Water is becoming scarce in many areas worldwide. Water mining reduces water levels, but high and stable groundwater tables are a prerequisite for the existence of riparian wetlands. In addition to direct water withdrawal, predictions about climatic changes include other threats. Increased stochasticity of the runoff patterns and reduced snowmelt floods are severe threats to the existence of riparian wetlands. The riparian zones of streams and rivers have been sought after by humans since early days. High productivity, reliable water supply, and climatic stability make these ecosystems suitable for a range of human-use types, such as wood extraction, hunting, aquaculture, and agriculture. In areas of intensive agriculture, riparian zones including their wetlands have shrunk to narrow strips or have completely vanished. On the other hand, the ecosystem services are good socio-economical arguments to restore and enlarge riparian wetlands.
For conservation planning, it is very important to bear in mind that riparian wetlands are very diverse and have typical regional characteristics. Secondly, the whole riparian zone is very dynamic. Many tree species are relatively short-lived and well adapted to changes in the floodplain morphology or in the hydrology of the wetland. The existence of variable hydrological patterns is a prerequisite for the coexistence of annually varying plant and animal communities. Often, large-scale projects restore riparian zones including wetlands according to a single pattern that does not consider these dynamic changes in habitat and species diversity. If large flood events are precluded by dam constructions in the upstream region, the natural habitat dynamics are blocked and the vegetation will develop towards a late-successional stage without pioneer vegetation, and with a reduced range of moisture tolerance. Several studies could prove that once the hydrological fluctuations become reduced by water-level regulation, exotic species can invade river valleys more efficiently.
While many animal species depend exclusively on the specific habitat conditions of wetlands, most riparian amphibians and reptiles migrate into the drier zones of the aquatic-terrestrial ecotones for a part of their life cycle. This makes them vulnerable to increased mortality in the neighboring ecosystems, especially if these have been converted into agricultural or urban use. Therefore, a buffer zone considering the home range of these species is needed to fully protect these species.
See also: Floodplains; Riparian Zone Management and Restoration; Rivers and Streams: Ecosystem Dynamics and Integrating Paradigms; Rivers and Streams: Physical Setting and Adapted Biota; Stream Restoration.
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