Freshwater ecosystems are classified according to the water movement. This division is relevant both in the study of nature as well as for the exploitation and management of continental waters

There are two large areas of standing water in the Serra de Collserola, in Can Borrell and Vallvidrera, in addition to a good number of small water points (ponds and watering holes, etc.) distributed throughout the Collserola mountains. A swamp is a shallow body of stagnant water, with an ecological dynamic completely different from rivers, in which the water is moving. Understood as an ecosystem, a freshwater swamp is home to submerged and floating plants such as algae, reeds, water lilies and so on. These make up a habitat in which it is possible for aquatic birds, small mammals, amphibians, insects and many other freshwater species to nest and pass the winter.

One of the main benefits of reclaiming the Vallvidrera swamp and its surrounding area was the consolidation of an aquatic habitat for the Serra’s amphibian populations. Thus, the banks of the swamp were shaped to make it easier for animals to enter and leave the water, reeds and rushes were introduced to create safe hiding places for the fauna and various species of trees were planted to provide shade and maintain humidity.

Technical guidance from Societat Catalana d’Herpetologia made it possible for the swamp reclamation project to include all the ingredients necessary to ensure the maintenance of its amphibian populations.