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 that manipulates 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.