Ocmulgee Flats   Jess Riddle
  Jan 14, 2006 09:04 PST 

After a tip from Matt Elliott, my dad and I decided to explore
Ocmulgee Flats for large trees. Ocmulgee Flats lies at the western
edge of the Oconee National Forest in central Georgia. The 390'
elevation floodplain site stretches for about two miles along the
eastern bank of the 250' wide Ocmulgee River. At the southern end the
floodplain is only about 150 yards wide and the northern end shows
signs of disturbance in the past few decades, but the central part of
the tract includes a third of a mile broad swath of mature bottomland
forest. No trenches or other artificial landforms indicate past
agricultural disturbance, so the site was likely cleared for timber 75
to 100 years ago.

Elevation differences of only a few feet within the floodplain produce
forest of distinctly different composition. The highest ground occurs
near the river as natural levees. These areas probably contain the
most coarse-grained, and well-drained soil. Bitternut hickory, black
walnut, and tuliptree make up the canopy under these conditions.
Florida maple dominates the midstory, and silverbell, American holly
and mock-orange (Philadelphus sp.) fill in the understory.

Loblolly pine dominates the extensive, flat, slightly elevated areas
within the floodplain with some cherrybark oak scattered in the
canopy. Shurmad oak, shagbark hickory, swamp chestnut oak, and
sweetgum often grow where these areas transition into lower forest.
The understory in this area is largely open with only scattered
American hornbeam and a few dogwoods and hophornbeam.

Puddles and water a few inches deep still covered much of the lower
floodplain. A mixture of oaks and a few hickories form a high
continuous canopy over this area. The hickories are primarily water
hickory (Carya aquatica) and confined to the lowest areas. Overcup
oak or willow oak, the most common species in the lower floodplain,
grow next to the hickories. Cherrybark oak commonly inhabits slightly
higher ground with other willow oaks. American hornbeam makes up most
of the understory, but possumhaw also occurs in the lower areas.

River bank and tributary streams also provide slightly different
habitat. The light trunks of sycamore and river birch periodically
project out of the riverbank over the brown water. Sycamore is more
common along to small tributaries within floodplain, but completely
absent from the rest of the floodplain. Above the floodplain, narrow
corridors of flat land snake along the tributaries between gentle
south-facing slopes and higher, steep, north-facing slopes. Many of
the floodplain species plus red maple grow in the flats. White oak,
shagbark hickory, pignut hickory and other hardwoods dominate on the
north facing slopes. A few chinquapin oaks and oakleaf hydrangea also
grew on the lower part of a north-facing slope.

Species Cbh Height
Beech, American 12'7" NA
Bumelia, Gum 1'4" 27.3'
Bumelia, Gum 1'8" 30.2'
Cottonwood, Eastern 8'5" 124.3'
Hickory, Bitternut 9'5" 105.9'
Hickory, Bitternut 9'9" 112.1'
Hickory, Bitternut* 6'11" 133.1'
Hickory, Shagbark 8'6" 123.7'
Hickory, Shagbark* 6'1" 129.3'
Hickory, Water 11'0" 120.2'
Hickory, Water 10'11" 124.8'
Hickory, Water 7'11" 128.1'
Oak, Cherrybark 9'11" 137.8'
Oak, Northern Red* 7'10" 126.8'
Oak, Overcup 9'4.5" 113.1'
Oak, Overcup 12'7" 122.0'
Oak, Shumard 11'1" 124.5'
Oak, Shumard* 9'9" 136.2'
Oak, Water 6'8.5" 123.5'
Oak, White* 7'4" 122.6'
Oak, White* 6'10" 126.6'
Oak, Willow 9'6" 130.1'
Oak, Willow 10'7.5" 131.4'
Oak, Willow 11'2" 133.7'
Oak, Willow 15'9" 144.9'
Pine, Loblolly 9'1" 130.1'
Pine, Loblolly 7'10" 130.3'
Pine, Loblolly* 7'9" 130.6'
Pine, Loblolly 4'11" 130.8'
Pine, Loblolly* 6'8" 137.5'
Redbud, Eastern 1'10" 53.1'
Sugarberry 9'4" 115.0'
Sweetgum* NA 128.2'
Sweetgum 7'11" 130.8'
Sycamore 7'0" 121.6'
Sycamore 8'5" 126.3'
Tuliptree 11'4" 128.4'
Willow, Black 3'1" 76.0'

Rucker Index 133.3'

Willow Oak 144.9'
Cherrybark Oak 137.8'
Loblolly Pine* 137.5'
Shumard Oak* 136.2'
Bitternut Hickory* 133.1'
Sweetgum 130.8'
Shagbark Hickory* 129.3'
Tuliptree 128.4'
Water Hickory 128.1'
Northern Red Oak* 126.8'

*Denotes tree growing in a ravine. All other trees grow in the floodplain.

Most heights were collected using the rangefinder at a steep angle
measured with a clinometer and adding a directly measured height
between eye level and the base. This method appears to give the best
results for broad crowned trees growing on flat ground. The beech has
a greatly swollen base. Gum bumelia (Bumelia lanuginosa) is scarce
and restricted to the levee. Cottonwood is rare in the area within
only two live and one dead individual seen. The bitternut hickory is
tied for second tallest known in Georgia. The shagbark hickory is the
tallest so far verified in the state, but taller individuals surely
exist. ENTS has not previously documented water hickory, overcup oak,
or black willow heights in Georgia. The shumard oak is within a foot
of the state height record and this measurement is probably more
reliable. The water oak slightly eclipses a tree at Rock Creek to be
the tallest documented so far in the state. The white oak is the
third tallest found so far in the state. Willow oaks approximately 9'
cbh x 130' tall are common at the site. The 15'9" x 144.9' individual
is likely slightly older than the surrounding forest and is a new
eastern height record. The sugarberry is the third tallest known.

Jess Riddle