The “Habitat Provision” Index for Assessing Floodplain Biodiversity and Restoration Potential as an Ecosystem Service—Method and Application

Abstract

River floodplains provide a large number of ecosystem services (ESSs) for human societies. However, human manipulations of rivers and floodplains have led to the loss of many ESSs, including the provision of habitats for typical floodplain flora and fauna. To quantify such losses, we present a new index, which incorporates the functional and structural quality of riverine and alluvial habitats and their communities. The assessment is based on publicly available biotic and abiotic data at a local scale (e.g., habitat type mapping, species data). The new evaluation method consists of three steps: First, an evaluation at habitat type level is done by using well-established assessment criteria (e.g., groundwater dependence, legal protection status, regenerability). Secondly, the individual habitats are assessed based on specific quality characteristics (e.g., presence of protected birds or backwater influence). Finally, these values are aggregated within 1-km floodplain compartments weighted by their spatial expansion. The index uses a five-step value to describe the importance of a floodplain area for typical species and habitats from "very high" (=5) to "very low" (=1). The aim of this "habitat provision index" is to provide a tool for planners and decision makers to compare and analyze the effects of past or future measures. The methodical approach is tested for two rivers: the Nahe and the Rhine. The performance of the index is analyzed by comparing the current conditions (status quo) against two different scenarios. The index is validated and shown to be sensitive to different water management scenarios (river restoration and technical polder scenario for flood risk enhancement), with both scenarios showing an improvement in the habitat provision value.

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

“…All assessments are calculated for standardised segments in the morphological floodplain on both sides of the river. These segments are oriented perpendicular to the river channel and separated into river, active floodplain (flooded area during a 100‐year flood) and inactive floodplain (areas of morphological floodplain that is separated from the river dynamics by regulation structures) compartments (Figure 2; Brunotte et al, 2009; Fischer et al, 2019). Given the wide variety of ESSs, RESI uses various index‐based methods to quantitatively assess the provision of the respective ESS, which can include both monetary and nonmonetary values.…”

“…Habitat provision assesses structural and functional habitat quality for floodplain-specific biota (Fischer et al, 2019). In contrast to flood Geodesy (LBM-DE2018, BKG) which were revised by ground-truthing during field investigations.…”

“…Natural rivers and floodplains are valuable landscape components that provide various benefits for human well‐being and ecological functioning (Fischer et al, 2019; Robinson et al, 2002; Schneider et al, 2018; Scholz et al, 2012; Ward et al, 1999). Due to their geomorphic diversity, their varied hydrological conditions, high rates of sediment and biomass turnover, and high productivity, they provide a multitude of ecological functions.…”

“…The index evaluates restoration measures on rivers and floodplains using existing data or, alternatively, is based on assumptions of future conditions (Stammel et al, 2021). Thus, it can be useful in establishing benchmarks for evaluating project goals and successes, as well as for comparing changes to ecosystems services under different hypothetical scenarios (Fischer et al, 2019). Furthermore, effects on ESSs can be illustrated in an easily understandable and spatially explicit format that enhances communication with public authorities and local stakeholders (Podschun, Thiele, et al, 2018).…”

Assessing land use and flood management impacts on ecosystem services in a river landscape (Upper Danube, Germany)

“…Proxy‐based methods (e.g., based on land cover or land use) have already been widely used to estimate large‐scale patterns of ES in floodplains (Clerici, Paracchini, & Maes, 2014; Large & Gilvear, 2015; Stürck, Poortinga, & Verburg, 2014). In addition, data derived from biological monitoring, yield statistics, hydrological modelling or interviews on recreation can enhance the level of detail (Burkhard, Kroll, Nedkov, & Müller, 2012; Fischer et al, 2019; Tomscha et al, 2017). Yet a spatially explicit quantifying assessment of all ES in floodplains represents a persistent challenge (Hanna et al, 2018; Keele, Gilvear, Large, Tree, & Boon, 2019), often mainly limited by the lack of suitable data.…”