Under certain conditions, forests can grow in response to climate change
By Kat Kerlin
After a tip-off from nomadic herders, a team of scientists has confirmed reports of a forest expansion in eastern Tibet, a region dominated by ancient grasslands. The forest growth, unprecedented since 1760, is due to a combination of climatic changes: rising atmospheric carbon dioxide, increased water related to warming, and greater nutrient availability released by thawing permafrost.
The results, published recently in the journal Science Advances and reported in Popular Science, contrast with recent studies — including some by the authors—that found widespread decline in tree growth in other forest ecosystems due to climate change. This study illustrates how, under specific conditions, forests can grow in response to climatic changes.
“Our study demonstrates how subtle, often overlooked connections between soil, plant and atmospheric transformations can determine the fate of forests under climate change,” said lead author Lucas Silva, an assistant professor of the University of Oregon who was a faculty member at UC Davis at the time of the study.
The study, which used tree ring measurements and lab analysis, suggests that the recent growth spurt has not yet reached a regional scale. But it counters recent descriptions of the eastern Tibetan Plateau as a stable region where climatically induced ecological thresholds have not yet been crossed.
Interactions may be key
Previous studies of potted plants in controlled laboratory and greenhouse conditions have shown that rising CO2 can speed plant growth. But field studies showed that CO2-induced growth could not counteract the negative effects of rising temperatures and drought stress in many forest ecosystems.
The results of the Tibetan Plateau assessment suggest that the study of soil-plant-atmosphere interactions might be the key to understanding past and predicting future changes in forest productivity and distribution.
Co-authors on the study include William Horwath and Xia Zhu-Barker from the UC Davis Department of Land, Air and Water Resources; Geng Sun and Ning Wu from Chengdu Institute of Biology in China; and Qianlong Liang from Sichuan University in China.
Kat Kerlin writes about the environment for UC Davis Strategic Communications. Follow her at @UCDavis_Kerlin.