Restoration of aquatic macrophyte vegetation in acidified and eutrophied softwater lakes: an overview

Abstract

Softwater lakes possess a highly characteristic vegetation adapted to limited carbon availability. Based on hydrology, vegetation and geographic distribution, a boreal and an atlantic lake type can be distinguished. In general, boreal softwater lakes occur in remote areas where eutrophication is a local phenomenon and acidifying input is low. A number of these lakes are, however, very susceptible to eutrophication and acidification. Reducing the input of nutrients and/or liming the stream or catchment is generally sufficient to restore typical softwater vegetation. The vegetation of atlantic softwater lakes are subject to many anthropogenic degradation processes. Removal of nutrient-rich, anoxic, organic sediments is a prerequisite for restoration of these lakes. In acidified or acid-sensitive lakes, subsequent controlled inlet of calcareous, nutrient-poor water is more adequate than direct liming. The effects of these restoration measures strongly depend on interaction with processes, such as atmospheric deposition, drainage, catchment acidification, eutrophication and reduced colonisation rates.