PhD position: aboveground-belowground linkages in beech masting dynamics - NIOO-KNAW - Wageningen

What you will be doing

Every day, hidden ecological processes unfold right below our feet. Are you excited about belowground ecology and interested in combining long-term ecological data, soil ecology, fieldwork, and predictive modelling to understand how forests respond to global change? We are looking for a PhD candidate to investigate how belowground processes contribute and respond to mast seeding dynamics in European beech (Fagus sylvatica). 

The production of beech seeds has high inter-annual variability, resulting in “boom” years with high total seed counts (masting) and “bust” years in which very few seeds are produced. These fluctuations have cascading consequences for whole forest food webs, as many animals depend on beech seeds as a key resource. While the climatic drivers of masting are relatively well understood, the role of belowground processes (soil properties, nutrient cycling, soil biota) in shaping resource accumulation and mast seeding remain underexposed. At the same time, masting patterns in many trees, including European beech, are shifting in response to climate change, with potentially major consequences for forest ecosystem functioning above and below ground.

In this interdisciplinary project, you will investigate how belowground processes both shape and respond to masting dynamics. You will combine long-term ecological monitoring with soil ecology and predictive modelling approaches to “open the belowground black box” underlying masting. During the PhD, you will develop skills in ecological field work, experimental design, soil ecology, statistical analysis and predictive ecology, statistical programming (in R), working with long-term data, scientific writing and publishing, and interdisciplinary collaboration.

Specifically, you will: 

1. Assess spatially explicit, among-individual variation using a 50-year time series of beech seed production at a long-term site in the Netherlands;
2. Collect extensive soil samples for biological and physicochemical characterization, and use sensors to monitor spatiotemporal variation in abiotic conditions; and
3. Conduct controlled experiments with beech litter to understand how mast-driven variation in litter quality influences belowground processes.

What you will be contributing

We are looking for an enthusiastic, motivated, and collaborative candidate with an MSc degree in ecology, plant ecology and physiology, soil science, forestry, or a related discipline. You actively seek out new skills and knowledge to further your research and career objectives. We highly value clear communication, adaptability, and open knowledge exchange. This project has great scope for interdisciplinary work, and you will collaborate closely with researchers working in both above- and below-ground contexts, including plants, animals, soil chemistry, physiology, community ecology, and population ecology. You are fluent in English (CEFR C1 or equivalent; no certificate necessary) and have a driver’s license B (or equivalent). Experience carrying out field sampling, analysis of time series, soil biota extraction and identification, and/or statistical analysis is an asset, but not essential. 

What do we offer?

A fully funded, four-year PhD position in the Departments of Terrestrial Ecology and Animal Ecology at the Netherlands Institute of Ecology (NIOO-KNAW), located in Wageningen. The initial appointment will be made for one year and will be extended an additional three years following a positive evaluation. Working 0.8 FTE (i.e., five years in total) is a possibility. The preferred starting date is 1 September 2026.

You will register as a Promovendus (PhD candidate) at Wageningen University and become a member of the graduate school PE&RC (https://www.pe-rc.nl/), through which you can follow courses on ecological subjects, research methods, statistical analyses, and transferrable skills. You will have opportunities to attend workshops and conferences as part of your professional development. The Departments and the Netherlands Institute of Ecology (NIOO-KNAW) organise weekly seminars, science lunches and journal clubs to stimulate scientific discussion and exchange ideas.

Your workplace

The Netherlands Institute of Ecology (NIOO-KNAW) is located in Wageningen, Netherlands. You will be embedded in two NIOO-KNAW departments: Terrestrial Ecology (TE) and Animal Ecology (AnE). You will share an office space with other PhD candidates and join an active community of researchers, postdocs, PhDs, research assistants and internship students.

In TE, we aim to understand, predict, and mitigate effects of climate change, biodiversity loss and land use change in terrestrial ecosystems. Our research focuses on interactions between plants, microbes, and (in)vertebrates, in the soil and aboveground. Our approach spans from conceptual to experimental, and ranges from evolutionary adaptation to community interactions and ecosystem processes.

In AnE, our research seeks to understand the causes and consequences of variation in life-history traits, including the underlying genomic mechanisms, as well as where such variation arises in time and space. Our work often leverages our impressive long-term, individually based datasets, including studies of hole-nesting birds and their food (caterpillar and beech seeds). Using these exception times, we seek to link individual variation in life-history traits and fitness outcomes to variation in population/community numbers and composition.

The Institute has state-of-the-art research infrastructure and expert research support personnel to support this project, including stable isotope, chemical, and molecular labs, climate-controlled and outdoor experimental facilities, and our long-term studies.

More information

For more information, please contact:

Dr. Justine Lejoly, Tenure-track Researcher, Terrestrial Ecology: j.lejoly@nioo.knaw.nl

Dr. Joseph Burant, Tenure-track Researcher, Animal Ecology: j.burant@nioo.knaw.nl

Application procedure

To apply, please use the Academy’s online application portal: https://vacatures.knaw.nl/. Your application should include (1) a cover letter summarising your research interests, experience, and motivation for the project, (2) a CV/résumé detailing your professional and educational background, and (3) the contact information for two professional referees (name, affiliation, telephone and email). The deadline for application submission is Sunday 21 June 2026.

The hiring committee consists of the supervisors (Drs. Justine Lejoly and Joseph Burant), the promotor (Prof. dr. Liesbeth Bakker), and a PhD candidate working on a closely related project (Cherine Jantzen). The committee will invite a subset of candidates for interviews by 23 June. Interviews will be held in person at NIOO or online, depending on the location of the candidate, and are scheduled for Monday 29 June. In the event a candidate is unavailable on the 29th, alternative arrangements can be discussed.