A long growing season and rich moist soils give the lower Mississippi River floodplain great potential for producing diverse and productive forest. Those same conditions create great agricultural potential. As reservoirs and levees have disconnected the floodplain from the river, corn and soybeans have replaced flood tolerant hardwoods.
Forest still dominates only the batture lands, the area between the levees. Timber companies, which take advantage of the easy transportation, and hunting clubs own most of these lands. In Arkansas, aside from a few small city parks, there are only three areas of public land along the Mississippi. At 9,431 acres, Choctaw Island Wildlife Management Area is by far the largest of the three.
Choctaw Island WMA consists of a point bar on the Mississippi River split by a side channel. The island portion is all sandbar and sandbar recently colonized by forest. A mix of forests, fields, and ponds covers the older land in the rest of the WMA. Sugarberry and pecan dominate the main block of forest on the WMA, usually mixed but tending towards pure sugarberry in the lower areas and pure pecan on the highest ground. Oaks are conspicuously absent; in two days of traversing the area, I saw only a single overcup oak and a single nuttall oak, neither of them mature. The lack of oaks probably reflects a combination of unfavorable soils conditions and limited availability of acorns. Below the sugarberry and pecans are more sugarberries and box elder with scattered pecans and green ash. Swamp privet, its clustered and arching stems reminiscent of its relative the olive, is the main understory species, and it sometimes forms thickets in the wettest areas with few or no other tree species.
The southern end supports a different mix of species, which may be due to some of the land being deposited within the last century. Sycamore and cottonwood are often components of the overstory, and cottonwood forms pure stands in some areas. Those stands have a sugarberry midstory and sparse understory. The wettest areas contain extensive pure black willow forest with little understory.
Choctaw Island came on my radar by being one the scattered areas in southern Arkansas with available LiDAR. I also wanted to check out the composition of the forests, since river front forests are always distinct from surrounding forests. I had also read about black willow becoming a large canopy species along the lower Mississippi, in contrast to the species’ behavior in the rest of its vast range, and willows are one of the primary groups of trees that colonize bare sediment deposited by rivers.
In addition to the trees above, I stopped immediately on the other side of the levee to measure the largest yard tree in Arkansas City. The 16’5” cbh by 127.3’ pecan gives a hint at what used to grow in the floodplain.
The gum bumelia is the first NTS has reported. The lower Mississippi seems to be much better habitat for swamp privet than the other parts of the species range where we have measured them previously. These trees dwarf our previous records for both height and girth. Several of them also easily exceed the national champion. The Sandbar willows are similarly larger than the few we have measured previously and the current national champion. The cottonwoods, while within 10 feet of the current height record, may not be exceptional at all. The site does not seem extraordinary, and I suspect most point bars along the lower Mississippi would produce 140’ cottonwoods if left alone for 100 years.
These black willows give credence to the claim that the species develops best in the lower Mississippi. These trees dwarf any we have found in other regions of the country, and this stand easily bests the previous height record. Given that the stands are still dense and most of the trees are healthy, 140’ seems possible for the species. In a way, these trees have already reached that height. They sprouted on moist sediment within a few feet of the river level. Since then, the river has dumped sand on the groves, and the tree bases are now 15 to 20 feet above the river level.
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