International Drought Experiment (IDE) on the Island of Hiddensee

Calluna vulgaris
rain out shelter
grazing as maintenance measures

Contact: Jürgen Kreyling, Irmgard Blindow, Andrey Malyshev

The coastal heath is an ecosystem greatly worth protecting, and its preservation strongly depends on the vitality of the common Heather (Calluna vulgaris). The persistence of the common Heather depends on the outcome of its competition with grasses. Aging and nutrient enrichment leads to Heather being outcompeted by grasses, which can be deterred by landscape management practices. It is not clear however, how anthropogenic climate change will influence this competitive balance. Evidence suggests that extreme weather events such as frost and drought are capable of tipping the scales of the competitive balance in an ecosystem. It is likely that such climate-driven changes will also modify the effectiveness of the undertaken landscape management practices.

To test the possible effects of climate change on the competitive balance among plant species, we have set up a small-scale manipulation experiment. The goal of the manipulation is to expose distinct plots of heath vegetation to extreme events and compare the reaction of the vegetation within these plots to non-manipulated vegetation. With respect to the type and set–up of the simulated extreme events, drought simulation via low roofs are carried out due to the realistic climate projections for the region. The experiment is replicated on two sites with heathlands of different age, to acquire a more complete reaction profile along two progressive heath vegetation stages. Additionally, grazing is simulated within the manipulated and control plots to test for the possible interaction between drought and the type of practiced landscape management. We conduct the experiment in close cooperation with the Biological Station Hiddensee.

On the one hand, the experiment will address specific questions related to the future of the coastal heath management. On the other hand, it is part of a global initiative aiming to better understand the effects of extreme events on ecosystems (Drought Net:  The goal is to identify vegetation types and climate zones which are most likely to react sensitively to climate change and finally to supplement global climate models with data based knowledge about feedback mechanisms between extreme events and vegetation responses. These are vital steps for improving the projections of climate change effects.