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Research article1998Peer reviewed

Control of bilberry vegetation by steam treatment - effects on seeded Scots pine and associated mycorrhizal fungi

Jaderlund, A; Norberg, G; Zackrisson, O; Dahlberg, A; Teketay, D; Dolling, A; Nilsson, MC

Abstract

In boreal forest, ground vegetation of bilberry (Vaccinium myrtillus L.) and feather mosses strongly suppress seed regeneration of Scots pine (Pinus sylvestris L.). We investigated a site preparation technique by steam treatment to control bilberry and moss vegetation after clear cutting. Sowing experiments were performed between 1993 and 1995 with Scots pine in four treatments: (1) untreated vegetation, (2) activated carbon added to the soil surface of otherwise intact ground vegetation, (3) steam treated vegetation, and (4) activated carbon added to the soil surface of steam treated vegetation. Activated carbon was added to adsorb possible phenolic compounds released from bilberry leaves and litter. Steam killed ground vegetation effectively and recolonisation of vascular plants and mosses was slow. Scots pine seedling establishment was improved by steam treatment especially when activated carbon was added to the soil surface. We interpret that activated carbon adsorbed and reduced the levels of phenolics from bilberry litter and humus, which otherwise may inhibit seed germination. Dry weight of four year old seedlings was three times higher in steam treated plots than in untreated plots. Seedling nutrient content was also strongly improved by steam treatment. We interpret the increased growth of seedlings in steam treated plots mainly as an effect of reduced resource competition from ground vegetation. Irrespective of treatment, almost all fine roots were colonised by ectomycorrhizal fungi. Using PCR-based molecular methods we were able to identify 28 taxa forming mycorrhiza on the seedlings. Steam treatment did not affect species richness and abundance of ectomycorrhizal inocculum. We conclude that steam treatment has the potential to be an efficient and environmentally acceptable method to reduce negative influence of bilberry vegetation on Scots pine seedling establishment and early growth. (C) 1998 Elsevier Science B.V.

Keywords

Activated carbon; Mycorrhizae; Pinus sylvestris; resource competition; seedling establishment; steam; Vaccinium myrtillus; vegetation control

Published in

Forest Ecology and Management
1998, Volume: 108, number: 3, pages: 275-285
Publisher: ELSEVIER

      SLU Authors

    • Jäderlund, Anders

      • Department of Forest Vegetation Ecology, Swedish University of Agricultural Sciences

      • Norberg, Gisela

        • Department of Forest Vegetation Ecology, Swedish University of Agricultural Sciences

        • Zackrisson, Olle

          • Department of Forest Vegetation Ecology, Swedish University of Agricultural Sciences