Responses of low Arctic tundra plant species to experimental manipulations: Differences between abiotic and biotic factors and between short- and long-term effects

ABSTRACT

Climate change in arctic tundra is projected to affect air temperature, snow depth, soil fertility, and caribou herbivory, which may alter plant community composition by shifting niche space to favor particular species’ life history strategies. We report responses of a Canadian mesic birch hummock tundra plant community to a range of manipulative experiments (greenhouse warming, fertilization, snow fence, and caribou exclosure treatments). Aboveground biomass of each plant species was measured in the same permanent 1 m² areas using the point frame method in 2005, 2011, and 2017. Although the greenhouse treatment had few effects on individual species, total vascular plant community biomass was enhanced between 2011 and 2017. Furthermore, species’ biomass across all control plots was stable from 2005 to 2011 but increased significantly from 2011 to 2017, with air temperatures also warmer over that same period. Species responded to high-level nitrogen and high-level nitrogen and phosphorus combined additions, with deciduous shrubs and graminoids increasing and evergreen shrubs decreasing. The snow fences and caribou exclosures had little effect on species biomass. Although vegetation greening trends have been reported in arctic environments that are primarily influenced by maritime climate, our study is one of the first to provide plot-based evidence of recent plant biomass increases in the low Arctic’s continental interior.

KEYWORDS:

• Climate change
• arctic tundra
• long-term biomass response
• shrub greening
• warming

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Acknowledgments

Many people have generously provided assistance with maintaining the study and collecting field measurements. We are particularly grateful to Greg Henry, Sarah DesRosiers, Tara Zamin, and Shawne Kokelj for collecting the point frame data and environmental data; Yvette Chirinian, Rhett Andruko, Shannon Petrie, Luca Bonifacio-Proietto, and our many volunteers for field and laboratory assistance; Mike Treberg, Robbie Hember, Peter Lafleur, Elyn Humphreys, and Greg Henry for support in establishing and maintaining the experimental manipulations; Karin Clark and Steve Matthews (Government of the Northwest Territories) for logistical support; and the Aurora Research Institute for overall administration. We are grateful to the Tłı̨chǫ Government for permission to conduct research on their lands.

Data availability statement

The data from this study will shortly be available on the Polar Data Catalogue website (https://www.polardata.ca/).

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This work was funded by the Natural Sciences and Engineering Research Council (NSERC) of Canada (388660), the Northern Scientific Training Program (NSTP), the Ontario Trillium Scholarship (OTS), and the Chinese Scholarship Council (CSC).