Bayou-Diversity (2 December 2018) Her days are numbered and she won’t likely last the winter. This prognosis is not arboreal soothsaying but rather the physics involved in supporting upright tons of wood fiber. Just look at the photo! Already she cants thirty degrees northwest and half her root system is embarrassingly exposed to all. Erosion, that hissing wave of gravity-fueled fluid that drags the main channel of the Mississippi River dozens of lateral miles across its floodplain like a writhing cottonmouth, works 24/7 on Bayou D’Arbonne also. It broke the anchor chains of this overcup oak.
Although with dying roots the tree has lost the ability to maintain intimate relationships with soil bacteria and fungi, interactions critical to her physical well-being, she managed to produce one last crop of acorns this year as notes of a fertile swansong. No oak is better adapted to live in swampy, flood-prone areas than overcup. Her parenchyma cells are closed to keep water out, a fact not lost on whiskey distillers who use the wood for barrels to keep spirits in. Closed cells may help overcups survive periods of frozen backwater. It is her acorns though that are most unique. Overcups are the only lowland oak species that produce viable acorns that float. What better way to distribute your progeny throughout a seasonally aquatic landscape?
The D’Arbonne oak was fortunate. She began life as an acorn perhaps forty feet from the bayou’s edge. In the last century her acorn crops have been naturally sporadic depending on climate variables and the availability of nutrients. In the best of years thousands of her acorns fell during autumn cold fronts and floated away on winter backwaters, a few lucky ones to land in sunlit harbors. All the while, the bayou crept closer to the parent tree.
When the tree falls her uppermost branches will stretch two-thirds the distance across the bayou; even in death she will contribute to the swamp ecosystem. Bark and leaves along with the resurrection fern that homesteaded her cleavage will be swept away in spring freshets to become detritus for those tiny protozoans at the bottom of the food web upon which all other bayou life depends. Crappie will spawn in the protective cover of the treetop. The hollow trunk will provide habitat for flathead catfish and snapping turtles. When the bayou is at pool stage some of the limbs will protrude above the surface like witches’ fingers – hunting perches for rattling kingfishers and patient anhingas. By then her last germinating acorns will be anxious seedlings struggling in the way of all life to take her place. (Note: The tree fell a week after the photo above.)