Anwendbarkeit von Bioindikationssystemen für planerische und naturschutzfachliche Fragestellungen in Auen

authored by

Mathias Scholz

supervised by

Christina von Haaren

Abstract

In this study, an indicator system is presented using floodplain grasslands along the Elbe to record and assess the hydrological status and ecological changes in floodplains for nature conservation and landscape planning. The indicator system on which this work is based was developed within the framework of the Elbe Ecology Joint Project RIVA "Transfer and further development of a robust indicator system for ecological changes in floodplains" (RIVA - funded by the BMBF) to indicate hydrological properties in floodplains. In particular, application-oriented questions were answered as part of this work: What methodological approaches are available for bioindication in riverine landscapes? As a methodological approach, a categorisation of known bioindication approaches into five categories has proven useful. These were combined into three main groups: 1. classification, 2. status indication with 2.1 environmental indication and 2.2 biodiversity indication, 3. assessment indication with 3.1 value indication and 3.2 target indication. Such indicator systems have been widely used in the water sector. Various methods have also been developed for floodplains, but these can only be applied regionally and have not yet been tested for standardised and robust use. How do site characteristics typical for floodplains influence the composition of plant communities? Important abiotic factors in a floodplain landscape are hydrodynamics and soil properties, which determine the occurrence of floodplain communities or bioindicators. Using the example of a floodplain meadow, it was possible to illustrate the dependencies between plants and environmental properties and to identify 55 relevant indicator species for three hydrological site types (flood channels and depressions, wet grassland and drier mesophilic grassland). How are extreme events (summer floods / droughts) to be assessed in terms of floodplain biodiversity? Further analyses as part of assessments following a summer extreme flood event on the Elbe showed different reactions of the investigated species groups plants, mollusks and ground beetles. Where are the fields of application for indicator systems in nature conservation and landscape planning? The indicator system on which this work is based makes it possible to record two essential environmental factors (depth of the natural groundwater level during the vegetation period and annual flooding duration as a seven-year average) for species and ecological communities in floodplains in a relatively simple way using plants, ground beetles and mollusks. For nature conservation and planning purposes, an indicator system should also be applicable to ecological spatial units (biotope types) within a study area. Therefore, the RIVA indicator system was tested for biotope types. The plot information from which the indicator system was developed was assigned to five biotope types. The measured and indexed values for the duration of flooding and the depth of the groundwater were similar in all biotope types, so that a high performance could be assumed. A comparison of the indicator results for vegetation surveys with different plot sizes showed that this had little influence on the indicator quality. The developed indicator system and its use with biotope types has proven to be transferable for floodplain meadows in terms of time and space and within the Elbe floodplains, which is an important prerequisite for its application in practice. The indicator system itself can thus be linked to ongoing work on the assessment or monitoring of alluvial meadows, especially if species lists and abundances or cover of the species used for the indicator system are available. How can environmental indicator results be integrated into a nature conservation assessment? The indicator results themselves do not constitute an assessment. They indicate an environmental status of the hydrological conditions without any value. It is only by assigning a value standard that these results can be evaluated. Most of the floodplain habitats considered here are to be addressed as Natura2000 habitat types or are protected as legally protected biotopes under state or federal law. Therefore, they have a very high relevance for planning and nature conservation. Assessment methods for good ecological status for hydro-morphology or water quality in water management refers to an ecological reference condition. This allows the performance to be assessed on the basis of a single survey. This approach does not make sense for the assessment of hydrological values in floodplains, as we generally do not have the information to define a suitable hydrological reference condition for this. We recommend the simple and widely used method in landscape planning of assessing biotope types based on predetermined or derived values for various landscape functions by means of environmental quality standards and environmental quality objectives (in the case of species and biotope protection, e.g. by using the criteria of rarity, naturalness, dependency on extreme site characteristics). Depending on how the ecological status was assessed at the time of recording with environmental quality objectives, the hydrological indication results can be used for a before-and-after comparison and also assessed. Can species typically found in floodplains and habitat diversity be assessed at the large-scale landscape level? As the indicator system presented here is particularly applicable for small-scale floodplain sections of nature conservation planning, a large-scale approach for a floodplain-adapted assessment for larger river floodplain sections is developed by applying habitat types. In an exemplary implementation on the Rhine and the Nahe, it shows a high sensitivity for management options. Since monitoring aspects in particular are imperative for the application and further development of indicator systems, finally, possibilities for a further development of a monitoring system in floodplains are discussed.

Organisation(s)

Institute of Environmental Planning

Type

Doctoral thesis

No. of pages

178

Publication date

12.12.2022

Publication status

Published

Sustainable Development Goals

SDG 6 - Clean Water and Sanitation

Electronic version(s)

https://doi.org/10.15488/13115 (Access: Open)