Articles by Ilkka Vanha-Majamaa

The prescribed burning of a 7.3 ha clear-cut and a 1.7 ha partially cut forest (volume 150 m³/ha) was carried out in Evo (61 °12'N, 25°07'E) on 1 June 1992. The forest was a mesic Myrtillus site type forest dominated by Norway spruce (Picea abies (L.) H. Karst.). Practically all the trees and the above-ground parts of the understorey vegetation died in the fire, while the mor layer was thinned by an average of 1.5 cm.

A study was made on the change of germinated seedling population in time and their dependence on environmental factors. Seedlings of Norway spruce, Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), pubescent birch (B. pubescens Ehrh.) and rowan (Sorbus aucuparia L.) were inventoried in 1993 and in 1994 on permanent plots, four times per growing season. Autoregression models were used to compare regeneration of tree species in the burned forest with regeneration in the burnt clear-cut area, and to study the effect of distance from nearest seed source to regeneration.

The average number of seedlings germinating in 1993 was higher than in 1994, probably because of differences between these consecutive years in regard to the amount of seed rain and weather conditions. The number of Norway spruce and rowan seedling was higher inside the forest area than in the clear-cut area. The distance to the bordering forest and to the closest seed tree did not explain the result. It is suggested that the more stable microclimatic conditions under the shade of dead tree promote germination and seedling establishment in the forest area. As rowan is a bird-dispersed species, it is likely that dead trees help the dispersal of rowan seed by providing birds place to sit and defecate. The shade provided by dead trees may influence the further succession of the tree stand and vegetation composition and diversity.

• Vanha-Majamaa, E-mail: iv@mm.unknown
• Suominen, E-mail: rs@mm.unknown
• Tonteri, E-mail: tt@mm.unknown
• Tuittila, E-mail: et@mm.unknown

• Rabinowitsch-Jokinen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301, Vantaa, Finland E-mail: rrj@nn.fi
• Vanha-Majamaa, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301, Vantaa, Finland E-mail: ilkka.vanha-majamaa@metla.fi

• Lilja-Rothsten, University of Helsinki, Dept. of Forest Ecology, Finland E-mail: saara.lilja@helsinki.fi
• Chantal, University of Helsinki, Dept. of Forest Ecology, Finland E-mail: mdc@nn.fi
• Peterson, Dept. of Plant Biology, University of Georgia, Athens, GA, USA E-mail: cp@nn.us
• Kuuluvainen, University of Helsinki, Dept. of Forest Ecology, Finland E-mail: tk@nn.fi
• Vanha-Majamaa, The Finnish Forest Research Institute, Vantaa Unit, Finland E-mail: ivm@nn.fi
• Puttonen, The Finnish Forest Research Institute, Vantaa Unit, Finland E-mail: pp@nn.fi

• Malmivaara, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: minna.malmivaara@metla.fi
• Löfström, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: il@nn.fi
• Vanha-Majamaa, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: ivm@nn.fi

In boreal forests fires often ignite and spread within the dominant moss and lichen cover of the ground layer vegetation, which thus greatly influences fire hazard. We used an experimental set-up in greenhouse conditions to study the differences in how (1) fuel moisture and (2) wind velocity influence the ignition probability and fuel consumption among four common circumboreal ground vegetation fuels, Pleurozium schreberi (Willd. ex Brid.) Mitt., Hylocomium splendens Schimp., Dicranum spp. and Cladonia rangiferina (L.) F. H. Wigg. Our results show that the reindeer lichen C. rangiferina was clearly the most flammable species, with high ignition probability even at high moisture contents and low wind velocities. Of the mosses, Dicranum was the least flammable, with low ignition probability and mass loss at low wind velocities regardless of moisture content. P. schreberi and H. splendens behaved somewhat similarly with wind velocities quickly increasing the initially low ignition probability and mass loss observed in the absence of wind. However, especially for mass loss, among-species differences tended to disappear with stronger winds. The observed differences can be explained by the different structures and growth forms of the studied species and open a potential avenue for improving forest fire risk predictions.

• Lindberg, Häme University of Applied Sciences, School of Bioeconomy, Visamäentie 35 A, P.O. Box 230, FI-13100 Hämeenlinna, Finland https://orcid.org/0000-0001-9045-2673 E-mail: henrik.lindberg@hamk.fi
• Aakala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-0160-6410 E-mail: tuomas.aakala@uef.fi
• Vanha-Majamaa, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: ilkka.vanha-majamaa@luke.fi