Judith SITTERS

My research focuses on the effects of mammalian herbivores on soil (e.g. carbon and nutrient cycling and storage, microbial composition) and plant processes (e.g. plant species competition,
functional characteristics, plant-microbe interactions) in grassland ecosystems. I aim to understand how these soil-plant-herbivore interactions drive ecosystem functioning and how they are affected by global change. I apply the theory of ecological stoichiometry, i.e. the balance of elements such as nitrogen (N) and phosphorus (P), to understand the impact of herbivores on nutrient availabilities for plant growth. My research aims to quantify the importance of herbivore dung on plant species competition. The results of my research indicate that the impact of herbivores on carbon (C) and nutrient cycling and storage is dependent on land use (e.g. managed livestock vs. wildlife), resource availability and climate. Dung of mammalian herbivores shows a large interspecific variation in N:P stoichiometry, which impacts plant communities in terms of nutrient limitation, plant quality, species competition and community composition. Recently I started working on dung microbes and their impact on microbe-plant interactions. I work in a variety of grasslands (tropical savanna, arctic tundra, temperate grasslands), but also conduct garden and greenhouse experiments. I am a member of the Nutrient Network (nutrient addition and herbivore exclusion experiments), giving me the unique opportunity to address my research objectives at a global scale.

J. Sitters, D.M. Kimuyu, T.P. Young, P. Claeys and H. Olde Venterink. 2020. Negative effects of cattle on soil carbon and nutrient pools reversed by megaherbivores. Nature Sustainability 3: 360-366, doi:
10.1038/s41893-020-0490-0.

J. Sitters*, E.R.J. Wubs*, E.S. Bakker, T.W. Crowther, P.D. Adler, et al. 2020. Nutrient availability controls the impact of mammalian herbivores on soil carbon and nitrogen pools in grasslands. Global Change Biology 26: 2060-2071, doi: 10.1111/gcb.15023. * equally contributing authors.

J. Sitters, M. Cherif, D. Egelkraut, R. Giesler and J. Olofsson. 2019. Long-term heavy reindeer grazing promotes plant phosphorus limitation in arctic tundra. Functional Ecology 33: 1233-1242, doi: 10.1111/1365-2435.13342.

E. Valdés-Correcher*, J. Sitters*, M. Wassen, N. Brion, C. Mourgues and H. Olde Venterink. 2019. Herbivore dung quality affects plant community diversity. Scientific Reports 9:5675, doi:
10.1038/s41598-019-42249-z. * equally contributing authors.

J. Sitters, E.S. Bakker, M.P. Veldhuis, G.F. Veen, H. Olde Venterink and M. Vanni. 2017. The stoichiometry of nutrient release by terrestrial herbivores and its ecosystem consequences. Frontiers in Earth Science 5:32, doi: 10.3389/feart.2017.00032.

J.Sitters, M.Maechler,P.J.Edwards,W.Suter,andH.OldeVenterink.2014.Interactions between C:N:P stoichiometry and soil macrofauna control dung decomposition of savanna herbivores. Functional Ecology 28: 776-786, doi: 10.1111/1365-2435.12213.