Tree Islands of the Everglades

Chapter 17.
What We Know and Should Know about Tree Islands

Arnold van der Valk¹ and Fred Sklar²
email: valk@iastate.edu
¹Department of Botany, Iowa State University, Ames, IA 50011 USA;
²Everglades Department, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, FL 33406 USA.

From Tree Islands of the Everglades edited by Fred H. Sklar (South Florida Water Management District) and Arnold G. van der Valk (Iowa Lakeside Laboratory)

Abstract

Tree islands are a feature of many large, flat wetlands. They develop in these wetlands around some point of formation. Points of formation can include topographic highs in the bedrock, blocks of floating peat and depressions in the bedrock. Their point of formation can even be the result of human activities. The flora and fauna of tree islands are not unique, but are a subset of those in surrounding areas. This chapter summarizes what we know about the origin, development and human use of tree islands. Tree islands are important to the Everglades because:

1) they are a major spatial feature of the landscape and provide much of its biocomplexity,
2) they enable many terrestrial plant and animal species to live in the Everglades ecosystem,
3) they are essential for many groups of wetland animals and birds during part of their life cycle, especially for nesting,
4) they concentrate nutrients and may play an important role in the overall nutrient dynamics of the Everglades ecosystem, and
5) they preserve important archaeological and cultural features of South Florida.

In short, their significance is much greater to the Everglades and South Florida than their modest total acreage would suggest.

With a few exceptions, only recently have tree islands begun to be studied. Consequently, our knowledge of most aspects of their geology, ecology and archaeology is still rudimentary. Most studies have focused on their geological origin or on their plant communities. Both, however, are still not well understood, and most aspects of tree island ecology (vertebrate and invertebrate population dynamics, primary production, peat accumulation rates and patterns, etc.) have received very limited or no attention. Recent landscape studies have indicated that there were significant losses of tree islands during the second half of the Twentieth Century. Studies of their archaeology indicate that larger tree islands have been used for thousands of years in a variety of ways and that many tree islands have been significantly altered as a result. In theory, it should be feasible to restore lost tree islands and even to create new ones. If properly implemented, the Comprehensive Everglades Restoration Plan provides an unprecedented opportunity to preserve existing tree islands and to restore many of those that have been lost.

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