Sammendrag
Changes in land-use and climate represent major threats to Atlantic heathlands, and extreme climatic events, such as droughts, are likely to increase in frequency and intensity in the future. This is of particular relevance for nature management, and conservation, as extreme events are expected to have system-wide impacts on species and ecosystems. During the winter of 2014 an intense drought combined with low temperatures resulted in a massive dieback of Calluna vulgaris in the Norwegian heathlands, and two severe heathland wildfires occurred. With this as a background, a new Norwegian research project: Land use management to ensure ecosystem service delivery under new societal and environmental pressures in heathlands (LandPress) were initiated. LandPress combines observational data on ecosystem responses and resilience after the 2014 event with targeted experiments, one of them the International Drought Experiment, integrating our project into an international context. Drought impacts in mature Calluna-stands is investigated along a 650-km latitudinal gradient in Norway. Our first results indicate more drought damage in northern heathlands than in southern. Healthy Calluna was only observed in scattered patches with more suitable micro-climate, and, interestingly, in some areas regenerating after recent prescribed management burning. Moreover, drying experiments to learn how quickly Calluna plants dry up at 20°C and 50% relative humidity from rain-wet conditions showed that old Calluna stands represents a severe fire risk within two days. Young and more vigorous plants in the building phase (6–15 years old), as well as freeze drought damaged (typically some dead small branches), old but still live plants, showed different drying characteristics and dried more slowly. LandPress interlaces five work packages, exploring the impact of land-use change in combination with extreme climatic events in terms of vegetation change, ecosystem resilience, ecosystem services provisioning, sustainability, and evidence-based management and fire risk prevention.
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