Paul M.J. Berghuis 1,2, Carlijn Lammers1,3, Max Rietkerk2, Johan van de Koppel3,4, Tjisse van der Heide1,3,Valérie C. Reijers5, Angeles G. Mayor6
1Department of Coastal Systems, Royal Netherlands Institute for Sea Research, the Netherlands;
2 Copernicus Institute of Sustainable Development, Utrecht University, The Netherlands;
3 Groningen Institute for Evolutionary Life Sciences, University of Groningen, The Netherlands
4 Department of Estuarine and Delta Systems, NIOZ Royal Netherlands Institute for Sea Research, The Netherlands
5 Department of Physical Geography, Utrecht University, The Netherlands
6 Department of Biodiversity, Ecology and Evolution, Universidad Complutense de Madrid, Spain
* Corresponding author: paul.berghuis@nioz.nl
Introduction
Coastal dunes systems are worldwide threatened by enforced erosion, due to climate change induced sea level rise and increased storm frequency. For these systems to persist, timely recovery from disturbance is essential. These ecosystems occur in harsh environments with limited fresh water, and physical stress of waves and wind. Dune grasses escape these conditions by trapping sediment, forming dunes as their density and patch size increases. This bio-geomorphic feedback enables vegetation to rapidly build dunes, but the self-facilitating component makes dune grasses vulnerable at an early stage.
Objective and Methods
How new established patches, crucial in recovery, will perform under the varying effects of climate change remains underexplored. In this study we investigate the effect of a experimental compound drought and heatwave (CDHW) event on the growth of a pioneer dune grass. We conducted a 4-week manipulative field experiment on the Dutch barrier island of Schiermonnikoog. In this full-factorial experiment we crossed small establishing patches of Elytrigia juncea with larger established patches growing in ambient conditions or under a greenhouse structure simulating a CDHW event.
Results
Both patch sizes of E. juncea did not show any plant decline in response to the CDHW treatment. On the contrary an increased growth was observed, most evident in the form of elongated shoots. Soil moisture content was found independent of patch size, but abundant underneath all patches. This availability of freshwater mitigated the drought effects of the CDHW treatment. Moreover, instead of amplifying drought effects, the increased temperatures could now promote plant growth. The occurrence of soil moisture to buffer drought effects on establishing dune grass patches and the role herein of bio-geomorphic feedbacks is something to be further explored.
