Using the River Ecosystem Service Index to evaluate Free Moving Rivers restoration measures: A case study on the Ammer river (Bavaria)

Restoring natural fluvial dynamics is fundamental for sustaining biodiversity and functional integrity of river and floodplain ecosystems. In Central Europe, however, pervasive river regulation and bank protection have greatly impaired ecosystem functioning and many water bodies fail to achieve a good ecological status within the European Water Framework Directive. The Free Moving Rivers approach seeks to restore the ecological integrity of rivers and floodplains by creating appropriate conditions for natural fluvial dynamics. Principal goals of the approach include removing artificial constraints on river processes and expanding the river corridor to restore natural river habitats and structures. Lacking, however, are complementary tools that evaluate and predict changes to ecosystem services (ESSs) after implementation. Here, we describe a case study of the Ammer river in Bavaria, Germany, to (i) calculate the extent of the Free Moving Rivers corridor, and (ii) assess changes to ESSs of a proposed river restoration measure under two alternative land-use scenarios. To do this, we apply the River Ecosystem Service Index (RESI), whereby individual ESSs are assessed in a spatially explicit way. We show how a proposed implementation of the Free Moving Rivers approach enhances three investigated ESSs: flood retention, sediment balance and habitat provision. We conclude that RESI is a potentially useful tool with wide applicability for restoration planning that synthesises floodplain complexity in such a way that facilitates decision making.

Automated summary

Restoring natural fluvial dynamics is crucial for maintaining biodiversity and functional integrity of river and floodplain ecosystems. However, extensive river regulation and bank protection in Central Europe have resulted in impaired ecosystem functioning and failure to achieve good ecological status. The Free Moving Rivers approach aims to restore ecological integrity by removing artificial constraints on river processes and expanding the river corridor. This study introduces the River Ecosystem Service Index (RESI) as a tool to evaluate and predict changes in ecosystem services after implementing the Free Moving Rivers approach.