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Rivers and river vegetation in North-Central Florida, A report of a short winter survey 1990-1. 1992. 73 pp.


THE RIVER HABITAT


INTRODUCTION

North Central Florida is forested, forested to a degree now unknown in lowland Europe, and these forests are not just dry land woods also found in Europe, but also wetland forests. Wetland woods are a true aquatic habitat with water rising to, perhaps, several metres deep. The Cypresses (Taxodium spp.) and Tupelos (Nyssa spp.) are the principal aquatic trees. This pattern is quite different to Europe, where there may be small alder (Alnus) woodlands, dry in summer, damp or perhaps barely flooded in winter and sallow or willow (Salix spp.) scrub or wood, and where dry places are needed for Salix establishment, which rarely floods more than 1ft (30cm) or so deep. The European habitat is damp woodland, the Florida aquatic woodland. Rivers are influenced by the type and degree of forestation.

There is some pasture in the area, and, locally, there are crops. Going south, towards Orlando, the proportion of woodland decreases, and that of built-up, developed land increases.

Wetlands carry a legal importance unknown in Europe. Waters are state property, dry land, private property. Hence the definition of jurisdictional wetlands, wetlands under state ownership and control, becomes of prime significance. Now that the role of wetlands in the water economy of the land is recognised, they receive an automatic protection not found in Europe., In Britain, for instance, a site has to be individually registered as a Site of Special Scientific Interest, and even then has only partial protection. In Florida, when a wetland is destroyed, it is expected that another, and reasonably comparable wetland is created (or restored). This is known as mitigation.

The necessity of defining wetlands leads to books identifying aquatic plants, like Dressler et al. 1991, listing the plants used by the Florida Department of Environmental Regulation for determining the landward extension of the waters of the State. This book gives about 300 species and aggregates, legally specified, as submerged, transitional and excepted species. (Almost twenty trees are classed as 'submerged aquatics'.) The disadvantage, of course, is that laws cannot be framed to cover all ecological situations. The advantage is that wetlands are in the forefront of environmental thinking.

North-Central Florida is extremely flat - flatter than even Denmark, the flattest European country (apart from The Netherlands, which is mostly reclaimed wetland). This immediately suggests very slow-flowing streams. However, with an annual rainfall of c. 54in (130cm), and storms of 10in (25cm) not uncommon, storm flows are very fierce, and scour can be great - excavating great holes in (soft-bottomed) rivers, and changing the courses of the water, as well as flooding wide areas of land, much of it forest, around rivers.

In some areas there are lakes with practically no streams. In orders, streams are present, but they are very sparse: even sparser than those on European chalks (soft limestones) where water sinks easily into the porous rock, and little runs off. Florida has much storm run-off, but a very porous subsoil.

Florida - and indeed many other parts of the USA - has what, compared to Europe, is a curious mixture of 'don't care', with unchecked pollution and disturbance to rivers and aquifer; and a standard of care and law which Europeans, including English, can only envy. This perhaps comes from the low density of population and extremely recent settlement. Enormous spaces with negligible impact, either let alone or protected, contrast with local bad spots.

Florida has a sub-tropical climate. Some water plants grow throughout the year, and most seasonal species have only a short winter phase. Growth and productivity are great. The animal life supported by the river vegetation is enormous. Fish are seen in most sites. Water birds, snakes, turtles abound (though birds have been much decreased by shooting over the past century). Water mammals include abundant otter (carnivore) and increasing beaver (herbivore). These two used to be common in Europe, and the present river yields resemble pre-nineteenth century European descriptions: much fish and fowl, supporting local human populations. Florida is sub-tropical, so has potentially greater productivity, and the rivers support larger animals: alligator (carnivore) and manatee (herbivore) which do no occur in the temperate climate of Europe.

CONTENTS

Acknowledgements

THE RIVER HABITAT

Introduction; rock and soil factors: river chemistry; water flow and force; size (of water course); Man's activities: water loss, drainage, channelling, chemical pollution (and total impact); changing residence time; recreation and ornament.

THE RIVER VEGETATION

Cover and diversity; habitat groups; communities; addendum: a few tentative notes on river distributions (autecology).

RIVER DESCRIPTIONS

Sweetwater Branch; Hogtown Creek; Santa Fé River; Waccasassa River; Oklawaha River.

Appendices 1. Methods (summary); 2. Information needed to complete Report

References

Photographic Illustrations

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