Plant response to climate change underestimated

An analysis of 50 plants over four continents published in Nature, has found that experiments may be dramatically underestimating the response of plants to climate change. They found flowering and leafing times were shifting much more dramatically than was suggested in experiments.

"This suggests that predicted ecosystem changes -- including continuing advances in the start of spring across much of the globe -- may be far greater than current estimates based on data from experiments," said Elizabeth Wolkovich, an ecologist at the University of British Columbia, who led the team involved in the study.

"These findings have extensive consequences for predictions of species diversity, ecosystem services and global models of future change," says Elsa Cleland from UC San Diego. “Long-term records appear to be converging on a consistent average response to climate change, but future plant and ecosystem responses to warming may be much higher than previously estimated from experimental data."

Phenology, or the study of the shifts in timings of annual plant events, is perhaps one of the best indicators of climate change, beyond the obvious instrumental measurements. It allows us to understand the some of the impacts climate change on the natural environment. It is essential because it has a huge knock on effect for the pollination of crops, water supply and the health of ecosystems.

The underestimation has come about due to the experiments carried out to estimate how crops will adapt to future warming. The lack of historical records in some regions means the scientists often rely on experiments involving warming small plots of land to estimate large scale responses. This method has now been shown to be underestimating impacts by up to four times; evidence in their newly constructed record shows that a warming of one degree is equivalent to a shift in phenology of 5 or 6 days.

The difficulty of creating an accurate experiment is clear. How the area is warmed, how the warming is measured and other influences all affect how the plants respond. It is extremely difficult to create a reliable experiment, and as such it is thought that many experiments have been producing wildly inaccurate results.

"Continuing efforts to improve the design of warming experiments while maintaining and extending long-term historical monitoring will be critical to pinpointing the cause of the mismatch," said Wolkovich. "These efforts will yield a more accurate picture of future plant communities and ecosystems with continuing climate change."