L (Liesje) Mommer L (Liesje) Mommer

Personal Professor

Research mission

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

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.

Currently, I aim to translate the ecological insights from these biodiversity experiments in order to diversify agricultural ecosystems. 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, Robert VeldmanDavide 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. The ecological insights gained from this fundamental research will also be translated to agricultural ecosystems, as I aim to use the power of plants to reduce pesticide inputs in sustainable 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. Together with dr Jasper van Ruijven and Lisette Bakker MSc, I aim to bridge that gap.

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.

The first success of this research theme in 2018 can be found in the paper of Bakker et al. in Journal of Plant Ecology. More to come, as Lisette will defend her PhD thesis on May 30th!Former lab members Monique Weemstra, Janneke Ravenek, Marloes Hendriks also worked on different aspects of root traits in a biodiversity context.

Cover crops and other agricultural potentials of plant diversity

Inaugural lecture

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