Recent Posts

Archive

Tags

No tags yet.

Hurrican Laura & the D'Arbonne Swamp


Bayou-Diversity (20 September 2020) During a period of four hours beginning at 10AM on Thursday, August 27, 2020, the D’Arbonne Swamp changed for many decades. The change was aeolian in the form of Hurricane Laura. She was obstinate, eschewing the normal shape-shifting impotence that occurs upon landfall, and for the first time in recorded history still maintained a Category 1 status when she passed within the D’Arbonne Swamp 200 miles inland. Thousands of trees, mostly the largest and oldest oaks, succumbed to the 70 mph gusts and were thrown to the forest floor. Their tentacled root-balls faced east toward the source of the most powerful winds following the eye of the hurricane. Some were caught in the arms of desperate neighbors, their trunks canted at oblique angles. Many of the larger ones though took their leeward comrades to the grave with them like royal retainers at an ancient Egyptian funeral. Their lives had been shared lives as inter-twining roots connected by invisible webs of microrhizoans dispensed nutrients to the needy and chemical warnings to all when dangers such as attacking insects arose. Scattered among the fallen trees were tall, limbless boles with jagged tops giving the appearance of surviving chimneys in photos of bombed-out cities.

This scenario of devastation elicits mixed emotions in humans. Some, who view all natural resources in terms of monetary value, see only rotting piles of potential lumber that could have been used to build a new strip mall. They won’t be consoled in this case as much of the downed timber is not even fit for salvage because of wind shake, a phenomenon that occurs when trees are subjected to extreme winds whereby the wood separates internally parallel to the rings. Even if the hardwood market would support salvage operations, most of the trees are useless as lumber. Other people lament the loss of the forest for its intrinsic values. For those who value it as a rich, natural ecosystem, there are reasons to be content, because what appears to be destruction and death is in the slow workings of a swamp actually destruction and life.

Oaks have growth habits that ecologists refer to as “shade intolerant,” meaning that young oaks cannot grow in the deep shade of other trees. It is not uncommon to see hundreds of oak seedlings under a parent tree in the forest. Most, however, will never grow taller unless the big tree falls and sunlight reaches the seedlings. This occurs naturally when strong thunderstorms pass over the swamp every few years leaving a few blowdowns in their wake. Over time a mosaic of small openings is created across the swamp in which oaks can regenerate for a while until lost to shade once again. Even though a hurricane such as Laura has not come this way in more than a hundred years, it has happened many times in the thousands of years that the floodplain has existed. On each occasion the mega-event causes a reset of ecological succession on a landscape scale as large areas of the forest floor are flooded with sunlight. It is not an overstatement to say that wind storms are critical to the well-being of the D’Arbonne Swamp.

So from the swamp’s perspective, Hurricane Laura was therapeutic. Young, vigorous seedlings of overcup, water, and willow oaks were released for rapid growth to become the future forest. Surviving older trees will produce acorns and provide structural diversity in the meantime. Tree species were not the only beneficiaries of the storm. The depressions, some three feet deep, created when the root-balls tilted on edge, serve as a critical water reservoirs for many animals during dry periods. Crawfish, frogs, and toads inhabit the potholes and are pursued there by mink and raccoons. The abundant tracks of various other swamp creatures reveal that they often drink from the pools. Violent forces of the hurricane resulted in the creation of countless new tree cavities, a habitat type necessary in the life cycles of many resident birds and mammals. Wood ducks, prothonotary warblers, squirrels, bats, and honey bees are dependent on tree cavities. Even fish, turtles, and other aquatic organisms benefit from a flush of new nutrients and habitat when trees toppled into the bayou. Decaying organic material from the fallen trees will eventually fertilize the entire ecosystem from the bottom up. In time, the devastating handwork of Hurricane Laura on the D’Arbonne Swamp will be lost in another mature forest patiently awaiting the rejuvenating changes of the next big storm. ©KO

 

©2018 by Bayou-Diversity. Proudly created with Wix.com