Global change impacts on ecosystem functions – the importance of interactive effects

Global change drivers such as climate change and atmospheric nutrient loads (particularly of nitrogen) have multiple effects on the functioning and services of ecosystems, and are (amongst others) the most relevant key drivers of biodiversity loss. Airborne nitrogen loads have tripled since the beginning of industrialisation, and are known to affect ecosystem functions such as primary productivity, nutrient cycling, and plant species competition. Climate change impacts are predicted to become more severe, particularly in the course of this century. The UN Intergovernmental Panel on Climate Change (IPCC 2007) predicts increasing mean annual temperatures, alterations in precipitation patterns and more frequent weather extremes (e.g. severe summer droughts, heat waves and heavy rainfalls). These shifts may influence nutrient cycles, carbon sequestration and ecosystem primary productivity.

Despite recent research on the effects of global change drivers on ecosystem functions, little is known about the interactive effects of co-occurring global change drivers. It is conceivable that ecosystem responses to simultaneous effects of global change drivers are not simply additive, but also interact and thus may be antagonistic or mutually amplifying. The talk will address the impact of interactive effects of climate change and atmospheric nitrogen deposition on ecosystem functions such as plant growth and competition, taking deciduous forest ecosystems (dominated by Fagus sylvatica and Quercus petraea) and heathland ecosystems (dominated by the dwarf shrub Calluna vulgaris) as examples. Based on recent research the talk will highlight some examples that high airborne nitrogen loads will interact with climate change. We hypothesize that nitrogen deposition will increase an ecosystem’s susceptibility to climate shifts (i.e. increasing summer temperatures, drought events). Thus, single factor studies are not always sufficient to predict conceivable impacts of co-occurring global change drivers. Moreover, the talk will explain underlying mechanisms for the ecosystem responses observed.

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Invited by Anke Jentsch, Disturbance Ecology

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