Louisiana Natural Communities: Introduction

SELECTED NATURAL COMMUNITIES OF LOUISIANA WEST OF THE MISSISSIPPI

Kisatchie Bayou, Kisatchie National Forest

The reports that will follow this post are an attempt to account for the many community types visited in the three week field course entitled "Field Biology" (See previous post) at ULM between May 13 to May 30, 2013. 

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Credit: Wikipedia. Terrestrial Biomes of Planet Earth

A Note on Natural Communities

The Encyclopedia of Earth defines a natural community as a "an interactive assemblage of organisms, their physical environment, and the natural processes that affect them." 

If a given species were considered a thread in the immense tapestry of biomes and ecoregions of life on earth, then I think a natural community might be comparable to a complicated floral motif. 

Bottomland Hardwood Forest

It is recognizable, distinct pattern of life forms, shapes, colors. The community exists within a mosaic of other motifs, nested within ever-broadening patterns and processes that define the landscape. It is useful sometimes to compare these communities to human communities and the unique expression of cultures within them. When you enter China Town, you know you are in China Town. The same with Cajun Country or New Orleans. The architecture is different, the faces, the language, the behaviors, the food, the smells. In the same way, the Southern Mesophytic Forests of Tunica Hills are incredibly different from a Longleaf Pine Savannah in Abita, not just because of the topography but because of the chemistry in the soils that influences the unique wildflowers and their perfumes, the animals and their ways of life.

Natural communities are a vital collection of ongoing relationships, interactions, stories and information. Within them, they hold much of the evidence of their evolutionary past and important clues to the present and future. The incredible genetic content each contains is both a blueprint for construction and a road map for survival. Each is its own Library of Congress.

In the natural community, plants have an incredible role to play, for not only do they provide many of the structures that define the "motif" but they are the primary providers of foodstuff. Like an endless industrial complex of storage vessels and pipes with modulating valves and sensors, plant communities work non-stop, pumping sugurs and a variety of novel chemical compounds into the surrounding system. In addition to providing the housing, food and chemicals, they provide the materials for weaving, say, a birds nest. This all gives a profound new meaning to the term "plant" so often used to describe our man-made facilities.

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The communities in the coming posts will be grouped more or less chronologically by the class field trips. Within weeks, however, communities, are not presented this way. Some reorganization was used to take advantage of themes and patterns in shifting hydrology, substrate and disturbance regimes, thus aiding in a more linear narrative of communities and how they have developed over geologic space and time.

Credit: EPA

The approach that I have adopted for thee reports attempts to follow abiotic gradients and patterns from coast to inland environments. It is my hope to constantly return to driving factors such as hydrology, substrate and the type disturbance because these are the forces that life has had to reckon with. They are the raison d'etre of adaptation. Like the unflinching hands of God, floods, wind, fire have sculpted the land and the living.

Delta Lobes of the Mississippi River, Credit: USGS

Week 1 begins at the far edge of this gradient in the dynamic, transitional communities of  the coast. Here, the soil is some of the youngest on earth, a muck deposited less than 1000 years ago by the Mississippi River Delta. 

At the coast, land is built or torn away, flooded and then not, beaten by intense wind energy, wildfire and salt, shaping a floristically simple but profoundly productive community. At the other end of the spectrum are the mesic hardwood slopes of the interior, where ancient deposits are now slowly erode form a rolling topography. These relatively stable, well drained, vertically structured communities are more complex floristically and boast a very different host of wildlife. Here the most significant disturbance might be insect outbreak or the windthrow of a 200 year old American Beech tree

In between each “community” of course, exists a vast, complex mosaic of other community types, the tapestry, if you will, of interwoven threads. Intergradation and complexity is the norm in nature, community overlap is to be expected in many cases. Not all species are "indicators" of a particular community but are more generalistic or opportunistic in habit. Thus natural communities may be better understood as a term of convenience. For more background read about Clements and Gleason.

Still the concept has its merits and an important resonance in the human psyche. What, ultimately, will be the relationship between human communities and their natural counterparts in a give place?We can only begin to pursue that question whenwe have a basic undestanding of the natural communities in and of themselves. So let's have a look this summer at some of them and see what we can learn about ourselves and each other and where we might fit in to the great tapestry!