United States Department of Agriculture 

Defoliation Effects on Growth and Mortality 

of Three Young Southern Pine Species 

David R. Weise, Dale D. Wade, Ragnar W. Johansen, Haiganoush K. Preisler, 

David C. Combs, and Edward E. Ach 

DEPAR TMENT OF AGRICULT URE 

Forest Pacific Southwest Research Paper September

Service Research Station PSW-RP-267 2016 
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Authors 

David R. Weise is a research forester, Pacific Southwest Research Station, 4955 

Canyon Crest Drive, Riverside, CA 92507; Dale D. Wade is a research forester 

(retired), Southern Research Station, Hayesville, NC 28904; Ragnar W. Johansen 

is a research forester (retired) and Edward E. Ach is a forest technician (retired), 

Southeastern Forest Experiment Station, Macon, GA 31210; Haiganoush K. 

Preisler is a mathematical statistician, Pacific Southwest Research Station, 800 

Buchanan Street, West Annex Building, Albany, CA 94710; David C. Combs is a 

forester (retired), Southern Research Station, Athens, GA 30602. 

Cover photos: Young slash (Pinus elliottii Engelm.) (top), loblolly (P. taeda L.) (middle), and longleaf (P. palustris Mill.) (bottom) pines can experience substantial crown 

scorch from wild and prescribed fires and recover successfully. Top row photos: 

David J. Moorhead, University of Georgia, Bugwood.org; Middle row photo: USDA 

Forest Service, Southeastern Forest Experiment Station, C. Wayne Adkins; Bottom 

row photos: Johnny Stowe, South Carolina Department of Natural Resources. 
Abstract 

Weise, David R.; Wade, Dale D.; Johansen, Ragnar W.; Preisler, Haiganoush 

K.; Combs, David C.; Ach, Edward E. 2016. Defoliation effects on growth 

and mortality of three young southern pine species. Res. Pap. PSW-RP-267. 

Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 70 p. 

Foliage from loblolly (Pinus taeda L.), slash (P. elliottii Engelm.), and longleaf 

(P. palustris Mill.) pines was hand plucked to isolate the effects of level and timing of foliage removal on growth and mortality. Slash and loblolly pine received 

one of five defoliation treatments during one of four months: January, April, July, 

or October. Longleaf pine received one of three defoliation treatments during one 

of five 2-week periods from September to December. Growth and mortality were 

measured for each species for several years after treatment. Increased defoliation resulted in increased growth loss. Only total October defoliation caused 

significant mortality in loblolly and longleaf pine and moderate mortality in slash 

pine. Estimated difference in volume between control and defoliated trees after 

5 or 6 years ranged from 0 to 2.3 ft3

 (about 30 percent) per tree depending on 

species, defoliation season, and amount of defoliation. Trees receiving 95 percent 

or greater defoliation were generally smaller than the control trees after 13 or 19 

years posttreatment. 

Keywords: Defoliation, growth, mortality, d.b.h., height, fire damage, crown 

scorch, Pinus taeda, Pinus elliottii, Pinus palustris. 
Summary 

In the mid-1980s, the causes of mortality in young southern pines were unknown 

although there were several mechanisms that had been postulated. The effects of 

crown scorch (CS), the heat-caused killing of foliage by a fire, on survival and 

growth were strongly debated and study results were often contradictory. We established a study to separate the effects of foliage removal from the combined effects 

of damage caused by a fire. In 1986, a study using 1,200 loblolly (Pinus taeda L.) 

and slash (P. elliotii Engelm.) pines grown in four separate plantations was established, and the trees were treated with one of several levels of manual defoliation. 

Survival and growth were measured for 5 years. In 1993, a similar study using 450 

longleaf pines (P. palustris Mill.) was established at two locations and used a subset 

of the defoliation treatments. Survival and growth were measured for 6 years. 

Final measurements were made 13 and 19 years after treatment for the loblolly/ 

slash study and the longleaf study, respectively. Increased defoliation resulted in 

increased growth loss. Only total October defoliation caused significant mortality in 

loblolly and longleaf pine and moderate mortality in slash pine. Estimated difference in volume between control and defoliated trees after 5 or 6 years ranged from 

0 to 2.3 ft3

 (about 30 percent) per tree depending on species, defoliation season, and 

amount of defoliation. Trees receiving 95 percent or greater defoliation were generally smaller than the control trees after 13 or 19 years posttreatment. 
 

 

 

 

 

 

 

 

 

 

 

 

Contents
 

1 Introduction 

3 Methods 

3 Study Sites and Design 

5 Measurements 

6 Analysis 

9 Results 

9 Mortality 

9 Growth–All Species 

13 Growth Flushes–Loblolly and Slash Only 

14 Discussion 

17 Management Considerations 

18 Conclusions 

18 Acknowledgments 

18 Metric Equivalents 

19 Literature Cited 

24 Appendix 1: R Language Commands for Analyses 

30 Appendix 2: Diameter at Breast Height (d.b.h.) and Height Measurements 

37 Appendix 3: Linear Mixed-Effects Model Results 

63 Appendix 4: Fitted Growth Response Curves 

66 Appendix 5: Size of Treated Trees Relative to Untreated Trees 

1 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Introduction 

Southern yellow pines evolved with frequent fire and developed traits that allow 

them to survive fires that kill most tree species, including other pines (Agee 2000). 

Southern yellow pine ecosystems benefit from frequent fire, which has been extensively used throughout the Southern United States to manage loblolly (Pinus taeda 

L.), slash (P. elliottii Engelm.), and especially longleaf (P. palustris Mill.) pine 

ecosystems for well over three centuries (Demmon 1935, Long et al. 2004, Melvin 

2012, Van Doren 1928). Prescribed burns conducted within commonly accepted 

guidelines (e.g., Waldrop and Goodrick 2012) are unlikely to damage bole cambium 

once loblolly and slash pine exceed 2.5 inches basal diameter (Wade 1987) or when 

longleaf root-collar diameter exceeds 0.5 inches diameter (Brockway et al. 2006). 

If, however, a humus layer is present and consumed, basal stem and root 

damage will occur, typically resulting in substantial mortality irrespective of tree 

size (Ferguson et al. 1960; Varner et al. 2005, 2007; Wade and Johansen 1986). 

Regardless of tree size, care should always be exercised when burning to prevent 

thermal bud damage, which means keeping fireline intensity below about 500 Btu/ 

sec/ft (~150 Btu/sec/ft for trees under 10 ft in height) and not burning even under 

mature trees when most are in candle (buds elongating without protective needles) 

nor under no-wind conditions when ambient temperatures are above roughly 80° F. 

Crown scorch (CS), “browning [not blackening] of needles or leaves in the crown 

of a tree or shrub caused by heating to lethal temperature during a fire” (National 

Wildfire Coordinating Group 2014), is a precursor to bud and branch damage. 

Bud damage has significantly more deleterious consequences on survival (Storey 

and Merkel 1960, Wade 1985) than CS. Southern pines are, however, commonly 

subjected to severe CS with virtually no associated bud or cambial damage. Many 

natural resource managers have indicated that understanding the effects of CS alone 

is a high-priority knowledge gap in southern pine management. 

When fiber production is a management objective, knowledge of the type 

and magnitude of crown damage and likely duration of recovery is requisite to a 

meaningful decision to either remove the existing stand and replant, or to retain 

the plantation and accept any thermal thinning and reduced growth (Caulfield 

1987, Caulfield and Teeter 1988, Prestemon and Holmes 2008). Studies that link 

the physical processes of fire to resulting physiological processes are also needed 

(Chatziefstratiou et al. 2013). 

Planted southern pines, particularly loblolly and slash pine, reach merchantable 

size in less than 15 years so managers interested in maximizing fiber production 

need to act quickly to minimize length of time the site is unproductive, and, if trees 

are merchantable, to prevent the fairly rapid deterioration of wood quality from 
2 

RESEARCH PAPER PSW-RP-267

Reported results from 

crown scorch range 

from growth loss to 

growth gain. 

various pathogens. However, replacing a stand based on just its postfire appearance 

without inspecting tree crowns for bud damage can be a mistake from an economic 

standpoint. If bud damage is minimal, the financial return on one’s investment will 

be greater if the survivors are retained in spite of reduced volume at harvest (Wade 

and Ward 1975). When assessing crown damage, CS should be separated from 

needle blackening and consumption because the latter conditions signal more serious meristematic damage to branches and buds (Wade 1985, Wade and Johansen 

1986). When there are no blackened or consumed needles, that portion of the crown 

probably did not suffer bud or branch cambial damage, which is an excellent field 

indicator of probable southern pine survival. 

This study is confined to the effects of defoliation and does not address cambial 

damage to buds, lower stem, or roots. Prior to this study, neither the probability 

nor magnitude of mortality from defoliation of young healthy southern pine, nor 

the length of the recovery period of survivors had been quantified. A large body of 

published reports of postfire tree responses exists. Although the results are generally accurately reported, virtually all lack crucial information necessary to quantify 

their results. 

Growth is closely linked to amount of live foliage (Albaugh et al. 1998, Colbert 

et al. 1990). Numerous studies have shown defoliation caused by insects and disease 

or fire results in either death or a temporary reduction in growth because of the loss 

of photosynthetic surface area (Chambers et al. 1986, Duryea et al. 2007, Kulman 

1971). The effects of defoliation differ widely depending on season of defoliation, 

species, and tree size and vigor. Quantifying the effects of fire, however, is problematic. Fire is a dynamic force that cannot be truly replicated because spatial and 

temporal changes in weather, topography, and fuels continually modify fire behavior and intensity, which determine thermal damage; all of these factors confound 

the effects of CS and preclude partitioning the individual effects of thermal injury. 

Season of burn is also confounded with fire intensity in most fire studies (Knapp et 

al. 2009). 

Published results cover the full range of possibilities from significant growth 

losses with near-total CS in southern pines (Cain 1985, Lilieholm and Hu 1987, 

Storey and Merkel 1960) to significant growth gains with near-total CS (Jemison 

1943, Johansen 1975, Waldrop and Van Lear 1984). A few studies documented a 

slight increase in growth when CS was less than 33 percent, sometimes statistically 

significant (Villarrubia and Chambers 1978) and sometimes not (Gruschow 1952, 

Weise et al. 1987). The theory behind this ancillary prescribed fire benefit is that 

the lower crown receives little sunlight and thus foliage there requires more carbohydrates for maintenance than produced, resulting in a decrease in available energy 
3 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

for overall tree growth. We are aware of managers who purposely subject young 

longleaf to high fireline intensities to fire prune lower branches thereby enhancing 

the value of the butt log. 

To avoid problems associated with the confounding effects of fire, we designed 

a study to determine the effects of CS on young southern pine by hand plucking 

needles. We quantified the effects of season and amount of CS on survival and 

growth of planted, sapling-size loblolly and slash. Based on preliminary results for 

these species, we adjusted both treatment variables to better evaluate the effects 

in the followup longleaf pine study. Our objective was to determine the effects 

of various levels of crown defoliation and the physiological season in which they 

occurred on survival and growth. We did not attempt to mimic or explain the full 

array of responses to thermal defoliation, which could conceivably produce other 

heat-induced physiological changes. Our purpose is to provide guidelines for 

resource managers along with the data and analyses used to formulate those recommendations. Although we did not couple any actual fires with this study, the results 

presented herein agree with our combined 100+ years of field observations of the 

effects of fire on southern pine. 

Methods 

Study Sites and Design 

We established the loblolly and slash pine study in 4-year-old plantations (two locations each) in January 1986 and the longleaf pine study (two locations) in August 

1993 (fig. 1). Trees selected for this study were young dominant/codominant saplings large enough (basal diameter >2.5 in and height >8 ft to withstand low-intensity fire (Wade 1987). Soils at the loblolly pine sites on International Paper land in 

Bainbridge, Georgia (BAIN), and Westvaco land in Branchville, South Carolina 

(BRAN), were Wagram, a loamy, kaolinitic, thermic arenic Kandiudult and Alpin, 

a thermic coated lamellic Quartzipsamment, respectively. Soils at the slash pine 

sites on Union Camp land in Palatka, Florida (PLKA), and Georgia Forestry 

Commission (GFC) Dixon Memorial Forest near Waycross, Georgia (WAYC), were 

Leon, a sandy, siliceous, thermic aeric Alaquod and Blanton, a loamy, siliceous, 

semiactive, thermic grossarenic Paleudult. Soils at the longleaf sites on the Savannah River Forest Station (SRFS) near Aiken, South Carolina, and the GFC Dixon 

Memorial Forest near Waycross, Georgia (LWYC), were Lakeland, a thermic, 

coated typic Quartzipsamment and a mixture of Leon and Blanton, respectively 

(Soil Survey Staff 1999, n.d.). Mean annual precipitation at the six sites ranged from 

48 to 55 in, ambient temperature ranged from 64 to 81 °F, and elevation ranged 

from 15 to 130 ft above mean seal level (MSL). A lightning fire that went out on its 
4 

RESEARCH PAPER PSW-RP-267

Loblolly 

Slash 

Longleaf 

South Carolina 

Georgia 

Alabama 

Florida 

Atlantic Ocean 

Branchville 

Waycross 

SRFS 

0 25 50 100 Miles 

Bainbridge 

Palatka 

N

S

W E

Figure 1—Location of southern pine defoliation sites in the southeastern United States coastal plain. Dashed 

line represents the location of the Fall Line—the boundary between the coastal plain and the piedmont. SRFS = 

Savannah River Forest Station. 

own burned a portion of the Branchville, South Carolina, site sometime in February 

or early March 1988; trees within the burn perimeter were dropped from the study. 

At all six locations, a full factorial treatment design was replicated 15 times 

using a randomized complete block design. Slash and loblolly pines randomly 

received one of five defoliation levels (0, 33, 66, 95, or 100 percent) during one of 

four seasons (April, July, October 1986, or January 1987). The initial results of the 

loblolly and slash pine study showed mortality only after October 100 percent defoliation (Weise et al. 1989). Based on those results, longleaf pines randomly received 

one of three defoliation levels (0, 95, or 100 percent) during one of five late-summer 

to early winter defoliation times (nominally August 18, September 15, October 13, 

November 10, or December 8), 1993. A plantation row comprised a replication/ 

block. Study trees were healthy with good form at the time of selection and similar 

in size. We manually removed foliage beginning at the crown base and progressed 

upward through the crown as a fire would (fig. 2). 
5 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

USDA Forest Service, Southeastern Forest Experiment Station, Wayne Adkins 

Figure 2—Manual foliage removal started at the base of the tree simulated the effects of fire-caused crown scorch. The treatments 

left to right are 66 percent, 95 percent, and 100 percent of foliage volume removed. Control (0 percent) and 33 percent not pictured. 

Measurements 

Slash and loblolly pine diameter at breast height (d.b.h.) and total height measurement began in early 1986 prior to bud elongation. Annual measurement took place 

in January from 1987 through 1991 and in the fall of 1999. Terminal bud condition 

determined survival status. Lost tags (all sites), a wildfire (WAYC), and thinning 

(BRAN, WAYC) between 1991 and 1999 prevented relocating some of the study 

trees in 1999. About one-third of the trees were found (92, 105, 104, and 91 at 

BAIN, BRAN, PLKA, and WAYC, respectively). All treatments except for October 

100 percent at BAIN and BRAN1

 were represented. Because the thinning was 

performed by removing rows of trees and a row comprised an experimental block, 

the effect of the thinning on the experimental design simply reduced the number of 

blocks. We recorded the number of annual growth flushes only at BRAN and PLKA 

for the 1986, 1987, and 1990 growing seasons. 

Longleaf pine d.b.h. and total height measurement began in August 1993 

during the first defoliation treatment. Subsequent measurements took place January 

through February 1995, November 1995, August 1999, and April 2012. The 2012 

remeasurement located 60 and 124 longleaf pine at LWYC2

 and SRFS, respectively. 

All longleaf treatments except for 100 percent defoliation on November 10 (LWYC 

only) were represented. 

1 These two replications were on pulp and paper company lands, and stunted trees were 

likely removed after the study ended in 1991. 

2 The stand was thinned in 2009 by removing every third row. 

We treated 1650 

young southern pines 

tovarious defoliation 

treatments. 
6 

RESEARCH PAPER PSW-RP-267

 

 

 l 

During the 2012 measurement, one control tree and two 95 percent defoliated trees were tallied with dead terminal leaders, and one November 95 percent 

defoliated tree was classed as suppressed; long-term survival of these four trees is 

questionable. Over the course of both studies, several trees developed double leaders irrespective of treatment. The tallest leader was measured in such cases. 

Analysis 

The study initially contained 600 loblolly, 600 slash, and 450 longleaf pines (Weise 

et al. 2014). Removing loblolly pines within the wildfire burn area from BRAN 

reduced that count to 544. Because of site differences, we analyzed each location 

separately. While all of the techniques used permit calculation of the probability 

values associated with the statistics, we use the term “significant” to indicate probability values < 0.05 and do not specify exact probabilities. The R3

 code (R Core 

Team 2013) used to perform the various tests that follow can be found in appendix 1. 

Mortality— 

We estimated mortality rate (^

p ) for each defoliation level for the fall defoliated 

trees by location and species using ^

p = nd /n where nd = number of dead trees 

and n = number of trees treated for location/species. The 95 percent confidence 

interval for mortality probability was estimated using (eq. 1) where u and l are the 

upper and lower confidence bounds. When no trees died in a defoliation class, a 

97.5 percent upper confidence bound for mortality probability, p , was produced o

^ by p0= 1-(0.025)l/n0, where n is the number of trees in the defoliation class. o

ˆ

θ

σˆ 

σˆ 

( ) ( )

( ) 

( ) ( ) ( ) ( ) ˆ 

log 1 ˆ

ˆ ˆ 1 

ˆ ˆ ˆ 1 1 e 1 ˆ

p 

p 

p 

p p n 

p p p θ

θ σ

= −

− − −

= -

= + 

− pˆ

− ( ) −θˆ + 2σˆ

θ −θˆ + 2σˆθ

− ( ) −θˆ + 2σˆ

θ −θˆ + 2σˆθ

(1) 

u 

Growth—
	

Linear mixed-effects models were used to analyze d.b.h. and total height-growth 

response to defoliation (Meredith and Stehman 1991, Pinheiro and Bates 2000, 

Uzoh and Oliver 2008). The fixed effects were defoliation season (S) and defoliation 

level (D); time (T) since defoliation application was expressed as fractional years. 

3 The use of trade or firm names in this publication is for reader information and does not 

imply endorsement by the U.S. Department of Agriculture of any product or service. 
7 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Two random effects were included—the effect resulting from experimental block 

(plantation row) and the effect resulting from the individual tree (repeated measure). 

An autoregressive covariance structure of order 1 modeled the repeated measure 

random effect, which described the serial correlation between successive growth 

measurements. Tree size generally increased linearly with time; however, we 

included a quadratic time term for curvature in the growth curves (Meredith and 

Stehman 1991). Defoliation level was treated as a continuous effect, and interaction 

with defoliation season was included: 

Degrees of freedom 

Source Loblolly, slash Longleaf 

Season of defoliation (S) 

Defoliation level (D) 

D2 

3 

1 

1 

4 

1 

S × D interaction 3 4 

S × D2 3 

Time since treatment (T) 

T2 

1 

1 

1 

1 

S × T 3 4 

S × T2 3 4 

The degrees of freedom for the mean squared error term used in the tests of the 

fixed effects (season of defoliation and defoliation level) was 274 for BAIN, PLKA, 

and WAYC; 219 for BRAN; and 201 for each longleaf site. The mean squared error 

term used in the tests of the random effects (repeated measurement of d.b.h. and 

height) had more than 1,200 degrees of freedom. The lme routine in R was used to 

estimate the various terms using reduced maximum likelihood for each location 

separately. The season/time interaction tested the equality of the d.b.h. or height 

response over time between seasons. Owing to the smaller number of treatments and 

convergence issues in estimation for the longleaf data, all terms involving D2 were 

dropped so only the linear growth response owing to defoliation level was tested 

for longleaf pine. The ratio of the measured size of the treated trees to the untreated 

controls was calculated to determine relative growth response. The standard error 

of the ratio was estimated using the delta method (Oehlert 1992) and the standard 

errors estimated from the fitted growth models. Ninety-five percent confidence 

intervals (± 2.5 percent) were constructed to determine when the ratios were significantly different from 1. These calculations were performed for d.b.h. and height. 

To view the combined effects of the treatments, tree volumes were estimated 

using published equations. Kush et al. (2006) recommended the form-class 

segmented-profile equations developed by Clark et al. (1991) for plantation-grown 

longleaf pine; for consistency, we used coefficients for loblolly and slash pine from 

the same reference (eq. 2). Diameter outside bark at 17.3 ft was calculated using 
8 

RESEARCH PAPER PSW-RP-267

 

 

 

 

D.b.h, height, and 

volume growth were 

studied. 

species-specific coefficients (table 4 in Clark et al. 1991), and volume at total height 

was calculated using the species coefficients for the Gulf and Atlantic Coastal Plain 

subregion (table 12 in Clark et al. 1991) as all six sites are located below the Fall 

Line—the division between the Piedmont and Coastal Plain (dashed line in fig. 1; 

Fenneman 1928). Although other equations could be used to estimate volume, these 

equations suffice to enable comparison. 

I1d2

{[1 - GW][U1 - L1] + W[(1 - L1/h)

T (h - L1) - (1 - U1/h)T(h - U1)]/[r + 1]} 

+ I2I3{T [U2 - L2]+ Z[(1 - L2/h)

F (h - L2) - (1 - U2/h)F(h - U2)]/[p + 1]} 

b[U3 - L3] - b[(U3 - 17.3)2 - (L3 - 17.3)2

]/[h - 17.3] 

V = 0.005454 (2) [b / 3][(U - 17.3)3

 - (L3 - 17.3)3

]/[h - 17.3]2 

+ I4F2 

+ I5 / 3[(1 - b)/a2][a(h - 17.3) - (L3 - 17.3)]

3

/[h - 17.3] 2 

- I5 / 3[(1 - b)/a2][a(h - 17.3) - (L3 - 17.3)]

3

/[h - 17.3] 2 

Where V is volume (ft3), I

1 to I6 are indicator variables, d is d.b.h. (inches), 

F is diameter at 17.3 ft, G, T, W, and Z are combined variables involving d.b.h., 

height and F, L, and U are lower and upper heights of interest, and a, b, p, and r are 

regression coefficients tabulated in Clark et al. (1991). In addition to the growthresponse modeling described above in which defoliation was treated as a continuous 

variable, we performed an additional analysis to determine if the defoliated trees 

were smaller than the control trees at the 5- or 6-year measurement. Dunnett’s test, 

which is a multiple comparison test that compares the treatment values with the 

control value, was performed using the multcomp procedure (Bretz et al. 2011, p. 

101). Analysis of variance was first performed; specific contrasts comparing growth 

for each defoliation percentage (33, 66, 95, and 100) with the control (0) were then 

tested simultaneously to maintain an overall 0.05 probability level. 

Loblolly, slash, and longleaf pine do not have fully preformed buds meaning 

that after initial spring shoot elongation, additional elongations (flushes) can, and 

typically do, occur through late summer (Lanner 1976). The effects of defoliation 

season, level, and time since treatment on the number of growth flushes (a discrete 

variable) were estimated using generalized linear models (R routine glm) (Agresti 

2013) assuming the Poisson distribution. Preliminary analysis revealed that overdispersion (variance greater than would be expected for a Poisson distribution) was not 

an issue for these data. While we initially analyzed the number of flushes at all four 

sites (Weise et al. 1987), 3 years of measurement (before and after defoliation) were 

only available for the BRAN and PLKA locations so these are the only two sites 

analyzed herein. 
9 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Loblolly

Bainbridge

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Branchville

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Waycross

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Slash

Palatka

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Longleaf

Waycross

1.0

0.8

0.6

0.4

0.2

0.0

0% 95% 100%

SRFS

1.0

0.8

0.6

0.4

0.2

0.0

0% 95% 100%

Results 

Mortality 

Loblolly and slash pine mortality occurred only after 100 percent defoliation in 

October (25 of 30 loblolly and 6 of 30 slash). Nearly all mortality occurred the 

first growing season following defoliation (all loblolly, five of the six slash pines). 

Mortality in longleaf occurred almost exclusively in the October and November 100 

percent treatments at both locations (34 of 60 trees); one tree each in September 100 

percent and December 100 percent treatments, and one tree receiving 95 percent 

defoliation in September also died. Nonoverlapping confidence intervals support the 

visually obvious difference between mortality after 100 percent foliage removal and 

all other levels for all three species (fig. 3). As would be expected given that treatments were randomly assigned to each tree at all locations, t-tests comparing initial 

d.b.h. and height of dead and living trees did not detect size differences. 

Growth–All Species 

Before discussing the effects of treatments on growth, the d.b.h., height, and 

estimated volume of the control trees are presented as a reference point (table 1) 

for each location. When averaged by species, loblolly pine size increased the most 

followed by slash and longleaf. Diameter at breast height increased by 4.2, 2.5, and 

1.9 in, and height increased by 22.1, 17.4, and 15.3 ft for loblolly, slash, and longleaf 

pine, respectively, over the 5- or 6-year period of the original studies (table 1). After 

13 years, the remaining loblolly pines continued to outgrow the remaining slash 

pines over the same time period with d.b.h. growth of 7.2 versus 4.7 in and height 

growth of 52 versus 43.1 ft. Diameter at breast height of the longleaf pine 19 years 

posttreatment (5.7 in) was similar to loblolly pine at 5 years (5.9 in) and slash pine 

at 13 years (6.8 in). Longleaf was the shortest of the three species as indicated by 

the final measurements. The difference in growth between species was particularly 

apparent in the final measurements. At 13 years posttreatment, mean loblolly 

volume was nearly double the volume of slash pine. At 19 years posttreatment, the 

longleaf pines were less than one-third the size of the loblolly at 13 years: 

Volume (ft3

) 

Species Initial Study end Final 

Loblolly 0.0 3.1 14.1 

Slash 0.0 1.7 7.5 

Longleaf 0.0 1.1 4.4 

Only 100 percent 

October defoliation 

caused mortality in 

loblolly and slash 

pines. 
10 

RESEARCH PAPER PSW-RP-267

Loblolly

Bainbridge

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Branchville

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Waycross

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Slash

Palatka

1.0

0.8

0.6

0.4

0.2

0.0

0% 33% 66% 95% 100%

Longleaf

Waycross

1.0

0.8

0.6

0.4

0.2

0.0

0% 95% 100%

SRFS

1.0

0.8

0.6

0.4

0.2

0.0

0% 95% 100%

Figure 3—Estimated mortality probabilities and two-sided 95 percent confidence bounds for different 

levels of fall defoliation of loblolly, longleaf, and slash pine. When mortality = 0, one-sided 97.5 percent 

confidence bound displayed. SRFS = Savannah River Forest Station. 

Table 1—Mean (standard deviation) growth of control (undefoliated) young southern pines 

Diameter at breast height Height 

Species Location Initial Study end Final Initial Study end Final 

-----------------Inches----------------- ----------------Feet------------------

Loblolly Bainbridge, 1.6 (0.4) 5.3 (0.6) 8.7 (1.0) 11.0 (1.7) 32.9 (2.2) 64.3 (3.1) 

Georgia 

Branchville, 1.8 (0.6) 6.7 (0.8) 9.1 (1.6) 10.7 (2.0) 33.1 (2.2) 63.4 (5.9) 

South 

Carolina 

Average 1.7 5.9 8.9 10.9 33.0 63.9 

Slash Palatka, 2.1 (0.4) 4.5 (0.6) 6.6 (1.0) 12.1 (2.1) 30.1 (2.0) 53.2 (5.7) 

Florida 

Waycross, 2.1 (0.4) 4.7 (0.6) 7.2 (0.8) 12.0 (1.8) 28.7 (2.5) 57.7 (3.5) 

Georgia 

Average 2.1 4.6 6.8 12.0 29.4 55.1 

Longleaf Aiken, South 1.7 (0.2) 3.3 (0.4) 5.0 (0.8) 10.0 (1.2) 23.9 (2.1) 40.6 (3.8) 

Carolina 

Waycross, 1.8 (0.3) 4.2 (0.6) 7.0 (0.9) 10.2 (1.1) 27.0 (2.6) 45.5 (4.1) 

Georgia 

Average 1.8 3.7 5.7 10.1 25.4 42.3 

Note: Study end measurements performed 5 years after treatment for loblolly and slash pine and 6 years for longleaf pine. 

Final measurements performed at 13 years for loblolly and slash pine and at 19 years for longleaf pine. 
11 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

As would be expected, mean size of all trees that survived the defoliation treatments increased over time (tables 4 to 7 in app. 2). The coefficient of variation (CV) 

for d.b.h. ranged from 0 to 37 percent and from 0 to 32 percent for height (table 8 

in app. 2). The variability of d.b.h. was slightly higher than the variability of the 

height data (mean CV was 14 percent and 9 percent for d.b.h. and height, respectively). Analysis of variance of the fitted growth curves revealed some common 

trends between the species. Season of defoliation (month for longleaf) significantly 

affected d.b.h. and height growth at five of the six locations (not significant for longleaf at LWYC). The percentage of defoliation affected d.b.h. and height at all six 

locations. Interaction between season and time significantly affected d.b.h. of slash 

and loblolly and height for all three species indicating different growth response 

curves between seasons (months) (app. 4, figs. 8, 9). 

The growth trend in d.b.h. and height was predominantly linear over time with 

some curvature for all three species at all locations; however, the curves fit to the 

first 5 or 6 years of data did not fit the longer term 13- and 19-year growth data 

(fig. 4) well. The full set of curves can be found in appendix 4 (figs. 8 and 9). The 

short-term model consistently overestimated d.b.h. for all longleaf (fall) and for 

spring, fall, and winter defoliation at one loblolly and for summer, fall, and winter 

at one slash site. At BAIN, observed d.b.h. for the 100 percent October defoliation 

did not fall on the fitted curve (circled data points) at all. A growth curve for the 5 

years of d.b.h. data at PLKA is not shown because the algorithm did not converge; 

however, the algorithm was able to fit a growth curve for the 13 years of d.b.h. 

data. The short-term height growth curves also tended to overestimate the longterm height data for all three species except loblolly at BRAN with all levels of 

summer defoliation. 

The results of Dunnett’s test to determine if the 5- or 6-year treatment means 

were greater than or equal to the control mean are displayed in table 2. For the 100 

percent defoliation, we rejected the null hypothesis that the d.b.h. of all three species at all six sites, and heights at one loblolly and all slash and longleaf sites were 

greater than or equal to the control trees. Similarly, we rejected the null hypothesis 

for 95 percent defoliation at all loblolly and slash and one longleaf site for d.b.h. as 

well as height at both slash and one loblolly and one longleaf site. This indicated 

that mean d.b.h. and height of the trees, which received 95 and 100 percent defoliation were significantly smaller than the controls for all three species at the end of 

the original study in most cases. 
12 

RESEARCH PAPER PSW-RP-267

1986 1987 1989 1986 1987 1989 1986 1987 1989 1986 1987 1989

1986 1987 1989 1986 1987 1989 1986 1987 1989 1986 1987 1989 July January July Year Year

Slash

April October April October

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

5

4

3

2

1

0

100

66

0

100

66

0

95

33

95

33

Loblolly

January

Year

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o o

o

o

o o

o

o

o

o

o

o

o

o

o

o

o o

o

o o

o

o

o

o

o

o

o

o

o

o o

o

o

o

o

o

o

o

o

o

o

o

o

o

o o

o

o

o o o

o

o

o

o o

o

o o

o

o o

o

o o

o

o o

o

o o

o

o o

o

o o

o

o

o o o

o

o

o

o o o o

o

o

o o

o

o o

o o

o

o o

o

o o

o

Figure 4—Estimated means (line) and observed medians (○) for number of height growth flushes produced annually by young loblolly 

(BRAN) and slash (PLKA) pines for various levels of seasonal defoliation. 

Table 2—Summary of Dunnett’s test to determine if diameter at 

breast height (d.b.h.) and height of defoliated southern pines are 

greater than or equal to d.b.h. and height of controls 

D.b.h. Height 

Species Location 33 66 95 100 33 66 95 100 

Loblolly Bainbridge, Georgia * ** *** *** * ** 

Branchville, South * * 

Carolina 

Slash		 Palatka, Florida * *** ** * 

Waycross, Georgia ** ** * *** 

Longleaf Aiken, South Carolina ** * 

Waycross, Georgia ** *** * *** 

Note: * indicates probability of a greater t-value is less than 0.05, ** indicates 

probability of a greater t-value is less than 0.01, *** indicates probability of a 

greater t-value is less than 0.001. The 33 and 66 percent treatments were not 

applied to longleaf pine. 

The ratio of observed d.b.h., height, and calculated volume of the treated trees 

to the control trees is another measure to determine similarity, and these ratios are 

located in appendix 5 (figs. 7, 8, and 9). The estimated confidence intervals around 

one used to determine if the ratios were equal to one are also shown in the figures. 

Summarized test results (by species across seasonal treatments) determining if the 

observed ratios were less than, equal to, or greater than one suggest that d.b.h. and 

height of all three species experiencing 95 or 100 percent defoliation did not regain 

the lost growth increment even though the fitted growth rates recovered: 
13 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Measurement time 

Species Study end Final 

Loblolly D.b.h. and height of 95 and 100 D.b.h. and height of 95 and 100 

percent less than controls; d.b.h. percent less than controls; d.b.h. 

of many 66 percent defoliation and height of many 33 percent 

less than controls greater than controls 

Slash D.b.h. and height of all 66, 95, and D.b.h. and height of most 66, 95, 

100 percent less than controls and 100 percent less than controls 

Longleaf D.b.h. and height of nearly all 95 D.b.h. and height of nearly all 95 

and 100 percent less than controls; and 100 percent greater controls; 

none greater than controls none greater than controls 

The combined effects of the treatments on d.b.h. and height were evident in the 

plots of the volume ratio (fig. 9). In most cases, the ratio of the volume of trees that 

lost 66 percent or more of their foliage and the control trees was significantly less 

than one for all three species at the original study end (5- or 6-year) measurements. 

Many of the slash and longleaf pines, in particular, had less volume at the final 

measurement as well. The 33 percent defoliation treatment often resulted in loblolly 

pines larger than the controls. 

Volume difference between the defoliated and control trees for all three species 

ranged from -2.3 to -0.1 ft3

 at the study end measurements 5 or 6 years after treatment (table 3) indicating that the defoliated trees were smaller than the control trees 

at this time. The range of longer term differences in volume growth was -3.8 to 2.1, 

-5.4 to -0.2, and -2.3 to -0.5 ft3 for loblolly, slash, and longleaf pines, respectively. 

Note that loblolly pine showed greater volume growth than the control trees for 

some of the defoliation treatments. 

One might expect January defoliation to have the smallest impact as the trees 

are without full foliage for the least amount of time with this treatment month; but 

that was not the case for slash pine where neither October 33 percent nor July 33 

percent and 66 percent had a negative effect on volume increment. The gap between 

volume of the controls and defoliated slash pines was still increasing at last measurement for all January levels and for October 95 and 100 percent. Defoliation had 

little effect on longleaf volume growth, particularly after defoliation in November. 

The maximum gap was less than 0.5 ft3

 after all treatment dates. Although longleaf 

had the longest time interval between initial and study-end measurement, at the 

study-end measurement, it still only had a mean estimated volume of 2.8 ft3 compared to 5.7 for slash and 15.9 for loblolly. 

Growth Flushes—Loblolly and Slash Only 

The trees at BRAN (loblolly) and PLKA (slash) reacted differently to defoliation 

treatments (fig. 4). At BRAN, the mean number of growth flushes decreased in 

1987, the year following defoliation, and returned to the pretreatment number by 

Defoliated trees were 

often still smaller than 

controls after 13 or 

19 years 
14 

RESEARCH PAPER PSW-RP-267

Table 3—Range of mean difference between estimated volume of defoliated

 and control treesa 

Study end Final 

Species Defoliation time Minimum Maximum Minimum Maximum 

- - - - - - - - - - - - - - Cubic feet - - - - - - - - - - - - - -

Loblolly April 

July 

October 

-0.9 

-1.0 

-2.3 

-0.4 

-0.1 

-0.2 

-3.8 

-3.7 

-2.2 

0.8 

2.1 

1.5 

January -0.9 -0.3 -2.4 0.6 

Slash April 

July 

October 

-0.5 

-0.7 

-1.0 

-0.2 

-0.1 

-0.1 

-3.0 

-3.8 

-4.6 

-0.9 

-0.2 

-0.6 

January -0.9 -0.4 -5.4 -0.5 

Longleaf August 

September 

October 

-0.4 

-0.3 

-0.6 

-0.3 

-0.3 

-0.4 

-1.1 

-1.6 

-2.3 

-0.8 

-1.5 

-1.6 

November -0.4 -0.2 -1.9 -0.5 

December -0.6 -0.4 -0.8 -0.7 

Note: Study end measurements performed 5 years after treatment for loblolly and slash pine and 6 years for longleaf pine. 

Final measurements performed at 13 years for loblolly and slash pine and at 19 years for longleaf pine. Positive value 

indicates volume of defoliated tree was larger than undefoliated control.
	 a Mean value initially calculated for each level of defoliation (33, 66, 95, 100 percent) at each location and then minimum 

and maximum value of mean determined for each treatment time by species.
	

the end of the 1989 growing season. In contrast, the number of slash pine flushes 

at PLKA decreased the year following treatment and continued to decline through 

1989, the last year flushes were tallied. Season and defoliation level did not affect 

the number of flushes for loblolly; defoliation level did affect the number of flushes 

in slash pine. The response over time was quadratic in loblolly and linear in slash. 

Our limited data set did not allow us to determine if this behavior occurred at the 

other two sites. For comparison purposes, the observed medians are included in 

figure 4. 

Discussion 

All 600 loblolly and 600 slash (including 120 control trees for each species) 

survived all treatment combinations except complete foliage removal in October; 

that one treatment combination resulted in high mortality for loblolly pine (25 of 

30 trees) and moderate mortality for slash pine (6 of 15 trees) at one of the two 

slash pine study locations. For unknown reasons, no slash pine died at WAYC. 

We do not know why all slash pine completely defoliated in October at Waycross 

survived while 40 percent of the same treatment died at Palatka, but we note 

the exceptional growth recovery of scorched trees reported by Johansen (1975) 

occurred within a few miles of this study area. The trees that died at Palatka were 

similar in size to surviving trees. There is obviously still much to learn regarding 

factors that determine recovery/mortality after severe defoliation. Genetically 
15 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

“improved” planting stock was used at each site, so differences in survival could 

be physiological rather than physiographical. 

Of the 450 longleaf (including 150 control trees), mortality was confined to the 

100 percent defoliation treatment except for a single tree that died after 95 percent 

foliage removal in August. Thirty-two of the 60 longleaf subjected to complete 

foliage removal in October or November died along with one each after September 

and December defoliation. 

Most surviving trees of all three species, however, suffered significant growth 

retardation compared to the controls. Although rate of growth recovered and the 

gap in tree volume between treated trees and controls was, in many cases, decreasing at last measurement, size differences were still visually obvious in many cases. 

There was no statistical difference in tree size when study trees were selected. 

Similar results have been reported in other studies. For example, Tew et al. (1989) 

reported that scorch greater than 80 percent from a November burn in a 14-yearold loblolly plantation killed 12 percent of the trees (all during the first postburn 

year), reduced d.b.h. growth by 97 percent the first year, and by 60 percent over the 

first 4 postburn years when compared to trees with no scorch. Increased foliage 

removal increased depression of growth, although height growth was less affected 

than radial growth. In that study, differences in diameter growth disappeared in the 

fourth postburn growing season. Similarly, Johansen and Wade (1987) reported CS 

exceeding 95 percent following a January burn reduced 2-year d.b.h. growth by 60 

percent in a 25-year-old slash pine plantation. 

Determination of growth responses to severe crown injury should include the 

possibility of missing tree rings. Their presence can be determined by using the 

pith or a wide reference ring to establish proper dating. Failure to determine their 

presence can result in invalid conclusions, which in turn could deleteriously affect 

future prescribed burn planning decisions. 

The life-threatening consequences of complete fall defoliation on southern pine 

are apparently due to the lack of photosynthate. Southern pines produce photosynthate year round; the amount produced dependent upon the amount of live foliage. 

This ability to produce photosynthate year-round means these species do not have 

to store large reserves of carbohydrate (starch) (Kozlowski 1992). But that doesn’t 

mean belowground reserves are not crucial for foliage production and maintenance. 

During the growing season, young southern pines use more starch than they 

produce to put on root, stem, and crown growth, nearly exhausting their starch 

reserves (e.g., Gholz and Cropper 1991, Kuehler et al. 1999, Ludovici et al. 2002). 

The photosynthate produced between the last flush of summer and budbreak the following spring is used to fulfill maintenance respiration requirements and to rebuild 

reserves. Gholz and Cropper (1991) showed that slash pine in Florida gained 19 

Not accounting for 

missing tree rings can 

cause spurious results. 
16 

RESEARCH PAPER PSW-RP-267

percent of its annual carbon during the winter. Onset of height and radial growth in 

spring requires substantial resources so if a lack of foliage prevents replenishment 

of these supplies, we hypothesize there may not be enough for spring budbreak. 

There is also a pulse of fine-root production in spring and early summer, which also 

requires considerable photosynthate (Sayer and Haywood 2006). 

Foliage removal interrupts the production of photosynthate thereby limiting the 

amount available for maintenance and growth. In this study as well as others (e.g., 

Haywood et al. 2004, Tew et al. 1989), defoliation affected radial growth more than 

height growth. In fact, removal of 66 percent of the foliage in our study had only 

minor effects on height growth of all three species. Photosynthetic tissues have a 

higher priority than diameter growth or storage tissues (Sword and Haywood 1999, 

Waring and Schlesinger 1995). Thus after crown damage, available starch will be 

redirected to refoliation, and there may not be enough remaining for radial growth, 

hence a missing ring. This would explain why height growth was not as severely 

impacted as diameter growth in our study, but leaves us in a quandary regarding 

work by Wahlenberg (1939) and McCulley (1950) who reported height growth was 

more depressed than radial growth. Further discussion of carbohydrate dynamics 

can be found in Kozlowski (1992) and Little and Pharis (1995). 

As southern pines become biologically mature, the amount of photosynthate 

required to maintain respiration approaches the amount produced so when trees 

reach this stage in their life cycle, even minor damage can result in mortality; that 

said, the base of the live crown of such trees is typically high enough that the lethal 

thermal threshold is not reached, particularly during dormant season burns. On the 

other hand, burning under inappropriate weather conditions such as when winds are 

calm and ambient temperature is above 90 °F can result in severe crown damage 

and death of even large mature longleaf (e.g., Boyer 1990). 

Martin and Mitchell (1980, p.142) lamented that fire-insect interactions had 

received little attention and that “increased knowledge of interactions can lead to 

greatly improved and ecologically sound forest and range management.” Secondary 

pests often infest trees after defoliation (Craighead and St. George 1928, Storey 

and Merkel 1960) and can be either assassins or undertakers (Menges and Deyrup 

2001). But there are also many cases where insect infestations have not followed 

severe fires (e.g., Ferguson et al. 1960, Hanula et al. 2003). The literature pertaining 

to bark beetle infestation after fire raises more questions than answers regarding 

conditions that favor attack, (e.g., Fischer 1980, Hanula et al. 2003, Santoro et al. 

2001). Many postfire reports (Dixon et al. 1984, Hanula et al. 2003, Storey and 

Merkel 1960, Sullivan et al. 2003) do not support the old adage that exploding 

bark beetle populations follow severe fire. In fact, Hanula et al. (2003) found lower 

populations of Ips spp. and Dendroctonus spp. (the assassins) in burned areas than 
17 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

in the controls; they also recorded increases in Temnochila virescens, a bark beetle 

predator, in burned areas and in ambrosia beetles (Xyleborus spp. and Monarthrum 

mali), which eat dead wood (the undertakers). Of a more serious nature, they found 

more than 75 percent of surviving trees were infected with Leptographium and/ 

or Graphium spp. compared to none in unburned areas; they speculate that trees 

weakened by this root disease may succumb in the future. 

Considerable genetic work has been conducted on these three species to 

increase growth rates, and all six locations were planted using genetically improved 

seedlings. The effect of these genetic alterations on photosynthate storage and 

allocation and thus recovery from severe defoliation is beyond the scope of this 

paper but a topic we think worthy of pursuing. It would also be of interest to track 

changes in root, stem, and branch carbohydrates after treatments such as those 

applied in this study. It has been suggested that other physiological changes such 

as the formation of resin ducts, and differences in and between early and late wood 

with respect to defoliation severity and timing are currently open questions that are 

worthy of future study. 

Management Considerations 

Although southern pine will survive complete CS during most seasons, it typically 

reduces both radial and height growth, is unsightly, and fosters negative images of 

prescribed fire in the minds of the public who will ultimately determine the future 

of intentional fire. When planning and executing prescribed fires to minimize CS 

and thermal bud damage (which is considerably more serious), the following should 

be considered: 

Pay attention to forecast minimum windspeed; very low windspeeds mean heat 

energy produced may not be cooled below the lethal temperature threshold before 

reaching tree crowns. With light and variable winds, lulls in the wind will occur 

resulting in vertical flames, thereby reducing the distance between flame tips and 

the base of the crown. 

Pay attention to forecast maximum windspeed and any mention of wind 

gusts; increased windspeed will dissipate the heat energy produced more 

quickly, but depending upon firing technique, can also increase flame length 

and fireline intensity. 

If the forecast wind direction contains the word “variable,” changes in wind 

direction are likely, which will influence rate of fire spread and thus flame length 

and fireline intensity. 

Do not use ignition patterns that will allow lines of fire to merge together all at 

once; substantial increases in flame height invariably occur along the juncture line. 

Before you ignite a fire when offsetting increased ambient temperature against 

Plan prescribed burns 

to minimize crown 

scorch and thermal 

bud damage. 
18 

RESEARCH PAPER PSW-RP-267

 

increased windspeed, be reasonably sure that the balance can be operationally 

achieved while keeping fireline intensity within planned limits. 

Pay attention to the forecast time period the weather will accommodate your 

burn prescription; calculate the number of hours it will take to execute the burn 

using the planned firing technique(s) to make sure the burn will be completed 

within the forecast prescription window. 

Vary season, burning conditions and technique on an area over time, and be 

very careful when conducting fall burns because of the specter of mortality after 

severe crown scorch at this time of year. 

Consider postponing a burn in sapling-size southern pine when a majority of 

the trees are in candle because of the potential lethal consequences of bud kill. 

Conclusions 

Results of this study show postfire mortality of young planted loblolly, slash, and 

longleaf pines with less than complete CS is rarely due to foliage loss alone. Even 

with total loss of foliage, mortality is very unlikely unless defoliation occurs during 

October or November. Based on the results herein, we conclude prescribed fires can 

be scheduled and safely conducted throughout the year to achieve many resource 

objectives while avoiding southern pine mortality and minimizing growth loss 

owing to CS. 

Further work is needed to better quantify postfire mortality from root and bud 

damage in southern pine and should be extended to include shortleaf (Pinus echinata Mill.) pine. We also suggest trees in this study be relocated at some point in 

the future to again compare the volume of treated trees with that of the controls. 

Acknowledgments 

The authors thank the Georgia Forestry Commission, International Paper Company, 

Union Camp Corporation, and Westvaco for their generous support of this study. 

Metric Equivalents 

When you know: Multiply by: To find: 

Inches (in) 2.54 Centimeters 

Feet (ft) .305 Meters 

Miles (mi) 1.609 Kilometers 

Cubic feet (ft3

) .0283 Cubic meters 

Degrees Fahrenheit .56(°F - 32) Degrees Celcius 

British thermal units (Btu) 1,050 Joules 
19 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

 

Literature Cited 

Agee, J.K. 2000. Fire and pine ecosystems. In: Richardson, D.M., ed. Ecology and 

biogeography of Pinus. Cambridge, United Kingdom: Cambridge University 

Press: 193–218. 

Agresti, A. 2013. Categorical data analysis. 3rd ed. Hoboken, NJ: Wiley. 714 p. 

Albaugh, T.J.; Allen, H.L.; Dougherty, P.M.; Kress, L.W.; King, J.S. 1998. Leaf 

area and above- and belowground growth responses of loblolly pine to nutrient 

and water additions. Forest Science. 44(2): 1–11. 

Bretz, F.; Hothorn, T.; Westfall, P. 2011. Multiple comparisons using R. Boca 

Raton, FL: Chapman & Hall/CRC Press. 187 p. 

Cain, M.D. 1985. Prescribed winter burns can reduce the growth of nine-yearold loblolly pines. Res. Note SO-312. New Orleans, LA: U.S. Department of 

Agriculture, Forest Service, Southern Forest Experiment Station. 4 p. 

Caulfield, J.P. 1987. Decision analysis in damaged forest plantations. Forest 

Ecology and Management. 22(1/2): 155–165. 

Caulfield, J.P.; Teeter, L.D. 1988. Using break-even analysis for replanting 

decisions in damaged pine stands. Southern Journal of Applied Forestry. 

12(3): 186–189. 

Chambers, J.L.; Dougherty, P.M.; Hennessey, T.C. 1986. Fire: its effects on 

growth and physiological processes in conifer forests. In: Hennessey, T.C.; 

Dougherty, P.M.; Kossuth, S.V.; Johnson, J.D., eds. Stress physiology and forest 

productivity. Dordrecht, Netherlands: Springer Netherlands: 171–189. 

Chatziefstratiou, E.K.; Bohrer, G.; Bova, A.S.; Subramanian, R.; Frasson, 

R.P.M.; Scherzer, A.; Butler, B.W.; Dickinson, M.B. 2013. FireStem2D–a 

two-dimensional heat transfer model for simulating tree stem injury in fires. 

PLoS ONE. 8(7): e70110. 

Clark, A.I.; Souter, R.A.; Schlaegel, B.E. 1991. Stem profile equations for 

southern tree species. Res. Pap. SE-282. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southeastern Forest Experiment Station. 113 p. 

Colbert, S.R.; Jokela, E.J.; Neary, D.G. 1990. Effects of annual fertilization 

and sustained weed control on dry matter partitioning, leaf area, and growth 

efficiency of juvenile loblolly and slash pine. Forest Science. 36(4): 995–1014. 

Demmon, E.L. 1935. The silvicultural aspects of the forest fire problem in the 

longleaf pine region. Journal of Forestry. 33(3): 323–331. 
20 

RESEARCH PAPER PSW-RP-267

Duryea, M.L.; Kampf, E.; Littell, R.C. 2007. Hurricanes and the urban forest: 

I. effects on southeastern United States coastal plain tree species. Arboriculture 

and Urban Forestry. 33(2): 83–97. 

Fenneman, N.M. 1928. Physiographic divisions of the United States. Annals of the 

Association of American Geographers. 18(4): 261–353. 

Gholz, H.L.; Cropper, W.P.J. 1991. Carbohydrate dynamics in mature 

Pinus elliottii var. elliottii trees. Canadian Journal of Forest Research. 

21(12): 1742–1747. 

Gruschow, G.F. 1952. Effect of winter burning on growth of slash pine in the 

flatwoods. Journal of Forestry. 50(7): 515–517. 

Johansen, R.W. 1975. Prescribed burning may enhance growth of young slash 

pine. Journal of Forestry. 73(3): 148–149. 

Johansen, R.W.; Wade, D.D. 1987. Effects of crown scorch on survival and 

diameter growth of slash pines. Southern Journal of Applied Forestry. 

11(4): 180–184. 

Knapp, E.E.; Estes, B.L.; Skinner, C.N. 2009. Ecological effects of prescribed 

fire season: a literature review and synthesis for managers. Gen. Tech. Rep. 

PSW-GTR-224. Albany, CA: U.S. Department of Agriculture, Forest Service, 

Pacific Southwest Research Station. 80 p. 

Kozlowski, T.T. 1992. Carbohydrate sources and sinks in woody plants. The 

Botanical Review. 58(2): 107–222. 

Kuehler, E.A.; Sword, M.A.; Andries, C.D. 1999. Seasonal fine-root 

carbohydrate and growth relations of plantation loblolly pine after thinning and 

fertilization. In: Haywood, J.D., ed. Proceedings of the 10th biennial southern 

silvicultural research conference. Gen. Tech. Rep. SRS-030. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southern Research Station: 420–425. 

Kulman, H.M. 1971. Effects of insect defoliation on growth and mortality of trees. 

Annual Review of Entomology. 16: 289–324. 

Kush, J.S.; Goelz, J.C.G.; Williams, R.A.; Carter, D.R.; Linehan, P.E. 2006. 

Longleaf pine growth and yield. In: Jose, S.; Jokela, E.J.; Miller, D.L., eds. The 

longleaf pine ecosystem: ecology, silviculture, and restoration. New York, NY: 

Springer: 251–267. 
21 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Lanner, R.M. 1976. Patterns of shoot development in Pinus and their relationship 

to growth potential. In: Cannell, M.G.R.; Last, F.T., eds. Tree physiology and 

yield improvement. London: Academic Press: 223–241. 

Lilieholm, R.J.; Hu, S.C. 1987. Effect of crown scorch on mortality and diameter 

growth of 19-year-old loblolly pine. Southern Journal of Applied Forestry. 

11(4): 209–211. 

Little, C.H.A.; Pharis, R.P. 1995. Hormonal control of radial and longitudinal 

growth in the tree stem. In: Gartner, B.L., ed. Plant stems: physiology and 

functional morphology. San Diego, CA: Academic Press: 281–319. 

Long, A.J.; Behm, A.; Cassidy, L.; DiMartino, D.; Doran, D.; Freeman, D.; 

Helmers, J.; Keefe, K.; Miller, A.; Ranasinghe, S.; Randall, C.; Rasser, M.; 

Ruth, A.; Shipley, D.; Van Loan, A. 2004. Prescribed fire and slash pine. In: 

Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. Slash pine: still 

growing and growing! Proceedings of the slash pine symposium. Gen. Tech. 

Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service, 

Southern Research Station: 66–78. 

Ludovici, K.H.; Allen, H.L.; Albaugh, T.J.; Dougherty, P.M. 2002. The 

influence of nutrient and water availability on carbohydrate storage in loblolly 

pine. Forest Ecology and Management. 159(3): 261–270. 

Melvin, M.A. 2012. 2012 national prescribed fire use survey report. Tech. 

Rep. 01-12. [Location of publisher unknown]: Coalition of Prescribed Fire 

Councils, Inc. 19 p. http://www.stateforesters.org/sites/default/files/publicationdocuments/2012_National_Prescribed_Fire_Survey.pdf. (18 March 2015). 

Meredith, M.P.; Stehman, S.V. 1991. Repeated measures experiments in forestry: 

focus on analysis of response curves. Canadian Journal of Forest Research. 

21(7): 957–965. 

National Wildfire Coordinating Group. 2014. Glossary of wildland fire 

terminology. PMS 205. Boise, ID: National Wildfire Coordinating Group. 190 p. 

http://www.nwcg.gov/pms/pubs/glossary/pms205.pdf. (18 March 2015). 

Oehlert, G.W. 1992. A note on the delta method. The American Statistician. 

46(1): 27–29. 

Pinheiro, J.C.; Bates, D.M. 2000. Mixed-effects models in S and S-PLUS. New 

York, NY: Springer. 528 p. 
22 

RESEARCH PAPER PSW-RP-267

Prestemon, J.P.; Holmes, T.P. 2008. Timber salvage economics. In: Holmes, T.P.; 

Prestemon, J.P.; Abt, K.L., eds. The economics of forest disturbances: wildfires, 

storms, and invasive species. New York, NY: Springer Netherlands: 167–190. 

R Core Team. 2013. R: a language and environment for statistical computing. 

Vienna, Austria: R Foundation for Statistical Computing. http://www.R-project. 

org/ (18 March 2015). 

Sayer, M.A.S.; Haywood, J.D. 2006. Fine root production and carbohydrate 

concentrations of mature longleaf pine (Pinus palustris P. Mill.) as affected by 

season of prescribed fire and drought. Trees. 20(2): 165–175. 

Soil Survey Staff. 1999. Soil taxonomy: a basic system of soil classification for 

making and interpreting soil surveys. Agric. Handb. 436. 2nd ed. Washington, 

DC: U.S. Department of Agriculture, Natural Resources Conservation 

Service. 871 p. http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/ 

nrcs142p2_051232.pdf. (18 March 2015). 

Soil Survey Staff. [N.d.]. Official soil series descriptions. Washington, DC: 

U.S. Department of Agriculture, Natural Resources Conservation Service. 

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/nedc/training/
	

soil/?cid=nrcs142p2_053587. (18 March 2015).
	

Storey, T.G.; Merkel, E.P. 1960. Mortality in a longleaf-slash pine stand following 

a winter wildfire. Journal of Forestry. 58(3): 206–210. 

Sword, M.A.; Haywood, J.D. 1999. Effects of crown scorch on longleaf pine 

fine roots. In: Haywood, J.D., ed. Proceedings of the 10th biennial southern 

silvicultural research conference Gen. Tech. Rep. SRS-030. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southern Research Station: 223–227. 

Tew, D.T.; Jervis, L.G.; Steensen, D.H.J. 1989. The effects of varying degrees 

of crown scorching on growth and mortality of young Piedmont loblolly pine. 

In: Miller, J.H., comp. Proceedings of the fifth biennial southern silvicultural 

research conference. Gen. Tech. Rep. SO-74. New Orleans: LA: U.S. Department 

of Agriculture, Forest Service, Southern Forest Experiment Station: 395–400. 

Uzoh, F.C.C.; Oliver, W.W. 2008. Individual tree diameter increment model for 

managed even-aged stands of ponderosa pine throughout the western United 

States using a multilevel linear mixed effects model. Forest Ecology and 

Management. 256(3): 438–445. 
23 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Van Doren, M., ed. 1928. Travels of William Bartram [based on Bartram, W. 

1791. Travels through North & South Carolina, Georgia, east and west Florida. 

Reprinted 1955 by Dover Publications, Inc., New York, NY. Philadelphia, PA: 

James & Johnson]. New York, NY: Macy & Masius 414 p. 

Villarrubia, C.R.; Chambers, J.L. 1978. Fire: its effect on growth and survival 

of loblolly pine, Pinus taeda L. The Proceedings of the Louisiana Academy of 

Science. 41: 85–93. 

Wade, D.D.; Ward, D.E. 1975. Management decisions in severely damaged stands. 

Journal of Forestry. 73(9): 573–577. 

Waldrop, T.A.; Van Lear, D.H. 1984. Effect of crown scorch on survival and 

growth of young loblolly pine. Southern Journal of Applied Forestry. 8(1): 35–40. 

Weise, D.R.; Johansen, R.W.; Wade, D.D. 1987. Effects of spring defoliation on 

first-year growth of young loblolly and slash pines. Res. Note SE-347. Asheville, 

NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest 

Experiment Station. 4 p. 

Weise, D.R.; Wade, D.D.; Johansen, R.W. 1989. Survival and growth effects of 

young southern pines after simulated crown scorch. In: MacIver, D.C.; Auld, 

H.; Whitewood, R. eds. Proceedings of the 10th conference on fire and forest 

meteorology. Ottawa, Canada: Environment Canada: 161–168. 

Weise, D.R.; Wade, D.D.; Johansen, R.W.; Combs, D.C.; Ach, E.E. 2014. 

Southern pine defoliation growth response data. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Research Data Archive. http://dx.doi. 

org/10.2737/RDS-2014-0019. (18 March 2015). 
24 

RESEARCH PAPER PSW-RP-267

Appendix 1: R Language Commands for Analyses 

The majority of the analyses were performed using the statistical package R version 

3.1. In general, the same code was used for each location to perform the analyses 

with only minor changes to address slight changes in format. Because the longleaf 

pine study design involved fewer and different treatments than the loblolly and slash 

pine study, the model statements differed. The code statements that follow outline 

the general analyses that were performed. The data are archived in the Forest 

Service Research Data Archive (Weise et al. 2014), and the details of inputting the 

data into R data structures are not included. The data set names for the locations 

were BAIN, BRAN, PLKA, WAYC, SRFS, and LWYC for Bainbridge, Branchville, 

Palatka, Waycross, Savannah River, and Waycross longleaf, respectively. 

Calculation of Summary Statistics in Appendix 2 

bain$def<-factor(bain$def) 

# select data for 13, 5, and initial measurement, md is measurement date, td is treatment date 

yr13<-subset(bain,md=="08/15/99") 

yr5<-subset(bain,md=="01/15/91") 

yr0<-subset(bain,(md=="04/15/86"|md=="07/15/86"|md=="10/15/86"| 

(td=="01/15/87" & md=="01/15/87"))) 

# calculate mean, standard deviation, and coefficient of variation for each 

season and defoliation combination for diameter at breast height (d.b.h.) and 

height by location 

bainmd<-tapply(yr0$dbh,list(yr0$seas,yr0$def),mean) 

bainsd<-tapply(yr0$dbh,list(yr0$seas,yr0$def),sd) 

baincd<-bainsd/bainmd 

Simultaneous Comparison of Defoliation Treatment Means With 

Control 

library(multcomp)
 

bain$def<-factor(bain$def)
 

bainaov_d<-aov(dbh ~ seas + def + seas*def, data=yr5)
 

summary(bainaov_d)
 

# perform a one-sided test with alternative hypothesis that treatment mean is less 

than control 

bain_mcd<- glht(bainaov_d,linfct = mcp(def="Dunnett"), alternative = "less") 

summary(bain_mcd,test = adjusted(type = "single-step")) 
25 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Effects of Treatments on Growth-Response Curves 

The effects of treatments on the growth-response curves for d.b.h. and height were 

estimated using the code below. In this code, defoliation level was treated as a 

continuous variable (covariate with 1 degree of freedom) in contrast to being treated 

as a factor as in the Dunnett test above. 

library(nlme);library(chron);library(lattice);library(latticeExtra);library(grid) 

# formula for fitted linear model, seas = defoliation season, def = defoliation level, 

trtdays = elapsed time since treatment applied 

fmlad <- as.formula(ht ~ seas + def + I(def^2) + seas:def + seas:I(def^2) + trtdays 

+ I(trtdays^2) + seas:trtdays + seas:I(trtdays^2)) 

lobsla<-read.table("c:\\Users\\dweise\\Documents\\defol\\data\\defol99mix. 

dat",header=TRUE) 

lobsla$seas<-factor(lobsla$seas,levels=c('SP','SM','FL','WN')) 

# elapsed days converted to years 

lobsla$trtdays<-(as.numeric(dates(as.character(lobsla$md))-dates(as. 

character(lobsla$td))))/365.25 

bain<-subset(lobsla,lobsla$loc=="BAIN" & !is.na(lobsla$ht)) 

# define correlation structure for repeated measurements 

cr2<-corAR1(0.5,form = ~ 1 | rownum/tree) 

# Separate models fit for 1st 5 (or 6) years of measurement and for all 13 (or 19) years 

bainh.fit3<-lme(fmlad, data=bain, random = ~1 | rownum/tree, correlation=cr2) 

bainh.fit4<-lme(fmlad, data=bain[bain$trtdays<10,],random = ~1 | rownum/tree, 

correlation=cr2) 

As indicated previously, the experimental setup for the longleaf study differed from 

the loblolly and slash pine setup. The linear mixed-effects model statements for the 

longleaf pine data follow. 

lfmlad <- as.formula(ht ~ trt + def + trt:def+ trtdays + I(trtdays^2) + trt:trtdays + 

trt:I(trtdays^2)) 

lnglef<-read.table("c:\\Users\\dweise\\Documents\\defol\\data\\lldefolmix. 

dat",header=TRUE) 

# treatment colors: RED – Aug, ORG – Sep, YEL – Oct, WHT – Nov, BLU - Dec 

lnglef$trt<-factor(lnglef$trt,levels=c("RED","ORG","YEL","WHT","BLU"))
 

lnglef$trtdays<-(as.numeric(dates(as.character(lnglef$md))-dates(as.
 

character(lnglef$td))))/365.25
 

srfs<-subset(lnglef,lnglef$loc=="SRFS" & !is.na(lnglef$ht))
 

cr2<-corAR1(0.2,form = ~ 1 | rownum/tree)
 

srfsh.fit3<-lme(lfmlad, data=srfs, random = ~1 | rownum/tree, correlation=cr2) 

srfsh.fit4<-lme(lfmlad, data=srfs[srfs$trtdays<10,], random = ~1 | rownum/tree, 

correlation=cr2) 
26 

RESEARCH PAPER PSW-RP-267

 

Ratio of Growth of Treated Trees to Controls 

To determine if the defoliated trees had recovered lost growth or exceeded the 

growth of the control trees, the ratios of d.b.h., height, and estimated volume of 

the treated trees to the control trees were calculated at each measurement time. 

Using the fitted linear mixed-effects model to estimate the variance, a 95 percent 

confidence interval (2.5 percent above and below) around 1 was determined for 

each season of defoliation by location. The variance at the end of the study was 

assumed to be greatest, which we used. Ratios that fell within the confidence 

interval indicated that the size of the treated tree was not different from the size 

of the untreated controls. 

fits<-update(bainh.fit3,method="ML") 

beta<-fixef(fits) 

varcov1=fits$varFix 

kx=max(fits$data$trtdays) #SE around line is highest at max day 

x0<-c(1,1,0,0,0,0,kx,kx^2,0,0,0,0,0,0,kx,0,0,kx^2,0,0) # season – SM, def = 0 

x2<-c(1,1,0,0,33,33^2,kx,kx^2,33,0,0,33^2,0,0,kx,0,0,kx^2,0,0) # def = 33 

x3<-c(1,1,0,0,66,66^2,kx,kx^2,66,0,0,66^2,0,0,kx,0,0,kx^2,0,0) 

x4<-c(1,1,0,0,95,95^2,kx,kx^2,95,0,0,95^2,0,0,kx,0,0,kx^2,0,0) 

x5<-c(1,1,0,0,100,100^2,kx,kx^2,100,0,0,100^2,0,0,kx,0,0,kx^2,0,0) # def=100 

var1<-t(x0)%*%varcov1%*%x0 

th1<-t(x0)%*%beta 

var2<-t(x2)%*%varcov1%*%x2;th2<-t(x2)%*%beta;mu2<-th2/th1;vart2<-var2/ 

(th1^2)+var1*(mu2/th1)^2 

var3<-t(x3)%*%varcov1%*%x3;th3<-t(x3)%*%beta;mu3<-th3/th1;vart3<-var3/ 

(th1^2)+var1*(mu3/th1)^2 

var4<-t(x4)%*%varcov1%*%x4;th4<-t(x4)%*%beta;mu4<-th4/th1;vart4<-var4/ 

(th1^2)+var1*(mu4/th1)^2 

var5<-t(x5)%*%varcov1%*%x5;th5<-t(x5)%*%beta;mu5<-th5/th1;vart5<-var5/ 

(th1^2)+var1*(mu5/th1)^2 

vartSM<-max(vart2,vart3,vart4,vart5) 

x0<-c(1,0,1,0,0,0,kx,kx^2,0,0,0,0,0,0,0,kx,0,0,kx^2,0) # season FL 

x2<-c(1,0,1,0,33,33^2,kx,kx^2,0,33,0,0,33^2,0,0,kx,0,0,kx^2,0) 
27 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

x3<-c(1,0,1,0,66,66^2,kx,kx^2,0,66,0,0,66^2,0,0,kx,0,0,kx^2,0)
 

x4<-c(1,0,1,0,95,95^2,kx,kx^2,0,95,0,0,95^2,0,0,kx,0,0,kx^2,0)
 

x5<-c(1,0,1,0,100,100^2,kx,kx^2,0,100,0,0,100^2,0,0,kx,0,0,kx^2,0) 

var1<-t(x0)%*%varcov1%*%x0
 

th1<-t(x0)%*%beta
 

var2<-t(x2)%*%varcov1%*%x2;th2<-t(x2)%*%beta;mu2<-th2/th1;vart2<-var2/
 

(th1^2)+var1*(mu2/th1)^2 

var3<-t(x3)%*%varcov1%*%x3;th3<-t(x3)%*%beta;mu3<-th3/th1;vart3<-var3/ 

(th1^2)+var1*(mu3/th1)^2 

var4<-t(x4)%*%varcov1%*%x4;th4<-t(x4)%*%beta;mu4<-th4/th1;vart4<-var4/ 

(th1^2)+var1*(mu4/th1)^2 

var5<-t(x5)%*%varcov1%*%x5;th5<-t(x5)%*%beta;mu5<-th5/th1;vart5<-var5/ 

(th1^2)+var1*(mu5/th1)^2 

vartFL<-max(vart2,vart3,vart4,vart5) 

x0<-c(1,0,0,1,0,0,kx,kx^2,0,0,0,0,0,0,0,0,kx,0,0,kx^2) #season WN 

x2<-c(1,0,0,1,33,33^2,kx,kx^2,0,0,33,0,0,33^2,0,0,kx,0,0,kx^2) 

x3<-c(1,0,0,1,66,66^2,kx,kx^2,0,0,66,0,0,66^2,0,0,kx,0,0,kx^2) 

x4<-c(1,0,0,1,95,95^2,kx,kx^2,0,0,95,0,0,95^2,0,0,kx,0,0,kx^2) 

x5<-c(1,0,0,1,100,100^2,kx,kx^2,0,0,100,0,0,100^2,0,0,kx,0,0,kx^2) 

var1<-t(x0)%*%varcov1%*%x0 

th1<-t(x0)%*%beta 

var2<-t(x2)%*%varcov1%*%x2;th2<-t(x2)%*%beta;mu2<-th2/th1;vart2<-var2/ 

(th1^2)+var1*(mu2/th1)^2 

var3<-t(x3)%*%varcov1%*%x3;th3<-t(x3)%*%beta;mu3<-th3/th1;vart3<-var3/ 

(th1^2)+var1*(mu3/th1)^2 

var4<-t(x4)%*%varcov1%*%x4;th4<-t(x4)%*%beta;mu4<-th4/th1;vart4<-var4/ 

(th1^2)+var1*(mu4/th1)^2 

var5<-t(x5)%*%varcov1%*%x5;th5<-t(x5)%*%beta;mu5<-th5/th1;vart5<-var5/ 

(th1^2)+var1*(mu5/th1)^2 

vartWN<-max(vart2,vart3,vart4,vart5) 
28 

RESEARCH PAPER PSW-RP-267

 

x0<-c(1,0,0,0, 0 , 0,kx,kx^2,0,0,0,0,0,0,0,0,0,0,0,0) # season SP
	

x2<-c(1,0,0,0, 33, 33^2,kx,kx^2,0,0,0,0,0,0,0,0,0,0,0,0) 

x3<-c(1,0,0,0, 66, 66^2,kx,kx^2,0,0,0,0,0,0,0,0,0,0,0,0)
 

x4<-c(1,0,0,0, 95, 95^2,kx,kx^2,0,0,0,0,0,0,0,0,0,0,0,0)
 

x5<-c(1,0,0,0,100,100^2,kx,kx^2,0,0,0,0,0,0,0,0,0,0,0,0) 

var1<-t(x0)%*%varcov1%*%x0
 

th1<-t(x0)%*%beta
 

var2<-t(x2)%*%varcov1%*%x2;th2<-t(x2)%*%beta;mu2<-th2/th1;vart2<-var2/
 

(th1^2)+var1*(mu2/th1)^2 

var3<-t(x3)%*%varcov1%*%x3;th3<-t(x3)%*%beta;mu3<-th3/th1;vart3<-var3/ 

(th1^2)+var1*(mu3/th1)^2 

var4<-t(x4)%*%varcov1%*%x4;th4<-t(x4)%*%beta;mu4<-th4/th1;vart4<-var4/ 

(th1^2)+var1*(mu4/th1)^2 

var5<-t(x5)%*%varcov1%*%x5;th5<-t(x5)%*%beta;mu5<-th5/th1;vart5<-var5/ 

(th1^2)+var1*(mu5/th1)^2 

vartSP<-max(vart2,vart3,vart4,vart5) 

vartm<-c(vartSP,vartSM,vartFL,vartWN) # variance estimates for each season 

xyplot(hrat~ trtdays | trt ,group=def, 

data=aggregate(hrat~def+trt+trtdays,rat[rat$loc=="BAIN" &
	

rat$def!=0,],mean),
	

type="p",outer=TRUE,layout=c(1,4),
 

lty=c(1,5,2,3),lwd=1,pch=c(1,3,8,19),col="black",
 

xlab="Time since defoliation (years)",ylab="Height ratio",ylim=c(0.7,1.3),
 

strip=function(..., bg,style) strip.default(...,bg="gray", style = 1),
 

panel = function(x, y, ...){
 

panel.superpose(x,y,...)
 

panel.xyplot(x, y, ...)
 

} )
 

for (i in 1:4) { 

trellis.focus("panel", 1, i, highlight=FALSE) 

panel.abline(h=1+sqrt(vartm[i])*qnorm(.975,0,1),lwd=1,lty=3,col="black") 

panel.abline(h=1-sqrt(vartm[i])*qnorm(.975,0,1),lwd=1,lty=3,col="black") 

} 
29 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

 

trellis.unfocus() 

grid.text("Loblolly (BAIN)", 

gp=gpar(fontface="bold"),x=unit(c(0.5),"npc"), 

y=unit(c(0.98),"npc"),draw=TRUE) 

grid.text(c("33","66","95","100"), gp=gpar(fontface="bold"), 

x=unit(c(0.5,0.6,0.7,0.8),"npc"), 

y=unit(c(0.74,0.74,0.74,0.74),"npc"),draw=TRUE) 

grid.points(x=unit(c(0.53,0.63,0.73,0.83),"npc"), 

y=unit(c(0.74,0.74,0.74,0.74),"npc"),pch= c(1,3,8,19), 

size=unit(0.55,"char")) 

grid.text("100 percent defoliation < 0.6",x=unit(c(0.7),"npc"), 

y=unit(c(0.55),"npc"),draw=TRUE) 

Effects of Treatments on Number of Height Growth Flushes 

Growth flush data were analyzed using a similar general linear model and specifying the Poisson distribution for discrete count data. These analyses were only 

performed on the Branchville, South Carolina, and Palatka, Florida, data. At this 

time, the lme4 routine in R cannot perform Poisson regression so the glm routine 

was used. 

flushes<-read.table("c:\\users\\dweise\\documents\\defol\\data\\defolflush. 

dat",header=TRUE) 

flushes$seas<-factor(flushes$seas) 

flushes$trtdays<-(as.numeric(dates(as.character(flushes$md))-dates(as.character(fl 

ushes$td))))/365.25 # elapsed days converted to yearsflushes$year<-factor(flush 

es$year,label=c('1986','1987','1990')) 

flushes$md<-factor(flushes$md,label=c("1986","1987","1989")) 

flushes$treeid<-(flushes$row-1)*20+flushes$tree 

flbran<-subset(flushes,flushes$loc=="BRAN" & !is.na(flushes$gflush)) 

flbran.fit1<-glm(fmlad,data=flbran, family=poisson) 

anova(flbran.fit1,test="Chisq") 
30 

RESEARCH PAPER PSW-RP-267

Appendix 2: Diameter at Breast Height (d.b.h.) and Height 

Measurements 

Table 4—Mean d.b.h. (standard deviation) of loblolly and slash pines 5 (study end) and 

13 (final) years after being manually defoliated to simulate crown scorcha (continued) 

Defoliation Diameter at breast height 

Location Level Season Initial Study end Final 

Percent - - - - - - - - - - - - - Inches - - - - - - - - - - - - -

Bainbridge, Georgia 0 SP 1.28 (0.27) 5.43 (0.49) 8.49 (1.12) 

SM 1.22 (0.25) 5.29 (0.69) 8.85 (1.59) 

FL 1.81 (0.18) 4.96 (0.43) 8.30 (0.78) 

WN 2.02 (0.33) 5.32 (0.71) 8.84 (0.59) 

33 SP 1.08 (0.23) 4.92 (0.45) 8.22 (0.88) 

SM 1.26 (0.23) 5.32 (0.49) 9.58 (0.60) 

FL 1.89 (0.23) 5.17 (0.61) 8.63 (0.91) 

WN 2.03 (0.22) 5.12 (0.40) 8.02 (0.96) 

66 SP 1.08 (0.21) 4.81 (0.48) 7.90 (0.80) 

SM 1.15 (0.27) 4.88 (0.69) 7.35 (0.66) 

FL 1.86 (0.28) 4.73 (0.34) 7.80 (1.68) 

WN 2.14 (0.31) 5.09 (0.53) 8.25 (0.54) 

95 SP 1.11 (0.19) 4.66 (0.52) 7.10 (1.25) 

SM 1.16 (0.24) 4.64 (0.50) 6.40 

FL 1.89 (0.28) 4.18 (0.57) 7.32 (0.87) 

WN 2.06 (0.38) 4.50 (0.60) 7.67 (0.88) 

100 SP 1.21 (0.23) 4.46 (0.61) 7.78 (0.68) 

SM 1.10 (0.18) 4.49 (0.49) 7.76 (1.02) 

FL 2.02 (0.19) 2.41 

WN 2.16 (0.19) 4.59 (0.35) 7.77 (0.38) 

Branchville, South 0 SP 1.49 (0.26) 6.79 (0.55) 9.10 (1.80) 

 Carolina SM 1.46 (0.26) 6.84 (1.13) 9.42 (2.38) 

FL 2.51 (0.38) 6.50 (0.94) 8.98 (1.48) 

WN 2.49 (0.36) 6.56 (0.51) 9.03 (1.00) 

33 SP 1.41 (0.23) 6.30 (0.96) 8.68 (0.93) 

SM 1.37 (0.24) 6.61 (0.61) 10.08 (1.97) 

FL 2.33 (0.30) 6.14 (0.46) 9.27 (1.55) 

WN 2.45 (0.32) 6.48 (0.80) 9.64 (1.17) 

66 SP 1.35 (0.34) 6.18 (0.46) 9.78 (2.05) 

SM 1.44 (0.23) 6.26 (0.81) 9.20 (0.56) 

FL 2.53 (0.28) 6.07 (0.70) 8.95 (1.48) 

WN 2.54 (0.28) 6.03 (0.69) 8.70 (1.01) 

95 SP 1.39 (0.32) 5.95 (0.81) 8.13 (0.46) 

SM 1.32 (0.28) 6.07 (0.94) 8.68 (2.22) 

FL 2.32 (0.29) 5.88 (0.80) 8.40 (1.89) 

WN 2.66 (0.35) 6.33 (0.72) 9.89 (1.25) 

100 SP 1.37 (0.38) 5.90 (0.81) 9.63 (1.80) 

SM 1.46 (0.34) 5.86 (1.04) 8.90 (0.93) 

FL 2.47 (0.21) 4.29 (0.25) 

WN 2.54 (0.37) 5.54 (1.00) 8.38 (2.37) 
31 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Table 4—Mean d.b.h. (standard deviation) of loblolly and slash pines 5 (study end) and 

13 (final) years after being manually defoliated to simulate crown scorcha (continued) 

Defoliation Diameter at breast height 

Location Level Season Initial Study end Final 

Percent - - - - - - - - - - - - - Inches - - - - - - - - - - - - -

Palatka, Florida 0 SP 1.86 (0.28) 4.52 (0.62) 6.41 (0.64) 

SM 2.00 (0.26) 4.31 (0.56) 5.80 (0.64) 

FL 2.46 (0.29) 4.54 (0.56) 6.60 (1.09) 

WN 2.54 (0.36) 4.66 (0.64) 7.25 (1.17) 

33 SP 1.81 (0.36) 4.25 (0.52) 5.87 (0.63) 

SM 2.23 (0.26) 4.51 (0.42) 6.75 (1.06) 

FL 2.40 (0.31) 4.48 (0.41) 6.03 (1.02) 

WN 2.32 (0.22) 4.09 (0.53) 5.86 (0.91) 

66 SP 1.92 (0.28) 4.12 (0.56) 5.10 (1.12) 

SM 2.21 (0.24) 4.13 (0.48) 4.30 

FL 2.47 (0.24) 4.15 (0.52) 5.83 (0.76) 

WN 2.42 (0.22) 3.94 (0.48) 5.87 (0.85) 

95 SP 1.84 (0.18) 4.02 (0.48) 4.98 (1.33) 

SM 2.24 (0.29) 3.87 (0.69) 5.00 (1.45) 

FL 2.37 (0.18) 3.50 (0.31) 4.50 (1.04) 

WN 2.28 (0.25) 3.42 (0.45) 4.73 (0.25) 

100 SP 1.93 (0.36) 3.83 (0.68) 5.31 (1.38) 

SM 2.16 (0.33) 3.48 (0.48) 4.71 (1.04) 

FL 2.28 (0.43) 2.93 (0.42) 3.63 (1.36) 

WN 2.34 (0.29) 3.48 (0.52) 4.31 (0.91) 

Waycross, Georgia 0 SP 1.83 (0.24) 4.63 (0.58) 7.34 (0.84) 

SM 2.17 (0.28) 4.73 (0.58) 7.60 (0.80) 

FL 2.32 (0.16) 4.63 (0.55) 6.83 (0.88) 

WN 2.45 (0.29) 4.73 (0.59) 6.93 (0.51) 

33 SP 1.78 (0.27) 4.52 (0.44) 7.06 (1.36) 

SM 2.09 (0.28) 4.46 (0.45) 6.75 (1.41) 

FL 2.26 (0.17) 4.44 (0.60) 6.80 (0.56) 

WN 2.34 (0.28) 4.38 (0.39) 8.00 (0.52) 

66 SP 1.86 (0.41) 4.34 (0.40) 6.58 (0.58) 

SM 2.01 (0.27) 3.96 (0.53) 5.93 (1.23) 

FL 2.34 (0.28) 4.01 (0.57) 6.38 (0.15) 

WN 2.43 (0.24) 4.35 (0.52) 6.20 (0.85) 

95 SP 1.82 (0.32) 4.00 (0.52) 5.95 (1.34) 

SM 2.25 (0.24) 4.07 (0.43) 7.05 (1.35) 

FL 2.31 (0.26) 3.59 (0.39) 5.16 (1.03) 

WN 2.45 (0.42) 3.85 (0.63) 6.90 (1.09) 

100 SP 1.88 (0.44) 4.04 (0.63) 5.07 (0.80) 

SM 2.11 (0.19) 3.71 (0.36) 6.08 (0.87) 

FL 2.34 (0.36) 3.49 (0.45) 4.88 (0.82) 

WN 2.24 (0.31) 3.53 (0.55) 5.30 (0.99) 

Note: Defoliation season: SP = spring (April), SM = summer (July), FL = fall (October), WN = winter (January). a Initial diameter at breast height (d.b.h.) generally measured at the time of treatment application. 
32 

RESEARCH PAPER PSW-RP-267

Table 5—Mean d.b.h. (standard deviation) of longleaf pines 6 (study end) and 19 (final) 

years after being manually defoliated to simulate crown scorcha 

Defoliation Diameter at breast height 

Location Level Month Initial Study end Final 

Percent - - - - - - - - - - - - - Inches - - - - - - - - - - - -

Aiken, South Carolina 0 Aug 1.64 (0.21) 3.10 (0.42) 4.76 (0.76) 

 (Savannah River Sep 1.79 (0.14) 3.39 (0.40) 5.23 (0.99) 

 Forest Station) Oct 1.83 (0.22) 3.43 (0.33) 5.27 (0.61) 

Nov 1.63 (0.22) 3.09 (0.35) 4.83 (0.77) 

Dec 1.73 (0.18) 3.27 (0.36) 4.97 (0.82) 

95 Aug 1.66 (0.27) 2.96 (0.46) 4.30 (1.13) 

Sep 1.71 (0.20) 2.88 (0.39) 4.32 (0.81) 

Oct 1.75 (0.28) 2.91 (0.42) 4.31 (0.84) 

Nov 1.79 (0.29) 2.89 (0.33) 4.08 (0.73) 

Dec 1.78 (0.21) 2.96 (0.29) 4.42 (0.71) 

100 Aug 1.70 (0.20) 2.75 (0.29) 4.29 (0.47) 

Sep 1.81 (0.23) 2.87 (0.39) 4.47 (0.88) 

Oct 1.70 (0.15) 2.73 (0.26) 3.93 (0.66) 

Nov 1.72 (0.27) 2.68 (0.24) 4.17 (0.61) 

Dec 1.68 (0.24) 2.86 (0.38) 4.55 (0.75) 

Waycross, Georgia 0 Aug 1.80 (0.29) 4.26 (0.52) 6.93 (1.00) 

Sep 1.69 (0.23) 4.12 (0.58) 7.14 (0.80) 

Oct 1.88 (0.27) 4.34 (0.68) 7.10 (1.21) 

Nov 1.71 (0.18) 4.04 (0.42) 6.98 (1.11) 

Dec 1.85 (0.21) 4.36 (0.67) 6.50 

95 Aug 1.71 (0.20) 3.67 (0.50) 6.27 (1.10) 

Sep 1.80 (0.29) 3.80 (0.79) 6.27 (1.55) 

Oct 1.72 (0.28) 3.60 (0.53) 5.25 (0.78) 

Nov 1.76 (0.22) 3.78 (0.46) 7.23 (0.72) 

Dec 1.79 (0.29) 3.79 (0.48) 6.41 (0.76) 

100 Aug 1.74 (0.19) 3.41 (0.45) 5.47 (1.29) 

Sep 1.79 (0.30) 3.57 (0.58) 3.30 

Oct 1.74 (0.32) 3.61 (0.42) 5.60 (0.14) 

Nov 1.76 (0.30) 3.51 (0.58) 5.96 (0.74) 

Dec 1.70 (0.25) 3.21 (0.56) 5.75 (0.07) 

a Initial diameter at breast height (d.b.h.) generally measured at the time of treatment application. 
33 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Table 6—Mean height (standard deviation) of loblolly and slash pines 5 (study end) and 

13 (final) years after being manually defoliated to simulate crown scorcha (continued) 

Defoliation Diameter at breast height 

Location Level Season Initial Study end Final 

Percent - - - - - - - - - - - - - - Feet- - - - - - - - - - - - - -

Bainbridge, Georgia 0 SP 

SM 

9.54 (0.78) 

9.63 (0.79) 

32.99 (1.83) 

33.56 (2.87) 

64.29 (3.57) 

65.50 (4.30) 

FL 12.49 (1.07) 32.23 (2.26) 62.33 (1.26) 

WN 12.30 (1.08) 32.63 (1.88) 64.60 (2.39) 

33 SP 9.34 (0.72) 32.49 (1.93) 64.33 (2.82) 

SM 9.68 (0.63) 33.33 (1.80) 66.80 (2.66) 

FL 12.79 (1.03) 32.40 (1.67) 64.92 (4.71) 

WN 12.61 (1.29) 32.51 (2.17) 65.30 (2.33) 

66 SP 9.00 (0.49) 31.66 (1.81) 60.00 (6.24) 

SM 9.40 (0.97) 32.62 (1.96) 62.58 (2.82) 

FL 12.69 (0.98) 32.30 (2.12) 62.00 (5.00) 

WN 13.21 (1.04) 33.05 (1.81) 64.88 (3.35) 

95 SP 9.21 (0.83) 31.08 (1.66) 59.67 (2.52) 

SM 9.47 (0.93) 32.02 (1.84) 61.00 

FL 12.39 (1.30) 29.98 (1.89) 62.40 (3.47) 

WN 12.23 (1.16) 30.70 (2.57) 62.92 (3.56) 

100 SP 9.44 (0.76) 30.72 (1.75) 62.50 (2.27) 

SM 9.42 (0.79) 31.63 (1.64) 64.90 (3.75) 

FL 12.95 (0.93) 19.55 

WN 12.79 (1.07) 31.38 (2.16) 62.00 (1.55) 

Branchville, South 0 SP 9.49 (0.97) 32.64 (2.43) 62.33(10.30) 

 Carolina SM 9.52 (0.83) 32.95 (2.35) 64.70 (4.52) 

FL 13.23 (1.02) 33.27 (1.61) 63.75 (3.70) 

WN 13.10 (1.42) 33.65 (2.61) 63.08 (3.87) 

33 SP 9.40 (0.66) 33.07 (1.75) 66.60 (1.43) 

SM 9.44 (0.59) 33.35 (1.16) 65.00 (3.42) 

FL 12.68 (0.75) 31.85 (3.05) 65.40 (4.52) 

WN 12.60 (0.92) 31.75 (2.41) 65.26 (1.55) 

66 SP 9.10 (0.92) 31.05 (1.88) 66.90 (2.04) 

SM 9.15 (0.65) 31.27 (1.83) 62.60 (2.41) 

FL 13.33 (0.82) 33.03 (1.74) 64.25 (4.35) 

WN 12.82 (0.78) 32.66 (1.94) 63.60 (2.79) 

95 SP 9.22 (0.77) 31.27 (1.65) 64.25 (0.29) 

SM 9.31 (0.88) 31.86 (1.87) 64.10 (3.15) 

FL 12.80 (1.04) 31.40 (2.25) 60.42 (7.19) 

WN 13.28 (0.74) 32.40 (1.98) 66.75 (3.87) 

100 SP 9.29 (0.94) 31.52 (2.76) 63.00 (3.12) 

SM 9.37 (0.67) 30.85 (2.50) 62.63 (4.03) 

FL 12.93 (1.11) 23.31 (1.56) 

WN 13.43 (1.57) 31.21 (2.67) 62.10 (6.23) 

Palatka, Florida 0 SP 9.64 (0.87) 29.98 (1.98) 51.71 (3.41) 

SM 12.69 (0.75) 29.39 (2.28) 51.00 (6.36) 

FL 14.16 (1.05) 30.99 (2.14) 53.81 (7.01) 

WN 14.04 (1.28) 29.96 (1.55) 55.83 (5.65) 
34 

RESEARCH PAPER PSW-RP-267

Table 6—Mean height (standard deviation) of loblolly and slash pines 5 (study end) and 

13 (final) years after being manually defoliated to simulate crown scorcha (continued) 

Defoliation Diameter at breast height 

Location Level Season Initial Study end Final 

Percent

33 SP 

SM 

FL 

WN 

66 SP 

SM 

FL 

WN 

95 SP 

SM 

FL 

WN 

100 SP 

SM 

FL 

WN 

Waycross, Georgia 0 SP 

SM 

FL 

WN 

33 SP 

SM 

FL 

WN 

66 SP 

SM 

FL 

WN 

95 SP 

SM 

FL 

WN 

100 SP 

SM 

FL 

WN 

 - - - - - - - - - - - - - - Feet- - - - - - - - - - - - - -

9.81 (0.91) 29.92 (1.66) 52.79 (3.57) 

13.45 (0.92) 28.96 (2.86) 53.50 (5.67) 

13.99 (1.33) 30.57 (2.51) 54.00 (5.63) 

13.64 (1.10) 29.70 (1.81) 51.70 (4.64) 

9.92 (0.73) 29.54 (2.23) 44.25 (6.28) 

13.52 (0.84) 29.73 (1.79) 45.00 

13.86 (1.08) 29.23 (2.00) 51.71 (3.59) 

13.56 (1.45) 28.82 (2.16) 55.17 (5.06) 

9.52 (0.68) 27.55 (2.00) 41.83 (7.63) 

13.40 (0.92) 28.04 (2.76) 44.17(11.27) 

13.91 (0.86) 26.85 (1.43) 43.17 (7.80) 

13.25 (1.39) 25.90 (3.03) 48.33 2.84 

10.03 (0.97) 28.01 (1.76) 48.56 (6.03) 

12.85 (1.00) 26.11 (2.48) 44.79 (4.41) 

13.71 (1.08) 24.06 (1.69) 38.33(12.17) 

13.86 (1.51) 26.71 (1.27) 44.75 (8.48) 

10.17 (0.93) 28.46 (3.00) 57.60 (3.76) 

12.39 (1.50) 28.61 (2.63) 59.42 (3.31) 

12.56 (1.01) 28.38 (2.42) 56.63 (4.31) 

13.44 (1.26) 29.24 (2.25) 56.50 (2.80) 

9.66 (0.97) 26.85 (2.61) 52.43(12.24) 

12.47 (1.21) 27.72 (2.36) 52.00 (8.97) 

12.21 (0.93) 27.12 (2.43) 55.70 (2.61) 

12.86 (1.09) 27.76 (1.91) 60.25 (2.22) 

10.19 (1.29) 27.47 (2.31) 53.10 (6.21) 

12.42 (0.99) 26.04 (2.33) 53.43 (6.88) 

13.11 (1.10) 26.51 (3.22) 54.88 (5.85) 

12.89 (0.91) 27.35 (1.69) 52.70 (6.12) 

9.78 (1.13) 26.30 (2.49) 52.00 (3.54) 

12.89 (1.10) 25.99 (1.66) 56.63 (3.47) 

12.51 (1.30) 23.68 (1.55) 50.00 (8.04) 

12.90 (1.14) 25.19 (2.34) 54.00 (3.34) 

9.75 (0.96) 25.27 (2.50) 46.83 (5.35) 

12.55 (0.89) 24.44 (1.86) 55.67 (3.54) 

12.61 (1.18) 22.03 (1.44) 46.00 (3.06) 

12.16 (0.97) 23.32 (2.04) 50.75 (4.60) 

Note: Defoliation season: spring (SP) = spring (April), SM = summer (July), FL = fall (October), WN = winter (January). 

a Initial height generally measured at the time of treatment application. 
35 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Table 7—Mean height (standard deviation) of longleaf pines 6 (study end) and 19 

(final) years after being manually defoliated to simulate crown scorch 

Defoliation Diameter at breast height 

Location Level Month Initial Study end Final 

Percent - - - - - - - - - - - - - - - Feet- - - - - - - - - - - - - - -

Aiken, South 0 Aug 9.99 (1.25) 23.50 (2.33) 40.67 (3.59) 

 Carolina Sep 10.28 (0.99) 24.73 (2.07) 40.55 (7.02) 

 (Savannah River Oct 10.23 (1.26) 24.00 (2.27) 41.45 (2.43) 

 Forest Station) Nov 9.43 (1.30) 22.97 (2.27) 39.67 (4.68) 

Dec 10.29 (0.95) 24.33 (1.25) 40.59 (2.84) 

95 Aug 9.67 (1.20) 22.11 (2.36) 36.78 (8.43) 

Sep 10.27 (1.09) 22.33 (2.11) 37.54 (6.29) 

Oct 10.19 (1.32) 22.97 (2.09) 38.24 (2.76) 

Nov 10.41 (1.24) 22.33 (2.14) 37.10 (6.60) 

Dec 10.08 (0.92) 22.10 (1.74) 36.66 (6.11) 

100 Aug 10.34 (1.16) 21.60 (2.09) 38.64 (3.10) 

Sep 10.37 (1.02) 22.33 (1.73) 40.11 (4.12) 

Oct 10.05 (1.20) 21.88 (1.11) 36.70 (1.73) 

Nov 10.51 (1.34) 20.00 (1.32) 37.30 (1.13) 

Dec 10.27 (1.57) 22.50 (2.04) 41.34 (3.21) 

Waycross, Georgia 0 Aug 10.17 (1.22) 26.61 (2.24) 43.30 (3.79) 

Sep 9.83 (1.07) 27.09 (2.28) 46.05 (3.56) 

Oct 10.54 (1.20) 26.75 (3.08) 45.20 (5.55) 

Nov 10.08 (1.02) 27.21 (2.44) 46.52 (3.75) 

Dec 10.38 (0.99) 28.00 (3.24) 49.50 

95 Aug 9.87 (0.97) 24.35 (1.82) 40.60 (3.96) 

Sep 10.02 (1.04) 25.12 (2.21) 39.35 (5.32) 

Oct 10.09 (1.23) 24.50 (2.73) 42.75 (3.46) 

Nov 9.97 (1.21) 25.13 (2.43) 44.70 (4.91) 

Dec 10.26 (1.12) 26.14 (2.16) 41.97 (3.13) 

100 Aug 10.04 (1.12) 23.23 (1.33) 37.80 (3.47) 

Sep 10.12 (1.16) 24.05 (2.92) 32.70 

Oct 9.87 (0.94) 23.44 (1.84) 36.00 (4.67) 

Nov 10.01 (1.24) 24.08 (1.99) 39.28 (3.49) 

Dec 9.96 (1.25) 22.31 (2.51) 42.80 (4.81) 
36 

RESEARCH PAPER PSW-RP-267

Table 8—Range of variability (expressed as coefficient of variation) in size of 

young southern pines subjected to manual defoliation to simulate crown scorch 

Initial Study end Final 

Variable Species Location Min Max Min Max Min Max 

d.b.h. Loblolly Bainbridge, Georgia 0.09 0.23 0.07 0.14 0.05 0.22 

Branchville, S. Carolina 0.09 0.28 0.06 0.18 0.06 0.28 

Slash Palatka, Florida 0.07 0.20 0.09 0.18 0.05 0.37 

Waycross, Georgia 0.07 0.23 0.09 0.16 0.02 0.23 

Longleaf Aiken, S. Carolina 0.08 0.16 0.09 0.16 0.11 0.26 

Waycross, Georgia 0.11 0.19 0.10 0.21 0.01 0.25 

Height Loblolly Bainbridge, Gerogia 0.05 0.11 0.05 0.09 0.02 0.10 

Branchville, S. Carolina 0.06 0.12 0.03 0.10 0.00 0.17 

Slash Palatka, Florida 0.06 0.11 0.05 0.12 0.06 0.32 

Waycross, Georgia 0.07 0.13 0.06 0.12 0.04 0.23 

Longleaf Aiken, S. Carolina 0.09 0.15 0.05 0.11 0.03 0.23 

Waycross, Georgia 0.09 0.13 0.06 0.12 0.07 0.14 

Note: Study end measurements performed 5 years after treatment for loblolly and slash pine and 6 years for 

longleaf pine. Final measurements performed at 13 years for loblolly and slash pine and at 19 years for longleaf 

pine. D.b.h. = diameter at breast height. 
37 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Appendix 3: Linear Mixed-Effects Model Results 

These tables summarize the results of fitting the linear mixed-effects model to the 

diameter at breast height (d.b.h.) and height data for the six locations. 

Bainbridge, Georgia—loblolly pine 

Diameter at breast height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,736 11407 <1E-04 

Season 3 274 30 <1E-04 

Defoliation 1 274 129 <1E-04 

Defoliation2 1 274 13 4E-04 

Trtdays 1 1,736 27845 <1E-04 

Trtdays2 1 1,736 2659 <1E-04 

Season:Defoliation 3 274 0.92 0.433 

Season:Defoliation2 3 274 1.17 0.323 

Season:Trtdays 3 1,736 32 <1E-04 

Season:Trtdays2 3 1,736 12 <1E-04 a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures. 

The AIC is the Akaike Information Criterion, BIC is the Bayesian Information 

Criterion, LRML is the log of the restricted maximum likelihood, σB is the standard 

deviation of the random effect for row (block effect), σ is the standard deviation of r

the random repeated measure effect, σ

^

 is the standard deviation of the residual, and 

o/ is the autoregressive correlation estimate. 

AIC BIC LRML σB σ σ^ 

r o/

634 775 -296 0.083 7E-05 0.507 0.883
	
38 

RESEARCH PAPER PSW-RP-267

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.536 0.114 1736 13 <1E-04 

seasSM -0.025 0.158 274 -0.16 0.876 

seasFL 0.456 0.158 274 2.88 0.004 

seasWN 0.712 0.160 274 4.46 <1E-04 

def -0.011 0.005 274 -2.11 0.036 

def2 6E-05 5E-05 274 1.14 0.255 

trtdays 0.928 0.017 1736 54 <1E-04 

trtdays2 -0.032 0.001 1736 -30 <1E-04 

seasSM:def 0.011 0.007 274 1.48 0.139 

seasFL:def 0.013 0.007 274 1.78 0.077 

seasWN:def 0.011 0.007 274 1.47 0.144 

seasSM:def2 -1E-04 7E-05 274 -1.62 0.107 

seasFL:def2 -1E-04 7E-05 274 -1.62 0.106 

seasWN:def2 -1E-04 7E-05 274 -1.36 0.174 

seasSM:trtdays 0.052 0.025 1736 2.12 0.034 

seasFL:trtdays -0.146 0.026 1736 -5.52 <1E-04 

seasWN:trtdays -0.087 0.025 1736 -3.45 6E-04 

seasSM:trtdays2 -0.003 0.002 1736 -1.73 0.083 

seasFL:trtdays2 0.007 0.002 1736 4.34 <1E-04 

seasWN:trtdays2 0.003 0.002 1736 1.60 0.110 a DF = degrees of freedom. 

Diameter at breast height—1986–1991 

Model summary 

DFa 

Source 

Intercept 

Season 

num 

1 

3 

den 

1,644 

274 

F-value 

13678 

25 

p-value 

<1E-04 

<1E-04 

Defoliation 1 274 97 <1E-04 

Defoliation2 1 274 9.92 0.002 

Trtdays 

Trtdays2 

Season:Defoliation 

1 

1 

3 

1,644 

1,644 

274 

20260 

253 

1.06 

<1E-04 

<1E-04 

0.369 

Season:Defoliation2 3 274 1.52 0.211 

Season:Trtdays 

Season:Trtdays2 

3 

3 

1,644 

1,644 

36 

24 

<1E-04 

<1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 
39 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

-319 -185 183 0.059 5E-05 0.431 0.904 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.505 0.099 1644 15 <1E-04 

seasSM -0.077 0.138 274 -0.56 0.576 

seasFL 0.467 0.138 274 3.38 0.001 

seasWN 0.711 0.139 274 5.10 <1E-04 

def -0.011 0.005 274 -2.36 0.019 

def2 6E-05 4E-05 274 1.36 0.174 

trtdays 0.966 0.023 1644 41 <1E-04 

trtdays2 -0.040 0.004 1644 -9.59 <1E-04 

seasSM:def 0.011 0.006 274 1.77 0.079 

seasFL:def 0.013 0.006 274 2.06 0.040 

seasWN:def 0.012 0.007 274 1.82 0.069 

seasSM:def2 -1E-04 6E-05 274 -1.90 0.059 

seasFL:def2 -1E-04 6E-05 274 -1.89 0.060 

seasWN:def2 -1E-04 6E-05 274 -1.71 0.088 

seasSM:trtdays 0.199 0.035 1644 5.69 <1E-04 

seasFL:trtdays -0.210 0.038 1644 -5.50 <1E-04 

seasWN:trtdays -0.145 0.036 1644 -4.07 <1E-04 

seasSM:trtdays2 -0.034 0.006 1644 -5.43 <1E-04 

seasFL:trtdays2 0.022 0.007 1644 3.01 0.003 

seasWN:trtdays2 0.016 0.007 1644 2.25 0.025 a DF = degrees of freedom. 

Height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1736 30036 <1E-04 

Season 3 274 75 <1E-04 

Defoliation 1 274 209 <1E-04 

Defoliation2 1 274 51 <1E-04 

Trtdays 1 1736 80058 <1E-04 

Trtdays2 1 1736 801 <1E-04 

Season:Defoliation 3 274 0.91 0.437 

Season:Defoliation2 3 274 2.49 0.061 

Season:Trtdays 

Season:Trtdays2 

3 

3 

1736 

1736 

9.15 

9.59 

<1E-04 

<1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 
40 

RESEARCH PAPER PSW-RP-267

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

7519 7654 -3736 0.418 0.452 1.839 0.664 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 9.795 0.373 1736 26 <1E-04 

seasSM 0.304 0.504 274 0.60 0.547 

seasFL 2.345 0.503 274 4.66 <1E-04 

seasWN 2.445 0.511 274 4.79 <1E-04 

def -0.025 0.016 274 -1.57 0.117 

def2 7E-05 1E-04 274 0.49 0.624 

trtdays 5.087 0.084 1736 61 <1E-04 

trtdays2 -0.082 0.005 1736 -15 <1E-04 

seasSM:def 0.019 0.022 274 0.85 0.399 

seasFL:def 0.048 0.022 274 2.11 0.035 

seasWN:def 0.063 0.023 274 2.78 0.006 

seasSM:def2 -1E-04 2E-04 274 -0.70 0.483 

seasFL:def2 -4E-04 2E-04 274 -1.86 0.064 

seasWN:def2 -6E-04 2E-04 274 -2.59 0.010 

seasSM:trtdays 0.484 0.120 1736 4.02 1E-04 

seasFL:trtdays -0.365 0.127 1736 -2.86 0.004 

seasWN:trtdays 0.147 0.125 1736 1.18 0.239 

seasSM:trtdays2 -0.024 0.008 1736 -2.98 0.003 

seasFL:trtdays2 0.022 0.009 1736 2.59 0.010 

seasWN:trtdays2 -0.010 0.008 1736 -1.17 0.244 

a DF = degrees of freedom. 

Height—1986–1991 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,644 34415 <1E-04 

Season 3 274 35 <1E-04 

Defoliation 1 274 117 <1E-04 

Defoliation2 1 274 36 <1E-04 

Trtdays 1 1,644 42266 <1E-04 

Trtdays2 1 1,644 270 <1E-04 

Season:Defoliation 3 274 0.74 0.527 

Season:Defoliation2 3 274 2.43 0.065 

Season:Trtdays 3 1,644 25 <1E-04 

Season:Trtdays2 3 1,644 15 <1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 
41 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

6371 6505 -3162 0.298 0.965 1.318 0.581 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 10.390 0.347 1644 30 <1E-04 

seasSM 0.109 0.478 274 0.23 0.820 

seasFL 2.365 0.477 274 4.95 <1E-04 

seasWN 2.330 0.482 274 4.83 <1E-04 

def -0.021 0.015 274 -1.38 0.170 

def2 4E-05 1E-04 274 0.28 0.782 

trtdays 3.471 0.128 1644 27 <1E-04 

trtdays2 0.265 0.025 1644 11 <1E-04 

seasSM:def 0.018 0.022 274 0.85 0.395 

seasFL:def 0.044 0.022 274 2.01 0.046 

seasWN:def 0.061 0.022 274 2.78 0.006 

seasSM:def2 -2E-04 2E-04 274 -0.75 0.454 

seasFL:def2 -4E-04 2E-04 274 -1.83 0.068 

seasWN:def2 -5E-04 2E-04 274 -2.59 0.010 

seasSM:trtdays 1.183 0.190 1644 6.22 <1E-04 

seasFL:trtdays -0.526 0.207 1644 -2.55 0.011 

seasWN:trtdays 0.124 0.200 1644 0.62 0.535 

seasSM:trtdays2 -0.171 0.037 1644 -4.59 <1E-04 

seasFL:trtdays2 

seasWN:trtdays2 

0.097 

0.054 

0.043 

0.043 

1644 

1644 

2.28 

1.27 

0.023 

0.205 

a DF = degrees of freedom. 
42 

RESEARCH PAPER PSW-RP-267

Branchville, South Carolina—loblolly pine 

Diameter at breast height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,355 5598 <1E-04 

Season 3 219 11 <1E-04 

Defoliation 1 219 37 <1E-04 

Defoliation2 1 219 7.35 0.007 

Trtdays 1 1,355 11420 <1E-04 

Trtdays2 1 1,355 2573 <1E-04 

Season:Defoliation 3 219 0.41 0.746 

Season:Defoliation2 3 219 0.17 0.920 

Season:Trtdays 3 1,355 20 <1E-04 

Season:Trtdays2 3 1,355 6.41 3E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

2038 2167 -995 0.166 1E-04 0.743 0.857 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.691 0.178 1355 9.52 <1E-04 

seasSM 0.112 0.244 219 0.46 0.648 

seasFL 0.663 0.245 219 2.70 0.007 

seasWN 0.895 0.248 219 3.60 4E-04 

def -0.006 0.008 219 -0.76 0.445 

def2 1E-05 7E-05 219 0.17 0.867 

trtdays 

trtdays2 

1.279 

-0.053 

0.029 

0.002 

1355 

1355 

44 

-29 

<1E-04 

<1E-04 

seasSM:def 0.003 0.011 219 0.30 0.767 

seasFL:def 0.003 0.012 219 0.23 0.821 

seasWN:def 0.008 0.012 219 0.71 0.478 

seasSM:def2 -5E-05 1E-04 219 -0.49 0.656 

seasFL:def2 -2E-05 1E-04 219 -0.21 0.837 

seasWN:def2 -6E-05 1E-04 219 -0.56 0.580 

seasSM:trtdays 0.085 0.043 1355 1.96 0.050 

seasFL:trtdays -0.128 0.047 1355 -2.75 0.006 

seasWN:trtdays 

seasSM:trtdays2 

seasFL:trtdays2 

seasWN:trtdays2 

-0.162 

-0.005 

0.004 

0.006 

0.045 

0.003 

0.003 

0.003 

1355 

1355 

1355 

1355 

-3.62 

-2.06 

1.50 

2.24 

3E-04 

0.041 

0.135 

0.025 

a DF = degrees of freedom. 
43 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Diameter at breast height—1986–1991 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,256 8632 <1E-04 

Season 3 219 8.34 <1E-04 

Defoliation 1 219 40 <1E-04 

Defoliation2 1 219 5.87 0.016 

Trtdays 1 1,256 11967 <1E-04 

Trtdays2 1 1,256 379 <1E-04 

Season:Defoliation 3 219 0.46 0.710 

Season:Defoliation2 3 219 0.30 0.827 

Season:Trtdays 3 1,256 25 <1E-04 

Season:Trtdays2 3 1,256 9.87 <1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

1114 1241 -533 0.111 1E-04 0.569 0.858 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.727 0.137 1256 13 <1E-04 

seasSM -0.039 0.189 219 -0.21 0.837 

seasFL 0.548 0.191 219 2.87 0.005 

seasWN 0.868 0.192 219 4.51 <1E-04 

def -0.009 0.006 219 -1.42 0.157 

def2 3E-05 6E-05 219 0.56 0.573 

trtdays 1.380 0.040 1256 34 <1E-04 

trtdays2 -0.074 0.007 1256 -10 <1E-04 

seasSM:def 0.004 0.009 219 0.50 0.620 

seasFL:def 0.003 0.009 219 0.29 0.770 

seasWN:def 0.009 0.009 219 1.02 0.307 

seasSM:def2 -4E-05 9E-05 219 -0.50 0.617 

seasFL:def2 -1E-05 8E-05 219 -0.11 0.910 

seasWN:def2 -7E-05 8E-05 219 -0.81 0.420 

seasSM:trtdays 0.306 0.061 1256 5.04 <1E-04 

seasFL:trtdays -0.022 0.069 1256 -0.32 0.751 

seasWN:trtdays -0.171 0.064 1256 -2.69 0.007 

seasSM:trtdays2 -0.055 0.011 1256 -4.86 <1E-04 

seasFL:trtdays2 -0.020 0.013 1256 -1.48 0.140 

seasWN:trtdays2 0.007 0.013 1256 0.53 0.599 

a DF = degrees of freedom. 
44 

RESEARCH PAPER PSW-RP-267

Height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,355 23829 <1E-04 

Season 3 219 54 <1E-04 

Defoliation 1 219 77 <1E-04 

Defoliation2 1 219 29 <1E-04 

Trtdays 1 1,355 68138 <1E-04 

Trtdays2 1 1,355 555 <1E-04 

Season:Defoliation 3 219 0.72 0.543 

Season:Defoliation2 3 219 0.20 0.897 

Season:Trtdays 3 1,355 8.15 <1E-04 

Season:Trtdays2 3 1,355 4.60 0.003 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

6204 6333 -3078 0.471 0.352 2.108 0.712 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 9.561 0.460 1355 21 <1E-04 

seasSM 0.554 0.628 219 0.88 0.379 

seasFL 2.683 0.639 219 4.20 <1E-04 

seasWN 3.456 0.644 219 5.37 <1E-04 

def 0.003 0.020 219 0.13 0.895 

def2 -1E-04 2E-04 219 -0.74 0.460 

trtdays 5.116 0.102 1355 50 <1E-04 

trtdays2 -0.070 0.006 1355 -11 <1E-04 

seasSM:def -0.008 0.028 219 -0.29 0.776 

seasFL:def 0.007 0.029 219 0.25 0.801 

seasWN:def -0.005 0.029 219 -0.17 0.867 

seasSM:def2 5E-05 3E-04 219 0.21 0.831 

seasFL:def2 -1E-04 3E-04 219 -0.50 0.620 

seasWN:def2 1E-04 3E-04 219 0.38 0.706 

seasSM:trtdays 0.417 0.149 1355 2.81 0.005 

seasFL:trtdays 0.044 0.162 1355 0.27 0.786 

seasWN:trtdays 0.098 0.157 1355 0.63 0.532 

seasSM:trtdays2 -0.035 0.010 1355 -3.71 2E-04 

seasFL:trtdays2 

seasWN:trtdays2 

-0.017 

-0.017 

0.011 

0.010 

1355 

1355 

-1.61 

-1.66 

0.109 

0.097 

a DF = degrees of freedom. 
45 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Height—1986–1991 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,256 27277 <1E-04 

Season 3 219 19 <1E-04 

Defoliation 1 219 46 <1E-04 

Defoliation2 1 219 20 <1E-04 

Trtdays 1 1,256 27870 <1E-04 

Trtdays2 1 1,256 1.05 0.306 

Season:Defoliation 3 219 0.45 0.717 

Season:Defoliation2 3 219 0.23 0.878 

Season:Trtdays 3 1,256 3.24 0.021 

Season:Trtdays2 3 1,256 4.69 0.003 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

5179 5306 -2565 0.331 0.958 1.443 0.597 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 10.125 0.393 1256 27 <1E-04 

seasSM 0.035 0.543 219 0.06 0.948 

seasFL 2.303 0.553 219 4.16 <1E-04 

seasWN 3.227 0.552 219 5.85 <1E-04 

def -0.018 0.017 219 -1.06 0.291 

def2 3E-05 2E-04 219 0.18 0.855 

trtdays 4.629 0.152 1256 30 <1E-04 

trtdays2 0.036 0.029 1256 1.24 0.217 

seasSM:def 0.012 0.025 219 0.49 0.628 

seasFL:def 0.019 0.025 219 0.74 0.458 

seasWN:def 0.007 0.025 219 0.28 0.781 

seasSM:def2 -1E-04 2E-04 219 -0.45 0.656 

seasFL:def2 -2E-04 2E-04 219 -0.80 0.427 

seasWN:def2 -3E-06 2E-04 219 -0.01 0.989 

seasSM:trtdays 0.960 0.228 1256 4.22 <1E-04 

seasFL:trtdays 0.160 0.267 1256 0.60 0.551 

seasWN:trtdays 0.147 0.245 1256 0.60 0.549 

seasSM:trtdays2 -0.159 0.045 1256 -3.55 4E-04 

seasFL:trtdays2 

seasWN:trtdays2 

-0.037 

-0.009 

0.054 

0.053 

1256 

1256 

-0.70 

-0.18 

0.487 

0.860 a

 DF = degrees of freedom. 
46 

RESEARCH PAPER PSW-RP-267

Growth Flushes—1986–1990 

Model summary—analysis of deviance table 

Residual 

Source DF Deviance DF Deviance 

Null 707 349.53 

Season 3 0.864 704 348.67 

Defoliation 1 1.908 703 346.76 

Defoliation2 1 1.365 702 345.39 

Trtdays 1 24.34 701 321.05 

Trtdays2 1 78.136 700 242.92 

Season:Defoliation 3 2.073 697 240.85 

Season:Defoliation2 3 1.877 694 238.97 

Season:Trtdays 

Season:Trtdays2 

3 

3 

43.42 

2.226 

691 

688 

195.55 

193.32 a DF = degrees of freedom. 

Fixed-effects estimates 

Coefficient Value Std. error z-value p-value 

Intercept 1.380 0.139 9.97 <1E-04 

seasSM 0.178 0.235 0.76 0.448 

seasFL 0.207 0.274 0.76 0.451 

seasWN -0.317 0.182 -1.74 0.082 

def 0.004 0.005 0.88 0.378 

def2 -6E-05 5E-05 -1.35 0.176 

trtdays -1.240 0.219 -5.66 <1E-04 

trtdays2 0.365 0.060 6.04 <1E-04 

seasSM:def -0.005 0.007 -0.76 0.446 

seasFL:def -0.001 0.007 -0.21 0.837 

seasWN:def -0.005 0.007 -0.78 0.434 

seasSM:def2 6E-05 7E-05 1.01 0.315 

seasFL:def2 3E-05 6E-05 0.41 0.682 

seasWN:def2 8E-05 7E-05 1.14 0.256 

seasSM:trtdays -0.002 0.334 -0.01 0.994 

seasFL:trtdays 0.215 0.341 0.63 0.528 

seasWN:trtdays 0.342 0.288 1.19 0.235 

seasSM:trtdays2 -0.042 0.086 -0.49 0.622 

seasFL:trtdays2 

seasWN:trtdays2 

-0.120 

-0.053 

0.082 

0.085 

-1.46 

-0.63 

0.144 

0.531 
47 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Palatka, Florida—slash pine 

Diameter at breast height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,718 12226 <1E-04 

Season 3 274 0.99 0.399 

Defoliation 1 274 79 <1E-04 

Defoliation2 1 274 0.65 0.420 

Trtdays 1 1,718 8707 <1E-04 

Trtdays2 1 1,718 1373 <1E-04 

Season:Defoliation 3 274 3.13 0.026 

Season:Defoliation2 3 274 1.80 0.148 

Season:Trtdays 3 1,718 9.42 <1E-04 

Season:Trtdays2 3 1,718 6.78 2E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

402 536 -177 8e-07 8e-05 0.575 0.925 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 2.124 0.129 1718 16 <1E-04 

seasSM 0.094 0.185 274 0.51 0.612 

seasFL 0.500 0.187 274 2.68 0.008 

seasWN 0.795 0.186 274 4.27 <1E-04 

def -0.006 0.006 274 -0.93 0.355 

def2 2E-05 6E-05 274 0.29 0.776 

trtdays 0.594 0.016 1718 37 <1E-04 

trtdays2 -0.023 0.001 1718 -24 <1E-04 

seasSM:def 0.015 0.009 274 1.74 0.084 

seasFL:def 0.009 0.009 274 0.97 0.331 

seasWN:def -0.005 0.009 274 -0.59 0.554 

seasSM:def2 -2E-04 8E-05 274 -1.81 0.071 

seasFL:def2 -1E-04 8E-05 274 -1.53 0.127 

seasWN:def2 -2E-06 8E-05 274 -0.02 0.982 

seasSM:trtdays -0.073 0.023 1718 -3.10 0.002 

seasFL:trtdays -0.104 0.025 1718 -4.22 <1E-04 

seasWN:trtdays -0.126 0.024 1718 -5.33 <1E-04 

seasSM:trtdays2 0.004 0.001 1718 2.54 0.011 

seasFL:trtdays2 

seasWN:trtdays2 

0.005 

0.006 

0.002 

0.001 

1718 

1718 

3.48 

4.05 

5E-04 

1E-04 

a DF = degrees of freedom. 
48 

RESEARCH PAPER PSW-RP-267

Diameter at breast height—1986–1991 

The model did not converge so no estimates or hypothesis tests are presented. 

Height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,718 34,680 <1E-04 

Season 3 274 11 <1E-04 

Defoliation 1 274 116 <1E-04 

Defoliation2 1 274 0.29 0.594 

Trtdays 1 1,718 25,262 <1E-04 

Trtdays2 1 1,718 700 <1E-04 

Season:Defoliation 3 274 2.95 0.033 

Season:Defoliation2 3 274 0.50 0.685 

Season:Trtdays 3 1,718 1.64 0.179 

Season:Trtdays2 3 1,718 10 <1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

8299 8434 4126 0.151 8E-04 2.625 0.768 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 10.726 0.511 1718 21 <1E-04 

seasSM 2.339 0.730 274 3.20 0.002 

seasFL 3.858 0.748 274 5.16 <1E-04 

seasWN 4.339 0.741 274 5.86 <1E-04 

def 0.005 0.023 274 0.22 0.829 

def2 -3E-04 2E-04 274 -1.18 0.238 

trtdays 

trtdays2 

4.658 

-0.131 

0.110 

0.007 

1718 

1718 

42 

-19 

<1E-04 

<1E-04 

seasSM:def 0.037 0.033 274 1.11 0.266 

seasFL:def 0.009 0.034 274 0.28 0.783 

seasWN:def 8E-04 0.034 274 0.02 0.981 

seasSM:def2 -3E-04 3E-04 274 -1.07 0.286 

seasFL:def2 -3E-04 3E-04 274 -0.91 0.362 

seasWN:def2 -1E-04 3E-04 274 -0.35 0.726 

seasSM:trtdays -0.860 0.159 1718 -5.40 <1E-04 

seasFL:trtdays -0.548 0.169 1718 -3.24 0.001 

seasWN:trtdays 

seasSM:trtdays2 

seasFL:trtdays2 

seasWN:trtdays2 

-0.679 

0.051 

0.032 

0.045 

0.163 

0.010 

0.011 

0.011 

1718 

1718 

1718 

1718 

-4.15 

5.04 

2.92 

4.22 

<1E-04 

<1E-04 

0.004 

<1E-04 a DF = degrees of freedom. 
49 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Height—1986–1991 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,614 47,075 <1E-04 

Season 3 274 17 <1E-04 

Defoliation 1 274 114 <1E-04 

Defoliation2 1 274 31 <1E-04 

Trtdays 1 1,614 20,155 <1E-04 

Trtdays2 1 1,614 16 1E-04 

Season:Defoliation 3 274 3.80 0.011 

Season:Defoliation2 3 274 0.63 0.594 

Season:Trtdays 3 1,614 18 <1E-04 

Season:Trtdays2 3 1,614 23 <1E-04 a DF = degrees of freedom, num=numerator, den=denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

5970 6104 -2961 0.174 0.001 1.739 0.817 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 10.320 0.359 1614 29 <1E-04 

seasSM 2.912 0.510 274 5.71 <1E-04 

seasFL 4.130 0.524 274 7.88 <1E-04 

seasWN 4.491 0.516 274 8.70 <1E-04 

def 0.013 0.016 274 0.83 0.411 

def2 -3E-04 2E-04 274 -1.71 0.089 

trtdays 4.430 0.126 1614 35 <1E-04 

trtdays2 -0.081 0.023 1614 -3.52 4E-04 

seasSM:def 0.028 0.023 274 1.18 0.239 

seasFL:def -0.003 0.024 274 -0.15 0.883 

seasWN:def -0.010 0.024 274 -0.42 0.672 

seasSM:def2 -3E-04 2E-04 274 -1.20 0.231 

seasFL:def2 -1E-04 2E-04 274 -0.58 0.562 

seasWN:def2 -4E-06 2E-04 274 -0.02 0.986 

seasSM:trtdays -1.916 0.188 1614 -10 <1E-04 

seasFL:trtdays -1.166 0.209 1614 -5.58 <1E-04 

seasWN:trtdays -0.931 0.193 1614 -4.82 <1E-04 

seasSM:trtdays2 0.284 0.035 1614 8.09 <1E-04 

seasFL:trtdays2 

seasWN:trtdays2 

0.173 

0.116 

0.040 

0.039 

1614 

1614 

4.32 

2.97 

<1E-04 

0.003 

a DF = degrees of freedom. 
50 

RESEARCH PAPER PSW-RP-267

Growth Flushes—1986–1990 

Model summary–analysis of deviance table 

Residual 

Source DFa Deviance DF Deviance 

Null 

Season 

Defoliation 

Defoliation2 

Trtdays 

Trtdays2 

Season:Defoliation 

Season:Defoliation2 

Season:Trtdays 

Season:Trtdays2 

3 

1 

1 

1 

1 

3 

3 

3 

3 

0.283 

13 

1.17 

36 

1.08 

1.70 

2.33 

0.25 

7.54 

893 

890 

889 

888 

887 

886 

883 

880 

877 

874 

253.35 

253.07 

240.16 

238.99 

202.78 

201.70 

200.00 

197.68 

197.43 

189.89 

a DF = degrees of freedom. 

Fixed-effects estimates 

Coefficient Value Std. error z-value p-value 

Intercept 1.350 0.120 11.21 <1E-04 

seasSM 0.017 0.195 0.09 0.932 

seasFL -0.400 0.230 -1.74 0.082 

seasWN -0.197 0.158 -1.25 0.213 

def 0.003 0.004 0.77 0.442 

def2 -6E-05 4E-05 -1.56 0.120 

trtdays -0.414 0.165 -2.51 0.012 

trtdays2 0.087 0.045 1.92 0.056 

seasSM:def -0.006 0.006 -0.97 0.333 

seasFL:def -0.006 0.006 -0.97 0.331 

seasWN:def -6E-05 0.006 -0.01 0.991 

seasSM:def2 7E-05 6E-05 1.21 0.226 

seasFL:def2 7E-05 6E-05 1.22 0.221 

seasWN:def2 2E-05 6E-05 0.36 0.717 

seasSM:trtdays 0.123 0.249 0.49 0.622 

seasFL:trtdays 0.682 0.261 2.61 0.009 

seasWN:trtdays 0.196 0.216 0.91 0.365 

seasSM:trtdays2 -0.043 0.064 -0.68 0.499 

seasFL:trtdays2 

seasWN:trtdays2 

-0.164 

-0.052 

0.063 

0.063 

-2.61 

-0.82 

0.009 

0.412 
51 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Waycross, Georgia—slash pine 

Diameter at breast height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,721 15784 <1E-04 

Season 3 274 1.84 0.141 

Defoliation 1 274 74 <1E-04 

Defoliation2 1 274 2.33 0.128 

Trtdays 1 1,721 14723 <1E-04 

Trtdays2 1 1,721 863 <1E-04 

Season:Defoliation 3 274 0.99 0.398 

Season:Defoliation2 3 274 1.16 0.325 

Season:Trtdays 3 1,721 25 <1E-04 

Season:Trtdays2 3 1,721 4.37 0.005 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

447 581 -199 2E-04 2E-05 0.534 0.908 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 2.017 0.121 1721 16 <1E-04 

seasSM 0.442 0.171 274 2.58 0.010 

seasFL 0.490 0.171 274 2.87 0.005 

seasWN 0.643 0.175 274 3.67 3E-04 

def -1E-04 0.006 274 -0.02 0.982 

def2 -4E-05 5E-05 274 -0.67 0.505 

trtdays 0.610 0.016 1721 37 <1E-04 

trtdays2 -0.019 0.001 1721 -19 <1E-04 

seasSM:def -0.012 0.008 274 -1.47 0.143 

seasFL:def -0.002 0.008 274 -0.25 0.806 

seasWN:def -5E-04 0.008 274 -0.06 0.953 

seasSM:def2 1E-04 8E-05 274 1.35 0.178 

seasFL:def2 -1E-05 8E-05 274 -0.16 0.872 

seasWN:def2 -2E-05 8E-05 274 -0.27 0.785 

seasSM:trtdays -0.074 0.024 1721 -3.09 0.002 

seasFL:trtdays -0.098 0.025 1721 -3.98 1E-04 

seasWN:trtdays -0.097 0.024 1721 -4.01 1E-04 

seasSM:trtdays2 0.004 0.001 1721 2.84 0.005 

seasFL:trtdays2 0.003 0.002 1721 1.76 0.079 

seasWN:trtdays2 0.005 0.002 1721 3.28 0.001 a DF = degrees of freedom. 
52 

RESEARCH PAPER PSW-RP-267

Diameter at breast height—1986–1991 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,630 18,879 <1E-04 

Season 3 274 3.19 0.024 

Defoliation 1 274 64 <1E-04 

Defoliation2 1 274 0.64 0.423 

Trtdays 1 1,630 9,444 <1E-04 

Trtdays2 1 1,630 1.64 0.201 

Season:Defoliation 3 274 1.48 0.220 

Season:Defoliation2 3 274 0.75 0.525 

Season:Trtdays 3 1,630 11 <1E-04 

Season:Trtdays2 3 1,630 9.17 <1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

-542 -408 295 9E-12 6E-05 0.438 0.920 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.974 0.101 1630 19 <1E-04 

seasSM 0.440 0.143 274 3.08 0.002 

seasFL 0.535 0.142 274 3.75 2E-04 

seasWN 0.673 0.146 274 4.61 <1E-04 

def -1E-04 0.005 274 -0.02 0.983 

def2 -3E-05 4E-05 274 -0.61 0.543 

trtdays 0.613 0.022 1630 28 <1E-04 

trtdays2 -0.020 0.004 1630 -5.09 <1E-04 

seasSM:def -0.008 0.007 274 -1.23 0.218 

seasFL:def -0.003 0.007 274 -0.37 0.708 

seasWN:def -5E-04 0.007 274 -0.07 0.943 

seasSM:def2 6E-05 6E-05 274 1.02 0.301 

seasFL:def2 -5E-06 6E-05 274 -0.08 0.933 

seasWN:def2 -3E-05 6E-05 274 -0.40 0.692 

seasSM:trtdays -0.162 0.033 1630 -4.96 <1E-04 

seasFL:trtdays -0.222 0.035 1630 -6.32 <1E-04 

seasWN:trtdays -0.157 0.033 1630 -4.73 <1E-04 

seasSM:trtdays2 0.023 0.006 1630 3.95 1E-04 

seasFL:trtdays2 0.030 0.007 1630 4.60 <1E-04 

seasWN:trtdays2 0.020 0.007 1630 3.05 0.002 

a DF = degrees of freedom. 
53 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,721 34,596 <1E-04 

Season 3 274 11 <1E-04 

Defoliation 1 274 119 <1E-04 

Defoliation2 1 274 11 0.001 

Trtdays 1 1,721 40,219 <1E-04 

Trtdays2 1 1,721 13 3E-04 

Season:Defoliation 3 274 2.85 0.038 

Season:Defoliation2 3 274 1.92 0.127 

Season:Trtdays 3 1,721 5.83 6E-04 

Season:Trtdays2 3 1,721 11 <1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

7888 8023 -3920 0.153 5E-04 2.443 0.788 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 10.990 0.499 1721 22 <1E-04 

seasSM 2.399 0.701 274 3.42 7E-04 

seasFL 2.219 0.709 274 3.13 0.002 

seasWN 3.548 0.722 274 4.92 <1E-04 

def -0.021 0.022 274 -0.95 0.342 

def2 3E-05 2E-04 274 0.13 0.898 

trtdays 3.719 0.101 1721 37 <1E-04 

trtdays2 -0.039 0.006 1721 -6.01 <1E-04 

seasSM:def -0.015 0.032 274 -0.46 0.646 

seasFL:def 0.034 0.032 274 1.07 0.284 

seasWN:def 0.017 0.032 274 0.53 0.600 

seasSM:def2 2E-04 3E-04 274 0.51 0.607 

seasFL:def2 -5E-04 3E-04 274 -1.61 0.108 

seasWN:def2 -3E-04 3E-04 274 -1.05 0.295 

seasSM:trtdays -0.637 0.146 1721 -4.37 <1E-04 

seasFL:trtdays -0.467 0.152 1721 -3.07 0.002 

seasWN:trtdays -0.256 0.149 1721 -1.72 0.086 

seasSM:trtdays2 0.052 0.009 1721 5.62 <1E-04 

seasFL:trtdays2 

seasWN:trtdays2 

0.031 

0.024 

0.010 

0.010 

1721 

1721 

3.16 

2.45 

0.002 

0.015 

a DF = degrees of freedom. 
54 

RESEARCH PAPER PSW-RP-267

Height—1986–1991 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 1,630 32018 <1E-04 

Season 3 274 10 <1E-04 

Defoliation 1 274 99 <1E-04 

Defoliation2 1 274 5.02 0.026 

Trtdays 1 1,630 16155 <1E-04 

Trtdays2 1 1,630 95 <1E-04 

Season:Defoliation 3 274 3.57 0.015 

Season:Defoliation2 3 274 0.92 0.430 

Season:Trtdays 3 1,630 9.65 <1E-04 

Season:Trtdays2 3 1,630 9.31 <1E-04 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

6026 6159 -2989 0.214 3E-04 1.859 0.845 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 10.780 0.405 1630 26 <1E-04 

seasSM 2.691 0.566 274 4.75 <1E-04 

seasFL 2.567 0.571 274 4.50 <1E-04 

seasWN 3.667 0.581 274 6.31 <1E-04 

def -0.007 0.018 274 -0.40 0.687 

def2 -7E-05 2E-04 274 -0.39 0.694 

trtdays 3.200 0.125 1630 25 <1E-04 

trtdays2 0.073 0.023 1630 3.22 0.001 

seasSM:def -0.005 0.026 274 -0.21 0.836 

seasFL:def 0.016 0.026 274 0.626 0.532 

seasWN:def 0.007 0.026 274 0.251 0.802 

seasSM:def2 2E-05 2E-04 274 0.099 0.921 

seasFL:def2 -3E-04 2E-04 274 -1.280 0.202 

seasWN:def2 -2E-04 2E-04 274 -0.939 0.348 

seasSM:trtdays -1.177 0.187 1630 -6.287 <1E-04 

seasFL:trtdays -0.584 0.203 1630 -2.869 0.004 

seasWN:trtdays -0.125 0.192 1630 -0.651 0.515 

seasSM:trtdays2 0.173 0.035 1630 4.976 <1E-04 

seasFL:trtdays2 

seasWN:trtdays2 

0.061 

0.010 

0.039 

0.039 

1630 

1630 

1.576 

0.271 

0.115 

0.787 

a DF = degrees of freedom. 
55 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Aiken, South Carolina—longleaf pine 

Diameter at breast height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 721 7263 <1E-04 

Month 4 201 1.81 0.128 

Defoliation 1 201 53 <1E-04 

Trtdays 1 721 7036 <1E-04 

Trtdays2 1 721 326 <1E-04 

Month:Defoliation 4 201 1.02 0.401 

Month:Trtdays 

Month:Trtdays2 

4 

4 

721 

721 

0.87 

0.33 

0.480 

0.858 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

597 714 -275 0.076 4E-05 0.427 0.789 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.775 0.071 597 25 <1E-04 

monthSEP 0.201 0.098 201 2.06 0.041 

monthOCT 0.207 0.098 201 2.10 0.037 

monthNOV -0.014 0.098 201 -0.14 0.889 

monthDEC 0.105 0.098 201 1.08 0.282 

def -0.001 8E-04 201 -1.50 0.134 

trtdays 0.165 0.020 597 8.12 <1E-04 

trtdays2 0.007 0.003 597 2.35 0.019 

monthSEP:def -0.002 0.001 201 -1.33 0.184 

monthOCT:def -0.002 0.001 201 -1.64 0.102 

monthNOV:def 6E-04 0.001 201 0.53 0.594 

monthDEC:def -9E-04 0.001 201 -0.73 0.468 

monthSEP:trtdays -0.010 0.029 597 -0.33 0.741 

monthOCT:trtdays 0.042 0.032 597 1.30 0.194 

monthNOV:trtdays 0.037 0.033 597 1.15 0.252 

monthDEC:trtdays 0.040 0.031 597 1.28 0.201 

monthSEP:trtdays2 0.003 0.004 597 0.67 0.502 

monthOCT:trtdays2 -0.004 0.005 597 -0.81 0.418 

monthNOV:trtdays2 

monthDEC:trtdays2 

-0.005 

-0.003 

0.005 

0.004 

597 

597 

-1.03 

-0.72 

0.305 

0.473 

a DF = degrees of freedom. 
56 

RESEARCH PAPER PSW-RP-267

Diameter at breast height—1993–1999 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 597 8959 <1E-04 

Month 4 201 2.88 0.024 

Defoliation 1 201 57 <1E-04 

Trtdays 1 597 5429 <1E-04 

Trtdays2 1 597 13 3E-04 

Month:Defoliation 4 201 1.71 0.150 

Month:Trtdays 4 597 1.40 0.233 

Month:Trtdays2 4 597 0.93 0.446 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

-131 -18 -90 0.065 3e-05 0.292 0.813 

Fixed effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.775 0.071 597 25 <1E-04 

monthSEP 0.201 0.098 201 2.06 0.041 

monthOCT 0.207 0.098 201 2.10 0.037 

monthNOV -0.014 0.098 201 -0.14 0.889 

monthDEC 0.105 0.098 201 1.08 0.282 

def -0.001 8E-04 201 -1.50 0.134 

trtdays 0.165 0.020 597 8.11 <1E-04 

trtdays2 0.007 0.003 597 2.35 0.019 

monthSEP:def -0.002 0.001 201 -1.33 0.184 

monthOCT:def -0.002 0.001 201 -1.64 0.102 

monthNOV:def 0.001 0.001 201 0.53 0.594 

monthDEC:def -0.001 0.001 201 -0.73 0.468 

monthSEP:trtdays -0.010 0.029 597 -0.33 0.741 

monthOCT:trtdays 0.042 0.032 597 1.30 0.194 

monthNOV:trtdays 0.037 0.033 597 1.15 0.252 

monthDEC:trtdays 0.040 0.031 597 1.28 0.201 

monthSEP:trtdays2 0.003 0.004 597 0.67 0.502 

monthOCT:trtdays2 -0.004 0.005 597 -0.81 0.418 

monthNOV:trtdays2 

monthDEC:trtdays2 

-0.005 

-0.003 

0.005 

0.004 

597 

597 

-1.03 

-0.72 

0.305 

0.473 

a DF = degrees of freedom. 
57 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Height–all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 721 10796 <1E-04 

Month 4 201 3.29 0.012 

Defoliation 1 201 42 <1E-04 

Trtdays 1 721 13179 <1E-04 

Trtdays2 1 721 500 <1E-04 

Month:Defoliation 4 201 0.82 0.517 

Month:Trtdays 

Month:Trtdays2 

4 

4 

721 

721 

0.45 

0.72 

0.776 

0.577 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

4415 4531 -2184 0.508 3E-04 2.528 0.515 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 9.652 0.519 721 18 <1E-04 

monthSEP 0.249 0.714 201 0.35 0.728 

monthOCT 0.275 0.716 201 0.38 0.702 

monthNOV -0.281 0.715 201 -0.39 0.695 

monthDEC 0.368 0.708 201 0.52 0.604 

def -0.012 0.006 201 -2.17 0.031 

trtdays 2.514 0.110 721 23 <1E-04 

trtdays2 -0.050 0.005 721 -9.55 <1E-04 

monthSEP:def -8E-04 0.008 201 -0.11 0.916 

monthOCT:def 0.003 0.008 201 0.42 0.676 

monthNOV:def 0.010 0.008 201 1.29 0.197 

monthDEC:def -0.002 0.008 201 -0.20 0.840 

monthSEP:trtdays 0.170 0.156 721 1.08 0.279 

monthOCT:trtdays 0.184 0.166 721 1.11 0.268 

monthNOV:trtdays 0.045 0.165 721 0.27 0.785 

monthDEC:trtdays 0.257 0.159 721 1.61 0.107 

monthSEP:trtdays2 -0.007 0.007 721 -0.92 0.360 

monthOCT:trtdays2 -0.008 0.008 721 -1.07 0.284 

monthNOV:trtdays2 

monthDEC:trtdays2 

-0.003 

-0.012 

0.008 

0.008 

721 

721 

-0.43 

-1.58 

0.665 

0.115 

a DF = degrees of freedom. 
58 

RESEARCH PAPER PSW-RP-267

Height—1993–1999 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 597 18465 <1E-04 

Month 4 201 7.13 <1E-04 

Defoliation 1 201 62 <1E-04 

Trtdays 1 597 18831 <1E-04 

Trtdays2 1 597 934 <1E-04 

Month:Defoliation 4 201 1.16 0.328 

Month:Trtdays 

Month:Trtdays2 

4 

4 

597 

597 

5.88 

1.41 

1E-04 

0.2287 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

2718 2831 -1335 0.247 2E-04 1.601 0.778 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 10.635 0.378 597 28 <1E-04 

monthSEP 0.531 0.527 201 1.01 0.314 

monthOCT 0.029 0.531 201 0.05 0.957 

monthNOV -0.439 0.531 201 -0.83 0.409 

monthDEC 0.441 0.527 201 0.84 0.404 

def -0.009 0.004 201 -1.95 0.053 

trtdays 0.492 0.121 597 4.08 1E-04 

trtdays2 0.267 0.017 597 16 <1E-04 

monthSEP:def -0.004 0.006 201 -0.58 0.565 

monthOCT:def 0.002 0.006 201 0.28 0.781 

monthNOV:def 0.008 0.006 201 1.26 0.208 

monthDEC:def -0.004 0.006 201 -0.57 0.567 

monthSEP:trtdays -0.030 0.174 597 -0.17 0.864 

monthOCT:trtdays 0.415 0.190 597 2.18 0.029 

monthNOV:trtdays 0.201 0.193 597 1.04 0.297 

monthDEC:trtdays 0.226 0.186 597 1.22 0.225 

monthSEP:trtdays2 0.027 0.024 597 1.09 0.278 

monthOCT:trtdays2 -0.036 0.027 597 -1.32 0.186 

monthNOV:trtdays2 

monthDEC:trtdays2 

-0.016 

0.003 

0.028 

0.027 

597 

597 

-0.58 

0.12 

0.563 

0.905 

a DF = degrees of freedom. 
59 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Waycross, Georgia—longleaf pine 

Diameter at breast height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 664 7333 <1E-04 

Month 4 201 1.88 0.116 

Defoliation 1 201 83 <1E-04 

Trtdays 1 664 7394 <1E-04 

Trtdays2 1 664 527 <1E-04 

Month:Defoliation 4 201 0.77 0.548 

Month:Trtdays 

Month:Trtdays2 

4 

4 

664 

664 

1.99 

1.60 

0.095 

0.172 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σr σ

^ o/ 

960 1075 -456 0.077 5e-05 0.495 0.742 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 1.983 0.117 664 17 <1E-04 

monthSEP -0.101 0.155 201 -0.65 0.514 

monthOCT 0.075 0.157 201 0.48 0.634 

monthNOV -0.138 0.158 201 -0.88 0.382 

monthDEC 0.093 0.178 201 0.52 0.602 

def -0.004 0.001 201 -3.31 0.001 

trtdays 0.403 0.018 664 23 <1E-04 

trtdays2 -0.009 9E-04 664 -10 <1E-04 

monthSEP:def 0.001 0.002 201 0.68 0.496 

monthOCT:def -8E-04 0.002 201 -0.42 0.676 

monthNOV:def 0.002 0.002 201 1.13 0.261 

monthDEC:def -1E-04 0.002 201 -0.05 0.959 

monthSEP:trtdays 0.024 0.025 664 0.96 0.337 

monthOCT:trtdays 0.040 0.026 664 1.54 0.124 

monthNOV:trtdays 0.010 0.025 664 0.40 0.691 

monthDEC:trtdays -3E-04 0.026 664 -0.01 0.991 

monthSEP:trtdays2 -0.001 0.001 664 -0.83 0.406 

monthOCT:trtdays2 -0.002 0.001 664 -1.80 0.072 

monthNOV:trtdays2 

monthDEC:trtdays2 

5E-04 

4E-04 

0.001 

0.001 

664 

664 

0.39 

0.28 

0.699 

0.781 

a DF = degrees of freedom. 
60 

RESEARCH PAPER PSW-RP-267

Diameter at breast height—1993–1999 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 604 6529 <1E-04 

Month 4 201 0.26 0.902 

Defoliation 1 201 61 <1E-04 

Trtdays 1 604 6691 <1E-04 

Trtdays2 1 604 28 <1E-04 

Month:Defoliation 4 201 1.52 0.199 

Month:Trtdays 4 604 1.14 0.336 

Month:Trtdays2 4 604 0.72 0.582 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

468 581 -210 0.089 1e-05 0.397 0.773 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 2.032 0.098 604 21 <1E-04 

monthSEP -0.168 0.129 201 -1.30 0.194 

monthOCT 0.052 0.131 201 0.40 0.689 

monthNOV -0.150 0.132 201 -1.13 0.258 

monthDEC 0.086 0.148 201 0.58 0.563 

def -0.004 0.001 201 -3.50 6E-04 

trtdays 0.233 0.031 604 7.56 <1E-04 

trtdays2 0.018 0.004 604 4.08 1E-04 

monthSEP:def 0.002 0.002 201 1.38 0.171 

monthOCT:def -7E-04 0.002 201 -0.45 0.650 

monthNOV:def 0.002 0.002 201 1.18 0.238 

monthDEC:def -5E-04 0.002 201 -0.30 0.762 

monthSEP:trtdays 0.068 0.045 604 1.52 0.129 

monthOCT:trtdays 0.074 0.046 604 1.60 0.110 

monthNOV:trtdays 0.074 0.046 604 1.60 0.109 

monthDEC:trtdays 0.066 0.048 604 1.38 0.168 

monthSEP:trtdays2 -0.008 0.006 604 -1.22 0.223 

monthOCT:trtdays2 -0.007 0.007 604 -1.05 0.292 

monthNOV:trtdays2 

monthDEC:trtdays2 

-0.009 

-0.009 

0.007 

0.007 

604 

604 

-1.38 

-1.36 

0.169 

0.175 

a DF = degrees of freedom. 
61 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Height—all measurements 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 664 23938 <1E-04 

Month 4 201 5.17 6E-04 

Defoliation 1 201 129 <1E-04 

Trtdays 1 664 11467 <1E-04 

Trtdays2 1 664 946 <1E-04 

Month:Defoliation 4 201 0.08 0.989 

Month:Trtdays 

Month:Trtdays2 

4 

4 

664 

664 

1.59 

0.67 

0.176 

0.613 

a DF = degrees of freedom, num = numerator, den = denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

4052 4167 -2002 1E-05 4E-04 2.389 0.514 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 9.950 0.496 664 20 <1E-04 

monthSEP -0.043 0.669 201 -0.06 0.949 

monthOCT 0.479 0.679 201 0.71 0.482 

monthNOV 0.259 0.681 201 0.38 0.705 

monthDEC 0.678 0.760 201 0.89 0.374 

def -0.017 0.006 201 -3.06 0.003 

trtdays 3.032 0.109 664 28 <1E-04 

trtdays2 -0.071 0.005 664 -13 <1E-04 

monthSEP:def -0.003 0.008 201 -0.37 0.712 

monthOCT:def -0.003 0.008 201 -0.44 0.662 

monthNOV:def -0.003 0.008 201 -0.33 0.743 

monthDEC:def -0.003 0.008 201 -0.39 0.694 

monthSEP:trtdays 0.273 0.154 664 1.77 0.077 

monthOCT:trtdays 0.104 0.159 664 0.65 0.515 

monthNOV:trtdays 0.290 0.155 664 1.88 0.061 

monthDEC:trtdays 0.249 0.157 664 1.59 0.113 

monthSEP:trtdays2 -0.011 0.008 664 -1.41 0.159 

monthOCT:trtdays2 -0.004 0.008 664 -0.51 0.611 

monthNOV:trtdays2 

monthDEC:trtdays2 

-0.010 

-0.007 

0.008 

0.008 

664 

664 

-1.31 

-0.91 

0.190 

0.362 

a DF = degrees of freedom. 
62 

RESEARCH PAPER PSW-RP-267

Height—1993–1999 

Model summary 

DFa 

Source num den F-value p-value 

Intercept 1 604 23454 <1E-04 

Month 4 201 1.43 0.227 

Defoliation 1 201 70 <1E-04 

Trtdays 1 604 18898 <1E-04 

Trtdays2 1 604 649 <1E-04 

Month:Defoliation 4 201 0.16 0.960 

Month:Trtdays 

Month:Trtdays2 

4 

4 

604 

604 

5.39 

0.82 

3E-04 

0.513 

a DF = degrees of freedom, num = numerator, den =denominator. 

Likelihood ratio tests and other measures 

AIC BIC LRML σB σ σ^ 

r o/

2982 3095 -1467 2E-05 2E-04 1.843 0.770 

Fixed-effects estimates 

Coefficient Value Std. error DFa t-value p-value 

Intercept 11.123 0.442 604 25 <1E-04 

monthSEP -0.351 0.594 201 -0.59 0.555 

monthOCT 0.187 0.602 201 0.31 0.757 

monthNOV -0.054 0.608 201 -0.09 0.929 

monthDEC 0.432 0.681 201 0.63 0.527 

def -0.015 0.005 201 -2.95 0.004 

trtdays 0.810 0.144 604 5.62 <1E-04 

trtdays2 0.282 0.020 604 14 <1E-04 

monthSEP:def 0.002 0.007 201 0.34 0.734 

monthOCT:def -0.002 0.007 201 -0.34 0.734 

monthNOV:def -2E-04 0.007 201 -0.03 0.979 

monthDEC:def -0.003 0.008 201 -0.32 0.746 

monthSEP:trtdays 0.326 0.210 604 1.55 0.121 

monthOCT:trtdays 0.373 0.216 604 1.73 0.085 

monthNOV:trtdays 0.585 0.215 604 2.73 0.007 

monthDEC:trtdays 0.394 0.222 604 1.77 0.077 

monthSEP:trtdays2 -0.020 0.030 604 -0.67 0.506 

monthOCT:trtdays2 -0.038 0.031 604 -1.22 0.222 

monthNOV:trtdays2 

monthDEC:trtdays2 

-0.052 

-0.019 

0.031 

0.032 

604 

604 

-1.69 

-0.60 

0.092 

0.550 

a DF = degrees of freedom. 
63 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Appendix 4: Fitted Growth Response Curves
 

Loblolly (BAIN) Loblolly (BAIN) 

April 0 5 10 October 0 5 10 April 0 5 10 October 0 5 10 

10 

8 

6 

4 

100 

10 

12 

8 

6 

4 

100 

2 2 ) 95 eight (in.

10 

8 

6 

4 

2 

) 95 eight (in.

10 

12 

8 

6 

4 

2 

10 

8 

6 

breast h

4

66 

10 

12 

8 

6 

breast h

4

66 

2 2

Diameter at 33 

10 

8 

6 

4 

2 

Diameter at 33 

10 

12 

8 

6 

4 

2 

10 

8 

6 

4 

2 

0 

10 

12 

8 

6 

4 

2 

0 

0 5 10 July 

Time (years) 

50 10 January 0 5 10 

Time (years) 

July 50 10 January 

Slash (PKLA) Slash (WAYC) 

April 0 5 10 October 0 5 10 April 0 5 10 October 0 5 10 

10 

12 

8 

6 

4 

2 

100 

8 

6 

4 

2 

100 

) 95 eight (in.

10 

12 

8 

6 

4 

2 

) 95 eight (in.

8 

6 

4 

2 

10 

12 

8 

6 

4 

2

at breast h

66 

at breast h

8 

6 

4 

2 

66 

33

Diameter

10 

12 

8 

6 

4 

2 

33

Diameter

8 

6 

4 

2 

10 

12 

8 

6 

4 

2 

0 

8 

6 

4 

2 

0 

0 5 10 

Time (years) 

July 50 10 January 0 5 10 

Time (years) 

July 50 10 January 

Figure 5—Observed diameter at breast height (d.b.h.) growth response and fitted growth curve of young southern pine subjected to 

various levels of defoliation. The solid line is growth response curve fit to 13 (loblolly, slash) or 19 (longleaf) years of data. The dotted 

line is fitted growth curve for 5 (loblolly, slash) or 6 (longleaf) years of data, points are observed data. Circled data points did not fall on 

the fitted curve. Sites: Bainbridge, Georgia (BAIN), Branchville, South Carolina (BRAN), Palatka, Florida (PLKA), Waycross, Georgia 

(WAYC), Savannah River Forest Station (SRFS), Waycross, Georgia (LWYC). 
64 

RESEARCH PAPER PSW-RP-267

Aug 18 0 5 

Longleaf (SRFS) 

10 15 Oct 13 50 10 15 Dec 8 Aug 18 0 5 

Longleaf (LWYC) 

10 15 Oct 13 50 10 15 Dec 8 

ht (in.) 

6 

4 

2 

100 

ht (in.) 

6 

8 

4 

2 

100 

Diameter at breast heig 95 

6 

4 

2 

Diameter at breast heig 95 6 

8 

4 

2 

6 

4 

2 

0 6 

8 

4 

2 

0 

0 5 10 15 Sept 15 10 1550 

Time (years) 

Nov 9 0 5 10 15 0 5 10 15 Sept 15 10 1550 

Time (years) 

Nov 9 0 5 10 15 

Figure 5—Continued. 

Aug 18 0 5 

Longleaf (LWYC) 

10 15 Oct 13 50 10 15 Dec 8 April 0 

Loblolly (BRAN) 

105 October 0 5 10 

Diameter at breast height (in.) 95 

6 

8 

8 

4 

2 

6 

4 

2 

100 

0 

8 

6 

4 

2 

Height (ft.) 

95 

33 

60 

40 

20 

60 

40 

20 

60 

40 

20 

100 

66 

0 

60 

40 

20 

60 

40 

20 

0 5 10 15 Sept 15 10 1550 

Time (years) 

Nov 9 0 5 10 15 0 5 10 50 

Time (years) 

July 10 January 

Figure 6—Observed height growth response and fitted growth curve of young southern pine subjected to various levels of defoliation. 

The solid line is growth response curve fit to 13 (loblolly, slash) or 19 (longleaf) years of data, dotted line is fitted growth curve for 5 

(loblolly, slash) or 6 (longleaf) years of data, points are observed data. Sites: Bainbridge, Georgia (BAIN), Branchville, South Carolina 

(BRAN), Palatka, Florida (PLKA), Waycross, Georgia (WAYC), Savannah River Forest Station (SRFS), Waycross, Georgia (LWYC). 
65 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

95 

33 

100 

April 0 

Longleaf (LWYC) 

105 October 0 5 10 April 0 

Slash (WAYC) 

105 October 0 5 10 

100 

60 

50 

30 

10 

40 

20 

60 

50 

30 

10 

40 

20 

Height (ft.) 

95 

66 

60 

50 

30 

10 

40 

20 

60 

50 

30 

10 

40 

20 

33 

0 

60 

50 

30 

10 

40 

20 

0 5 10 50 

Time (years) 

July 10 January 0 5 10 50 July

Time (years) 

10 January 

Aug 18 0 5 

Longleaf (LWYC) 

10 15 Oct 13 50 10 15 Dec 8 Aug 18 0 5 

Longleaf (LWYC) 

10 15 50 Oct 13 10 15 Dec 8 

50 

40 

100 30 

20 

10 

40 

Height (ft.)

30 

20 

95 

10 

50 

40 

0 30 

20 

10 

60 

50 

40 

30 

20 

10 

60 

50 

40 

30 

20 

10 

60 

50 

40 

30 

20 

10 

50 

40 

30 

20 

Height (ft.)

10

Height (ft.)

60 

50 

40 

30 

20 

10 

60 

50 

40 

30 

20 

10 

40 

30 

20 

10 

95 

40 

30 

20 

10 

0 5 10 15 0 5 10 15 0 5 10 15 0 5 10 15 0 5 10 15 0 5 10 15 Sept 15 Nov 9 July January

Time (years) Time (years)
 

Figure 6—Continued 

66 

0 

100 

0 
66 

RESEARCH PAPER PSW-RP-267

Appendix 5: Size of Treated Trees Relative to 

Untreated Trees 

Loblolly (BAIN) 

January

October

July

April

0 5 10

Time since defoliation (years) 

Diameter at breast height ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Loblolly (BRAN) 

January

October

July

April

0 5 10

Time since defoliation (years) 

Diameter at breast height ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Slash (PKLA) 

January

October

July

April

0 5 10

Time since defoliation (years) 

Diameter at breast height ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Slash (WAYC) 

January

October

July

April

0 5 10

Time since defoliation (years) 

Diameter at breast height ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Figure 7—Ratio of observed diameter at breast height (d.b.h.) of young defoliated southern pine to control trees. Dashed line indicates the 

±2.5 percent confidence interval around 1 used to determine if treated trees differed in size from control trees. Sites: Bainbridge, Georgia 

(BAIN), Branchville, South Carolina (BRAN), Palatka, Florida (PLKA), Waycross, Georgia (WAYC), Savannah River Forest Station 

(SRFS), Waycross, Georgia (LWYC). 
67 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Longleaf (SRFS) 

December

November

October

September

August

0 5 10 15

Time since defoliation (years) 

Diameter at breast height ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Longleaf (LWYC) 

December

November

October

September

August

0 5 10 15

Time since defoliation (years) 

Diameter at breast height ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Figure 7—Continued 

Loblolly (BAIN) 

December

November

October

September

0 5 10

Time since defoliation (years) 

Diameter at breast height ratio

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

December

November

October

September

0 5 10

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

Loblolly (BRAN) 

Time since defoliation (years) 

Diameter at breast height ratio 

Figure 8—Ratio of observed height of young defoliated southern pine to control trees. The dashed line indicates the ±2.5 percent 

confidence interval around 1 used to determine if treated trees differed in size from control trees. Sites: Bainbridge, Georgia (BAIN), 

Branchville, South Carolina (BRAN), Palatka, Florida (PLKA), Waycross, Georgia (WAYC), Savannah River Forest Station (SRFS), 

Waycross, Georgia (LWYC). 
68 

RESEARCH PAPER PSW-RP-267

Slash (PLKA) Slash (WAYC) 

January

October

July

April

0 5 10

Time since defoliation (years) 

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

January

October

July

April

0 5 10

Time since defoliation (years) 

Height ratio 

Longleaf (SRFS) 

December

November

October

September

August

1.2 

1.1 

0.9 

1.0 

0.8 

1.2 

1.1 

0.9 

1.0 

0.8 

Longleaf (LWYC) 

December

November

October

September

August

Diameter at breast height ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.2 

1.1 

1.0 

0.9 

0.8 

1.2 

1.1 

1.0 

0.9 

0.8 

1.4 

1.2 

1.0 

0.8 

0.6 

1.4 

1.2 

1.0 

0.8 

0.6

Diameter at breast height ratio Height ratio 1.2 

1.1 

1.0 

0.9 

0.8 

1.2 

1.1 

1.0 

0.9 

0.8 

1.2 

1.1 

1.0 

0.9 

0.8 

1.2 

1.1 

1.0 

0.9 

0.8 

1.2 

1.1 

1.0 

0.9 

0.6 

0 5 10 15 0 5 10 15 

Time since defoliation (years) Time since defoliation (years) 

Figure 8—Continued. 
69 

Defoliation Effects on Growth and Mortality of Three Young Southern Pine Species

Loblolly (BAIN) Loblolly (BRAN) 

January

October

July

April

January

October

July

April

1.5 1.5 

1.0 1.0 

0.5 0.5 

1.5 1.5 

Volume ratio Volume ratio1.0 

0.5 

1.5 

1.5 

1.0 

Volume ratio1.0 

0.5 

0.5 

1.5 

1.0 1.0 

0.5 0.5 

5 10 5 10 

Time since defoliation (years) Time since defoliation (years) 

Slash (PLKA) Slash (WAYC) 

1.5 

1.0 

0.5 

1.5 

1.0 

0.5 

January

October

July

April

1.0 

1.5 

0.5 

1.0 

1.5 

0.5 

January

October

July

April

Volume ratio1.0 

1.5 

0.5 

1.0 

1.5 

0.5 

1.0 

1.5 

0.5 

1.0 

1.5 

0.5 

5 10 5 10 

Time since defoliation (years) Time since defoliation (years) 

Figure 9—Ratio of estimated volume of young defoliated southern pine to control trees. Dashed line indicates the ±2.5 percent confidence interval around 1 used to determine if treated trees differed in size from control trees. Sites: Bainbridge, Georgia (BAIN), 

Branchville, South Carolina (BRAN), Palatka, Florida (PLKA), Waycross, Georgia (WAYC), Savannah River Forest Station (SRFS), 

Waycross, Georgia (LWYC). 

1.0 

1.5 

0.5 
70 

RESEARCH PAPER PSW-RP-267

Longleaf (SRFS) 

December

November

October

September

August

5 10 15 5 10 15

Time since defoliation (years) 

Volume ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Longleaf (LWYC) 

December

November

October

September

August

Time since defoliation (years) 

Volume ratio 1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

1.4 

1.2 

0.8 

1.0 

0.6 

Figure 9—Continued