Ecology

Within this theme, ecologists from our department investigate the mechanisms that regulate biodiversity and how biodiversity contributes to maintaining ecosystem functioning in the face of environmental change. We seek to explain and predict responses of species to stressors such as N-deposition, warming, drought, deoxygenation and how these responses lead to changes in species interactions and affect ecosystem functioning, such as nutrient cycling, carbon sequestration, and dike resilience. We pay special attention to plant and soil communities in different types of ecosystems.  

Our department has a strong track record in research in aquatic ecosystems, peatlands and temperate forests. Overall we focus on fundamental topics as the framework of ecological stoichiometry and conduct applied research focussing on, measures to bend the biodiversity curve. 

Plant and soil communities

Project leaders: Bjorn Robroek, Dina in 't Zandt, Eelke Jongejans, Hans de Kroon, Eric Visser, Henk Siepel

How plant species coexist in species-rich communities is one of the central questions in ecology. We approach this question by studying the responses of plant individuals in different abiotic and biotic settings (see also Adaptation and resilience to environmental stressors), and how they influence population performance in different plant communities. Particular attention is on belowground interactions, disentangling the complexity of effects of nutrients, plant competition and soil biota. We are set up for experiments at different scales, but also employ modelling to shed light on biodiversity mechanisms.  

Aquatic ecosystems

Project leaders: Sarian Kosten, Wilco Verberk, Casper van Leeuwen, Annelies Veraart, Leon Lamers, Bjorn Robroek, Andrea Kölzsch, Christian Fritz

How do species interact and how does aquatic biodiversity change as a result of for instance eutrophication, re-oligotrophication and climate change? These are questions we focus on with emphasis on aquatic vegetation, macrofauna, fish, waterfowl, provision of ecosystem services and sediment-water column interactions. We study biodiversity aspects on small experimental scales (such as aquaria), based on field observations and measurements, as well as based on meta-analyses using large national and global datasets. Moreover, we work on biodiversity aspects related to the creation of newly formed nature areas such as the Markerwadden in the Netherlands.  

Spatial population dynamics of animals 

Project leaders: Andrea Kölzsch, Eelke Jongejans, Casper van Leeuwen, Henk Siepel

Mobile animals like birds and fish are affected by environmental change throughout their life cycle, potentially at different locations. How individuals respond determines their survival chances and reproductive output, and ultimately their population sizes and distributions across larger spatial scales. We study demographic and migratory patterns in wild animal populations to quantify the overall consequences of global change and conservation and mitigation efforts. 

Other topics

• Biodiversity Ecosystem Functioning 
• Aquatic communities 
• Below ground communities 
• Responses to environmental change (warming, deoxygenation, N-deposition, drought) 
• Restoring Biodiversity, bending the curve 
• Ecological stoichiometry 
• Grassland ecology 

This theme aims to unravel adaptation of populations and acclimation of individual organisms to stress factors brought about by climate change, human intervention and local extreme weather conditions. Among these stress factors are drought, flooding, salinity, low oxygen, high temperatures, and extreme weather events in general.  

Plant root responses to their environment

Project leaders: Dina in 't Zandt, Hans de Kroon, Eric Visser

Plants have a variety of mechanisms to cope with abiotic and biotic stresses, including an array of physiological, genetic and morphological responses. We are interested in these responses, as well as their interactions and trade-offs, and how they influence plant growth and fitness. Our team is particularly well-equipped to study root responses in grassland communities and crop agroecosystems.   

Resilience of wetland ecosystem functions

Project leaders: Annelies Veraart, Bjorn Robroek, Sarian Kosten

Wetlands and aquatic ecosystems are facing numerous environmental stressors, including drought, eutrophication and warming. We study the resistance and resilience of critical ecosystem functions such as carbon cycling, and the mitigation of greenhouse gas in the light of these pressures. The microbiome of the sediment, rhizosphere and water column of these ecosystems plays a key role in the stability of ecosystem functioning, and hence is a key component of our studies.  

Disturbance in an anthropogenic world 

Project leaders: Andrea Kölzsch, Eelke Jongejans, Casper van Leeuwen

In a world where human population density is increasing, more and more ecological processes and phenomena are influenced by direct as well as indirect human disturbance. This topic focusses on direct disturbance of animals by, for example, human approach, noise, visual triggers and waste, but also changes in vegetation by farming or the introduction of invasive species. We focus on the influence on behaviour, space use and ecosystem functioning, quantifying it on different temporal and spatial scales. 

Other topics

• Adaptation of terrestrial dike grasslands to management and climate change
• Environmental stress of crops in agroecosystems  
• Responses of root systems 
• Responses of aquatic animal species to oxygen and temperature
• Risks of invasive alien species and ecosystem resilience to invasions   

Both natural and artificial wetlands actively exchange carbon and nitrogen compounds with the atmosphere (sequestration, emission). We aim to understand the fate of carbon and nitrogen in wetlands and focus on greenhouse gas emissions (carbon dioxide, methane and nitrous oxide) from inland waters and peatlands, and carbon sequestration in lake sediments and peat soils. We are interested in how abiotic factors (e.g. temperature, organic matter loading, water level) and biotic factors (e.g. the presence of vegetation and fish) influence the greenhouse gas balance. 

We work in a wide range of systems across the world, including lakes, urban ponds, fish-ponds, reservoirs, ditches, large rivers and peatlands. Our knowledge contributes to the quantification of current and future greenhouse gas emission from, and carbon storage in, these systems. Furthermore, it contributes to the development of climate change mitigation options for wetlands.  

Peatlands

Project leaders: Christian Fritz, Bjorn Robroek, Leon Lamers

Our research focusses on peatland landscapes in Europe and Asia, including near-natural bogs and fens, rewetted peatlands, peatlands drained for agricultural and forestry as well as productively used wet peatlands like Paludiculture. We study greenhouse gas related processes from the landscape management level down to the microbial level, assess greenhouse gas production and consumption rates, carbon sequestration through biomass production, the interaction between plant community-soil microbial and water as well as annual emission budgets informing National and International climate authorities in the LULUCF sector. We do this using large-scale field studies, Paludiculture field surveys, mesocosms and modelling. We collaborate internationally to better quantify GHG emissions and to mitigate trade-offs in ecosystem service provisioning – particularly in managed peatlands – to mitigate GHG emissions and co-create sustainable use of peatland ecosystems including Paludiculture. 

Aquatic ecosystems 

Project leaders: Sarian Kosten, Annelies Veraart

Working in aquatic systems around the world, including arctic lakes, temperate and tropical lakes and ditches, rivers and aquaculture ponds we consider the combined assessment of abiotic and biotic drivers of greenhouse gas emissions to be our niche in the international academic field. We study greenhouse gas related processes at the microbial level, assess greenhouse gas production and consumption rates as well as sediment-water columns and water-atmosphere diffusive and ebullitive greenhouse gas emissions. We do this using large-scale field studies, mesocosms and modelling. We collaborate with researchers world-wide to better quantify GHG emissions, understand the drivers and – particularly in human made systems and in human-impacted natural systems – to mitigate GHG emissions.  

Sub-themes

• Global change 
• Aquatic / wetland / terrestrial 
• Carbon, nitrogen, phosphorus 
• Microbial ecology (plant – microorganism) 
• Applied: Eutrophication / warming / drought / salinization 
• Applied: restoration & management / water treatment / paludiculture  

Pursuing healthy landscapes requires ecological management and climate sensitive restoration ecology. The Nijmegen ecology group offers a holistic approach using novel quantitative methods and modelling.  

Ecosystem service provisioning, pricing and ecosystem functioning for healthy landscapes  

Project leaders: Christian Fritz, Bjorn Robroek, Fons Smolders, Henk Siepel, Sarian Kosten, Leon Lamers, Hans de Kroon, Eric Visser

Paludiculture and climate neutral land use of organic soils

Project leaders: Christian Fritz, Fons Smolders, Annelies Veraart, Leon Lamers

The large-scale use of peatlands for agriculture is based on severe drainage, generating serious environmental and societal issues including land subsidence, carbon loss, deterioration of water quality, damage to infrastructure and flooding risks.  

Our aim is to investigate a more sustainable alternative for this traditional drainage-based agriculture: the use of rewetted peatlands for the production of food, fiber, and energy, and the simultaneous restoration of ecosystem services, including strong reduction of greenhouse gas (GHG) emission and land subsidence, increased water and nutrient retention, and water purification. This so-called paludiculture is a form of climate smart agriculture with specialized perennials crops that thrive on waterlogged or flooded soils, such as Sphagnum (peat moss), Phragmites (reed), Typha (cattail), Salix (willow) and Zizania (wild rice). The main objective is to develop and extend the scientific base for paludiculture by identifying the optimal abiotic and biotic conditions for paludiculture crops, and by quantifying the different ecosystem services in different experimental settings in the greenhouse and in the field.  

Similar techniques, using combinations of organisms, are also being studied in collaboration with Dutch water authorities (water boards) to develop novel ways to simultaneously purify wastewater to ecologically acceptable quality, recycle phosphate, and generate new high-grade products. 

Peatland rewetting and wetland restoration

Project leaders: Christian Fritz, Bjorn Robroek, Sarian Kosten, Leon Lamers, Eric Visser

Nitrogen deposition effects on landscape scale ecological processes 

Project leaders: Henk Siepel, Annelies Veraart, Leon Lamers, Fons Smolders, Sarian Kosten

Lake management and landscape scale nutrient management 

Grassland and heathland management 

Management for stable population or changing populations

Project leaders: Eelke Jongejans, Hans de Kroon, Eric Visser, Annelies Veraart, Andrea Kölzsch, Christian Fritz

Large-scale monitoring of species requires innovative techniques. DNA and eDNA-based analyses of community samples open new opportunities to track composition and abundance of species. The deployment of small GPS tags on animals allows the continuous tracking of their movements and behaviour. Smart cameras are developed for non-stop (and non-destructive) quantification of insect activity. Below-ground monitoring of root dynamics without disturbing the soil is possible in our root lab and other experimental set-ups. Biogeochemical fingerprinting algorithms are developed to quantify carbon and nutrient accumulation rates in rewetted peatlands. Greenhouse gas flux measurements using custom-made auto-chambers on water and land allow for continuous monitoring of ecosystem functioning.