Dying Aspen Sunflower Could Signal Future Climate Warming Damage

Newswise — David Inouye, professor of biology at the University of Maryland, has found that climate change is damaging the Aspen sunflower of the Rocky Mountains. The sunflower could be a "canary in the mine," warning of future ecological consequences of a warming climate. Here Inouye talks about implications of his findings, which he will present at the MTNCLIM conference in Mt. Hood Oregon, Friday, Sept. 22. The conference will be Web cast.

What did you find about the aspen sunflower that concerns you?

The buds of aspen sunflowers have been killed by frost in seven of the past years at my study site. This means that they are not producing flowers, and therefore not producing seeds. If they don't produce seeds for many years, the population of plants won't replace itself.

Does your research indicate climate change?

Yes, the increasing frequency of frost damage appears to be a consequence of climate change. Specifically, the decline in winter snowfall and increasing spring temperatures are causing plants to begin growth earlier in the spring, and then to have sensitive flower buds at the time in mid-June when we are still likely to have hard frosts.

Why is the fate of one flower species important?

This one flower for which I have detailed data is representative of several other wildflower species whose flowers are also sensitive to frost damage, so the fate of the aspen sunflower is important as an indicator of what can happen to these other species as well. The reduction in flowers means that there are fewer resources (nectar and pollen) for pollinator species such as bumble bees, for herbivores such as deer and elk that eat some of the flowers, for seed predators whose larvae eat some of the developing seeds, and for the parasitic insects that prey upon the seed predators or pollinators.

What can climate change in the Rockies tell us about overall change in the Earth?

High altitudes are one of the areas expected to show early effects of global climate change. So the kinds of ecological effects we are seeing in the Rockies give us an early warning that the effects of climate change can be unexpected and significant, such as finding that frost is having a greater effect than it used to. Long-term research is also essential; I only get one data point each year in this study so it takes many years to gain insight into what is happening.

Do your findings indicate what the reason for climate change would be? Warming spring temperatures are one of the consequences of global climate change that affect these wildflowers. Regional climate change such as the consequences of the North Pacific Oscillation and also the El-Nino Southern Oscillation appear to have a role as well, as they affect the amount of snowfall.

David Inouye has spent summer field seasons since 1971 at the Rocky Mountain Biological Laboratory, studying the effects of climate change at high altitudes on a variety of species. He also directs the graduate program in Sustainable and Development and Conservation Biology at the University of Maryland.