Plants in a changing world: biological invasion and the role of biodiversity and species traits during climate extremes

Date: 18 December 2017

Venue: Campus Drie Eiken, Promotiezaal Q0.02 - Universiteitsplein 1 - 2610 Antwerpen-Wilrijk (route: UAntwerpen, Campus Drie Eiken)

Time: 4:00 PM

Organization / co-organization: Department of Biology

PhD candidate: Evelyne Elst

Principal investigator: Ivan Nijs & Hans De Boeck

Short description: Public defence of the PhD thesis of Mrs. Evelyne Elst - Faculty of Science - Department of Biology


Over the last two centuries, rapid growth of the human population, industrialization and globalization have caused an exponential increase in the anthropogenic pressure on nature. In this changing world, plants experience negative effects from climate change and modifications of ecosystems like altered biodiversity and/or biological invasion. This thesis focusses on biological invasion and the role of species richness and species traits during climate extremes.

In chapter 1 we determined whether high competitiveness, abundant reproduction and high phenotypic plasticity in Impatiens glandulifera were already present before invasion (pre-adaptation) or evolved after introduction (genetic shift) by comparing traits between populations collected from the invasive or native range. In chapter 2 we explored the effects of species characteristics (drought tolerance and functional group) and species richness on the resistance, resilience and biomass production of communities during extreme drought with or without an additional heat wave. Chapters 3 and 4 investigate the effect of neighboring plants on the resistance of a target plant during extreme drought. First, we did an experimental study in which a single herbaceous target species (Holcus lanatus) was planted in mesocosms with one of 14 herbaceous neighbor species. In addition, we developed a conceptual model based on the ecosystem’s water balance to investigate neighbor interactions during a drought extreme in communities with two species.

From the results of this PhD thesis we conclude that the community a plant is growing in has a strong influence on the plant’s reaction to climate extremes. Trends at the community level are determined by functional groups, response groups and species composition, which influence each other and therefore require simultaneous focus. In addition, not only the characteristics of the plants themselves but also the traits of their neighbors determine survival and productivity during drought and heat extremes. More insight at this level of complexity is needed to generalize from individual studies to universal patterns. In addition, our findings stress the importance of knowing which communities are most susceptible to disturbances since these communities generally have available niches that are prone to invaders. These invaders take advantage of the beneficial conditions (e.g. high nutrient availability) in their new habitat to be able to thrive. To properly predict the fate of a species in a future climate, with more extreme events and biological invasions, species interactions and invasive pressures need to be incorporated more realistically in experiments and models.