Anna Katharina Pilsbacher introduces her M.Sc. work at the Arctic University of Norway ‘Interfering with neighbouring communities: Allelopathy astray in the tundra delays seedling development’, speaks about the importance of understudied interactions and her journey from ecology to linguistics.

About the paper

A picture of myself in the field (on Svalbard). Photo credited to Fumino Maruo
A picture of myself in the field (on Svalbard). Photo credited to Fumino Maruo

Allelopathy is the chemical inhibition of one organism by another, causing decreased fitness of the recipient organisms, and a competitive advantage of the producer of the chemicals. While most work on terrestrial allelopathy focuses on effects in the immediate vicinity of the study organism, our study investigated whether allelopathy can inhibit organisms in a larger geographical area than currently understood.

The paper, which was born out of work on my M.SC. thesis, documents the ability of one allelopathic species, the ericaceous dwarf shrub Empetrum nigrum L., to negatively influence seedling health not only in its immediate vicinity, but also in environments away from its homefield. Already common in circum-boreal heaths, Empetrum is projected to benefit from a warming climate and encroach into new areas.

A picture of the vegetation of an early season snow bed. The forbs and grasses in the picture grow on top of detritus, mostly Empetrum nigrum leaves, accumulated during the snowmelt.
A picture of the vegetation of an early season snow bed. The forbs and grasses in the picture grow on top of detritus, mostly Empetrum nigrum leaves, accumulated during the snowmelt.

Empetrum’s evergreen leaves contain an array of secondary metabolites. Sharing functional traits with anemochorous seeds, the leaves are transported into new ecosystems by means of wind and snowmelt. These leaves accumulate in topographic depressions, such as snow beds, where allelopathic chemicals leach out of the withered leaves and enter the soil. In a greenhouse experiment, we showed that mixing soil with withered Empetrum leaves reduced seedling growth both in plants found in dwarf shrub heaths (the source of Empetrum leaves) as well as in snow beds (a sink environment).

We term the process of using biochemicals to affect organisms in an ecosystem that differs from the one in which these chemicals have originally been produced allochtonous allelopathy. We hypothesize that it can be used as a niche construction mechanism, making new habitats more suitable for future encroachment of Empetrum.

About the research

Ecosystems global distribution is changing in reaction to a warming climate. While the current study was conducted in the Fennoscandic tundra in which snow beds are threatened by shrub encroachment due to the lengthening of the growing season, the phenomenon of ecosystems and plant species exposed to climatic stress is widespread in all ecosystems.

A representative picture of our study area in Ifjord
A representative picture of our study area in Ifjord

Research shows that ecosystem resilience to one stressor is weakened by the cumulative exposure to the stress. Understanding the factors determining ecosystem health is crucial to predict the extent and the directionality of future ecosystem changes. Prior research on plant communities’ response to stress has focused on the role of abiotic factors and anthropogenic disruptions, for example agricultural grazing pressure. Our study establishes allochthonous allelopathy as another stressor to be taken into account. By exploring an understudied aspect within the complex ecosystem interactions web, we thus expand the toolkit of ecologists interested in predicting ecosystem responses to increased climatic stress.

The influx of allolepathic leaves into neighbouring communities might appear a small matter. The ubiquity of leaf litter originating from Empetrum plants and the low concentrations needed to significantly decrease plant development regardless of growth form or origin, however, suggest that its effects might be stronger than suspected. Moreover, it is expected that the mechanism of allochthonous allelopathy is at play in many environments, not just in dwarf shrub heaths, as long as plants possessing functional traits enabling the dispersion of allelopathic plant material are present.

About the Author

I am currently a PhD candidate in Theoretical Linguistics associated with the CASTLFish research group at the University in Tromsø. I work on the phonological behaviour of prefixes in Austro-Bavarian and Attic Greek. While my professional life has moved away from ecology and into areas that might seem Greek to many readers, I appreciate the skillset that has imparted to me throughout my education in ecology. In my spare time, I enjoy hiking and skiing in the great Northern Norwegian outdoors. I am also an avid swimmer and part of my university’s women’s choir. I am also spending my time brushing up on my Italian ahead of a research stay in Verona.

Read the paper in full here.