Search staff/organisations L Mommer
Name L Mommer

Job details
DescriptionFull Professor
OrganizationDepartment of Environmental Sciences
Organization UnitPlant Ecology and Nature Conservation
Phone+31 317 486 944
Secretarial phone+31 317 483 174
Phone 2
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Note by telephonist
Visiting addressDroevendaalsesteeg 3
Postal addressPostbus 47
Regular availability
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Side activities
  • Geen - Geen nevenwerkzaamheden
    Jan 2017 - Jul 2099


Research mission

In my research the focus lies belowground: the plant root and the rhizosphere. Initially, I focussed on the role of  root-root interactions for the relationship between biodiversity and ecosystem functioning. Howver, my research focus has widened towards including belowground plant-fungal interactions, because root-root interactions cannot be understood without considering the myriad of microbes in the rhizosphere.

To reveal these ‘hidden’ interactions and the consequences for ecosystem functioning, I and my team integrates insights from plant ecology, molecular biology, soil chemistry and phytopathology.

My mission is to translate the ecological insights from these biodiversity experiments to diversify agricultural ecosystems, as I described in this blog If you would like to have more information on my research ambitions, write an email to Liesje.Mommer[at]

Playing hide and seek: the VIDI project

In 2015, I was awarded a personal VIDI Innovational Research grant to reveal the interplay between soil-borne pathogenic fungi, conspecific and heterospecific grassland plants in order to provide a mechanistic basis for the positive biodiversity effects and maintenance of coexistence. Together with the VIDI team members,- Eline Ampt and Davide Francioli -  I aim to reveal the functional interactions of the main fungal actors with plant roots by performing 1) community assembly studies with both fungal and plant communities in order to test host-specificity 2) focus-expansion experiments with plant monocultures and mixtures to study density-dependence and neighbour effects. The insights obtained from these controlled experiments will be tested at larger spatial scales and over longer time scales, in more natural settings. This research will contribute to the fundamental understanding of plant-microbe rhizosphere processes, essential to maintain biodiversity and ecosystem functioning. We aim to provide proof-of-principle that the power of neighbouring plants can be used to reduce pesticide inputs in agriculture.

Root traits and biodiversity-ecosystem functioning

Plant roots perform multiple functions, including plant anchorage and belowground resource uptake, especially nitrogen, phosphorus and water. They have evolved a wide range of root traits to simultaneously perform these functions, which respond to spatial and temporal changes in soil properties and resource availabilities. Variation in root traits also implies large impacts on soil and ecosystem functions. However, despite the exponential interest towards root ecology, the connections of root traits to plant and ecosystem functioning remain poorly understood.

The development of a coherent root trait framework will allow a better prediction of plant community effects on ecosystem processes. The development of such an integrated framework will be particularly relevant for predicting effects of plant biodiversity on ecosystem functioning (BEF). There is consensus in BEF research that it is not plant species richness per se, but the value and range of functional traits of the species and their interactions that determine ecosystem functioning. Until now, the trait approach has only had limited success in BEF research. This may be due to the initial focus on aboveground traits, but also due to a lack of knowledge regarding the trait combinations driving ecosystem functions such as community producivity and nutrient cycling.

A recent success of this research theme is the PhD thesis of Lisette Bakker, which can be found here. Former lab members Monique Weemstra, Janneke Ravenek, Marloes Hendriks who also worked on different aspects of root traits in a biodiversity context.

Beyond my research team I have initiated the sROOT Initiative together with prof. dr. Alex Weigelt from University of Leipzig, Germany. This synthesisinitiative aims to understand root trait vatiation in whole-plant and ecosystem contexts.

Cover crops as a potential way to diversify agro-ecosystems

Cover crops are planted to maintain and improve the quality of probably the most precious asset in agriculture: healthy soils. These crops are currently widely applied to improve soil structure and prevent nutrient leaching. Next to these abiotic goals, cover crops have a major potential to lower the soil-borne disease pressure. The latter is a pressing issue as numerous pesticides that have been applied for decades to manage soil pathogens were banned recently. Particularly for the management of plant-parasitic nematodes and pathogenic fungi there is an urgent need for alternative measures, which may be provided by cover crops suppressing pathogens directly or indirectly via the stimulation of antagonists. However, the presence of multiple soil-borne diseases is commonplace, and a poorly-informed cover crop choice may even result in unintentional accumulation of one of these pathogens. Collborating with Sara Cazzaniga, Hans Helder and Joeke Postma and stakeholders we will provide a scientific basis for optimal cover crop combinations that suppress pathogens and boost soil biodiversity. .

Inaugural lecture

A sneak preview of my inagural lecture (Wageningen University February 2016)

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  Liesje Mommer on Linkedin

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VIDI project: Belowground plant-fungal interactions in natural grasslands

The diverse worlds of plants and soil meet in the rhizosphere, where they collectively drive ecosystem functioning. However, recent studies also suggest that these interactions determine plant species coexistence. Plants make their direct environment increasingly unsuitable for themselves, a phenomenon known as negative plant-soil feedback (PSF), caused by soil pathogens. PSF increases opportunities for other species to establish, promoting plant coexistence. However, for this hypothesis to work, PSF should meet two criteria. The first is host-specificity: negative effects should be restricted to the focal species. The second is density-dependence: the strength of negative PSF should increase with host density. In this project we aim to reveal the interplay between soil-borne pathogenic fungi, conspecific and heterospecific grassland plants in order to provide a mechanistic basis for coexistence. More information: Eline Ampt and Robert Veldman

PhD project Lisette Bakker - Root traits in a changing world

Plant communities have to cope with environmental changes that can cause dramatic reductions in the primary productivity and ecosystems’ stability, among which biodiversity loss and drought events. In this project, we aim to determine the factors that make plant communities resilient to extreme summer drought by looking at the diversity in certain plant functional traits. The focus will be on root traits, as they play an important role in the water and nutrient uptake. In a common garden experiment, plant monoculture plots of 16 grassland species are established to measure the plant traits and responses to a simulated summer drought. More information: Lisette Bakker

The Jena Experience

The Jena Biodiversity Experiment (Jena, Germany, The Jena experiment) was established with the aim to link biodiversity to ecosystem functioning. Sixty plant species, native and common to the Central European Arrhenatherum grasslands, served as a pool from which experimental plant communities of different diversities were assembled.

Over the first 10 years of the Jena Experiment we could observe increasingly positive complementarity effects among plant species and the emergence of stronger diversity signals in ecosystem element fluxes and pools. In the coming years we expect these trends to continue, allowing us to study the underlying mechanisms. We aim to see whether the increasing complementarity effects, that are partly counterbalanced by increasingly negative selection effects of particular plant species, can be explained by abiotic or biotic feedbacks and how they are related to functional differences among species. For an overview of the research over the last 15 years, please click HERE

Together with dr Alex Weigelt (Uni Leipzig, Germany) I am responsible for managing the team that studies of belowground plant-plant interactions by performing detailed measurements of root distribution based on classical root coring and innovative molecular species identification, combined with state-of-the-art isotopic and non-isotopic tracer applications to quantify root activity patterns in space and time. Recently, we have started to broaden our scope to belowground plant-fungal interactions, since dr. Davide Francioli is investigating soil-borne fungal communities in roots along the diversity gradient.

PhD students and postdocs that contributed to the root projects within the Jena Experiment: Janneke Ravenek; Annette Jesch; Natalie Oram; Hongmei Chen and Katie Barry.


Students (BSc and MSc) are invited to participate actively in my ongoing research projects and on plant fungal interactions. In particular, I am looking for students who are willing to translate ecological insights about the benefits of biodiversity in natural ecosystems to applications in agriculture. Both fundamental and applied projects are available within my root research team.

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