Water, Earth, Fire: Louisiana's Natural Heritage

By Paul A. Keddy

Louisiana is one of the most beautiful parts of North America. It offers much more than Mardi Gras and Bourbon Street. With 25 maps and 60 illustrations, this is the first book to introduce the full range of wild places in Louisiana. Certainly the states magnificent swamps are described, but Louisiana showcases a great diversity of natural habitats prairies, longleaf pine savannas, oak forests, Appalachian forest, river valleys, cliffs, sand dunes, and cheniers. Each has its distinctive plant and animal species. Frogs living in trees, fish digging burrows, pelicans nesting on offshore islands and plants eating insects, as well as wild orchids, dwarf palmettos, armadillos, and Some of the authors favorite places to visit are highlighted and he describes the challenge of conserving wild places for the enjoyment of future generations. The book is titled for the water that carries the earth that builds Louisiana, and the fires that create the prairies, pine forests, and savannas. If you own only one book about Louisiana nature, this is the one to have a perfect gift for student, tourist, hunter, or neighbor.


Advance Praise

This is an impressive guide to the magical and bountiful world of Louisiana nature, and an excellent primer in why we should save itnot only for the sake of pelicans and woodpeckers and tupelos, but for the sake of ourselves.

Michael Grunwald, author of The Swamp: The Everglades, Florida and the Politics of Paradise


Dr. Paul Keddy captures what truly is the best about Louisianaits many and varied natural habitats. Dr. Keddy is more than a gifted scientist. He takes the science out of science. He describes complex processes in terms that are easy to understand, enlightening, and enjoyable. From the rolling pine forest to cypress swamps to barrier islands; from birds to bugs to bears; from frogs to fi sh, Dr. Keddy covers all that makes Louisiana one of the most unique places on the good planet Earth.

Carlton Dufrechou, Executive Director, Lake Pontchartrain Basin Foundation

• Language: English
• Publisher: Xlibris US
• Release date: Dec 20, 2008
• ISBN: 9781465316684

Paul A. Keddy

Paul Keddy, a professor of biology for thirty years, lived on the edge of a Louisiana swamp while he wrote this book. He has authored several prize-winning books on ecology and received the National Wetlands Award for Science Research. He has helped develop conservation programs for the pelican state, advising groups including The Nature Conservancy, the Lake Pontchartrain Basin Foundation, and Earthjustice. He is frequently invited as a speaker to both small meetings and large scientific conferences. In this book he shares his passion for the natural environment of Louisiana. www.drpaulkeddy.com

Book preview

Water, Earth, Fire:

Louisiana’s Natural Heritage

Paul A. Keddy

Copyright © 2008 by Paul A. Keddy.

All rights reserved. No part of this book may be reproduced or transmitted in

any form or by any means, electronic or mechanical, including photocopying,

recording, or by any information storage and retrieval system, without permission

in writing from the copyright owner.

This book was printed in the United States of America.

To order additional copies of this book, contact:

Xlibris Corporation

1-888-795-4274

www.Xlibris.com

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Contents

Acknowledgments

Introduction

1

BUILDING A LAND IN THE SEA

2

COVERING THE LAND WITH VEGETATION

3

PATTERNS IN THE DISTRIBUTION OF SPECIES

4

VOYAGES INTO THE PAST

5

SEE FOR YOURSELF: SOME PLACES TO VISIT

6

A VISION FOR CONSERVING OUR NATURAL HERITAGE

APPENDIX 1

Going Further: Some Books for the Beginning Louisiana Naturalist

NOTES

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Map 1. Selected major roads, towns,

and cities of Louisiana.

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Map 2. Parishes and selected water

bodies of Louisiana.

Acknowledgments

I must begin by thanking the many people of Louisiana who took their valuable time to educate me and share their knowledge of the state. Some of you have faded from my memory over the eight-year odyssey of this book; forgive me. The list includes Michaelyn Broussard, Larry Burch, Robert Hastings, Nelwyn McInnis, Glen Montz, Robert Moreau, Gary Shaffer, Latimore Smith, and Phil Stouffer. Hayden Reno finally convinced me that alligators really do call at night (at first I thought he was making fun of me) although I have not yet heard any. And then there are those who may not have taken me directly to the field but whose work or activities contributed to my appreciation of the state, including John Day, Carlton Dufrechou, Jim Grace, John Lopez, Shea Penland, Bill Platt, Julia Sims, Eugene Turner, Robert Twilley, and David White. George Lowery wrote two incomparable reference books on the birds and mammals of Louisiana.

And then there are those of you I have never met who took the initiative to protect our natural heritage, who lobbied for new natural areas, and who continue to look after them. I still hope to meet some of you in the future—meanwhile, keep up the good work. Several people generously took me to places they loved, particularly Larry Burch, Latimore Smith, Ben Taylor, and Chris and Brooks O’Connor—thank you for the effort and the companionship.

I thank my many students whose enthusiasm and curiosity encouraged me to believe that there was an audience for (not to mention a need for!) this book. Brent Perrin of Lees Landing made me two sets of bookshelves to store my growing accumulation of books and papers on Louisiana.

With regard to the book itself, some of the figures were first prepared by Kim Fisher, and then evolved through multiple versions until finally all 82 were brought to completion by my son, Ian Keddy. Although colored figures were the plan, I finally made the tough decision to go with black and white in order to keep the book affordable for students. At least three editors have helped me express myself—Brooks O’Connor, Ben Taylor, and Cathy Keddy, while Bryan McMahon cultured my appreciation of the written and spoken language in general. Christa Frangiamore gave me early encouragement with the manuscript although circumstances prevented her from seeing the book to completion with her publisher. Some of the expenses of production were covered by the Schlieder Foundation.

Introduction

In order to appreciate our lives, we have to appreciate where we live. I researched this book to increase my own appreciation of Louisiana, and now I wish to share what I have learned with you. Whether you are a resident, or a short-term visitor, you will enjoy this book. It introduces our landscape and the creatures that live here. Whether you have spent your life here, or traveled a thousand miles just to visit, you still need a friendly guide to our wild places and wild species. On any day in Louisiana, we could come across a graceful white egret feeding in a marsh, watch an alligator cruise down a bayou, observe a baldcypress silhouetted against the sunset, meet a lizard climbing up our front door, discover a wild orchid in flower, or watch a turtle sunning itself on a fallen tree. Too often we ignore these simple sources of pleasure. Louisiana has many stories to tell. Frequently, the story of Louisiana is recounted as if it were only about people: early explorers, the Acadian expulsion, slavery, the Louisiana Purchase, the Battle of New Orleans, the Civil War, Mardi Gras, and some colorful stories about New Orleans, most likely exaggerated. In reality, humans are only one of tens of thousands of species that live here. I find many of them more interesting than people. Certainly, each has its own story. Here, I introduce you to some of them, and where possible, let them speak for themselves.

Concern for protecting our natural environment is growing. Once we understand our landscape, the actions we need to take to protect it become obvious. Too often, we ignore threats to our natural environment (and our own economic well-being) until they reach our own backyard, when a subdivision or factory or clear-cut is proposed right next to our home. By then, it is too late to act. We need to see the bigger picture. Here are over twenty maps, thirty photographs, and thirty illustrations that tell the big story of the state. I enjoyed finding them and look forward to sharing them with you. Some appear here for the first time. Others were dug out of dusty old books and reproduced after a century in obscurity. Some old photos came from libraries far away. And a couple of these pictures hang on the walls of my home today.

Water, earth, and fire are Louisiana’s three special ingredients (you could call Tabasco sauce the fourth, but that is another story, although it does show up here when we visit the egrets on Avery Island). Thus the book begins with water—with the creation of Louisiana by the Mississippi River. Mark Twain too wrote about how the river builds the coast and creates wet places and dry places. The wet places we call wetlands, and here you are likely to find baldcypress and water tupelo trees, or one of four different kinds of marsh. The dry places that remain, the uplands, are often covered by forests with pine and oak. The lowlands flood. The uplands burn. As I tell my students, if you live in Louisiana, there are only two possibilities: either your land will eventually flood, or it will eventually burn. Most of our native plants and animals are therefore dependent on either flooding or fire or, in some cases, both. Many of the books about Louisiana will tell you about cypress swamps and flooding, but I want to tell you about the rest of the state as well—about our pine forests and pine savannas and prairies and beech-magnolia forests. There is more to Louisiana than swamp. So after you enjoy your swamp tour, plan on seeing more.

I also want to make some introductions. I would like you to meet my neighbors and friends. Among these companions are fish such as the bowfin and sturgeon, birds including the brown pelican and ivory-billed woodpecker, and mammals such as the armadillo and opossum. And not just animals—my neighbors include plants. Magnolias, palmettos, carnivorous plants, and wild orchids are among those you will become acquainted with.

Of course, you cannot write about Louisiana without saying something about humans and their activities. Our effects have not always been positive. Some wildlife species painted by Audubon have disappeared forever, including the ivory-billed woodpecker, Carolina parakeet, and passenger pigeon. Other species now at risk of the same fate include the Bachman’s warbler, gopher tortoise, red wolf, and Florida panther. Another group of species including the brown pelican, bald eagle, and American alligator came close to extinction but are now a common sight again. That is good news to celebrate. Finally, I will share with you a few of my favorite places, including the Atchafalaya Swamp and Kisatchie National Forest. So get some walking boots, and perhaps a camera or binoculars, and prepare to set off to discover Louisiana’s natural beauty.

1

BUILDING A LAND IN THE SEA

Although people have sometimes had an adversarial relationship with the Father of Waters, we shall see how the Mississippi River is largely responsible for building and maintaining much of Louisiana and how its management affects the future of the state. We shall also learn that flooding, seemingly disastrous from a human perspective, is actually part of a healthy, dynamic natural environment. Ironically, far more long-reaching and potentially radical changes to this landscape are being brought about by human efforts to control the river and curtail natural processes.

With our understanding of the modern Mississippi system, we will retrace Louisiana’s history further back in time from its conception beneath the warm, shallow waters of an ancient sea to the influences of glaciation. The chapter concludes by examining landscape futures—changes by stealth and imprints of hurricanes.

Foundations of New Orleans

How better to introduce the natural environment of Louisiana than by telling the story of the river that shaped it? The mighty Mississippi, the main trunk of the continent’s largest river system, drains 41 percent of the nation’s area—over 1.25 million square miles. From Cairo, Illinois, all the way to the Gulf of Mexico, the river travels across a vast plain formed from sediment the river scavenged from the rest of its basin. When the river passes through Louisiana, having been fed by its enormous funnel of tributaries, some 543,800 cubic feet of water pour down its channel each second.¹ At this rate, it would take just over three minutes to fill the Superdome in New Orleans. This huge volume of moving water carries and delivers 231 to 265 million tons of sediment to the gulf each year—the equivalent of over nine million dump trucks full. Bumper to bumper, they could encircle the entire state almost four times.

In our short life span, the Mississippi may seem unchanging. Yet its history is one of a highly dynamic force, constantly reworking the face of the state, destroying in one place and creating in another. If we could compress the eons of time and watch it at work from above, we would see an unceasing, writhing water course, slithering back and forth across its alluvial plain, leaving behind abandoned segments and the wrinkles of reworked soil. Occasionally it would bump up against the higher ground that delimits the plain, sometimes devouring this borderland. Sometimes the river would flow as a single channel, and sometimes, depending on geological and climatic events, it would widen its path and split into many channels. Every year, for a brief instance, the river would spill over its banks, flooding and depositing sediment on the surrounding bottomlands. At the river’s mouth a seesaw battle of delta construction and destruction would take place with the Gulf of Mexico. A delta would grow out into the gulf, but, when it is abandoned by the river when it changes course, these sediments might be cast by ocean currents into long strands along the shore or sink into the gulf. At a new location, the river’s next delta would evolve, and the cycle would begin again. In the next sections, we will look at these alternating processes of creation and decomposition more closely.

Flooding Builds Land

In the lower portion of the Mississippi valley, on the deltaic plain (figure 1-1), the river builds new land in two different ways. As it meets the Gulf of Mexico, its current speed diminishes. Sediments carried along by the moving water in the river’s channel now begin to drop to the ocean floor. First the larger, heavier particles fall from the water column, then the finer particles, which can be carried even further by ocean currents. Layer after layer of sediment accumulates on the sea floor, and they gradually build up to protrude above the water when the river and tides are not in flood stage. This process of land building seems slow to us but is rapid in terms of the geological time scale, especially when the river empties into shallow areas at the edge of the sea.

In addition to creating deltaic land, the river also builds land along its banks during times of spring flood. Sediment settles out of the floodwater, forming broad, slightly raised levees. The deepest layers of sediment are actually deposited closest to the river. In this peculiar way, the river builds a wall of sediment—a levee, along either side of the watercourse, and its path across the floodplain may become higher than the surrounding land (here it is important to keep in mind the difference between these naturally formed levees and the artificial kind meant to curtail flooding—see The River Short-circuited). A quick glance at a map of south Louisiana will show that levees from current and past courses of the Mississippi, stretching finger-like to the sea, have left the only high ground suitable for towns, roads, and farms.

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Figure 1-1. The Mississippi valley cuts Louisiana north-south. Vast areas of swamp and freshwater marsh form on its floodplain (from Abington, O. D., H.W. Bullamore and D.C. Johnson. 1993. Louisiana: A Geography. 2nd ed. Dept. of Geography/Urban & Regional Planning, University of Southwestern Louisiana, Lafayette, LA).

Count the Deltas

The Mississippi delta we know is actually a composite of the last six deltas the river created over the past 7,000 years: the Maringouin, Teche, St. Bernard, Lafourche, Modern (or Plaquemine plus Balaize), and Atchafalaya (figure 1-1). Before these deltas were laid, the shoreline of Louisiana was far inland—roughly the southern edge of the Florida Parishes uplands. The oldest sediments are to the west, in the Maringouin and Teche deltas (Bayou Teche is the modern day name of the shrunken remains of what was once the main Mississippi River channel).

About 4,000 years ago, the river changed its course and headed east to build the huge St. Bernard delta, where today’s Biloxi marshes now stand (the Chandeleur Islands arc marks the delta’s edge). Thus the land we now call the River Parishes was laid down. In the process, water was trapped between it and the highlands to the north, creating both Lake Maurepas and Lake Pontchartrain.² Having built up land both to the west and the east, the river returned to a more north-south orientation and built up the Lafourche delta about 2,500 years ago. Like Bayou Teche, today’s Bayou Lafourche is a reminder of an old Mississippi. About 1,000 years ago, the river began to carve a new channel in the south side of the St. Bernard delta, near New Orleans, following a different direction to the gulf. The resulting delta, known as the Modern delta, is relatively small. Part of the reason is that the sediment carried by the river is now falling into deeper water instead of accumulating in shallow water near the shore as the wide St. Bernard delta had done. The final part of the story, which has taken place over the last 50 years, is the rise of the river’s second delta—at the mouth of the Atchafalaya River (figure 1-2). This river carries one-third of the Mississippi’s water to the sea. Without controls built to keep the main part of the Mississippi’s flow going past New Orleans (see chapter 5), it is possible that most of the water and sediment would now flow through this outlet to create a sizeable delta.

Because of low elevation, the vegetation on the deltaic plain is strongly influenced by flooding. If this were the sole important factor, then presumably much of this area would resemble the alluvial valley farther inland (figure 1-1) and naturally be dominated by baldcypress-tupelo swamp forests. Marshes, however, dominate this region, and a number of factors combine to prevent forests from developing. In some areas, the duration of flooding is apparently so great that trees cannot survive. In other cases, such as the Atchafalaya delta, it may be that the sediments are so new that forest has not had time to develop. But most importantly, this entire region is subject to occasional flooding by the sea. Saline water puts a severe stress on plants. The greater the salinity, the fewer the kinds of plants that can survive. So those areas that are most exposed to flooding by the sea have become salt marshes, whereas those protected from the sea are freshwater marshes. In between lie brackish and intermediate marshes. The different plant communities in these deltaic-plain marshes are described in chapter 2.

The River Short-circuited

In our desire to construct cities and farms along the Mississippi and its tributaries, we have drastically altered the river’s natural plumbing and the way it once interacted with its floodplain. The biggest change occurred in response to the disastrous flood of 1927 (chapter 4). The federal government constructed

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Figure 1-2. The Mississippi River delta is a composite of six distinct delta lobes produced by different courses of the river over the past 7,000 years (from Spearing, D. 1995. Roadside Geology of Louisiana. Mountain Press Publishing Company, Missoula, MT after Coleman, J. M. 1988. Dynamic changes and processes in the Mississippi River delta. Geological Society of America Bulletin 100: 999-1015.).

a basin-wide system of dams to hold water in reservoirs during the spring flood. These waters can be released later in the year. This has the effect of holding back some of the sediment that used to enter the river. An extensive system of levees was also built to permanently block the river from its floodplain and keep it contained. These artificial levees keep the river from naturally eroding adjacent land, thereby diminishing the amount of sediment that gets into the channel. Secondly, the levees prevent or decrease sediment deposition by the river on its adjacent floodplain. The fabulous quantities of free sediment delivered to Louisiana and no longer deposited are, instead, carried out to the sea, where they settle in deep water. Thus the deltaic floodplain, particularly the lower part closest to the gulf, can no longer increase in elevation. As the old sediments settle, the land slowly falls below sea level. It is counterintuitive, but repeated flooding is necessary to build this land and keep it above sea level. The result: one kind of disaster has been replaced by an even larger one—without the river’s water and sediments, the entire landform is disappearing.

To avert this loss, river-sediment deposition must be returned to its natural regimen while continuing to protect man’s activities as much as possible. One method chosen to do this is by building what are called river diversions (some prefer to call them river reintroductions). These are manmade channels through the manmade levee, usually controlled by gates, that allow fresh river water and sediments to flow into surrounding wetlands. Only two significant diversions have been built. One occurs at Caernarvon on the east bank below New Orleans, and the other is at Davis Pond, across the river from Kenner, which flows into the Barataria Bay system. Unfortunately, these are designed to divert mostly water and only a little silt. They freshen the marshes, but to truly strengthen and rebuild the delta, larger sediment diversions have to be built. Another method under serious consideration is pumping sediment from offshore sources to rebuild shorelines and marshes. Will we be able to bring sufficient new sediment into the delta system?

Give and Take: Alluvial Valleys

Although the massive alluvial valley produced by the Mississippi is the largest in the state, it shares many features with valleys produced by