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Bayou-Diversity (7 April 2019)

The title of this blog is “Bayou-Diversity,” which is of course a play on the term biodiversity. Biodiversity can be defined as all the varieties of life forms in a certain area. The area can be as large as planet Earth, where an estimated 10 million species of plants, animals, and microbes live (95 percent of which are made up of arthropods and microbes) or as small as a single drop of bayou water. Although the diversity of life is sometimes viewed at levels as minute as individual genes, it is more commonly considered at the scale of ecosystems. Within Louisiana several broad ecosystems are delineated by dominant vegetation types and include coastal marshes, bottomland hardwoods, prairies, pine forests, and mixed pine/upland hardwood forests. Each of these categories can be divided into more refined classifications (e.g., saline, brackish, and freshwater marshes).

Species richness denotes the number of different species of plants, animals, and microbes in a given area. Different ecosystems vary in their natural capacity to support different types of life. In general, biodiversity decreases as one moves farther from the equator or higher in elevation. An important indicator of an ecosystem’s health is derived by comparing current species richness against what might be expected in the area if unaltered by human disturbance. As an example, a dredged bayou draining a polluted swamp would likely have low species richness and thus poorer biological health compared to a free-flowing bayou with a pristine watershed.

The health of human societies depends on ecosystems that are species rich by supporting processes that provide benefits to everyone. Air and water are filtered. Climate changes are moderated when forests sequester carbon dioxide. Wetlands mitigate the impacts of hurricanes and store floodwaters that could otherwise be devastating. Critical agricultural benefits are amassed in the genetic traits found in wild varieties of domestic crops. Likewise, human health benefits accrue with biodiversity, as many drugs are derived, directly or indirectly, from biological origins. At least 50 percent of pharmaceuticals in the U.S. market stem from natural compounds found in plants, animals, and microorganisms. Fish, seafood, and some species of native plants and wildlife are biodiversity components that provide food and recreational opportunities. For many people the aesthetic and spiritual values of intact biodiversity are vital and immeasurable. I sit squarely in the midst of that lot on an old cypress stump. (adapted from Bayou-Diversity: Nature & People in the Louisiana Bayou Country, LSU Press)


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