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

Proceedings-Research on Coniferous Forest Ecosystems-A symposium .
Bellingham, Washington-March 23-24, 197 2
Litter, foliage, branch, and ste m
production in contrasting lodgepole
pine habitats of the Colorado Front Rang e
William H . Moir '
Colorado State University
A bstrac t
Harvest data are presented from a 70-year-old naturally thinned stand of lodgepole pine (Pins contorta
Dougl.) in the subalpine P . contorta/Vaccinium myrtillus habitat and from five stands of similar-aged lodgepole
pine in the drier P . contorta/Geranium fremontii habitat. These latter stands include both naturally thinned and
artificially uniform-thinned treatments . Stand structure, natural mortality, biomass components, growt h
increments of stem wood, branches, and foliage, and net primary production of these materials are given in
tables. Litter production over a 4-year period is also reported for each stand ; sources of variation in litte r
production are discussed.
Introduction
Forests of lodgepole pine (Pinus contorta
Dougl.) are extensive in the central and northern
Rocky Mountains and portions of the
Cascade Range . Studies on net primary production
are lacking, however, in virtually al l
habitats in which this pine is the major re -
source. Biomass studies in certain lodgepole
pine habitats in Alberta have been publishe d
(Kiil 1968, Johnstone 1971), and in Colorado,
the biomass of forest floor humus and
pine foliage has been reported (Moir and Grier
1969, Moir and Francis 1972) . These studies
were not extended to net primary productivity
. Our rather extensive knowledge of net
stem wood production in the central Rocky
Mountains (Myers 1967) does not reveal th e
relationship between productivity and th e
lodgepole pine habitats or include branch an d
foliage production. I report below, therefore ,
results of a 4-year study in Colorado concerning
aspects of net primary productivity i n
mostly 70-year-old natural stands of lodgepole
pine .
Methods
Six stands on the east slopes of the Front
Range in Boulder County, Colorado, wer e
studied . Stand LH2 occurs in the subalpine P .
contorta/Vaccinium myrtillus habitat; the
others occur in the drier, montane P .
contorta/Geranium fremontii habitat. Habitat
features and pine population statistics ar e
given by Moir (1969), Moir and Francis
(1972), and table 1 . In each stand a rectangular
study plot was established in an area
where the forest structure appeared homogeneous.
Plot size varied with stem density
(table 1). Annual litter fall was periodicall y
measured from randomized 0 .25 m 2 micro -
plots permanently located within each plo t
(Moir and Grier 1969) . All surface organi c
material in the microplots was collected a t
4-month intervals in 1969, and in late August,
the remaining years . Mineral contamination a t
collection was minimized by computing litter
'Present address: Box 31, Rodeo, New Mexico
88056 .
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