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Articles by Staffan Jacobson

Category: Research article

article id 1265, category Research article
Eva Ring, Lars Högbom, Hans-Örjan Nohrstedt, Staffan Jacobson. (2015). Soil and soil-water chemistry below different amounts of logging residues at two harvested forest sites in Sweden. Silva Fennica vol. 49 no. 4 article id 1265. https://doi.org/10.14214/sf.1265
Highlights: Soil-water chemistry, ground vegetation cover and water flux were affected by the amounts of logging residues stored on the ground after harvest; A strong response on soil-water chemistry was recorded at only one of the two sites; At the site showing a weak response, less residue remained after seven years in the treatments giving the most pronounced effects.
Logging residues (LR), i.e. tops, branches, and needles, are increasingly being harvested for energy production in Fennoscandia. These residues are temporarily piled on site awaiting transport. This study was undertaken to investigate effects on the soil and soil-water chemistry below different amounts of LR at two recently harvested coniferous sites in Sweden. Seven treatments were included and the studied amounts of LR ranged from no LR left on the ground to four times the estimated LR amount of the harvested stands. Two treatments included eight times the estimated LR amount of the harvested stands but here the LR were removed after 7 or 20 weeks. Soil-water samples were collected during the first six or seven growing seasons. Effects of treatment were detected in the soil water for 11 chemical variables at the northern site, and for the NO3- and Cl- concentrations at the southern site. The strongest response was generally found in the treatment with four times the estimated LR amount, for which the highest concentrations were recorded in most cases. In the first three seasons, the water flux through the LR decreased with an increasing amount of residue. Effects on the exchangeable store of Ca2+ in the mor layer and the upper 20 cm of the mineral soil was detected at both sites. At the northern site, the weight of the remaining LR, ground vegetation and all other material above the mor layer in the treatments with two and four times the estimated LR amount was roughly twice the corresponding weights at the southern site seven years after treatment. Although strong effects on the soil-solution chemistry were detected at one of the study sites, in the treatments corresponding to two and four times the estimated logging residue amount, the effect on the leaching from an entire regeneration area is likely to be relatively small given the percentage of the area hosting these logging residue amounts (ca. 20% after stem-only harvesting and 9% after fuel-adapted felling).
  • Ring, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: eva.ring@skogforsk.se (email)
  • Högbom, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: lars.hogbom@skogforsk.se
  • Nohrstedt, Swedish University of Agricultural Sciences, Department of Soil and Environment, P.O. Box 7014, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: hans-orjan.nohrstedt@slu.se
  • Jacobson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se
article id 123, category Research article
Staffan Jacobson, Folke Pettersson. (2010). An assessment of different fertilization regimes in three boreal coniferous stands. Silva Fennica vol. 44 no. 5 article id 123. https://doi.org/10.14214/sf.123
In 1981–82 three field experiments were established with the aim of elucidating (i) the growth response of middle-aged coniferous stands at different fertilization intensities and, hence, the economic outcomes; and (ii) the need to add nutrients other than nitrogen (N). Nutrient additions were performed at intervals of two, four, six and eight years. The experiments were established on typical podzolized and N-limited mor-humus sites, two in Scots pine (Pinus sylvestris L.) stands and one in a Norway spruce (Picea abies (L.) Karst.) stand, at three different locations in Sweden. The ages of the stands were 65–70 years at the time of establishment. Growth responses were calculated after a 22-year study period. The growth responses were significant in all treatments. The addition of nutrients other than N did not affect stem growth at any of the sites. The growth response tended to increase with decreasing application interval. The results also revealed that the efficiency of fertilization is reduced as the interval between fertilizations is shortened. Accordingly, the growth effect per kg of added N was negatively correlated to fertilization intensity. The least intensive fertilization regime (an eight-year interval) resulted in an average net increase in C sequestration of 35 kg per kg N added. The profitability, in terms of internal rate of return, the present net value at different interest rates and the cost of production, i.e. the cost to produce one extra m3 under the different N regimes, are presented and discussed.
  • Jacobson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se (email)
  • Pettersson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail:
article id 423, category Research article
Olle Rosenberg, Staffan Jacobson. (2004). Effects of repeated slash removal in thinned stands on soil chemistry and understorey vegetation. Silva Fennica vol. 38 no. 2 article id 423. https://doi.org/10.14214/sf.423
The increased interest in harvesting logging residues as a source of bio-energy has led to concerns about the potentially adverse long-term impact of the practice on site productivity. The aim of this study was to examine the effects on soil chemistry (pH, C, N and AL-extractable P, K, Ca and Mg) in three different soil layers (FH, 0–5 cm and 5–10 cm mineral soil) and understorey vegetation after the second removal of logging residues in whole-tree thinned stands. The study was performed at four different sites, established in the period 1984–87, representing a range of different climatic and soil conditions: a very fertile Norway spruce (Picea abies (L.) Karst.) site in south-western Sweden and three Scots pine (Pinus sylvestris L.) sites located in south, south-central and central Sweden. The effects of whole-tree thinning on soil chemistry and understorey vegetation were generally minor and variable. Across all sites the concentrations of Ca and Mg were significantly lower when slash was removed.
  • Rosenberg, Skogforsk – The Forestry Research Institute of Sweden, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: olle.rosenberg@skogforsk.se (email)
  • Jacobson, Skogforsk – The Forestry Research Institute of Sweden, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail:
article id 483, category Research article
Staffan Jacobson. (2003). Addition of stabilized wood ashes to Swedish coniferous stands on mineral soils - effects on stem growth and needle nutrient concentrations. Silva Fennica vol. 37 no. 4 article id 483. https://doi.org/10.14214/sf.483
Increasing use of forest fuels for energy production is generating increasing quantities of wood ash. A common understanding is that this ash should be spread in forests to counteract soil acidification and potential future nutrient deficiencies, and thus help sustain long-term forest productivity. A series of seven field experiments was established in Sweden in 1988–1995 to study the stem growth and needle nutrient concentrations of 30–60-year-old Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands on mineral soil after additions of wood ash in different doses or a combination of wood ash and N. The results showed that the most pronounced growth responses occurred when N was added, either alone or in combination with wood ash. The stem growth responses to additions of wood ash without N were small and variable, and not statistically significant at any of the studied experimental sites. However, there were indications that the addition of wood ash may increase stem-wood growth on fertile sites and decrease it on less fertile sites. In the short term, the addition of wood ash tended to increase the needle nutrient concentrations of most analyzed elements, except for N, but this could not be correlated to responses in stem growth.
  • Jacobson, The Forestry Research Institute of Sweden, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se (email)

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