Elisa Männistö, Johanna Jetsonen, Heli Peltola, Teemu Rouvinen, Samuli Launiainen, Annamari Laurén, Marjo Palviainen. (2026). Short-term impacts of nitrogen fertilization on the cover of vascular plant and bryophyte species in boreal Scots pine and Norway spruce stands. Silva Fennica vol. 60 no. 2 article id 25052. https://doi.org/10.14214/sf.25052

Keywords: herbs; understorey vegetation; shrubs; grasses; bottom layer vegetation; field layer vegetation

Highlights: Nitrogen fertilization had no significant impact on the cover of any vascular plant or bryophyte species in the boreal forest stands studied; The cover of many species decreased over the years, regardless of fertilization treatment; The exceptionally warm and dry summer of 2021 may have contributed to the decrease in the cover of many species.

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Nitrogen (N) fertilization increases carbon sequestration and wood production in boreal upland forests and thus supports climate change mitigation. Excess N may, however, alter the cover, biomass and biodiversity of the ground vegetation. But little is known about how the species composition and cover are affected by the different intensities of N fertilization. Here, we evaluated the short-term impacts of N fertilization on the cover of vascular plant and bryophyte species in two Scots pine (Pinus sylvestris L.) -dominated and two Norway spruce (Picea abies (L.) H. Karst.) -dominated stands in Eastern Finland. The fertilization was done using a forwarder in the Scots pine stands and a helicopter in the Norway spruce stands, which are typical vehicles for this work in practical forestry. Funnel traps were used to measure the applied N doses at the plot level. Each study site also included unfertilized control plots. The percentage cover of vascular plant and bryophyte species was estimated at the beginning of the experiment, and then twice within 2–4 years after the fertilization. Overall, N fertilization had no significant impact on the cover of any vascular plant or bryophyte species. The cover of many species also decreased over the years, both in the fertilized and unfertilized plots. The exceptionally warm and dry summer of 2021 may have contributed to this result. However, further studies are needed to evaluate long-term responses in the ground cover and species composition to the N fertilizer doses used in practical forestry.

Männistö, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-3869-6739 E-mail: elisa.mannisto@uef.fi
Jetsonen, Department of Forest Sciences, University of Helsinki, PO Box 27, 00014 University of Helsinki, Finland https://orcid.org/0009-0006-4878-8951 E-mail: johanna.jetsonen@helsinki.fi
Peltola, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-1384-9153 E-mail: heli.peltola@uef.fi
Rouvinen, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland E-mail: teemu.rouvinen2@outlook.com
Launiainen, Natural Resources Institute Finland, Bioeconomy and Environment, Latokartanonkaari 9, 000790 Helsinki, Finland https://orcid.org/0000-0001-6611-6573 E-mail: samuli.launiainen@luke.fi
Laurén, Department of Forest Sciences, University of Helsinki, PO Box 27, 00014 University of Helsinki, Finland https://orcid.org/0000-0002-6835-9568 E-mail: annamari.lauren@helsinki.fi
Palviainen, Department of Forest Sciences, University of Helsinki, PO Box 27, 00014 University of Helsinki, Finland https://orcid.org/0000-0001-9963-4748 E-mail: marjo.palviainen@helsinki.fi

article id 23058, category Research article

Johanna Jetsonen, Annamari Laurén, Heli Peltola, Olli Muhonen, Juha Nevalainen, Veli-Pekka Ikonen, Antti Kilpeläinen, Eeva-Stiina Tuittila, Elisa Männistö, Nicola Kokkonen, Marjo Palviainen. (2024). Effects of nitrogen fertilization on the ground vegetation cover and soil chemical properties in Scots pine and Norway spruce stands. Silva Fennica vol. 58 no. 1 article id 23058. https://doi.org/10.14214/sf.23058

Keywords: boreal forest; competition index; forest fertilization; upland forests; vegetation cover

Highlights: Nitrogen (N) fertilization decreased the total cover of ground vegetation; N fertilization decreased the cover of mosses and dwarf shrubs and increased the cover of herbaceous plants; N concentration of the mor humus layer increased with the N fertilization; The magnitude of these changes depended on the intensity of the N fertilization.

Abstract | Full text in HTML | Full text in PDF | Author Info

The aim of this study was to investigate the short-term effects of nitrogen (N) fertilization intensity on the ground vegetation cover and soil chemical properties in two Scots pine (Pinus sylvestris L.) and two Norway spruce (Picea abies (L.) Karst.) dominated stands on upland forest sites in Eastern Finland. The fertilizer was applied using a helicopter in the spruce stands and a forwarder in the pine stands. The distribution and the amount of fertilizer was measured with funnel traps. Cover of each species of ground vegetation was estimated before fertilization and 3–4 years after it in pine and 2–3 years after it in spruce stands. Further, the cover observations were aggregated by plant types. Based on measurements, we analyzed the effects of the funnel-trap-observed amount of N fertilizer on the cover and plant type composition of ground vegetation and soil N and C concentration. In addition, we analyzed the impacts of competition caused by trees on the ground vegetation cover based on competition indices. N fertilization increased the cover of herbaceous plants and decreased the cover of mosses and dwarf shrubs, and the total cover of ground vegetation. Further, it increased the N concentration of the mor humus layer. The magnitude of the changes increased with the intensity of the N fertilization. The competition caused by trees did not affect the cover of ground vegetation.

Jetsonen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland E-mail: johanna.jetsonen@helsinki.fi
Laurén, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland; Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0002-6835-9568 E-mail: annamari.lauren@helsinki.fi
Peltola, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland E-mail: heli.peltola@uef.fi
Muhonen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0009-0007-4051-8567 E-mail: olli.muhonen@forestvital.com
Nevalainen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0009-0000-2972-4385 E-mail: juha.hs.nevalainen@gmail.com
Ikonen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-1732-2922 E-mail: veli-pekka.ikonen@uef.fi
Kilpeläinen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-4299-0578 E-mail: antti.kilpelainen@uef.fi
Tuittila, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland E-mail: eeva-stiina.tuittila@uef.fi
Männistö, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-3869-6739 E-mail: elisa.mannisto@uef.fi
Kokkonen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-0197-2672 E-mail: nicola.kokkonen@uef.fi
Palviainen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland E-mail: marjo.palviainen@helsinki.fi

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