Effects of slash retention and wood ash addition on fine root biomass and production and fungal mycelium in a Norway spruce stand in SW Sweden |
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| Authors: | Hooshang Majdi Laimi Truus Ulf Johansson Jan-Erik Nylund Håkan Wallander |
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| Institution: | 1. Swedish University of Agricultural Sciences, Department of Ecology, P.O. Box 7044, SE-750 07 Uppsala, Sweden;2. Institute of Ecology, Tallinn University, Uus-Sadama 5, EE-10120 Tallinn, Estonia;3. Swedish University of Agricultural Sciences, Tönnersjöheden and Skarhult Experimental Forests, P.O. Box 17, SE-310 38 Simlångsdalen, Sweden;4. Swedish University of Agricultural Sciences, Department of Forest Products, P.O. Box 7008, SE-750 07 Uppsala, Sweden;5. Lund University, Department of Microbial Ecology, Ecology Building, SE-223 62 Lund, Sweden |
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| Abstract: | In the study reported here we examined the short-term effects (1–3 years) of slash retention (SR) and the long-term effects (13–15 years) of wood-ash application (A) on fine roots and mycorrhizae in a 40-year-old Norway spruce forest in southwest Sweden. Soil cores were used to obtain estimates of the biomass (g m−2) of roots in three diameter classes (<0.5, 0.5–1 and 1–2 mm), root length density (RLD), specific root length (SRL) and mycorrhizal root tip density (RTD). Fine root (<1 mm) length production and mortality, and mycelium production, were estimated using minirhizotron and mesh bag techniques, respectively. Compared with the control plots (C), the biomass of fine roots in diameter classes <0.5 mm and 0.5–1 mm was significantly higher in A plots, but lower in SR plots. In addition, RLD was significantly lower in the humus layer of SR plots than in the humus layers of C and A plots, but not in the other layers. None of the treatments affected the SRL. In all soil layers, the SR treatment resulted in significant reductions in the number of ectomycorrhizal root tips, and the mycelia production of fungi in mesh bags, relative to the C treatment, but the C and A treatments induced no significant changes in these variables. Fine root length production in the C, A and SR plots amounted to 94, 87 and 70 mm tube−1 during the 2003 growing season, respectively. Fine root mortality in treated plots did not change over the course of the study. We suggest that leaving logging residues on fertile sites may result in nitrogen mineralisation, which may in turn induce reductions in root biomass, and both root and mycelium production, and consequently affect nutrient uptake and the accumulation of organic carbon in soil derived from roots and mycorrhizae. |
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| Keywords: | Fine roots Mortality Mycelium Production Slash retention Soil cores Minirhizotrons Wood ash |
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