Big Oak Tree State Park, MO report   Don Bragg
  Aug 03, 2005 07:25 PDT 

I was able to make a trip on July 29 to Big Oak Tree State Park in
Missouri. It turned out to be a glorious summer day (especially for
late July in SE Missouri)--clear blue skies, low humidity, temperatures
in the low 80s, and not too many bugs. A perfect day for measuring big

According to their brochure, Big Oak Tree State Park was set-aside for
protection in the 1930s when the state made a Depression-era purchase of
slightly more than 1,000 acres of bottomland hardwood timber from the
Mississippi Valley Hardwood Company. Most of the remaining old-growth
was found in an 80-acre tract surrounding the "Big Oak Tree," a 400 year
old bur oak (this oak died in 1952, but they have a cross-section in the
interpretive center).

49inchsweetgum.jpg (79292 bytes) Sweetgum, ht.  123.8 feet, cbh 12.7 feet

The area is an island of mature forest in a heavily agricultural portion
of southeastern Missouri. The site is relatively low and fairly wet
during the winter and spring of the year, with decently good Mississippi
Delta soils. The stands are hardwood-dominated, with the only conifer
being baldcypress. The overstory is a diverse mixture of oaks,
cottonwoods, gums, hickories, ashes, etc., while the understory is
dominated by low-stature trees/shrubs, cane, and woody vines (e.g.,
pawpaw, giant cane, poison ivy, grape, etc.). I'm not very familiar
with the multitudes of herbaceous understory species, but there was at
least one species of nettle (I felt these very clearly).

With over 1,000 acres, there is a lot of ground to cover at this state
park, and I only had about a 1/2 day to explore, so I stuck to the main
trails and the more developed areas. Right as you enter the park, there
is a mowed area with picnic tables and playground equipment under a
towering canopy of oak, hickory, and sweetgum. This area was open
enough to make for easy height measurements:

Picnic area    DBH     CBH   SineHT
Species        (in.)    (ft)      (ft)     Comments
sweetgum     38.6    10.1    112.3
sweetgum     40.8    10.7    113.7
cow oak        43.0    11.3    120.0   a.k.a. swamp chestnut oak, or Quercus michauxii
cow oak        32.9     8.6    109.2
persimmon      29.6    7.7    118.2   state champion
sweetgum      48.7    12.7   123.8
Am. elm         36.6     9.6    101.5
shellb hickory  26.7    7.0     117.7   shellbark hickory (Carya laciniosa)
cow oak        45.6   11.9     113.7
cow oak        39.0   10.2     117.1
Shumard oak  44.0   11.5     117.9
pumpkin ash   26.2    6.9     106.4

The persimmon was particularly impressive, given how few big examples of
this species can be found. 

bo_persimmon.jpg (90856 bytes) Persimmon, ht. 118.2 feet, cbh 7.7 feet

I then followed a trail from the picnic area
to an impoundment on the property. Most of the trees listed below were
right off of this trail, and I'm sure there are plenty of others that I
missed that are also quite impressive:

Pond Trail      DBH      CBH    SineHT
Species         (in.)      (ft)      (ft)    Comments
cow oak        54.0     14.1    111.9    DBH adjusted for vines
white ash      46.8     12.3     113.5
e. cottonwood 58.9   15.4     117.8   Populus deltoides
cherrybark oak 61.5    16.1    114.1
bur oak          57.5     15.1    107.0   DBH adjusted for vines
sugarberry      34.3     9.0       93.4
Shumard oak   37.5     9.8      112.9
possumhaw     3.4       0.9    ~15.0   Ilex decidua (state champion)
baldcypress    40.8     10.7    101.1
pawpaw          4.0      1.0       39.0
e. cottonwood  50.8    13.3    122.1
e. cottonwood  55.1    14.4    131.2
overcup oak     50.0    13.1     92.4
e. cottonwood 52.6    13.8     109.0
cow oak         80.0     20.9     115.8 bigger in diameter than my D-tape!!

The cow oak (a.k.a. swamp chestnut oak) was literally the biggest
diameter oak I have every personally seen. Massive! Unfortunately, it
has lost a large portion of its top in recent years to wind (or ice) and
decay. The park brochure puts its DBH at 86.6 inches, although I think
this value may include some was literally too big to reach my
D-tape around, and is easily 80 inches in diameter. I threw in a few of
the smaller dimensioned species especially for Will Blozan (I'm sure
there are larger pawpaw in the park, this happened to be the largest
convenient one). Many impressively large cottonwood along this trail.

80inchcowoak.jpg (78846 bytes) Cow oak (Quercus michauxii) ht. 118.5 feet, cbh 20.9 feet

The final section of park I traveled along was the boardwalk area (which
was under construction). Several state champion trees along this
section, and the national champion pumpkin ash. This trail was at the
end of my day, so I skipped to only the biggest of the trees along about
half of the trail:

Pond Trail    DBH    CBH    SineHT
Species       (in.)    (ft)       (ft)     Comments
sycamore     36.7    9.6     126.4
bur oak        67.2   17.6     116.7   state champion
pumpkin ash  59.0   15.4    102.8 national champion
Shumard oak 50.0   13.1   122.6

67inchburoak.jpg (126776 bytes)  Bur Oak, ht. 116.7 feet, cbh 17.6 feet

Note that the pumpkin ash is listed as the American Forests national
champion at 150 feet tall when measured in 2003. Now, while it is
possible that I did not measure the tallest of the leaders, I did have a
pretty good shot at the crown, and would not have missed it by almost 50
feet! This is a classic example of the problems of the tangent method
when measuring large hardwoods--this individual had a widely spreading
crown, and was almost certainly overestimated in height. The list of
current and former champion trees listed on a billboard outside the
exhibition hall also list 150+ foot heights for the big bur and cow oaks
I have listed (also dramatic overestimates), and had the state champion
persimmon at 133 feet (15 feet too tall). The stand's RI10 is a better
reflection of the height of the canopy:

Species             SineHT
e. cottonwood     131.2
sycamore            126.4
sweetgum           123.8
Shumard oak       122.6
cow oak             120.0
persimmon          118.2
shellb hickory      117.7
bur oak              116.7
cherrybark oak    114.1
white ash           113.5

Given that this was a very quick trip over a small portion of the state
park, sticking to trails and developed areas, I think this Rucker Index
could go higher, perhaps 130+. I suspect the tallest of all of these
species may reach 5 to 10 feet higher, and some of the individual big
trees I looked at may actually have taller branches. The thick hardwood
overstory and broadly spreading crowns frequently makes height
determination difficult in this stand. There are also a number of
species that are out there that I did not measure at all (e.g., pecan,
several hickories, red maple), and others that only had one individual
measured (e.g., shellbark hickory, baldcypress).

This easy-to-access and big tree-filled state park is well worth a
visit, if you happen to be in this part of the world. I will send Ed
some pictures I took of this park for the website.

Don Bragg

Don Bragg, Ph.D.
Research forester

RE: Big Oak Tree State Park report    Don Bragg
   Aug 06, 2005 11:09 PDT 

I have been continually amazed by some of the more unusual bottomland
species we have in the Midsouth. I hope to further explore some other
bottomland sites to add to this list.

I also must admit being a little disappointed that these trees didn't
work out to be taller than what I found. I suspect the cottonwood may
reach or exceed 140 feet, as there are a lot of big ones, and I didn't
get to measure many of them. Some of the sycamore may also exceed 130
feet, as will some of the oaks, but I think a Rucker Index of
approximately 130 to 135 may be the max on this site. This stand is of
fairly good site quality, but probably is not great, and given how level
the area is, you would not expect to see the ravine-type influences on
height that are found in other areas. There is more vertical relief in
the Congaree than what is found here.

We may also have height limitations imposed by weather events. The 80+
inch cow oak is breaking up from the top down, losing branches from wind
and ice events (which are fairly frequent in the Midsouth). The
relatively small area of the stand and exposed nature may have also
contributed to some elevated windthrow. I cannot also discount the
possibility that some timber may have been high-graded out of the stand
over the years (it had been owned by a timber company before they sold
it to the state).

It may also be possible that the matrix of the forest, though old, is
still a long way from species longevities, and therefore there is a lot
of height growth left to do. Only a handful of trees like the big cow
oak and the big bur oaks had serious "gnarlage", suggesting to me that
some of the other species have some aging to do. I would think that the
biggest, most gnarly oaks are near their expected longevity (~400
years), but I did not see many real old cypress, gum, cottonwoods,
overcup oaks, etc.

So, the long and the short is, there may be many reasons why this stand
seems kind of short. I will continue to make visits to Big Oak Tree
State Park to see if this will increase the RI, but I would not expect
big changes.

Don Bragg

-- wrote:

Fantastic! Thanks for the thorough report. Having a report on a
prominent site in a region little explored by ENTS seems very valuable.
Starting to build data on shellbark hickory, pumpkin ash, is great.

Taking into account that you only had time to measure easily accessible
trees, I'm surprised the canopy isn't higher. The Rucker Index looks
comparable to second growth piedmont bottomland sites along creeks in
Georgia and South Carolina. Do you have a feel if the sites exposed
nature is reducing canopy height or if the climate and soils of the site
simply can not support taller forest? The one species that appears to
brake the general pattern is cottonwood. The 131.2' figure is close to
the best we've found at several widely separated sites much farther
I certainly would have enjoyed seeing the big persimmon and oaks too.