PE EIE[R-Rg RESEARCH ON - HJ Andrews Experimental Forest

Table 1 .-Some population characteristics of Pinus con torta in stand s
on the east slopes of the Colorado Front Range
Stand
and
year
Age'
Plot
area
Number of stems by d.b.h. classes
0 .2 .5 2 .5-5 5-7 .5 7 .5-10 10.15 15-20 20-2 5
Density
Mortalit y
Years m 2 cm Stems/ha Stems/ha x yr
2 .2 71 8 4
1966 130 136 27 2 35,700
1970 82 135 25 4 29,300 1,60 0
4 .1 72 12 6
1966 3 35 56 38 5 10,900
1970 1 24 49 39 8 9,600 32 5
1 .1 72 12 6
1966 1 26 46 30 10 9,000
1970 24 35 36 12 1 8,600 100
1 .3 103 15 0
1966 2 7 5 25 8 3,10 0
1970 5 5 23 12 3,000 2 5
4 .3 71 37 5
1966 29 1 1 12 45 2 1,600 2
1970 25 2 7 45 8 1,650 0
LH2 77 15 0
1966 2 4 10 18 19 4 3,80 0
1970 2 4 9 18 20 4 3,800 0
' Reference year 1970 . Stand age is based upon the oldest trees .
2 This stand was thinned in 1934-35 . Density refers to stems over 2 .5 cm d .b .h .
fall as loss-on-ignition (Moir and Grier 1969) ,
and the tendency of debris of the forest floo r
to "drift" into the microplots was offset b y
slightly increasing the effective area of th e
microplot during computation .
In each of plots 1 .1, 4.3, and LH2 of table
1, the stems of lodgepole pine were placed
into five diameter (d .b.h.) classes, with an
equal number of stems in each class. In September
1969, the tree at the midpoint of eac h
d .b .h. class was harvested (Ovington, Forrest ,
and Armstrong 1967), giving five trees fro m
each plot. Current and second year foliage
and twigs were separated from each other an d
from older material. Branches with any livin g
foliage whatever were classified as living an d
separated from dead branches at harvest time .
From each stem replicate disks were obtained
at the stem base, at 3 to 4 dm ., and just belo w
the lowest living branch (crown base) . From
each disk I measured diameter inside bark ,
diameter outside bark (d .o .b.), wood density
(volume determined by water immersion) ,
bark density at 102° C., and average radial
growth during each of growing seasons 196 8
and 1969. In addition, measurements of
19 0