The Period of Seasonal Growth of Ponderosa Pine and
Associated Species
H. A. Fowells
CaliJorniaForestand RangeExperimentStation•
The periodof seasonal
growthof treesis not only an interestingnaturalphenomenon,
but also
may be an importantfactorin the executionof certainfield studies. The data presentedindicate
somesignificantdifferencesamongthe periodsof growthof certain coniferousspeciesand in the
period of growth of ponderosapine at differentlocations.
whereas that amount of growth of the
ciesin one area and of ponderosa
pine at larch required about 15 weeks. In Penn•'
five elevationshas been measuredfor a sylvania, Illick (8) noted that 80 percent
numberof yearsin a workingcenterin theSierra of the height growth of white pine was
Nevada. These data have been taken in order
completedin 30 days. Kienholz (9) conto providea basisfor pro-ratingthe time inter- cludedthat whitepine,pitchpine,and Norway
val betweenperiodicmeasurements
of treesin pine behavedsimilarlybut differedfrom white
yieldstudies.It is the purposeof thispaperto spruceand balsamfir in the time of inception
presentsome of the observations
on seasonal and cessation
of heightgrowth. Reed (13) degrowth.
terminedthat Ioblolly pine began its shoot
Althoughthe literatureabounds
with reports growth2 weeksbeforeshortleafpine and also
of observations
on the seasonal
growthof trees, ceasedgrowingbeforeshortleafpine. Gustarson
there is little knowledgeof the seasonal
distri- (7)observedthat the height growth of Scotch
butionof growthof someof theprincipalconif- pine wascompleted
by the end of Juneandthat
erousspecies
of the SierraNevadaof California. diametergrowth was completedby the end of
MacDougal(10, 11) has reportedexhaustivelyAugust. Rees (14), studyingradial growth of
ontheperiodof growthof Monterey
pineonthe red sprucein the Adirondacks,
found that the
central coast of California. He indicated that the period of growth on four sitesvaried from 6
period of diametergrowth varied from 2 to 8 weeks to 14 weeks. He observed also that the
monthsand that heightgrowthlastedfor 10 growthof shootsceasedaboutthe time that the
months.Glock(6) reported
thatthe maximum spring wood was completed. Brown (2, 3),
growthof juniper in the high Sierra occurred studyingthe radial growth of pitch pine and
within two weeks after winter snows had melted. white pine, observedafter the first surge of
Pearson(12) found the period of diameter growtha restperiodfollowedby a second
period
growthof ponderosa
pinein Arizonavariedfrom of growth.
87 to 117 days.
PROCEDURE
In other regionsmany investigators
have
studiedthe periodand progressof seasonal Sampletreesand locations.•Thesix species
growthandhave found variabilityassociatedstudiedwere ponderosa
pine (Pinusponderosa
withspecies,
withyears,andwithplace. Bald- Law.), sugar pine (P. lambertianaDougl.),
win (1), studyingthe heightgrowthof white lodgepolepine (P. contortalati/olia Engelm.),
pine,balsamfir, whitespruce,red spruce,and Jeffreypine (P. }e#reyi "Oreg. Corn."), white
black spruce,found differences
in the time and fir (•4bies concolorLindl. and Gord.) and Cali-
HE
seasonal
growth
ofsix
coniferous
spe-
the rate of growthamongthe species
but noted fornia incense-cedar(LibocedrusdecurrensTorconsistency
in theperformance
of any onespe- ray). Ten treesof eachof the six species,
3 to
ciesin a givenlocation. Tryon and Finn (17) 6 feet high, were selectedfor height measurefoundthatthe culmination
of heightgrowthoc- mentsand an additionalten treeseachof only
curredthreeto four weeksearlierin Norway four species,
ponderosa
pine, sugarpine,white
spruce,
whitespruce,
andNorwaypinethanin fir, and incense-cedar,
5 to 25 inchesin diameter,
European
larch. Ninetypercentof the growth were selected for radial measurements. Radial
of pine and spruceoccurred
in about7 weeks, growthmeasurements
werenot madeon lodgeenoughtrees
•Maintainedin 'cooperation
with the Universityof polepine and Jeffreypine because
of this size did not occur in the area. The trees
California, at Berkeley,Calif.
601
602
JOURNAL OF FORESTRY
used for radial growth measurements
were'iso- the tip of the terminaleachperiodon a stick
lated, dominant,or codominantand were classed fastenedalongthe stem. No deformities
of the
as 1, 2, or 3 accordingto the Dunning (5) stemwerecausedby the pin. At the end of the
tree classification.
season,
the pinswereplacedbelowthe nodejust
Trees of the six speciesmeasuredfor height formed, and a measurementwas made to serve
growthwerecontainedin an area of aboutten as the base for the next season. Thus any
acres,locatedon the west slopeof the Sierra growthoccurringbeforethe first examination
in
Nevadaalongthe SouthFork of the Stanislaus thespringwasmeasured.Thedateof emergence
River in the Stanislaus National Forest. The ele-
of the needles from the fascicle sheath was noted
vation is about 5,200 feet. The trees of the four
and the needlelengthwasobservedconcurrently
speciesmeasuredfor radial growth were scat- with height measurements.
tered over about 60 acresin the samelocality
Measurements
of radial growthwere obtained
at an elevation of about 5,300 feet. The site
by
use
of
the
Reineke
(15) dendrometer.This
quality of the generalarea is very good,being
device
consists
of
three
parts: a hook screwed
quality I in the commonscaleof site classification.
into the wood of the tree until about half an inch
Seasonalheight and radial growthof ponderosa pine was measuredalso at elevationsof
1,800, 3,000, 4,000, 5,000, and 6,000 feet. At
each elevationheight growth was measuredon
ten trees2 to 6 feet high, and radial growthon
of spaceremainedbetween
thepointof thehook
ten other trees 5 to 30 inches in diameter of tree
and the smoothedbark; a small, round-headed
screwimbeddedin the bark directlybeneaththe
hook; and a dial gaugeto measurethe distance
between the hook and the screw. The dendrometer is so constructed that the measurement of
classes
1, 2, 3, or 6. The groupof treesmeasured growth includesgrowth of both xylem and
at 1,800 feet grew on a northwestslope; the phloemandexpansion
or contraction
of thehook
groupsmeasuredat the other elevationsgrew and screwand of the 1/•-inchof bark in which
on slopesvarying from southeastto southwest. the screw is imbedded. Two or more sets of
The groupof treesat 1,800 feet grew at about hook and screw were affixed to each tree.
the lower edgeof the Transitionlife-zone,which Changes
in the distancefrom the hookto the
includesponderosapine and associated
species. screwweregauged
to onethousandth
of an inch.
The group of trees at 6,000 feet was.approxi- The dendrometer was selected from other devices
mately25 milesdistantfrom the groupat 1,800 such as the dendrograph(10, 11) or various
feet and was about at the upper edge of the growthbands(10) to measure
radialgrowthbeTransition life-zone.
causeof its cheapness,
simplicity,and apparent
Height and radial growth measurements
of accuracy.
the different speciesextendedover a period of
The reliability of the dendrometerin measur8 and 7 years,respectively,
from 1932 and 1933 ing radial growthwasverifiedby two testsin
to 1939, inclusive. Height and radial growth which the dendrometermeasurement
of growth
measuremdnts
of ponderosapine at differentele- was comparedwith the width of the actual
vationsextendedover a period of 6 years,from growthring. In the first test incrementcores
1933 to 1938, inclusive. The first measurements were taken under the small screws of the den-
each year were made in Februaryor March at
drometerson 32 trees at the end of a growing
elevationsof 5,000 feet and below, and in March
season
andthe coreswerepreserved
in soluiion
or April at elevationsabove5,000 feet. Each to preventshrinkage. The width of the last
tree was measuredat intervals of 10 days, or growthring of eachcorewas measured
micronearly so, until the middle of November.
scopically
to the nearestthousandth
of an inch.
of ring width werecompared
Methodso] measurement.--Height
growthwas The measurements
dendrometermeasuremeasuredfrom a pin placedin the stem below with the corresponding
the last nodeto the tip of the terminalbud with
a steel rule, notched at zero to fit the pin.
mentsby the "t-test" and by linear correlation.
Measurements were made to the
3 inchesapart aroundthe peripheryof onetree.
nearest
five-
In the second test 25 dendrometers were installed
hundredth
of aninch. Thismethod
isessentiallyOne
dendrometer was removed each week and
the sameas that usedby Kienholz(9) and Reed an increment core was taken under the small
of ring width were
(13), or by Tryon and Finn (17), who marked screw. The measurements
GROWTH
OF PONDEROSA
PINE AND ASSOCIATED
SPECIES
603
comparedwith thoseby the dendrometeras in
the first test.
In the first test,the meandifferenceresulting
from
the subtraction
of the core measurement
from the dendrometermeasurementwas +0.0184
inches,with a standard error of -+0.0043 inches.
The correlationcoefficient
wasq-0.936, a highly
significantvalue explaining88 p•rcent of the
variation.
In the second test the mean differ-
ence,resultingfrom the sameorder of subtraction, was +0.0234 incheswith a standarderror
of ñ0.0043
inches.
The correlation
coefficient
was q-0.886, a highly significantvalue explaining 78 percentof the variation. Sincethe differencesbetweenthe measurements
by the den-
Fig. 1.--Progress
of seasonal
heightgrowthof different
species, 1937.
drometer and the measurements from the incre-
ment coreswere positiveand highly significant
in both tests,and sincethe correlation coefficients
also were highly significant,the dendrometer
measurement
of radial growthapparentlyis reliable even though the measurementincludes
more than growth of the xylem.
Methodso! analysis.--Thestudyof differences
in the distributionof seasonalgrowthof the six
speciesand of ponderosa
pine at five elevations
Fig. 2.--Progress
of seasonal
radial growthof different
wasbasedon comparisons
of the time at which
species, 1937.
growthstartedin the spring,the length of the
growing period, and the relative rapidity of
growthduringthe periodof greatestgrowthrare
or the "grand period of seasonalgrowth" referred to by Biisgen(4). Thesedata were extractedfrom seasonal
growthcurves,of the logistic or S-shaped
type,constructed
from the periodic measurements.The average amount of
growth of each set of 10 treesfor each 10-day
period was accumulated
for the season.The averagecumulative
growth,by periods,wasdivided
by the averagetotal growthof the groupof trees
andthe dividendconverted
to a percentage.
The
of seasonal
heightgrowthof pondeconversionto a percentagebasiswas expedient Fig. 3.--Progress
rosa pine at differentelevations,1937.
becausethe rate of growth of all the trees was
therebyreducedto a comparablebasisand becausetime and relativerapidity of growth,and
/I, I][ 114411
•øI_.L•Lt_.I LLLI I I i i .,•1 i i i L-•r•3rq_k-'TI I I I I
not actualamount,werebeingstudied. The ac/1
II/]
I I/I
I I I/
_.i i
•a/I I I I / t t I•
I I/1/I I I/g.J-k'l I I I
t /
cumulatedpercentages
were plotted over time, ••7o I
I
I I I/ I I/1 I
, ,v/,,Y';1+111111111111
formingthe curvesmentioned
above. Examples
of the growth curvesof the 4 setsof data are
shownin Figures1, 2, 3, and 4.
The beginningof growthwasdefinedfor comø,i I, ,/-n..,'.",
L,IIil II ..... :oo: :
parativepurposesin this studyas the date by
,•,1 I I I 3'/J•'f I ..t'"•
• I/q I I I I J I I 5-:-_---' •o• which5 percentof the total seasonal
growthhad
beencompleted.This time wasmeasuredfrom
Jr.nuary1 eachyear. The endof seasonal
growth
Fig.4.--Progress
of seasonal
radialgrowthof ponderosa
wasdefinedas the date by which95 percentof
pine at different elevations,1937.
604
. JOURNAL OF FORESTRY
the seasonal
growthhad occurred. The time in-
Significantvariationsin startof growth,length
of the growingperiod,and rapidity of growth
lengthof the growingperiod. Thesearbitrary amongspeciesor elevationsand from year to
limits were established
to avoid the employment year were determinedby analysisof variance
of personaljudgmentin determiningthe dateon (16). The form of analysisuseddistributedthe
which growthactuallystartedor stopped.The total variationto years,to speciesor elevations,
selectionof the 5 percentpoint as the beginning and to error. The significanceof a difference
'of growthlargelyavoidedthenecessity
of extend- betweenspeciesor betweenelevationswith reing the curvetowardthe datumestablished
the spectto the start, lengthof period,or rapidity
previousfall wheneverthe initial spring mea- of growthwasestablished
by the t-test,in which
surement did not precede growth inception. the standarderror was derivedfrom the approThese artificial limits, it is believed, are not in priate varianceanalysis.
disagreement
with the practicalpurposeof the
The adequacyof a sampleof only 10 treesof
studyanddo notchangethe positions
of thespe- eachspecies
or at eachelevationwasindicatedby
cies or elevations in their time or rate relationanalysisof variancefor one seasonof the indiships.
vidual periodicgrowth measurements
converted
The minimum number of days required to to percentages
of total seasonalgrowth. These
complete50 percentof the total growthwasse- analysesrevealedsignificantdifferencesin the
lectedas a measureof the rapidity of growth proportionate.
amountof total growthcompleted
di•ringthe periodof greatestgrowthrate. The in 10-dayperiodsby differentspecies
or by ponminimumnumberof daysrequiredto complete derosapine at differentelevations. The use of
50 percentof thegrowthwasalwaysincludedbe- the averageof 10 treesin the main analysishas
tweenthepointsof curvature
of thegrowthcurve. not distorted,apparently,the differences
between
To extract these data from the curves, a cellu- speciesor betweenelevations.
loid grid, calibratedwith abscissa
in daysand
with a fixed ordinateequal to 50 percent,was
RESULTS
movedalong each growthcurve until the abTables1 to 4 giveaveragevaluesof the dateof
scissa,or numberof days,becamea minimum.
This processresulted,in effect,in the determin- start of growth (Start), the lengthof the growing of the minimumbaseof a right-angled
tri- ing period (Length), and the minimumnumber
anglewhosealtitude,parallelto the ordinateof of daysrequiredto complete50 percentof the
the growthcurve,was equalto 50 percentand total growth (Rapidity) togetherwith the magwhichare significantat the
whosehypotenuse
wasrepresented
by a segment nitudeof differences
5-percentand 1-percentlevels.
of the growthcurve.
terval between these two dates was used as the
TABLE 1.--HEIGHT GROWTHOF DIFFERENTSPECIES,8-YEARAVERAGE
Significant difference
Species
Lodgepole
JeffreyPonderosa
Sugar Incense-White 5 percent1percent
Variable
pine
Start, days• ............................................. 127
Start, date ...............................................
May 7
Length, days ......................................
69
Rapidity, days ........................................ 21
pine
136
May 16
78
21
pine
pine
cedar
fir
146
144
175
133
May 13 May 26 May 24 June 24
51
91
46
81
15
37
20
22
level
level
5
7
6
3
8
4
•Number of daysfrom January 1.
TABLE2.--RADIAL GROWTHOF DIFFERENTSPECIES,
7-YEARAVERAGE
Significantdifference
Species
Variable
Ponderosa
pine Sugarpine Incense-cedarWhitefir 5 percentlevel 1 percentlevel
Start, days• ....................................
105
107
105
121
12
16
Start, date .............................................
April 15
April 17
April 15
May 1
Length, days ..................................
147
129
136
108
23
32
Rapidity, days ..................................
47
46
39
44
5
7
XNumberof daysfrom January1.
GROWTH OF PONDEROSA PINE AND ASSOCIATED SPECIES
605
in timebetween
eitherof thesespeThe start of growth,lengthof the growing thedifference
washighlysignificant.
period,andminimum
number
of daysrequiredciesandanyotherspecies
tocomplete
50percent
ofgrowth
alsovariedwith The lengthof the growingperiodof lodgepole
pine,Jeffrey
yearsin mostof the variance
analyses.Years pinewaslessthanthatof ponderosa
wereunimportant
statistically
in onlythreeanal- pine, or incense-cedar.The lengthof the growwasgreaterby a highyses:thelengthof theperiodof radialgrowth ing i•eriodof incense-cedar
ly
significant
number
of
days
than that of the
of different
species,
thelengthof theperiodof
heightgrowthof ponderosa
pineat different
ele- otherspecies. In order of cessationof growth,
vations,and the minimumnumberof daysre- lodgepolepine wasfirst, followedby sugarpine,
pine, white fir, and inquiredto complete
50 percent
of the height Jeffreypine, ponderosa
growthof ponderosa
pineat different
elevations.sense-cedar.
The minimumlengthof time requiredto comUndoubtedly
the variationfromyearto yearis
the result of climatic conditionsduring these plete50 percentof the heightgrowthwasfound
shortfor sugarpine and very
years. No attempt
wasmadeto correlate
the to be surprisingly
phases
of seasonal
growthwithclimaticcondi- long for incense-cedar.The 15-dayperiodretions.
quiredfor sugarpine was significantlyshorter
than the periodrequiredfor the other species.
DISCUSSIONOF RESULTS
The veryrapidgrowthof sugarpinemay be reof sugar
Thedateat whichseasonal
growthstarted,the latedto the fact that needleelongation
lengthof thegrowing
period,andtheminimum pine doesnot occuruntil after the period of
numberof daysrequired
.to complete
one-halfrapid heightgrowth. Brown (2, 3) and Kienthatthereis competition
thetotalgrowthwerefoundto varyfor different holz (9) havesuggested
species.
Lodgepole
pinebeganseasonal
height withinthe plantfor foodmaterialsfor different
growth
firsteachyear. Whitefir began
seasonalgrowingpoints. Lodgepolepine, Jeffreypine,
pine,andwhitefir did not differfrom
heightgrowthonemonthto oneandone-halfponderosa
monthslaterthantheotherspecies.By thetime eachotherwith respectto the lengthof this perirequiredalheightgrowthof whitefir started,
lodgepole
pine, od of rapid growth. Incense-cedar
ponderosa
pine,Jeffrey
pine,sugarpine,andin- mosttwice as muchtime to completethe most
cense-cedar
hadcompleted
88, 63, 67, 45, and25 rapid 50 percentof growthas the otherspecies.
percent
of theirseasonal
growth,
respectively. The slowrelativerate of growthof incense-cedar
Whitefir andsugarpinecompleted
theirtotal may be due to the fact that, having no large
bud asthe pineshave,its growth
heightgrowthin the shortest
periodof time. over-wintering
The difference
in the lengthof growingperiod is the result of a continual cell differentiation
between
thesetwospecies
wasnotsignificant
but and elongation. In pine and in fir the sudden
TABLE3.--HEIGHT GROWTHOF PONDEROSA
PINE AT DIFFERENT
ELEVATIONS,
6-YEARAVERAGE
Elevations
Variable
1800feet
Start,days
* .........................................
88
Start,date.........................................
March29
3000feet
4000feet
5000feet
6000feet
92
April2
105
Aprill5
116
April26
128
May8
22
25
21
Length,
days
....................................
122
108
Rapidity,
days....................................
24
Significant difference
5 percent 1 percent
105
97
89
26
level
level
11
16
]}
24
6
5
•Number of days from January 1.
TABLE4.--RADIALGROWTHOF PONDEROSA
PINE AT DIFFERENT
ELEVATIONS,
6-YEARAVERAGE
Elevation
Variable
1800feet
Start,days
• .......................................
47
Start,date........................................
Feb.17
Length,days...................................
241
Rapidity,
days...................................
58
•Number of days from January 1.
3000feet
55
Significantdifference
5 percent 1 percent
4000feet ' 5000feet
70
Feb.25 March11
148
183
49
59
82
March23
177
57
6000feet
level
level
107
17
23
26
12
36
16
April17
143
48
606
JOURNAL OF FORESTRY
spurtof growthmaybe the elongation
of cells of the radial growthoccurreddid not change
with the
differentiatedin the large bud. Biisgenand with elevation,a findingin agreement
Munch(4) haveindicatedthat'thedifferencein height growth findings. No regularity assoin elevation
wasapparentin
the rapidityof seasonal
heightgrowthbetweenciatedwithchanges
beechand ash is due to the fact that beechhas a
thelengthof theperiodof radialgrowth.
The
statisticalreasonfor this irregularitywas obvious when the growth curveswere examined.
Eachyear the seasonal
growthcurveof the trees
at 1,800 feet leveledoff at about90 percentof
total growthfor a periodof abouttwo months
and then graduallyincreased. The curveof the
trees
at 3,000 feet, however,leveled off at about
ingperiod
of whitefir wassignificantly
shorter
95 percentfor a similar period and then also
thanthat of ponderosa
pineandincense-cedar
but the otherdifferences
amongspecieswerenot graduallyrose. Obviously,the 95 percentlevel
significant.
Theminimum
number
of daysre- arbitrarily chosenas the end of growthinterquired
tocomplete
50percent
ofthegrowth
was ceptedthe curveof 3,000feetat an early dateand
lessfor incense-cedar
thanfor ponderosa
pineor interceptedthe curve of 1,800 feet at a late
largeoverwintering
budin whichthecellsfor
theshoot
growtharelaiddownandashhasnot.
In thestudyof theseasonal
radialgrowth
of
thefourspecies,
theonlydifferences
in thestart
of growth
werebetween
thetardywhitefir and
theotherthreespecies.
Thelengthof thegrow-
sugar
pine.There
isnoapparent
explanation
of date.
the fact that incense-cedar
requiredthe least A comparisonof Tables1 and 2 and of Tables
number
of daysto complete
50 percent
of its 3 and 4 indicatesthat the beginningof radial
the beginningof heightgrowth.
radial
growth
butthegreatest
number
ofdays
to growthprecedes
Only
in
the
pines
did radial growthcontinuefor
complete
50percent
ofitsheight
growth.
The start of seasonal
heightgrowthof pon- any appreciableperiod after the cessationof
derosa
pinewaslaterwitheachriseof 1,000 height growth.
At the time height growth of
ponderosa
pine
ended,
84 percentof the radial
feetin elevation,
except
between
1,800feetand
growth
had
occurred.
At
the cessation
of height
3,000feet. An increase
of 2,000feetin elevationcaused
a verysignificant
delayin the growthof sugarpine, 80 percentof the radial
growth had occurred.
inception
of height
growth.Table3 indicates
thatgrowth
started
overa month
laterat6,000 The stage of seasonalgrowth may be estiof the needles.
feetthan it did at 1,800feet or 3,000feet.At matedroughlyby the development
At
the
time
of
needle
emergence
from
the fascicle
thetimegrowth
started
at 6,000feet(5 percent
completed),
15 percent,
25 percent,
52 percent,sheath,lodgepolepine, Jeffreypine, ponderosa
and56 percent
of theseasonal
growth
hadoc- pine, sugarpine, and white fir had completed
curredat 5,000,4,000,3,000,and 1,800feet, 59 percent,50 percent,54 percent,80 percent,
and 18 percent,respectively,of their seasonal
respectively.
arenotin agreement
There was a decrease
in the lengthof the growth. Theseobservations
with
the
general
statement
by Reed (13) that
period
of height
growth
withincrease
in altiof the
tude,butthedecrease
in number
of dayswas heightgrowthbeginswith the appearance
season's
needles.
Possibly
differences
of
insignificant
onlywhentheincrease
in altitude
appearwas3,000feet. Although
the lengthof the terpretationexistas to what constitutes
growing
period
wasshown
to varywithele- ance of needles,the presenceof the fascicle
vation,the cessation
of growth
did not.The sheath,or the emergenceof the needlefrom it.
(3, 9, 14) havereportedthat
minimumnumberof days requiredto com- Otherinvestigators
the
needles
of
pines
do not appearuntil after
plete50 percent
of thegrowth
didnotvary
with akitude.Thesefactsindicatethat differ- height growth has.started and that the foliar
ences
in thelengthof the growingperiodwere budsof sprucebreaka weekafterheightgrowth
largely
theresult
of thedifferences
in thetime has started.
In this study all height growth
was
completed
by the time needlegrowth was
at whichgrowthstarted.
completed.
Thebeginning
of radial growthwas significantly
laterwitheachadditional
2,000feet The resultspresentedindicatethat there are
of elevation,
with the exception
that therewas great enoughdifferencesin the period of seaa significant
delay
between
5,000feetand6,000 sonal growth among speciesto warrant con-
feet. The shortest
periodin which50 percent sideration
of these differences in the schedules
GROWTH OF PONDEROSA PINE AND ASSOCIATED
SPECIES
607
for examinationof field plots. A further com- was shortenedsignificantlywith an increaseof
plicationis that changesin the period of sea•, 3,000 feet in elevation.
sonal growth are causedby place differences. Radial growth of ponderosapine startedsigExactcomparisons
of growthratesor yieldsover nificantlylater with an increaseof 2,000 feet
periodsof a few yearsbetweenspeciesor be- in elevation.
The rate of height and radial growthof pontweenareasclimaticallydifferentcan be made
only if growthmeasurements
are takenbefore derosapine duringthe grandperiodof growth
or after the periodof seasonal
growth.For ex- did not vary with elevation.
Needlesof the pinesdid not emergefrom the
ample,the averageannualincreasein total
heightof seedlings
andsaplings
is usedoftenasa fasciclesheathuntil 50 percentor more of the
measurement
of the effectof standimprovement. growthhadoccurred.
Thesedata may be the result of measurements Becauseof the differencesapparentin the pemade after a 5-year interval. But unlessthe riod of seasonalgrowth amongspecies,among
calendaryears includegrowthyears,the ac- areas,and from year to year, the useof calentual growingperiodduring5 calendaryears dar yearswithoutregardto the periodof seamight be 41J2yearsfor ponderosa
pine and sonalgrowth in the calculationof averageanonly4 yearsfor whitefir. Suchdiscrepancies
nual growth in short time studiesmay give
mightbe introduced
alsoin the comparison
of
measurements
taken during a short period of
time in areasdifferingby severalthousandfeet
biased results.
LITERATURE CITED
in elevation. These discrepanciescould be
avoidedif measurements
takenduring the grow-
1. Baldwin,H.I. 1931. The periodof height
growthin somenortheastern
conifers.
Ecology 12: 665-689.
therecognition
of currentheightgrowthof some
species,
asincense-cedar,
is difficult;andtheex- 2. Brown, H. P. 1912. Growth studiesin
clusionof currentradial growthin measurements
foresttrees. 1. Pinus rigida Mill. Bot. Gaz.
54: 386-402.
of tree diameteris, of course,impossible.It ap-
in• season
excluded
currentgrowth.However,
pearsnecessary
thenthat therebe a continuous 3.
recordof the seasonalgrowthof somekey species at eachworkingcenterafter the relation-
est trees.
II.
1915. Growth studies in forPinus strobus L. Bot. Gaz.
59: 197-241.
shipsamong
species
havebeenestablished.
This 4. Biisgen,
M. andE. Munch. (1931Thomson
recordshouldfacilitatethe adjustmentof the
time interval in growth studies.
translation). Structureand life of forest
trees. 436 p. illus. JohnWiley and Sons,
Inc.
SUMMARY
A comparison
of the seasonal
heightgrowth
of six conifersover a period of 8 yearshas
revealeddifferencesin time of start of growth,
lengthof growingperiod,andtheminimumnumber of daysrequiredto complete
50 percentof
5. Dunning,Duncan. 1928.A treeclassification for the selection forests of the Sierra
Nevada.Jour.Agric.Research
36: 755-771.
6. Glock,W. S. 1937. Observations
on the
westernjuniper. Madrono4: 21-28.
7. Gustarson,Felix G. 1936. When does a
the growth. The first species
to startgrowth
waslodgepole
pine and the last waswhitefir.
pine tree complete
its seasonalgrowth?
Papersof theMich.Acad.Sci.Art andLet-
of four conifers revealed that white fir was the
fers and their interrelations.
ters 22: 83-84.
White fir had the shortestgrowingperiodand
8.
Illick, J.S. 1919. Whentreesgrow.Amer.
incense-cedar
the longest. Sugarpine required
Forestry
25: 1386-1390.
the leastnumberof daysto complete
50 percent
9.
Kienholz,
Raymond.1934. Leader,needle,
of its growthandincense-cedar
the most.
cambial,
and
root growth of certain coniA comparison
of the seasonal
radialgrowth
73-92.
Bot. Gaz. 96:
lastto startseasonal
growthand had the short10. MacDougal,D. T., and ForrestShreve.
estgrowingperiod.
1924. Growth in trees and massive orHeightgrowthof ponderosa
pinestartedvery
gans
of plants.Carnegie
Inst.Wash.Pub.
significantly
laterwitheachriseof 2,000feetin
350. 115 p., illus.
elevation. The lengthof the growingperiod
608
JOURNAL OF FORESTRY
11. MacDougal,D. T. 1936. Studiesin tree 14. Rees,L.W. 1924. Growth studiesin forest
growthby the dendrographic
method.Cartrees.PicearubraLink. Jour.Forestry27:
384-403.
negieInst. Wash. Pub. 462. 256 p., illus.
12. Pearson,G.A. 1924. The growingsea- 15.Reineke,
L.H. 1932.
• precision
dendromson of westernyellow pine (Pinus scopueter. Jour. Forestry 30: 692-697.
lorum). Jour.Agric.Research
29: 203-204. 16. Suedecor,G.W. 1937. Statisticalmethods.
13. Reed,J.F. 1939. Root and shootgrowth
Ames,Iowa. 341 p., illus.
of shortleaf and loblollypinesin relation 17. Tryon, H. H., and R. F. Finn. 1937.
to certain environmental
factors. Duke
Notes on the terminal growth of coniferUniv. SchoolForestryBull. No. 4, 52 p.,
ous plantationsin the Hudsonhighlands.
illns.
BlackRockForestPapers1:54-56.
National Defense--A Drain on the Timber Supply
Nearly3,000sawmills,
includingovera hundrednewmillssetup since1939,are
nowoperatingat full capacitythroughout
the Tennessee
Valley. Totalproductionof
thesemillsincreased
nearly12 percentfrom 1938through1940. Because
of defense
activities,
the NationalLumberManufacturers
Association
predictsa furtherincrease
of 21 percentin nationallumberproduction.
This increased
timberconsumption,
stimulated
by nationaldefense,
presents
a
seriousproblemwhenpresenttimbergrowthand drain are compared.Forestinventory and drain data showthat the 21/• billion feet of pine saw-timber
reservein the
Valleyis beingcut abouttwo andone-halftimesfasterthanit is growing,and depletion of the Valley's10 billion feet of pine and hardwoodsawtimberis at least70
percentgreaterthantheincrement.
The problemis lessseriouswhenall speciesandsizesof treesare combined.Consideringtreesunder as well as over sawlogsize,presentdrain exceedsgrowthonly
lightly. This balancecan, however,rapidly swingtowardthe depletionside by the
introductionof newwood-using
industriesandpulpmills.
Increaseddemandfor timber productsis alsoreflectedin rising stumpageand
lumberprices. Locallmnberpriceshaveincreased
$5 to $10 per thousand
boardfeet
within the pastyear. Stumpage
prices,in the sameperiod,havejust aboutdoubled.
A recenttimber sale on T.V.A. lands adjacentto the PickwickReservoirillustrates
very wellthe increased
demandfor pinesawtimberandthe resultinghigherstumpage
prices. On this operation,
pinetreesassmallas6 inchesin diameterbreasthigh are
beingcutasthinningsandsawedinto "roofers." Furthermore,
he bid $6.05perthousandInternationalrule. A year ago,the samestumpage
wouldprobablyhavebrought
no morethan $3.05 per thousand,and it wouldhavebeennext to impossible
to sell
the small,lessdesirabletreesneedingremovalto improvethe stand.
Notwithstanding
the profitsaccruingto timberoperators
andthe opportunities
to
practice
closerutilization
in managed
stands,
asa resultof increased
lumberdemands,
the net effectof nationaldefenseon timberconsumption
in the Valley will inevitably
be detrimentalto the long-timepublic interestsunlessstrenuous
effortsare madeto
directthe impetusinto constructive
channel.
s.--T.V.A. ForestLog, April 1941.