Institut für Evolution und Ökologie

WhoIsNext - Climate change and escaping ornamentals


Svenja Block, Madalin Parepa, Oliver Bossdorf, Luisa Conti (University of Rome), in collaboration with the groups of Mark van Kleunen (Konstanz), Wilfried Thuiller/Sebastien Lavergne (Grenoble), and Stefan Dullinger/Franz Essl (Vienna)


DFG (in the framework of the FP7 ERA-NET programme BiodivErsA)


2014 – 2017

In a nutshell

In order to prevent biological invasions, we need to be able to recognize potential future invaders. In this project we carry out experiments to test whether currently inconspicuous exotic ornamental plants might spread in Central Europe under future climate conditions, in particular under reduced summer precipitation and increased precipitation variability.


Project description

Many invasive plant species have originally been introduced as ornamentals. However, we continue to plant a large number of exotic species in our parks and gardens, thus creating a huge potential for future invasions. At the same time, global climate is changing, with an increase in temperature, a reduction in summer precipitation and increased precipitation variability predicted for Central Europe. These climatic changes might further promote the invasion potential of exotic ornamentals.

In this BiodivERsA project we investigate whether certain ornamental plant species might naturalize and become invasive under future climatic conditions, and in which habitats and regions in Central Europe these potential invasions might happen. In order to find answers to these complex ecological questions, a consortium of four research groups are combining experimental work in the garden and in the field (Bossdorf, van Kleunen) with different modelling approaches (Thuiller/Lavergne, Dullinger/Essl).

Within the WhoIsNext framework, the Tübingen team focuses on precipitation change. In a series of complementary garden experiments we test the effect of reduced summer precipitation and increased precipitation variability on the competitiveness of ornamentals in native plant communities.

In the first of these experiments, which was conducted in summer 2014, we compared the potential invasiveness of 25 ornamental species in a native European grassland community, using a semi-natural mesocosm approach where we experimentally created four climate scenarios: (1) constant beneficial precipitation, (2) a reduction of mean precipitation, (3) an increase of precipitation variability, and (4) a combination of the previous two. The experimental set-up allows testing interactive effects of changes in precipitation mean and variability, and it in particular enables us to make a broad comparison of many different ornamental species. Preliminary results suggest that indeed some ornamental species might be promoted by reduced water amounts and/or increased variability.

In follow-up experiments we will work with a reduced number of ornamentals. For 2015 we are planning two main experiments. In one of them we want to test the performance of the ornamentals in grassland mesocosm communities under more detailed precipitation scenarios that differ in timing, duration and strength of drought. In the other one we will introduce the ornamentals into different native communities (grasslands, ruderal communities) and compare their competitiveness in these communities under constant, reduced and variable precipitation. Besides these two experiment, we are also interested in the germination and establishment characteristics of our ornamental species, and in the variation between different cultivars of the same ornamental species.


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