Ecosystems

The impacts of wolf willow on a Canadian grassland ecosystem

How do the architecture and spatial arrangement of shrubs impact understory species in a Canadian savannah ecosystem?

Tall woody plant species can play a dramatic role in the structure and function of low-lying herbaceous plant communities. Within savannah ecosystems, the presence of trees and shrubs can have particularly significant impacts on grassland species. Yet, species diversity can have a large influence on the exact effects a shrub may have on its surroundings, making comparisons between studies difficult. Studying traits related to shrub architecture and spatial arrangement may overcome this difficulty.

In their new study published in AoBP, Heida et al. test whether shrub spatial arrangement and architecture impact the surrounding plant community. Specifically, they investigated how these traits influenced standing biomass, community composition, and overall nutrient cycling of neighbouring grassland understory communities within the Aspen Parkland of central Alberta, Canada. Large areas of the parkland are becoming dominated by wolf willow (Elaeagnus commutata), a native woody shrub that possesses a suite of traits that are likely to have unique impactas on grassland species.

A typical stand of wolf-willow (Elaeagnus commutata) in the Aspen Parkland of Alberta, Canada. The shrubs are typically 50-200 cm tall and occur as loose aggregations in a grassland matrix. Image credit: M.A. Dettlaff.

Compared to binary shrub-grassland analyses, their trait-based approach was able to detect significant associations between shrub presence and plant community function. These results suggest that stem dispersion patterns, as well as local stand architecture, are influential in determining how shrubs may affect their herbaceous plant counterparts.

The results of this study provide baseline information on the functionality of wolf willow dominated areas in the Aspen Parkland and highlight the importance of shrub architecture in driving shrubland dynamics. The shrub architecture approach used by Heida et al. is likely applicable to other shrub-focussed research and may help to increase our understanding of patterns of shrub presence in a variety of ecosystems.

Researcher highlight

Isaac Peetoom Heida grew up in Alberta and completed his BSc at the University of Alberta. Post-graduation, he has worked a variety of jobs in environmental and wildlife monitoring. Currently, he is volunteering with sustainable agriculture non-profit groups in Calgary, Alberta and is hoping to purse his interest in this field into graduate school. He is in the process of finding the right graduate position.

Isaac is interested in researching sustainable cropping systems, more specifically how cropping systems can shape plant-soil feedbacks.  Long-term, his career plans get more nebulous, but generally he is hoping to find a position that lets him contribute to research and help producers transition towards more sustainable agricultural systems.

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