Research Projects


Plant traits and species interactions along gradients of N:P:K stoichiometry

PIs: Dr. Vanessa Minden, Prof. Dr. Harry olde Venterink (U of Brussels, Belgium)

Nutrient enrichment, as a consequence of fertilization, atmospheric deposition and modification of landscape has changed the relative importance of nutrient elements in limiting productivity, with many formerly phosphorus (P) limited aquatic systems being today nitrogen (N) limited and many terrestrial systems showing patterns of P limitation. Ecological consequences of higher nutrient input rates are shifts in ratios of nutrients and higher productivity rates, loss of species and increase in number of endangered species.

Research so far focused on the effects of N and P on plant growth and competition, whereas studies on the role of K in direct comparison to N and P are still missing. The evidences collected in the fields of ecological stoichiometry have contributed greatly to the understanding of ecosystem structure and function. Nonetheless, in their review, Sardans and Peñuelas (2015) emphasize the ‘…urgent need to include K in studies of biogeochemistry and stoichiometry in terrestrial systems…’. This reserach poject explores the effects of N, P and K on plant competitive interactions, and by this improves our understanding of the plant traits that drive these interactions. Traits include relative growth rate, biomass allocation patterns, morphological traits and physiological traits, such as enzyme activities.

Project location: Vrije Universiteit Brussel, Department of Biology, Ecology and Biodiversity, Brussels, Belgium

Banner1linie.jpgIBR: Interdisciplinary approach to functional biodiversity research

Subproject: Biodiversity effects on dune biogeomorphology: a trait based approach

PIs: Dr. Vanessa Minden, Dr. Thorsten Balke (U of Glasgow), Prof. Dr. Michael Kleyer (U of Oldenburg)

Coastal dunes and salt marshes are valuable ecosystems, both in terms of nature conservation and coastal protection. Understanding the responses of plant traits to environmental constraints and their effects on ecosystem functioning is key to reach conservation targets and ensure a resilient natural coastal defense. This project focuses on the interaction of environmental processes with plant traits for understanding and predicting ecosystem functioning and biogeomorphic development of coastal dunes and salt marshes. We seek to develop a conceptual framework of plant traits and biogeomorphology via meta analysis and literature review of coastal dune and salt marsh studies. In-depth studies on the importance of plant traits for germination, resistance and resilience of biogeomorphic ecosystems will focus on dune pioneer vegetation. 

Main research questions:

1. Can we formulate a conceptual framework to unify biogeomorphic concepts (such as biogeomorphic succession and ecosystem engineering) and recent developments in plant trait ecology and BEF studies (Biodiversity effects on Ecosystem Functioning) using dune and salt marshes as model systems?

2. Does species composition of the seed source in dunes increase the chance of vegetation establishment and therefore the chances for initiating a biogeomorphic succession towards a resilient and resistant dune system?

3. To what extend do trait expressions of dune plants affect ecosystem resistance and resilience of coastal dunes? We hypothesize that stability traits (e.g. stiffness, dry matter content, C:N ratio, root architecture) can be identified and are positively correlated to pioneer dune stability and resilience. 

This project is part of the PhD-thesis by Julia Bass

Banner2Linietibass: Tidal Bank Science and Services

Subproject: Plant trait responses to the environment and their effects on ecosystem properties

PIs: Dr. Vanessa Minden, Prof. Dr. Stijn Temmermann (U of Antwerp, Belgium)

The Elbe is one of the major waterways of central Europe and is connected to many parts of Europe via an extensive network of shipping canals. The immense amount of cargo transported along the river has led to a massive transformation of both its riverbed and shore, with major implications on natural ecosystems. Riparian ecosystems are characterized by strong variability and dynamics of e.g. salinity, tidal range and turbidity, and are inhabited by various brackish-water and estuary-endemic species, which makes them of special importance for nature protection. It has been recognized that a management towards a natural bank protection should be favored over an artificial embankment, provided that the economic use of the Elbe estuary for shipping and transportation of cargo remains assured (see e.g. BfG-project “Biogene Uferstabilisierung” and KLIWAS).

Natural vegetation along the estuary predominantly consists of reeds, including common reed (Phragmites australis), softstem bulrush (Schoenoplectus tabernaemontani) and saltmarsh bulrush (Bolboschoenus maritimus). Projects like KLIWAS (“Ästuarvegetation und Vorlandschutz”) and the BfG-Project “Biogene Uferstabilisierung” have evaluated the responses of reed vegetation on tidal influence, hydraulic stress and land use. They come to the conclusion that natural vegetation in some areas along the Elbe estuary delivers sufficient bank protection and recommend a combination of both artificial and natural bank protection.

The subproject “Plant trait responses to the environment and their effects on ecosystem properties” as part of the tibass project aims at the evaluation of the delivery of ecosystem services by the natural reed vegetation of the Elbe estuary in order to identify embanked areas suitable for restoring natural vegetation. For this, the responses of plant functional traits to environmental drivers (wave energy, sediment conditions etc.) and the effects of these traits on ecosystem services (wave attenuation) are studied.

The tibass-project is part of the PhD-theses by Tilla Schulte Ostermann and Ken Schoutens

Banner3LinieEffects of anthropogenically distributed antibiotics on plants and plant-insect interactions

PIs: Dr. Vanessa Minden, Dr. Gesine Pufal (U of Freiburg), Dr. Sara D. Leonhardt (U of Würzburg)

Veterinary antibiotics are intensively used in livestock farming to prevent and treat infections. However, they are often poorly absorbed in the animal gut and thus excreted unmetabolized. Through the use of contaminated manure as fertilizer, large amounts of antibiotics can enter the environment unintentionally and might accumulate in the soil of crop fields and adjacent natural vegetation. A number of studies have shown that a variety of antibiotics can be taken up by plants and accumulate in different plant parts with possible negative consequences, for example inhibited shoot and root growth or change of branching pattern. Plant responses are usualy dose-dependent and vary with the type of antibiotic. Studies on the effects of antibiotics on higher trophic levels are rare and the majority of them use artificial diets enriched with antibiotics as experimental set-up. So far, there is no knowledge on how antibiotics transferred from manure to soil affect plant and animal communities in croplands and adjacent habitats.

This project therefore studies the effects of antibiotics in soil on specific plant traits and on their interaction partners (higher trophic levels), using concentrations often found in manure-amended soils of croplands. Specifically, we investigate the effect of different concentrations of the three most commonly sold antibiotic compound classes (sulfonamide, penicillin, tetracycline) on plants species from two functional groups (herbs, grasses) and agricultural cultivation (crop, non-crop). Here, we determine germination responses and plant traits such as canopy height, internode length, leaf chlorophyll content, biomass allocation, root length and element allocation in repsoen to antibiotic treatments. We also test whether these antibiotics taken up by the plants affect the behaviour and reproductive success of herbivores (aphids) and pollinators (bees) in feeding and choice experiments. Our key objectives are to provide specific information on the responses to antibiotics in soil at the plant individual level, plant-trait level, plant community level and responses of higher trophic levels. This information will give us the basis to predict changes in plant and insect communities due to antibiotics at the landscape level.