Timo Domisch, Saija Huuskonen, Juho Matala, Ari Nikula. (2024). Interactive effects of moose browsing and stand composition on the development of mixed species seedling stands. Silva Fennica vol. 58 no. 4 article id 23077. https://doi.org/10.14214/sf.23077

Keywords: boreal forest; tree species; Alces alces; ungulates; moose damage; mixed stands; meta-analysis

Highlights: We conducted meta-analyses assessing effect sizes of moose exclusion on seedling density and height, as well as regressions between stand density and deciduous seedling proportion and effect sizes; The more deciduous trees in a seedling stand, the smaller was the fencing effect, but at some point, the conifer seedling growth was impaired by too many deciduous seedlings. At the same time, the protective fencing effect increased with stand density; An appropriate deciduous admixture in conifer-dominated mixed seedling stands seems to improve moose damage tolerance.

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The moose (Alces alces L.), a common large herbivore in the boreal region, impairs forest regeneration by browsing on tree seedlings and saplings. Moose prefer deciduous species, but during winter more coniferous seedlings are used. We used meta-analyses, separately for deciduous and coniferous seedlings, for evaluating whether excluding moose browsing affected seedling density and height. In addition, we compared (1) deciduous seedling proportion, (2) stand density, (3) elapsed time from fencing and (4) estimated moose density with moose exclusion effect sizes. Fencing had a positive effect on coniferous seedling height. With more deciduous trees in a seedling stand, the fencing effect for both seedling height and density of coniferous seedlings decreased. On the other hand, the fencing effects increased with denser stands. At some point effect sizes turned to negative, and conifer species varied in their response to browsing. This implies that deciduous seedlings can protect conifers from browsing by moose up to some mixing ratio, but when deciduous seedling densities are too high, their negative effect increases, presumably through increased competition. Our results suggest that a moderate deciduous admixture in conifer-dominated mixed seedling stands can decrease moose damage but also underline the significance of timely silvicultural measures to minimize the negative effects of excessive deciduous seedlings and too dense stands. Due to differences in coniferous and deciduous species, as well as their compositions and amounts in studied experiments, more studies adjusted to local conditions are still needed to give exact measures for silvicultural recommendations.

Domisch, Natural Resources Institute Finland (Luke), Natural Resources, Yliopistokatu 6B, FI-80100 Joensuu, Finland https://orcid.org/0000-0001-7026-1087 E-mail: timo.domisch@luke.fi
Huuskonen, Natural Resources Institute Finland (Luke), Natural Resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: saija.huuskonen@luke.fi
Matala, Natural Resources Institute Finland (Luke), Natural Resources, Yliopistokatu 6B, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-5867-5057 E-mail: juho.matala@luke.fi
Nikula, Natural Resources Institute Finland (Luke), Natural Resources, Ounasjoentie 6, FI-96200 Rovaniemi, Finland https://orcid.org/0000-0001-8372-8440 E-mail: ari.nikula@luke.fi

article id 1693, category Research article

Olalla Díaz-Yáñez, Blas Mola-Yudego, José Ramón González-Olabarria. (2017). What variables make a forest stand vulnerable to browsing damage occurrence? Silva Fennica vol. 51 no. 2 article id 1693. https://doi.org/10.14214/sf.1693

Keywords: moose; forest damage; cervid; machine learning; risk modelling; ungulates

Highlights: Stands more vulnerable to browsing damage are young with lower densities and dominated by birch, pine or mixed species; Stand size could play a role on forest susceptibility to browsing occurrence.

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Ungulate browsing results in important damages on the forests, affecting their structure, composition and development. In the present paper, we examine the occurrence of browsing damage in Norwegian forests, using data provided by the National Forest Inventory along several consecutive measurements (entailing the period 1995–2014). A portfolio of variables describing the stand, site and silvicultural treatments are analyzed using classification trees to retrieve combinations related to browsing damage. Our results indicate that the most vulnerable forest stands are young with densities below 1400 trees ha^–1 and dominated by birch, pine or mixed species. In addition, stand diversity and previous treatments (e.g. thinnings) increase the damage occurrence and other variables, like stand size, could play a role on forest susceptibility to browsing occurrence although the latter is based on weaker evidence. The methods and results of our study can be applied to implement management measures aiming at reducing the browsing damages of forests.

Díaz-Yáñez, School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland http://orcid.org/0000-0003-3829-5759 E-mail: olalla.diaz@gmail.com
Mola-Yudego, Norwegian Institute of Bioenergy Research, P.O. Box, 115, 1431 Ås, Norway; School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland http://orcid.org/0000-0003-0286-0170 E-mail: blas.mola@uef.fi
González-Olabarria, Forest Sciences Centre of Catalonia (CTFC-CEMFOR), Ctra. de St. Llorenç de Morunys, km 2, 25280 Solsona, Spain http://orcid.org/0000-0002-5040-712X E-mail: jr.gonzalez@ctfc.es

Category : Review article

article id 550, category Review article

Lars Edenius, Margareta Bergman, Göran Ericsson, Kjell Danell. (2002). The role of moose as a disturbance factor in managed boreal forests. Silva Fennica vol. 36 no. 1 article id 550. https://doi.org/10.14214/sf.550

Keywords: management; boreal forest; disturbance; forestry; Alces alces; monitoring; herbivory; large ungulates; moose

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We review the interactions between moose (Alces alces) and native tree species in Fennoscandia. The Fennoscandian boreal forests have been intensively managed for wood production over decades. Moose population density is also relatively high in these northern forests. Forest management affects habitat characteristics and food resources from regeneration to final harvest, with the most significant effects occurring early in the stand development. The plant-animal interactions found in such a situation may be different from what has been observed in natural boreal forests with low densities of moose (e.g. in North America). The strong focus on Scots pine (Pinus sylvestris) in forest regeneration in conjunction with a homogenisation of the landscape structure by clear-cutting has favoured moose. Forest development is controlled by man from regeneration to final harvest, and in relation to human-induced disturbances the disturbance by moose is relatively small, but occurs on different spatial levels. At the landscape level, the most prominent effects of moose seem to be suppression and/or redistribution of preferred browse species. At the forest stand level moose primarily induce spatial heterogeneity by browsing patchily and exploiting existing gaps. At the tree level, moose damage trees and lower timber quality, but also create substrate types (e.g. dead and dying wood) valuable for many organisms. Co-management of moose and forest requires good monitoring programmes for both plants and animals, as well as extensive ecological knowledge on the relations between moose and their food plants on different spatial levels.

Edenius, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden E-mail: lars.edenius@szooek.slu.se
Bergman, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden E-mail: mb@nn.se
Ericsson, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden E-mail: ge@nn.se
Danell, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden E-mail: kd@nn.se

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