weather – Gardening at Last

Old Growth Refuge

Characteristics of older forests can buffer effects of climate change for some bird species: Old-growth forests and managed forests with old-growth characteristics can provide relief from climate change for some bird species, research by the Oregon State University College of Forestry suggests.

The study led by former Oregon State doctoral student Hankyu Kim builds on earlier research led by co-author Matt Betts, a professor in the Department of Forest Ecosystems and Society, that showed that old forests with big trees and a diversity of tree sizes and species can offer refuge to some types of birds threatened by a warming climate.

The latest findings bear important implications on conservation decisions regarding mature forests, the scientists say, and have even greater relevance because of the new Inflation Reduction Act, which calls for increased resources to map and protect the United States’ remaining old-growth forests.

The research, published in Global Change Biology, looked at forest “microclimates.” Microclimates are local atmospheric conditions, in areas ranging from a few square meters to many square kilometers, that differ from those of the surrounding area.

Stressed Plants

Plant-nibbling insects may make it cloudier and cooler: Plants can release certain chemicals to shield themselves from high temperatures and potentially communicate with other plants. They also release these chemicals in response to stress, including when insects chomp on their leaves.

Now, in a study published in the Journal of Geophysical Research: Atmospheres, scientists have found that insect-damaged plants could release enough of these molecules, called volatile organic compounds, to locally alter the atmosphere and radiative budget above a forest. Once panicking plants release the compounds into the air, the compounds can oxidize, transforming into organic aerosols. Like aerosols emitted from human activity, these aerosols can theoretically change how clouds form and how much sunlight clouds reflect.

Now for the first time in a global atmospheric model, Holopainen et al. consider the potential influence insect-munched plants can have on aerosol concentrations and clouds. These results suggest that insects eating plants could lead to stronger cooling effects from clouds, as greater aerosol concentrations typically correlate with sending more solar radiation back into space. These localized impacts won’t happen in an instant, but still, climate models could incorporate aerosol emissions from areas with intense insect herbivory to best estimate potential impacts on local atmospheric processes, the authors say.