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Comparing Growth Rates Between Quercus falcate, Pinus taeda, and Juniperus

virginiana

*Jennifer Luther, Ryan Grubb, Carl Chmielewski

White Hall, Union University, Jackson, TN 38305 (JL, RG, CC)

Abstract--- It is generally accepted that there is a noticeable difference in the

diameter growth rates of softwood trees and hardwood trees. It is important to

know the growth rate of certain tree species that are commercially valuable in

order to know when it is the proper time to harvest. In this study, we evaluated

the growth rates of a hardwood tree, southern red oak, and two softwood trees,

the loblolly pine and eastern red cedar. Each of these species are extremely

commercially valuable. One of the easiest ways to assess the growth rate of a

tree is to take a core sample. Twenty cores were taken from loblolly pine (Pinus

taeda), southern red oak (Quercus falcata), and eastern red cedar (Juniperus

virginiana) at two locations in Carroll County, Tennessee. Growth rings were

measured and counted for a period of 10 years in order to find the difference in

the average width of the growth rings between each of the species. We looked at

the difference between each species with the assumption that the loblolly pines

and eastern red cedar would contain a larger growth width than that of the

southern red oak. Our null hypothesis is there was no difference in the average

diameter of growth rings between Quercus falcata, Pinus taeda, and Juniperus

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virginiana. We found that eastern red cedar had a much larger growth width than

the other two species, but there was a significant differences between the growth

width of southern red oak and loblolly pine.

Introduction

The three species involved in this study, loblolly pine (Pinus taeda), southern red

oak (Quercus falcata), and eastern red cedar (Juniperus virginiana), are all very

common species in the southeastern United States. (Sewell et al., 1999). Loblolly pine

is one of the most commercially important species due to its wide range, rapid juvenile

growth, and multiple uses for wood products. It has a range that extends through 14

states from New Jersey to central Florida, and as far west as east Texas (1999). It does

not natively grow in the Mississippi flood plain, but has been introduced due to its

commercial value and ability to fight erosion. The loblolly is an adaptable species and

has been found to be intolerant to moderately intolerant to shade. Most of its range is

considered humid with warm temperatures, and having long, hot summers with mild

winters (1999). The southern red oak is important for area wildlife who use it for shelter

and food, and its hard, strong wood is used for general construction, furniture, and fuel.

It is one of the more common upland southern oaks. Its range extends from Long

Island, New York to northern Florida and west to eastern Texas. The southern red oak

is a moderately fast growing tree of medium size. Most of the range is humid with warm

temperatures, with hot summers and mild winters, but without any distinct dry season

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(Belanger et al., 2004). The Eastern Red Cedar is also important species, not as much for its

commercial value, but the wood is considered to be valuable for its beauty and durability (Sewell

et al., 1999).

Since these are both important species in the area, learning as much about them

as possible is beneficial. There is already a known difference in the growth between all

of these species, but databasing growth for different areas is important to the

commercial industry (Houck et al., 2013). However, environmental factors can affect

growth rates, making them highly variable. Forest crowding or how close each tree is to

one another, soil, moisture, nutrients, insects, and disease are all factors that can affect

a tree being able to grow to its full potential (Perry, 1978). Also, trees have been found

to not grow at a constant rate during their life span because they tend to have a faster

growth before reaching maturity so they will not be overtopped in the canopy (Lutz,

2011). Our null hypothesis is that there is no difference in the average diameter of

growth rings between Quercus falcate, Pinus taeda, and Juniperus virginiana.

Materials and Methods

Coring is the process of removing a small cylinder, or core, from the tree’s

trunk. . When a core is taken, it is used for collecting general data about the trees past

such as age and amount of growth per year. Core samples were collected at two

properties in Carroll County, Tennessee. Property 1 was located at Grooms Rd, and

property 2 at Tate School Rd. Core samples were taken from Southern Red Oak

(Quercus falcata), Loblolly Pine (Pinus taeda), and Eastern Red Cedar (Juniperus

virginiana). Trees were chosen at random which measured between 68 cm to 181 cm in

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diameter at breast height. Any trees found outside of these measurements were thrown

out. Trees were identified by GPS coordinates, and can be seen in figures 1-4. Ten

trees from each species were selected at each site for a total of twenty sample cores

per species.

To remove the core from the selected trees, an increment borer is drilled into the

tree and then a tray was inserted into the bore to release the core and slid it out. Bees

wax was applied to lower friction, as to much friction would scar the wood with burn

marks. The presence of burn marks on the cores make measuring the rings difficult.

The cores were allowed to dry for 1-2 days to remove any moisture that could alter

results.

Tree rings were counted and the width of each ring measured to obtain data for a

total of 10 years. Southern red oak was measured by finding the lighter area of the core,

and then finding the porous vessel tissue. Loblolly pine cores where measured from a

light strip to a dark strip, this was 1 year of growth. Eastern red cedar cores where

measured from a darker red strip to the next darker red strip. Each ring width was

marked with a pencil and then measured with a metric ruler. Each of these

measurements was considered one year’s growth. An example of this method can be

seen in Figure 7.

Statistics, tables, and graphs were calculated using R-Studio and Excel software.

The dependent variable for the study was the growth of each species per year, and the

independent variable was each of the three species. An alpha level of 0.05 was used as

a significance level. To find each species percentage of accumulated growth for the

total 10 year period, the diameter at breast height of the trunk was averaged for all

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samples of each species and the number of rings were counted per inch of each core

and then averaged together for each species. The formula used was: Growth % =

(4/DBH x RPI)) x 100, where DBH = diameter at breast height and RPI = rings per inch

(Synder, 2001). On average for any tree, two to three percent is a common

measurement and anything that measures four percent or more is excellent growth

(2001).

Results

When data was put into R-studio, the mean growth width per year for each species

was found to be 4.92 mm for loblolly pines, and 2.23 mm for southern red oaks and

11.74 mm for eastern red cedar. The average DBH for each species was 992.03 mm for

loblolly pine, 2042.25 mm for southern red oak, and 1054.42 mm for eastern red cedar.

The RPI for loblolly pine was 5.95, southern red oak was 11.7, and eastern red cedar

was 2.25. This can be seen in Figure 8. Data was analyzed to show a comparison of the

average growth width for each species which is shown in Figure 9. A shapiro-wilks

normality test was performed and the data was found to be normally distributed (loblolly

pine: p = 0.38, southern red oak: p = 0.87, eastern red cedar: p = 0.095). A Bartlett Test

was further performed and the data was found to have a homogeneity of variance (p =

0.084). Since the data passed both of these tests and found to be parametric, an

ANOVA test for the ring width growth was performed and since the Fcalc was extremely

larger than Fcrit, the null hypothesis was rejected (p = <2e-16, Fcalc = 1514, Fcrit = 5.4). To

find a comparison between each of the species a Tukey Post Hoc Test was performed

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and a significant difference was found when comparing each of the species (Oak-

Cedar: p = 0, Pine-Cedar: p = 0, Pine-Oak: p = 0).

Conclusion

Based on the data compiled, we found a statistical difference between the

average width of the growth rings of each species. The growth percentage data showed

a much higher average growth width rate in eastern red cedar than either the southern

red oak or the loblolly pine. These differences can be seen in figures 8 and 9. This

means we reject our null hypothesis which states there was no difference between the

average width of the growth rings between Quercus falcata, Pinus taeda, and Juniperus

virginiana. There is a significant difference in the width of the growth rings between

each of the species. The fact that the eastern red cedar is especially affected by its

environment could be one of the reasons for this tremendous difference (Grissino-

Mayer, Undated). The eastern red cedars that were sampled could be in the optimal

conditions for this species to reach its maximum growth potential.

In the future, the eastern red cedar should be sampled at sites which include

multiple soil and moisture types. Changes in the environmental conditions could prove

to cause measurable changes in the growth of each of these species. So, another factor

which could be researched in the future is to investigate the some of the ways the

environment affects the growth rate of each species. Changes in the environment could

be proven to be the reason for variations in growth rates, particularly the growth rates

between site 1 and site 2 or even between samples at the same site. This could include

canopy cover, rainfall, or temperature.

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Literature Cited

Belanger, R. P., Krinard, R. M. 2004. Southern Red Oak. Silvics of Forest Trees of the

United States USDA Ag Handbook. 654:2.

Grissino-Mayer, H. D. The Science of Tree rings. The University of Tennessee.

Available at: http://web.utk.edu/~grissino/index.htm.

Houck, J. E., Eagle, B. N. 2007. Hardwood or Softwood? Hearth & Home. 12:49-50.

Lutz, J. 2011. How Trees Grow. Forest Research Notes. 8:1-4.

Perry, T. O., 1978. Trees and Their Typical Ages and Growth Rates. Metro. Tree Impr.

1:1-12.

Sewell, M. M., Sherman, B. K., and Neale, D. B. 1999. Consensus Map for Loblolly Pine

(Pinus taeda L.). I. Construction and Integration of Individual Linkage Maps From

Two Outbred Three-Generation Pedigrees. Genetics. 151:321-330.

Snyder, Michael. 2001. How Do I Measure the Growth of My Trees? Wood Whys?

Northern Woodllands.org

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Fig. 1. Randomly selected loblolly pine from site 1. GPS coordinates for each sample

are: loblolly 1 at 36 03’ 29.39” N -88 32’ 58.11” W, loblolly 2 at 36 03’ 30.60” N -88 ⁰ ⁰ ⁰ ⁰

32’ 61.17” W, loblolly 3 at 36 03’ 31.61” N -88 32’ 58.46” W, loblolly 4 at 36 03’ 34.95”⁰ ⁰ ⁰

N -88 32’ 60.01” W, loblolly 5 at 36 03’ 37.20” N -88 32’ 55.78” W, loblolly 6 at 36 03’⁰ ⁰ ⁰ ⁰

32.54” N -88 32’ 69.18” W, loblolly 7 at 36 03’ 31.92” N -88 32’ 77.44” W, loblolly 8 at ⁰ ⁰ ⁰

36 03’ 31.70” N -88 32’ 40.30” W, loblolly 9 at 36 03’ 32.80” N -88 32’ 76.80” W, ⁰ ⁰ ⁰ ⁰

loblolly 10 at 36 03’ 32.74” N -88 32’ 76.26” W.⁰ ⁰

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Fig. 2. Randomly selected loblolly pine from site 2. GPS coordinates for each sample

are: loblolly 1 at 35 96’ 81.98” N -88 44’ 72.50” W, loblolly 2 at 35 96’ 83.21” N -88 ⁰ ⁰ ⁰ ⁰

44’ 71.46” W, loblolly 3 at 35 96’ 82.76” N -88 44’ 74.11” W, loblolly 4 at 35 96’ 82.45”⁰ ⁰ ⁰

N -88 44’ 73.67” W, loblolly 5 at 35 96’ 83.70” N -88 44’ 60.12” W, loblolly 6 at 35 96’⁰ ⁰ ⁰ ⁰

84.66” N -88 44’ 59.99” W, loblolly 7 at 35 96’ 84.39” N -88 44’ 59.21” W, loblolly 8 at ⁰ ⁰ ⁰

35 96’ 84.57” N -88 44’ 60.42” W, loblolly 9 at 35 96’ 84.51” N -88 44’ 60.52” W, ⁰ ⁰ ⁰ ⁰

loblolly 10 at 35 96’ 82.75” N -88 44’ 60.60” W.⁰ ⁰

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Fig 3. Randomly selected southern red oak from site 1. GPS coordinates for each

sample are: oak 1 at 36 03’ 30.43” N -88 32’ 61.24” W, oak 2 at 36 03’ 31.36” N -88 ⁰ ⁰ ⁰ ⁰

32’ 63.67” W, oak 3 at 36 03’ 32.57” N -88 32’ 61.50” W, oak 4 at 36 03’ 34.72” N -⁰ ⁰ ⁰

88 32’ 62.54” W, oak 5 at 36 03’ 34.95” N -88 32’ 60.06” W, oak 6 at 36 03’ 32.35” N⁰ ⁰ ⁰ ⁰

-88 32’ 69.91” W, oak 7 at 36 03’ 32.43” N -88 32’ 69.40” W, oak 8 at 36 03’ 30.63” ⁰ ⁰ ⁰ ⁰

N -88 32’ 71.97” W, oak 9 at 36 03’ 29.01” N -88 32’ 77.29” W, oak 10 at 36 03’ ⁰ ⁰ ⁰ ⁰

32.18” N -88 32’ 74.39” W.⁰

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Fig. 4. Randomly selected southern red oak from site 2. GPS coordinates for each

sample are: oak 1 at 35 96’ 77.17” N -88 44’ 67.21” W, oak 2 at 35 96’ 79.84” N -88 ⁰ ⁰ ⁰ ⁰

44’ 68.71” W, oak 3 at 35 96’ 00.32” N -88 44’ 70.70” W, oak 4 at 35 96’ 79.95” N -⁰ ⁰ ⁰

88 44’ 72.86” W, oak 5 at 35 96’ 79.49” N -88 44’ 74.59” W, oak 6 at 35 96’ 80.57” N⁰ ⁰ ⁰ ⁰

-88 44’ 74.52” W, oak 7 at 35 96’ 84.44” N -88 44’ 83.11” W, oak 8 at 35 96’ 84.04” ⁰ ⁰ ⁰ ⁰

N -88 44’ 82.21” W, oak 9 at 35 96’ 86.60” N -88 44’ 85.29” W, oak 10 at 35 96’ ⁰ ⁰ ⁰ ⁰

88.03” N -88 44’ 86.17” W.⁰

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Fig. 5. Randomly selected eastern red cedar from site 1. GPS coordinates for each

sample are: cedar 1 at 36 03’ 31.45” N -88 32’ 71.10” W, cedar 2 at 36 03’ 30.31” N -⁰ ⁰ ⁰

88 32’ 73.93” W, cedar 3 at 36 03’ 29.07” N -88 32’ 76.99” W, cedar 4 at 36 03’ ⁰ ⁰ ⁰ ⁰

31.07” N -88 32’ 78.78” W, cedar 5 at 36 03’ 31.30” N -88 32’ 78.37” W, cedar 6 at ⁰ ⁰ ⁰

36 03’ 30.88” N -88 32’ 62.27” W, cedar 7 at 36 03’ 32.73” N -88 32’ 63.95” W, cedar⁰ ⁰ ⁰ ⁰

8 at 36 03’ 35.20” N -88 32’ 68.35” W, cedar 9 at 36 03’ 40.58” N -88 32’ 55.32” W, ⁰ ⁰ ⁰ ⁰

cedar 10 at 36 03’ 35.93” N -88 32’ 53.17” W.⁰ ⁰

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Fig. 6. Randomly selected eastern red cedar from site 2. GPS coordinates for each

sample are: cedar 1 at 35 96’ 84.54” N -88 44’ 64.42” W, cedar 2 at 35 96’ 81.52” N -⁰ ⁰ ⁰

88 44’ 63.52” W, cedar 3 at 35 96’ 82.98” N -88 44’ 66.68” W, cedar 4 at 35 96’ ⁰ ⁰ ⁰ ⁰

77.83” N -88 44’ 66.27” W, cedar 5 at 35 96’ 75.07” N -88 44’ 65.45” W, cedar 6 at ⁰ ⁰ ⁰

35 96’ 78.68” N -88 44’ 47.42” W, cedar 7 at 35 96’ 83.82” N -88 44’ 71.09” W, cedar⁰ ⁰ ⁰ ⁰

8 at 35 96’ 83.17” N -88 44’ 74.07” W, cedar 9 at 35 96’ 83.58” N -88 44’ 69.12” W, ⁰ ⁰ ⁰ ⁰

cedar 10 at 35 96’ 81.66” N -88 44’ 60.07” W.⁰ ⁰

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Fig. 7. Example of reading tree core to find ring width. Image found at

http://academic.emporia.edu/aberjame/ice/lec10/lec10.htm.

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Loblolly Pine Southern Red Oak Eastern Red Cedar0

0.5

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4.5

5Gr

owth

%

Fig 8. Total growth percent of each species seen graphically. The growth percent for

each species is loblolly pine = 1.72%, southern red oak = 0.65%, and eastern red cedar

= 4.33%.

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2005 2006 2007 2008 2009 2010 2011 2012 2013 20140

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Loblolly Pine Southern Red Oak Eastern Red Cedar

Aver

age

ring

wid

th (m

m)

Fig 9. Comparison of average growth width between species for each of the 10

years.

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