Warmer climate could stifle carbon uptake by trees

Research co-authored by Dr David Moore and Dr Sean Burns of the University of Colorado at Boulder, suggests that as the climate warms and growing seasons lengthen subalpine forests are likely to soak up less carbon dioxide.
 
"In this paper we show that trees in these high alpine forests depend heavily on water from snow melt for photosynthesis and growth. This means that the forests will likely take up less carbon from the atmosphere if snowfall is reduced. Warming temperatures and reduced snowfall in the Rocky Mountains makes the forest less effective as a carbon sink. In future, as winter snow fall predicted to reduce further it is not certain that these tree species will be able to adapt to the change in precipitation pattern." Dr Moore says.
 
"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 researchers found that even as late in the season as September and October, 60 percent of the water in stems and needles collected from subalpine trees along Colorado's Front Range could be traced back to spring snowmelt. They were able to distinguish between spring snow and summer rain in plant matter by analyzing slight variations in hydrogen and oxygen atoms in the water molecules.