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 44

45 0.16

(a)

40 0.14

35 0.12

30 0.1

25 0.08

20 0.06

15 0.04

10 0.02

5

0

140 160 180 200 220 240

70 0.14

(b)

60 0.12

50 0.1

40 0.08

30 0.06

20 0.04

10 0.02

0

0

150 160 170 180 190 200

DAY OF YEAR

Fig. 3.1 Seasonal dynamics of radial tracheid size ( filled triangles ), cell number in cambial zone
( dashed line , divide by 5), and specific growth rate ( solid line )in( a ) Abies sibirica and ( b ) Pinus
sylvestris (from Sviderskaya 1999 ) . A good relationship is seen between the intraseasonal changes
in the specific growth rate and changes in the size of tracheids leaving the cambium at that time.
The radial tracheid dimension is primarily determined by the average radial growth rate in the
cambial zone or by the average rate of cell division within the cambial zone, and therefore also
corresponds quite well to the magnitude of cell production

zone varies during a season. Usually the cycle is shorter when earlywood cells
form and longer during formation of latewood cells, especially at the end of the
growing season.
3. The total annual xylem cell production is closely related to the number of cells in
the cambial zone. There is, however, a curvilinear relationship between the cell
number of annual xylem increment and the average cambial cell number (Skene
1972 ) or the maximum cell number in the cambial zone (Vaganov et al. 1985 ;
Sviderskaya 1999 ) . This relationship indicates that a low rate of cell production
during a season is supported mainly by an increase of the cambial zone (more