How Well Understood Are the Processes that Create Dendroclimatic Records? A Mechanistic Model of the Climatic Control on Conifer Tree-Ring Growth Dynamics - Dendroclimatology - page 52

3.5 Effect of Climatic Factors on Tree-Ring Structure (Light,
Temperature, and Water)
3.5.1 Temperature
Dendrochronologists have made many investigations of the effect of temperature on
radial tree growth and wood density (Fritts 1976 ; Hughes et al. 1982 ; Schweingruber
1996 ) . Significantly less data are available for the temperature effect on the anatom-
ical features of tree rings. Much of the relevant research was conducted on trees
growing at high latitudes where temperature is presumably a leading limiting factor.
Some research concerning anatomical structure was made on seedlings in controlled
conditions. There are some common findings:
1. Temperature is the most important factor for growth initiation in boreal and
temperate climates (Creber and Chaloner 1984 ; Iqbal 1990 ) . At high latitudes,
growth (new cell production) ceases in about the middle of August and the dura-
tion of the season of wood production is mainly determined by the starting date
of cambial activity (Mikola 1962 ) . Leikola ( 1969 ) showed that a 0.5 ◦ C deviation
in the mean April-May temperature caused significant shifts in the starting date
of cambial activity. For the Siberian subarctic, we found early summer (mid-June
to mid-July) temperature and snowmelt timing to be very important for the vari-
ation in radial growth of larch trees (Hughes et al. 1999 ; Vaganov et al. 1999 ;
Kirdyanov et al. 2003 ) . Wood production ceases at a much higher temperature
than is necessary for its initiation (Denne 1971 ) .
One of the best examples of environmentally controlled tracheid production
and differentiating were given in a recent study of Deslauriers et al. ( 2003 ) .
Analyzing the kinetics of cells in each phase of tree-ring formation (division,
expansion, wall thickening) during seasonal growth and development in Abies
balsamea L. growing in boreal forest, they demonstrated a high degreee of vari-
ation in the timing of the beginning of the growing season (about one month),
the earlywood-latewood transition (around half of a month), and the end of the
growing season (about one month). This result is in a good agreement with other
high-latitude observations and simulations (Vaganov et al. 1999 ; Kirdyanov et al.
2003 ) . On the other hand, Deslauriers et al. ( 2003 ) estimated a duration of
cell expansion in the stage of cell enlargement that gave significantly shorter
times (less than one week for earlywood and 5-10 days for latewood) than
those recorded in lower latitudes (Wodzicki 1971 ; Skene 1972 ; Antonova et al.
1995 ; Vaganov et al. 2006 ) . These differences could be genetically determined
because of the short season for tree-ring growth and maturation of the tracheids.
Deslauriers and Morin ( 2005 ) found that cell production in the cambium was
correlated with the temperature during the same period. Artificially lagging the
daily temperature data even by a single day decreased the correlation with cell
production substantially, indicating that the cambium reacted quickly to external
environmental variability.