I am a plant ecologist and I am intrigued to better understand how different global change drivers affect plant population dynamics and what consequences arise for biodiversity and ecosystem functioning at the community and ecosystem level. I am fascinated by the interplay of different organisms and I am aiming to disentangle direct effects of global change from indirect effects via changes in biotic interactions.
I am using a combination of experiments, modeling and synthesis to answer these research questions. By means of
experiments I am able to gain mechanistic understanding in the role of global change drivers for different biological processes, with IPM models I am able to project how climate change will affect population growth and dynamics of plant species while meta-analytical tools help me to synthesize existing data of experiments to detect more general patterns and to unravel knowledge gaps.
I am using a combination of experiments, modeling and synthesis to answer these research questions. By means of
experiments I am able to gain mechanistic understanding in the role of global change drivers for different biological processes, with IPM models I am able to project how climate change will affect population growth and dynamics of plant species while meta-analytical tools help me to synthesize existing data of experiments to detect more general patterns and to unravel knowledge gaps.
Effects of global change on plant populations and communities
A main part of my current research is tightly connected to the Global Change Experimental Facility (GCEF) of the Helmholtz Centre for Environmental Research (UFZ). The GCEF is a global change experiment to investigate the effects of climate change on ecosystem processes under different land-use scenarios (e.g. intenively used meadowand extensively used meadows and pastures). Climate manipulations are based on regional climate model projections for the years 2070–2100. Projected future changes in seasonal precipitation patterns are experimentally simulated by mobile roofs and irrigation systems: an increase in spring and autumn precipitation (+10%) and a decrease in summer precipitation (-20%). Furthermore, mean annual temperature is increased for about 0.5°C at a height of 5 cm above soil surface. Demographic models are a useful tool as they allow a mechanistic understanding of the factors influencing the vital rates of populations, and can be used to project how plant populations develop in the future. To better understand how climate change affects the population dynamics under different management regimes we monitor the demography of multiple key grassland plant species in meadows and pastures (see Lemmer et al. 2021) (running PhD project of M. Andrzejak in collaboration with Prof. T Knight ).
Biotic interactions and global change
Global change may not only have direct effects on plant populations and communities, but may be modulated via changes in biotic interactions (e.g. plant-hemiparasite, plant-herbivore, plant-plant, plant-pathogen, plant-pollinator). For example, I used experiments in the greenhouse and in the field to study how herbivory affects the diversity-productivity relationship and seedling establsihement of exotic vs. native grassland species (see Korell et al. 2016a, Korell et al. 2016b, Korell et al. 2017) and how the relationship between the hemiparasite Rhinanthus alectorolophus and several host plants is affected by N-fertilization and drought (see Korell et al. 2019). In a current study at the GCEF we compared how the effect of pollen limitation on the reproductive success of two grassland species is altered by future climate conditions (Andrzejak et al. 2022). Furthermore, since 2018 we study how the presence and abscense of antagonists (i.e. pathogens, insects and the combination of both) alter the demography and the vegetation dynamics under current and future climate conditions in the GCEF (running PhD project of M. Andrzejak project in collaboration with Dr. H. Auge (UFZ) and Prof. T Knight (UFZ/iDiv)).
Context and scale-dependency of global change on biodiversity
Meta-analyses may provide a quantitative synthesis of existing experimental patterns, which come from studies that vary in experimental design as well as a variety of other factors (e.g. background climatic conditions). They may help us to find generalities, and form hypotheses for why certain communities or ecosystems are more sensitive to global change. Together with colleagues from the UFZ (Dr. H. Auge, Prof. S. Harpole, Prof. T Knight) and iDiv (Prof. J. Chase) I synthesized data from climate change experiments around the globe and discovered that the biodiversity response to climate change depends on the background climate and the spatial scale (Korell et al. 2021). Furthermore, we were able to show that most climate change experiments manipulate temperature and/or precipitation at one level that is well outside the level expected in the future for the region (Korell et al. 2020a, Korell et al. 2020b). This meta-analysis highlights the unique features of the GCEF experiment, and the need for other experiments with realistic climate manipulations. Since 2019, I am involved in the sCoRRe working group where we synthesize data from global change experiments and study how phylogeny and traits may help to understand context-dependent community responses to global change. I am also involved in different global research networks (PlantPopNet, BugNet) and I am the PI of the experimental add-on SEED-DarkDivNet within the DarkDivNet.