SP13: Novel Plant Systems for Storm Water Management
Head: Prof. Dr. Johannes Kollmann
Execution: Nadja Berger
Plant communities at SUDS have to be designed to provide at least some of the above-mentioned ESS, and innovative plantings should be based on theory of community assembly and trait-based restoration. Moreover, there are strong linkages between above- and below-ground processes, and vegetation structure and composition may modify below-ground functioning, including microbial communities, nutrient cycling and soil composition. Thus, the species-specific root systems affecting below-ground carbon storage, water retention and the interactions with microorganisms that degrade some pollutants, have to be taken into account when developing SUDS. This subproject will investigate plant communities using ecological criteria that combine water management, urban soil development, pollutant immobilization and biodiversity maintenance, and thus aims to boost synergies of ESS in SUDS, using ecological criteria.
The objectives are:
- (O1) Designing experimental plant communities, using assemblage theory and below-ground functional traits, that improve the functioning of SUDS, while also providing biodiversity services, e.g., increasing resource offer and habitat for urban wildlife;
- (O2) Investigating the role of root systems in water regulation, erosion control, pollutant stabilization or extraction, and identifying below-ground traits that enhance SUDS;
- (O3) Analyzing and evaluating the relationship between below-ground traits of experimental plant communities on ecosystem processes such as water infiltration, nutrient cycling, carbon storage, and pollutant stabilization;
- (O4) Evaluating large-scale experiments on both above- and below-ground ecosystem functioning and assessing the multifunctionality of newly established communities.
We predict that
- (H1) Higher functional diversity of plant traits will increase below-ground ESS;
- (H2) Trait-based plant communities show higher resistance against invasive alien plants;
- (H3) Below- and above-ground functional diversity and the resulting ESS are correlated;
- (H4) Small-scale patterns in functional diversity and ecological processes can be up-scaled.
At stage 1 we will grow individual plants of ten key species with contrasting root traits in 1-m depth tubes (10-cm diameter) on three substrates within climate chambers. We will include typical urban ruderal species (e.g., Echium vulgare and Leucanthemum vulgare) as well as plants that tolerate soil pollution (e.g., Armeria maritima und Silene vulgaris). In a factorial experiment, we will apply two climatic scenarios and two flooding regimes. Above-below-ground traits, root system development, and the potential ability to contribute to water infiltration, soil aggregate formation, and pollutant immobilization will be assessed. In stage 2 we will use mesocosms as larger experimental units. We will test the establishment of three experimental communities (15–20 species each), designed using below-ground traits. The communities will be exposed to three substrates and two watering regimes simulating the current rainfall amounts and heavy downpours. In stage 3 we will focus on 30–40 SUDS already existing in Munich and the surrounding area to implement and to test community establishment and multifunctionality. All in all, SP13 will investigate SUDS multifunctionality to understand the role of plant biodiversity for ecosystem services, i.e., water regulation or pollutant uptake and/or degradation. It will be developed in close cooperation with the three other subprojects within the research cluster including the use of common experimental set-ups and units. Additionally, interactions are expected with SP1 to improve the understanding of urban biodiversity networks.