Climate extremes. How do grasslands cope with increasing variation in rainfall?

More intense rain events, fewer rain days and longer dry spells are forecasted in high latitude areas of Europe. It is therefore likely that plants will experience more frequent periods of drought stress alternated by rain events with ample water supply in the future, as opposite to moderate, frequent rainfall events. How do grasslands cope with this variation? Are species-rich grasslands better able to resist these alternating conditions than species-poor grasslands?

These questions have been investigated in a 3-year experiment in the Nijmegen Phytotron. We subjected monocultures and 4-species mixtures to an extreme rainfall regime: 4 weeks of drought alternated by a few days of heavy rain. This regime was maintained throughout the summer and compared to a control treatment where plots received regular rainfall.

We already analysed the biomass data of the plots, showing that plants responded quickly belowground by making less roots in the top soil layer under the extreme watering treatment. In all, plants were very resistant, with only 20% less aboveground biomass production compared to the control.

Your internship:

The research question to address is: what are the effects of water extremes on the nutrient dynamics in the soil, the nutrient uptake by the plants and the nutrient losses? We have collected extensive data on soil nutrient contents, plant nutrient concentrations and nutrient losses in drainage water that are ready to be analysed. The results are very important for understanding the long-term consequences of water extremes to the grassland ecosystem.

In this internship, you will primarily work on data analysis and statistics. The experiment itself has been terminated, but other Phytotron experiments are running and you can gain practical experience with running a big experiment and its harvests. You need to have some experience with data analysis and statistical programs. Your skills are needed to make sense of a complicated but also very interesting and rewarding dataset.

For more information, please contact Hans de Kroon,