Growth rates of eastern redcedar depend  largely on site quality, competition from other species, and stand  density. These factors probably reflect competition for available soil  moisture on most sites. Trees 20 to 30 years old are generally 5 to 8 m  (18 to 26 ft) tall and 6 to 8 cm (2.3 to 3.0 in) in d.b.h. Mature trees  are usually 12 to 15 m (40 to 50 ft) tall and 30 to 61 cm (12 to 24 in) in  d.b.h. On good sites, trees may reach 37 m (120 ft) in height and 122 cm   (48 in) in d.b.h. (25).

    Some of the earliest data on diameter growth in natural eastern redcedar  stands is presented in table 2 (3). Site classes mentioned are those  described in table 1. Analysis of these data provided equations to compute  the height-age relationships in table 3. The relation of height of  dominant and codominant trees to d.b.h. and stand density was also  determined, after pooling of data for age and site classes (11). Height  growth, a reflection of soil depth and fertility, increases with stocking  density (fig 1).

    Table 2- Average annual diameter growth of dominant  eastern redcedar by site 
class and stand density¹            Site Class              Stand character   
I   
II 
  III   
IV              mm      Under-stocked  7.6  8.1  4.6  3.6      Well-stocked  -  8.1  4.3  3.0      Over-stocked  -  3.8  2.5  1.8        in      Under-stocked  0.30  0.32  0.18  0.14      Well-stocked  -  0.32  0.17  0.12      Over-stocked  -  0.15  0.10  0.07      ¹Based on  increment core measurements of 456 trees (3).              Table 3- Total height of eastern recedars by age¹  and site class            Site Class              Growth rings  II  III              m  ft  m  ft      10    4.6  15    3.7  12      15    5.5  18    5.2  17      20    7.6  25    6.1  20      25    8.5  28    7.3  24      30    9.8  32    7.9  26      35  10.7  35    8.8  29      40  11.3  37    9.4  31      45   12.2   40  10.1  33      50  12.8  42  10.7  35      ¹Age was computed using the  total number of growth rings; false rings make accurate determinations  difficult.         
Figure 1- Relation of height to d.b.h. by stocking class.

    Other studies in Arkansas have shown that growth and yield are affected  by stand density and hardwood competition. In a 45-year-old eastern  redcedar stand, highest volume growth was obtained in unthinned stands  from which hardwoods had been removed. Volumes averaged 1.96 m³/ha  (28 ft³/acre) per year during a 14-year period. This was double the  growth of stands where hardwoods were left. A stand containing 432 crop  trees per hectare (175/acre), 7.6 cm (3.0 in) d.b.h. and larger grew  nearly the same volume after 14 years when 80 percent of the competition  was removed as an unreleased stand of 988 trees per hectare (400/acre)  (11).

    Over a 10-year period in northern Arkansas, completely released stands  averaged higher growth in d.b.h., basal area, and volume than stands where  only crown competition was removed. The greatest mean d.b.h. growth, 6.4  cm (2.5 in), occurred with the lightest stocking, 124 crop trees per  hectare (50/acre). As stocking increased, mean d.b.h. growth decreased.  Basal area increase was greatest in stands having 988 crop trees per  hectare (400/acre), and as stocking decreased, basal area and volume  growth decreased. An initial stocking of 988 eastern redcedar crop trees  per hectare (400/acre), averaging about 7.6 cm (3 in) d.b.h., produced  over 28 m³/ha (2,000 fbm/acre) in 10 years. A stocking of 432 trees  per hectare (175/acre), averaging 10.2 cm (4 in) d.b.h., produced slightly  more volume during the same period on similar sites (11).

    On most sites eastern redcedar grows slowly, and long rotations are  required to produce conventional sawlogs. Because the wood is used for  small items, however, and there is wide latitude in acceptable defects,  shortening of rotations and intermediate harvesting of merchantable wood  are possible. About 20 to 30 years are required for posts and 40 to 60  years for sawtimber (11,25).

    Maintaining relatively dense stands can maximize post production.  Thinning one or more times before harvest cut hastens sawlog production  but may not increase total yield. The ideal density for growing sawlogs is  not known, but excessive thinning may promote excessive formation of  sapwood and growth of lower branches.