Warmer climate could stifle carbon uptake by trees

(University of Colorado at Boulder) Contrary to conventional belief, as the climate warms and growing seasons lengthen subalpine forests are likely to soak up less carbon dioxide, according to a new University of Colorado at Boulder study. As a result, more of the greenhouse gas will be left to concentrate in the atmosphere. “Our findings contradict studies of other ecosystems that conclude longer growing seasons actually increase plant carbon uptake,” said Jia Hu, who conducted the research as a graduate student in CU-Boulder’s ecology and evolutionary biology department in conjunction with the university’s Cooperative Institute for Research in Environmental Sciences, or CIRES. The study will be published in the February edition of the journal Global Change Biology. Working with ecology and evolutionary biology professor and CIRES Fellow Russell Monson, Hu found that while smaller spring snowpack tended to advance the onset of spring and extend the growing season, it also reduced the amount of water available to forests later in the summer and fall. The water-stressed trees were then less effective in converting CO2 into biomass. Summer rains were unable to make up the difference, Hu said. “Snow is much more effective than rain in delivering water to these forests,” said Monson. “If a warmer climate brings more rain, this won’t offset the carbon uptake potential being lost due to declining snowpacks.” Drier trees also are more susceptible to beetle infestations and wildfires, Monson said. …

Warmer climate could stifle carbon uptake by trees, says CU-Boulder study