Global warming may initially make the grass greener, but not for long, according to new research results.
The findings, published this week in the journal Nature Climate Change, show that plants may thrive in the early stages of a warming environment but then begin to deteriorate quickly.
"We were really surprised by the pattern, where the initial boost in growth just went away," said scientist Zhuoting Wu of Northern Arizona University (NAU), a lead author of the study. "As ecosystems adjusted, the responses changed."
Ecologists subjected four grassland ecosystems to simulated climate change during a decade-long study.
Plants grew more the first year in the global warming treatment, but this effect progressively diminished over the next nine years and finally disappeared.
The research shows the long-term effects of global warming on plant growth, on the plant species that make up a community, and on changes in how plants use or retain essential resources like nitrogen.
"The plants and animals around us repeatedly serve up surprises," said Saran Twombly, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research.
"These results show that we miss these surprises because we don't study natural communities over the right time scales. For plant communities in Arizona, it took researchers 10 years to find that responses of native plant communities to warmer temperatures were the opposite of those predicted."