DECElqBE• 1932
other end by the termination of tile
cycle.
At the end of the e?.le. a new inheaviest stands are chosen fi.r the
yentory is made, new growth rates
starting point and the lightest are coralrated, assessmentis made
areas for tile final years. A lo,g'ieal of the new conditions, and the regsequenceof cutting' areas eau be ulation of ent repeated. Eventually
to equality in the first cyclewill be
blocked out on the inventory map,
by ticking off the 40 volumes until
they total the volume indicated
for the first year of cut: then startin• afresh for tile second year of
cut, and so on. Area control, or
equality of size in the annual cutting area is thus subordinated. This
will be approached gradually in
subsequent eyclcs with the continued development of the forest
growin? stock. A closer approach
obtained if those major areas of
the worklug circle bearing the
arranged casily so that tile cuttin• at tile beginnin,,zof the cycle
wheu stocking and age of the for-
starts at one end of the working
the
circle and subsequent areas flow
smoothly through the circle to the
determined by longer periods and
possiblyeven by rotations.
est has attained the desired goal,
size of the arereal
cut
can be
%%%
Epicormic Branchin
Richard
on Pruned White Fir
Forester,
Division
of
D. Cosens
Forest
Mannge-
merit, ½'alifornia Forest and Range Experiment Station, Berkeley, ½'alif.
El'If'ORIel 1(' Bt,tAN('ItES have
devel-
fir
both
in cut
and
uncut
areas.
oped on white fir (Abics concolor Here tile Sln'(mts are generally less
((lord & Glen&) Hoopes) one to
vigorous and often die.
two years after part of the live
Data for this study of epicormie
limbs were removed in a pruninu' hram.hing were co]locD•dfrom two
experiment. The appearauce of an experimental plots. Both are loaverage of six epieormic sprout• cated near Pinecrest ou the •tanisper tree raises some doubt as to the
laus
Xati(mal
Forest
iu
(.eutral
desirabilityof printing this species. ('alifornia. ()n I'lot A, 28 white fir
Althongh epicm'miehranehesare were prmwd as a part of a patho-
(.o111111Oll
ou Illally tree species. the
eausea of sl)routin R' are not clear.
The sprouts develop •rom both
dormant
and
adventitious
hnds.
Exposure to light after thinuin•
appears to stimulate sprout formation in somespecies.suchas yellowpoplar2 • h• the other hand. sprouts
eomntonlycalled"agony hranches"
develop on birch as a result of
shading? Sprouts are also common on injured white fir. especially
where part of the crown has been
lost and the bole raked by the falllug' of other trees. In such cases
the hrauehesappear as a feathery
•'rowth on the part of the tree
where the crown was lost. Althona'h
not so obvious, a few epieormie
branchesare found on undamaged
'Wahlenberg, W. G. Epieormie branching of young ydlow-poplar.
estry
4•:417-419.
Jour. For-
1950.
aBiisgen. M. The structure and life of
forest tr•s.
Ed. roy. and enlarged by
E. Miinch. EngliM• translation by T.
q'homson. John Wiley & Sons, Inc., New
York.
1931.
logical
stu(ly
by
I)r.
W.
W.
Wageuer and his ass(..iates of the
'5 ....
llurem] of Plant Industry, San
Francisco, ('slit. The stand had
been selectivob- logged in 1947
when approximately one-half the
.
volume was removed.
The area is
of a medium site and the forest
type is predominantly white and
red fir with a few scattered sugar
and ,leftroy pines. 1)iameter, ('town
classification.and nmnher and posi-
Fid. 1.
tion
white
of live branches
cut were
re-
Plot
B, 50 white
.-g•
--.•.
y•,
Epicormie branches in a pruned
fir.
One-third
of the green limbs
bad been removed by pruning 15 months
before this photograph was taken.
corded for each tree.
(h•
•.•
fir
;vere
prmmd in 3une 1950, shortly after
the eonnnen(,emenl of the growing
til the trees had overtopped the intermingled brnsh some 5 to 15
season. These treo• wore in an understocked stand of fir on land of
years later. Dimneter.
a hig'h site quality. The area had
crown removed, and portion of
bole exposed to annlight were re-
been loe'ged of all merchantable
trees in 192g. Borings showed that
all trees pruned had been present
as advance growth at the time of
lo•ging' and that •rowth had not
shown appreciable acceleration un-
eroxxm classi-
fication. peroenl of length of live
corded.
An exmnination of the plots in
geptemher 1951 disclosedthat most
of the pruned trees on both areas
had acquired a number of epicof
940
Jou•
Item
Plot A
Year area logged ............................
Date pruned ..................................
A regressionanalysis was made Number of trees pruned .................
for each plot, comparingthe num- Diameter breast height when pruned _.
ber of sproutsper tree with growth
rate, tree size, and amount of live Diameter growth--time of pruning
crown
removed.
These factors
ex-
plained only 28 percent of the
variation on Plot A and 13 percent
of the variation
on Plot B.
trees in Plot B leave no doubt that
most of the sprouts have developed
as a result of pruning. It is probable that
more
of the variation
would be explained if the plot contained trees with a smaller portion
of the crown removed.
The number and position of
quadrants of the pruned bole exposedto skylight were recorded on
Plot B. Analysis showed that only
exposureof the bole to direct sunlight, i.e., east, south, and west
quadrants,had an apparent effect
on the number of sprouts. Exposure
of the north quadrant to skylight
had no apparent effect. Trees with
two or three sides (disregarding
north) of the pruned bo]e exposed
to direct sunlight had an average
of 7.22 sproutsper tree, while those
with one or no sides exposedhad
only 2.46 sprontsper tree. This was
a highly siffnificant difference as
determined by the "t test." Although the number of sprouts per
tree was influenced by the number
of quadrantsexposedto direct sunlight. there was no apparent relationship between sprout location
and quadrant exposed.
Theseanalysesgive definite indications that high incidenceof epicormicbranching is associatedwith
the following conditions:
1. Exposure of a large portion
of the boleto sunlight as a result of
pruning.
2.
Small diameter
until September 1951 ..........................
Percentage of length of live crown
removed
of the tree at
the time of pruning.
3. Rapid growth rate of the tree.
4. Removal of a large portion of
the green crown.
Observations of epicormic
branches on injured white fir indi-
1947
l•rovember 1949
28
14.5 inches average
(Range: 9.0-21.9)
Plot B
1926
June
1950
50
9.2 inches average
(Range: 3.8-14.9)
0.48 inch average
0.70 inch average
(Range .2-.8)
(Not recorded)
33 average
11 average
(Range: 20-40)
(•ot reeor(lecl)
.............................................
Number of live limbs removed..............
(Range .3-1.1)
(Range: 2-31)
How-
ever, observations on unpruned
Fo•s?•Y
TABLE 1.--DEscRIPtIVE DATA ON PRUNF2 WHITI• FIl{ '•ItErS
mic branches(Table 1). An analysisof data from this study indicates some of the factors affecting
sprout formation.
o•
Number of pruned trees with no epieormic
branches
6
.............................
Number of epicormlc branches per
tree .....................................................
6 average
(Range: 0-26)
6 average
(Range: 0-25)
develop on . By proper selectionof the trees to
reprune, it may be possibleto keep
moved is not known at his time, the number of sprouts at an allowbut observationson other sprout- able level. This study indicated
several conditions that influenced
ing species indicate that new
the
number of sprouts, including
sprouts may appear.
the size and growth rate of trees.
Epicormic branches are a seriPruning larger, slower growing
ous obstacle to the production of trees, however, will not yield
clear lumber or peeler bolts from enoughclear wood to be profitable.
white fir. The species is tolerant Therefore, until a practical method
and a notably slow natural pruner, of controlling sprouts is found,
and to defer pruning until all the either by selectingtrees for prunbranches on the prunable portion ing or by subsequentremoval of
of the bole are dead would prob- the sprouts, any money available
ably be uneconomical. From evi- for pruning may well be more
denceon the plots studied, sprouts profitably spent on speciesthat do
may appear on any tree from which not form epicormicbrancheswhen
live limbs are removed in pruning. pruned.
Whether more will
white
fir
if
the
first
ones are
Journal of Forestry SubscriptionRates Increased
Effectivewith the January 1950 issueof the JOURNAL
Or FORESTRY
formatwaschanged,
allowingmorematerialto be printedin a volume
andincreasing
the servicegenerallyto readers.An increase
in subscription rateswasnot madeat that time. However,in viewof the additional
serviceto JOUR•,•AL
readersand increasededitorial, clerical,and printing
costs,annualsubscription
rate of the JOURNAL
OFFORESTRY
will be increased
to $7.50annually,effectiveJanuary1953. (Additionalpostage,
foreign$1; Canadian,50 cents.)
Current rate of $6 annually will apply for renewalsubscriptions
ex-
piring prior to December
31. Renewals
and newsubscriptions
starting
sprouts will persist and grow. January1953will be billedat the newrate of $7.50annually.
cate that
some if not all of the