Drought, diversity and production: a multi-stakeholder and long-term experiment

The Netherlands has many meadows or pastures where plant diversity is not very rich, or not as rich as potentially could be. This may jeopardize ecological functions, such as water retention, water quality and water infiltration. Of course, there are several interests at play, but long-term consequences are often not yet clear. The long-term resilience of such systems to maintain their function while simultaneously safeguarding their role in the ecosystem as habitats for birds, insects and other organisms, however, is becoming increasingly important given climate change forecasts.

Natural systems could provide a buffer for these changes, specifically in regard to drought. For example, by storing water in dry periods by reducing evaporation and removing excess precipitation, while preserving water quality and functioning. Previous experiments suggest that biodiverse systems can buffer against climate extremes, for example because they contain species that can reach water at lower depths or because not all species bloom and are active at the same time, leading to a higher stability of the system over time. These are just two examples but increasing and preserving biodiversity can have far-reaching consequences for both these grasslands and the surrounding natural areas. With this project, we not only want to clarify this relationship between biodiversity and drought, but also provide farmers and other landowners with the necessary resources to make the best trade-off between production and biodiversity.

The experiment is carried out on a meadow grassland that was previously used as production for animal feed. In total there will be 48 square plots of 9 square meters each subdivided into different treatments with a difference in biodiversity and the amount of water they receive. The first is done by seeding the plots with different seed mixes commonly available to landowners, ranging from mixes that simulate intensive (low diversity) to extensive (high diversity) land use along a diversity gradient. The second is done by building shelters on some but not all plots and providing them with EPDM foil all around in the ground (which is of course removed later). With special sensors that wirelessly take various measurements of the soil and the atmosphere (temperature, humidity and conductivity), we know exactly what the consequences are of the different treatments. Finally, we will measure the amount of production by mowing the test areas every year and measuring how much biomass has been produced. All in all, this information gives us more insight into the relationship between biodiversity, drought and production.

This project is a collaborative project between Utrecht University (Botanic Gardens and the Department of Biology), Stichting Landschap Erfgoed Utrecht, Movares and T-mobile, including many volunteers and a land-owner who has provided a location and is a result of a grant by the Prins Bernhard Cultuurfonds.