The main authors were assisted by several collaborators who provided information on specific topics: wetland fisheries by T. Backiel (Inland Fisheries Institute, Poland), lake restoration by S. Björk (Institute of Limnology, Sweden); changes in wetlands by R.J. de Boer and V. Westhoff (The Netherlands). Some of these manuscripts and data are deposited in the library of the Institute of Botany at Trebon, Czech Republic, where they may be consulted.
It used to be said that most wetlands were commercially useless, but they have long been used, and their varied uses and importance have slowly become recognised (National Academy of Sciences, 1976; Szczepanski, 1983). The first uses were for fishing and hunting (fowl and mammals), and, in times of stress, as refuges for the local populations. Shelters could be built and roofs covered, by wetland materials. Some species could be used for fodder. Early specialisations included more-developed hunting and fishing, and the cultivation of rivers. Most of these are still practised, even in affluent and industrial countries, and in some countries wetlands are used on an industrial scale. Large-scale 'uses' involving habitat destruction, such as conversion to arable land through drainage, etc. are not discussed here.
In sparsely populated non-industrial countries, especially in the tropics, large flood-plains (e.g. of the Upper Nile, Niger, Central African Republic) are very important for grazing and fishing. In the advanced industrial countries, in contrast, large wetlands are more often under complete human control, and are rarely as important for living space.
Wetlands, merely by their existence, regulate water regimes, acting as storage reservoirs. They are also biological filters, changing the quality of percolating water by adsorbing or releasing nutrients, decreasing suspended matter, and retaining many pollutants. They provide materials for handcrafts as well as for industrial use. Their peat is used in horticulture and for fuel. Fowl and mammals are sought for food and sport, and marshes and waters are becoming used increasingly for other forms of recreation. Much food for domestic animals can also be obtained from them.
Wetlands have relatively fast rates of succession, and have been relatively undisturbed. They are, therefore, especially suitable for the study of plant succession. Their importance is increased by frequent presence of the remains, in peat, etc., of earlier stages of the successions. Palaeobotanists, palaeolimnololgists and phytosociologists can fruitfully investigate wetlands as models of natural ecosystems. Both undisturbed and managed wetlands act as refuges for plants and animals, often having a unique flora and fauna. The gene pools and structure of wetlands should therefore, be protected against alteration or destruction, and when new reserves are acquired, wetlands should be given priority.
Thus the users of wetlands may consume their production, utilise their physical and chemical properties, enjoy their recreational potentialities or conserve their life and environment.
Wetlands are living entities, taking many years to form. They are often slowly changing, or undergoing cyclic changes. Forms of exploitation not based on sound ecological theory tend to upset the pattern of development and lead to rapid destruction of the ecosystem. Regeneration may be impossible, very costly, or very slow. Many wetlands are thus seriously endangered by change of any sort.
Large areas of wetland are often drained in order to increase arable land. Wetlands are also imperilled by channelling and deepening rivers, by water abstractions, and by the consequent lowering of the groundwater table. Examples are the proposal for diverting the White Nile (Jonglei Investigation Team, 1954; Howell et al., 1988) which would completely alter present papyrus swamps; and drainage operations in Florida and Louisiana which are damaging the Everglades and coast swamps (Stone et al., 1977).
They are exceptionally susceptible to mechanical damage to the underground parts of the plant populations because these long-lived organs are required for the maintenance and propagation of the community. Consequently, damage by harvesting, heavy vehicles or other management practices must be prevented.
Uses of wetland production
Uses of physical and chemical properties of wetlands