With an increasingly warmer climate, there is a trend for springs to arrive earlier and summers to be hotter. Since spring and summer are the prime growing seasons for plantswhen flowers bloom and trees increase in girth and heightdo these climate changes mean greater seasonal growth for plants? This is a critical question for forest management, especially in the boreal regionan area particularly sensitive to the effects of climate change.
Dr. Jian-Guo Huang, currently a post-doc at the University of Alberta, and colleagues from the University of Quebec at Montreal were interested in assessing whether a potentially extended growing season affects stem xylem formation and growth in black spruce (Picea mariana) in Western Quebec, Canada. They published their findings in the May issue of the American Journal of Botany (http://www.amjbot.org/content/98/5/792.full.pdf+html).
Xylem cells conduct water and nutrients from roots to the leaves, but also provide mechanical support and form the wood of trees. Growth patterns of xylem are of interest to foresters because thicker-walled xylem cells produce denser woodand aspects of the climate, such as temperature and rainfall, may impact not only the number of cells produced during a growing season, but also cell wall thickness.
By taking microcore samples from black spruce trees at three different latitudes ranging from 47.5o to 50oN in Western Quebec throughout the growing season (MaySeptember) in 2005 and 2006, Huang and colleagues were able to determine when xylem cell production began and ended, as well as the pattern of xylem cell growth. They then compared these data to soil and air temperature and precipitation data gathered from local climate stations.
"Every small wood xylem cell contains meteorological information during its growing process," Huang commented. "Exploring a series of micro-
|Contact: Richard Hund|
American Journal of Botany