecosystem. They are subjecting the world’s only enclosed rain forest to 4-month-long controlled drought and recovery. Here with us now is Laura Meredith, assistant professor at the University of Arizona’s School of Natural Resources & the Environment.

What is Biosphere 2?

Meredith: “Biosphere 2 is a giant greenhouse located between Tuscan and Phoenix in the dessert ecosystems. It houses a number of different ecosystems itself. Inside there’s a rain forest, an ocean, a savanna, dessert. We use this experimental research facility to study how our ecosystems and our biosphere interacts with the atmosphere and is responding to climate change.”

What specific research are you doing?

“We’re really interested in understanding how drought affects tropical rain forest, because with global change the frequency and the intensity and severity of the droughts are increasing in those ecosystems.”

The researchers studied the rain forest ecosystem for over 4 months, forcing it into a drought.

What did you find?

“We found the plant species responded uniformly to drought. Plants grouped in to two major groups. Either they were very sensitive to drought and shut down activity almost immediately as soon as the soil started to dry, and then we had a more drought tolerant group that was actually able to chug along and persist and carry the ecosystem throughout this intense drought. That helped our ecosystem be more resilient to this severe drought, and it helped set the ecosystem up for a faster more swift recovery once we started the rain again.”

Were you surprised at the resilience?

“I have to say I was pretty surprised.”

“One thing that we discovered was that we had these two groups of plants, especially the tall trees that were either sensitive to drought and shut down their activity and the ones that were tolerant. And we were thinking that the sensitive plants didn’t have deep roots that let them access the deep soil reserves… what we found out.. we actually determined that the sensitive trees and the drought tolerant trees all had access to that deep water. But for some reason that drought sensitive trees decided not to use it during that drought.”