University of Oulu

Kantola, N., Väisänen, M., Joshua Leffler, A. and Welker, J.M. (2023), Contrasting impacts of short- and long-term large herbivore exclusion on understory net CO2 exchange in a boreal forest. Ecography e06724.

Contrasting impacts of short- and long-term large herbivore exclusion on understory net CO₂ exchange in a boreal forest

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Author: Kantola, Noora1; Väisänen, Maria1; Leffler, Alan Joshua2;
Organizations: 1Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
2Department of Natural Resource Management, South Dakota State University, Brookings, SD, USA
3Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, USA
4University of the Arctic (UArctic), Rovaniemi, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.3 MB)
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Language: English
Published: John Wiley & Sons, 2023
Publish Date: 2023-11-08


Across boreal forests, trees are the main living biomass carbon (C) stock, but the understory vegetation can contribute significantly to the C cycling and net forest carbon dioxide (CO₂) balance. The patchy understory vegetation, which consists of sunlit (i.e. lichen-like) and shaded habitats (i.e. dwarf shrub-like), is often altered by ungulate grazers. Grazers may influence understory CO₂ exchange and, consequently, the forest CO₂ balance. Grazing affects differently the biomass of slow-growing lichens compared to the faster-growing mosses and dwarf shrubs, and therefore the effects of grazing on CO₂ exchange in the patchy understory vegetation may vary temporally. We studied how excluding grazing for short and long periods affects the CO₂ exchange and vegetation biomass in the understory of an oligotrophic Scots pine forest. We measured growing season (2019, 2020) CO₂ exchange across sunlit and shaded habitats inside fences that had excluded large grazers for 0–1 and 25–26 years and in the adjacent grazed area. In addition, we measured the height of understory vegetation. We found that short-term grazer exclusion increased ecosystem CO₂ source fluxes only in the shaded habitats. However, long-term exclusion of grazing decreased CO₂ net release regardless of the habitat type. Furthermore, grazer exclusion increased moss depth immediately, which coincided with an abrupt intensification of CO₂ net release. Considering the impacts of grazing over both short- and long-term periods may help to forecast C fluxes more accurately, which may be relevant for informed climate solutions regionally and even on a larger scale.

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Series: Ecography
ISSN: 0906-7590
ISSN-E: 1600-0587
ISSN-L: 0906-7590
Issue: Early view
Article number: e06724
DOI: 10.1111/ecog.06724
Type of Publication: A1 Journal article – refereed
Field of Science: 1172 Environmental sciences
1181 Ecology, evolutionary biology
Funding: This research was funded in part by UArctic Research Chairship (JMW) and by the Kvantum Institute of the University of Oulu (JMW and MV).
Copyright information: © 2023 The Authors. Ecography published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.