Profiling plants to predict success and longevity of climate change-induced invasions
Final Report Abstract
This project aimed to predict the potential of range expansion of non-native plants based on their ecological strategies or trait profiles. Each trait profile was built as a three-dimensional vector of strong or weak ability to compete with other plants, defend against herbivores and disperse seeds. We developed a simulation model which we parameterised using a greenhouse experiment. The greenhouse experiment focused on growth and fitness measures (dry aboveground biomass and seed output) of profiled non-native, Mediterranean plants in mesocosms with mixtures of native plant species from Central Europe and presence or absence of generalist insect herbivores. Negative impacts of competition on growth measures were much greater than negative impacts of herbivory with largely expected differences between trait profiles. However, we found a significant and unexpected tolerance of competition by very small plant species. We conclude that a) biotic resistance of native communities can slow down, but not prevent the establishment of non-native species and b) tolerance traits present in non-natives may partly account for this establishment success. The other important outcome of this project was a running simulation model of local interactions between non-native and native plants and herbivores. During model development, we found that mortality of individuals was overestimated when we implemented competitive interactions via the established zone-of-influence approach. This insight reinforces the potential importance of tolerance traits. Tolerance traits may be accounted for by introducing a competitive asymmetry that is sensitive to the identity of the interaction partner. However, in our case this approach would have resulted in 55 possible combinations of interaction partners, so that its implementation is left for future projects. For future combined empirical-modelling endeavours of this type, we thus suggest to plan ample time for first model development and to use only three species, but with different mixtures of interacting species in the associated greenhouse experiment. Other results of the model broadly resembled the experimental results: Effects of competitive pressure and competitive traits were greater than effects of herbivory and defensive traits. An interesting effect was that the presence of herbivores was beneficial for weak competitors. We suspect that the weakening of strong competitors through herbivory benefited the weaker competitors during resource capture. We thus advise against the exclusion of herbivores from modelling or field studies of establishment of non-native species as there might be unexpected interactions. These may result in a greater establishment success and modified range shift dynamics. The insights from this project will also help to improve future range expansion models, especially with respect to the development of parameterization experiments and trait profile-based simulation models.
Publications
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(2012) “When aliens attack! Modelling range expansion in a traitbased cross-scale approach”, GfÖ Workshop Young Modellers in Ecology (YoMos) in Wetzhausen (DE), 02. – 05.05.2012
J Radny, KM Meyer
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(2012)“Predicting invasive potential of range expanding plants - A trait-based multitrophic cross-scale approach”, “Multitrophic Interactions” Workshop in Göttingen (DE), 22.-23.03.2012
J Radny, KM Meyer, WH van der Putten
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(2013) “Right here, right now? – Plant invasions as a scaling problem in ecology”, 6th International Conference of the ERCIM WG on Computational and Methodological Statistics in London (UK), 15.12.2013
J Radny, KM Meyer
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(2013) „Trait profiles and exotic annual plant species performance under different biotic pressures”, 11th INTECOL Congress in London (UK), 22.08.2013
J Radny, KM Meyer, K Tielbörger, WH van der Putten
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(2017) The role of biotic factors during plant establishment in novel communities assessed with an agent-based simulation model. PeerJ Preprints 5:e3088v1
J Radny, KM Meyer
