eDiValo – Ecological Effects of Light on Diversity

Anthropogenic nutrient enrichment and shifts in herbivore pressure can both lead to dramatic changes in the composition and diversity of terrestrial plant communities. Most of the hypotheses proposed to explain these changes relate to competition for light. We experimentally test the role of competition for light in mediating the effects of fertilization and exclusion of herbivory on diversity using novel methods (illumination by LED-lighting). We also address the extent to which climate change can reinforce or mitigate competition for light, and affect diversity. Our experiment is carried out at Global Change Experimental Facility (GCEF) in Bad Lauchstädt at a research station belonging to Helmholtz Centre for Environmental Research.

Project in collaboration with: Dr. Stan Harpole, Dr. Harald Auge, Dr. Yann Hautier

We are working with the following approaches:

  1. We use seed additions and transplants to assess the roles of seed germination and seedling survival, and adult survival and fitness in mediating the impacts of light under herbivory, nutrients and future climate.
  2. We use plant functional and physiological traits in different life stages (seeds, seedlings, adult plants) to predict competitive ability for light and changes in plant community composition and diversity under light addition, fertilization, herbivory and future climate.

Herbivory and Climate Warming

Global climate warming is expected to lead to dramatic shifts in plant community assembly and diversity in tundra ecosystems. However, these changes can be modulated or reversed by herbivory and nutrient availability which can affect immigration of lowland species and losses of native tundra species. Trait-based mechanisms and plant-soil interactions are likely to mediate these shifts. We use a long-term field experiment located in northern Finland to manipulate temperature (using open top chambers), soil nutrients (using fertilization) and herbivory (using fences) to investigate interactions among climate warming, nutrients, herbivory, plant functional traits and ecosystem functioning.

Main question:

Can herbivory and nutrient availability modulate climate warming effects on tundra plant communities and ecosystem functioning?

Main approaches:

  1. We use addition of lowland seeds and transplants to address invasion success and plant fitness under warming, fertilization and exclusion of herbivory. Project in collaboration with: Dr. Elina Kaarlejärvi, Dr. Johan Olofsson
  2. We follow changes in community composition and diversity over the years and use plant functional traits to predict species losses and gains.
  3. We investigate intraspecific trait variation in response to the Treatments and the relationship between intraspecific trait responsiveness and species abundance. Main collaborators: Dr. Elina Kaarlejärvi, MSc Mia Jessen
  4. We measure different soil functions, pools and stoichiometry variables (e.g. nutrients and nutrient cycling, microbial biomass, fungal to bacterial ratio via PLFA) to examine interactions between above- and below-ground systems. We are especially interested in whether lowland species invasion to open Tundra can trigger ecosystem-level changes and drive transition towards faster cycling ecosystem. Main collaborators: Dr. Elina Kaarlejärvi, Dr. Kristiina Karhu, Dr. Chhaya Werner

Some earlier publications:

  • Eskelinen, A., Kaarlejärvi, E. & Olofsson, J. 2017. Herbivory and nutrient limitation protect warming tundra from lowland species’ invasion and diversity loss. Global Change Biology 23: 245 – 255.
  • Kaarlejärvi, E., Eskelinen, A., Olofsson, J. 2017. Herbivores rescue diversity in warming tundra by modulating trait-dependent species losses and gains. Nature Communications 8, art. 419.
  • Kaarlejärvi, E., Eskelinen, A. & Olofsson, J. 2013. Herbivory prevents lowland plants benefiting from warmer and more fertile conditions at high altitudes. Functional Ecology 27: 1244–1253.

Multiple Global Change Effects on Californian Grasslands

General description of the project:

The effects of anthropogenic climate change on plant communities are likely to depend on biotic and environmental context, and interact with other global change factors. Growing evidence suggests that multiple resources simultaneously control plant communities. Climate change effects may therefore depend on other growth limiting factors, such as soil nutrients, which can naturally vary between habitats and increase due to anthropogenic nutrient enrichment. We test the impact of multiple global changes on plant communities in a naturally heterogeneous grassland system in California. We also investigate the impacts of climate change and nutrient enrichment on plant-soil interactions, ecosystem functioning and seed bank.

Main ongoing approaches:

  1. We investigate how the rainfall and nutrient addition affect soil seed bank and whether soil seed bank can help in recovery from global changes. Main collaborators: Dr. Jennifer Gremer, Elise Elwood, Dr. Susan Harrison
  2. Using multiple ecosystem functions, pools and stoichiometry variables both above- and belowground, we examine whether resource-adding global changes can trigger whole ecosystem shifts along slow-fast cycling gradient. Main collaborators: Dr. Yann Hautier, Dr. Stan Harpole, Dr. Risto Virtanen, Dr. Susan Harrison, Dr. Kelly Gravuer

Some earlier publications:

  • Eskelinen, A. & Harrison, S. 2015. Resource co-limitation governs plant community responses to altered precipitation. Proceedings of the National Academy of Sciences 112: 13009 – 13014.
  • Gravuer, K., Eskelinen, A. 2017. Nutrient and rainfall additions shift phylogenetically estimated traits of soil microbial communities. Frontiers in Microbiology 8, art 1271.
  • Eskelinen, A. & Harrison, S. 2014. Exotic plant invasions under enhanced rainfall are constrained by soil nutrients and competition. Ecology 95: 682-692.
  • Eskelinen, A. & Harrison, S. 2015. Erosion of beta diversity under interacting global change impacts in a semiarid grassland. Journal of Ecology 103: 397 – 407.
  • Virtanen, R., Eskelinen, A., Harrison, S. 2016. Comparing the responses of bryophytes and short-statured vascular plants to climate shifts and eutrophication. Functional Ecology 31: 946 – 954.
  • Eskelinen, A. & Harrison, S. 2015. Biotic context and soil properties modulate native plant responses to enhanced rainfall. Annals of Botany 116: 963 – 973.

Nutrient Network (NutNet)

Nutrient Network is a global research network addressing the joint impacts of herbivory and nutrients on grassland plant productivity and diversity . Together with Dr. Risto Virtanen I am a PI of two NutNet sites in Northern Finland.