Malcolm K. Hughes

Ph.D., University of Durham, U.K., Ecology

SPONSOR: Roger G. Barry

TITLE: Is tree-ring response to climate changing, and if so, why? Application of a process-based model to this problem, with special emphasis on forests in regions of continuous permafrost, and on trees at the highest elevations in the mountains of the western USA.

THEME:

Office: RL-2, Rm. 222
E-mail: Malcolm.Hughes@Colorado.edu
Phone: 303-735-0213

Malcolm Hughes is in the business of "thencasting," as he calls it. He predicts what past climates looked like using tree rings.

Hailing from the University of Arizona's Laboratory of Tree-Ring Research, Hughes will be visiting CIRES during the "07-'08 academic year. While he's here, he plans to entirely revamp the way we think about using tree rings to infer past climate conditions.

Until now, dendrochronologists like Hughes have used a straight-forward statistical approach to relate tree rings to climate: the larger the ring, the more likely a favorable climate existed for growth.

But Hughes calls this method "scientifically unsatisfying."

"When looking at tree growth during the 15th century, is using the statistical relationship between growth and climate from the 20th century appropriate?" he asks.

Hughes wants dendrochronological methods to incorporate the internal growth processes at work in the tree. Key to this is testing and refining a model that describes the behavior of cell growth in the soapy layer under the tree's bark.

How many cells are there and of what size? When do the cells start multiplying and dividing? When does the new wood thicken up? These are the kinds of questions Hughes is after.

Once we understand the internal mechanisms at work in the tree, it will be easier to isolate the role of climate in shaping the tree's growth, explains Hughes.

Hughes also suspects that some trees, especially at higher elevations, may be changing their relationship with the climate, growing more rapidly during the past 50 years than previously, with no obvious boost from increases in atmospheric CO2 concentration. He and others have observed this unexpected growth spurt in bristlecone pines at high elevations in the White Mountains along the California-Nevada border.

So don't be surprised if you see him up out at Niwot Ridge, near Colorado's continental divide, poking around the high elevation forest and peeling back bark (only if he gets a permit, of course). As I left him, he was already threatening to buy a chisel at the nearest hardware store.

EXTRA: Don't miss Malcolm Hughes' lecture on Tuesday, October 17, 2006 at the University of Arizona: Global Climate Change: The Evidence. http://cos.arizona.edu/climate/