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
Nutrient cycling in throughf all
and litterfall in 450-year-old
Douglasfir stands
Albert Abee
an d
Denis Lavender
School of Forestry
Oregon State University
Corvallis, Orego n
Abstract
Comparisons of nutrient concentrations (N, P, K+, Ca ++ , Mg++) found in canopy throughfall and litterfall
were made on the H. J. Andrews Experimental Forest. Six old-growth Douglas-fir (Pseudotsuga menziesii )
stands were studied which represented six forest communities common to the western Cascades ofOregon. These
community types span a large portion of the temperature and moisture gradients present in the area. The
preliminary data indicate that nutrient concentration in throughfall was highest during the summer and fall, and
lowest during the winter. Nutrient input through throughfall generally followed the same trends . Nutrient
return through litterfall was greatest in the needles. More amounts of N, P, and Ca++ were transferred to the soil
through litterfall than through throughfall, while more K + and Mg++ were added to the soil through throughfall.
Litterfall was maximum during the winter. Future studies will correlate the results from the nutrient analysis to
the moisture and temperature gradients .
Introduction
The worldwide interest of scientists in litterfall
production during the past century, has
been shown by Bray and Gorham (1964) i n
their review of litter production in the forest s
of the world. Methodology reports ranged
from utilization of randomly located collection
devices of varied design, separation, oven -
drying, and chemical analysis of several litter
components, to merely raking up and air drying
the litter on a unit area basis. In spite of
the large number of papers cited in the abov e
review, data of litter production from natural ,
old-growth ecosystems are meager. Even less
is known about litterfall in old-growth
Douglas-fir (Pseudotsuga menziesii) forest
types. The examination of seasonal fluctuations,
nutrient concentration changes associated
with defoliation, and nutrient composition
of various litterfall categories are scarce
(Kira and Shidei 1967) .
The first published report of an investigation
of litterfall in coniferous forests of the
Pacific Northwest is that of Tarrant, Isaac ,
and Chandler (1951). These workers collected
the litter of several species for 1 year and estimated
nutrient movement by multiplyin g
litter weight by the percent elemental conten t
of foliage collected from trees, an inexact procedure
. More detailed measurements of th e
nutrient cycle in Douglas-fir forests have bee n
published for stands in New Zealand (Wil l
1959) and the United States (Dimock 1958) .
In addition, workers at both the University o f
Washington (Rahman 1964) and Oregon Stat e
University 1 have collected substantial dat a
describing litterfall in both managed an d
natural Douglas-fir stands . Riekerk and Gessel
(1965) and Cole and Gessel (1968) summariz e
1 D . P . Lavender, unpublished data .
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