Saana Kataja-aho, Aino Smolander, Hannu Fritze, Sini Norrgård, Jari Haimi. (2012). Responses of soil carbon and nitrogen transformations to stump removal. Silva Fennica vol. 46 no. 2 article id 53. https://doi.org/10.14214/sf.53

Keywords: biofuel; boreal forest; carbon; nitrogen; nutrient dynamics; stump removal

Abstract | View details | Full text in PDF | Author Info

We studied in central Finland whether stump harvesting after clear felling of coniferous forest poses further short-term changes in soil carbon and nitrogen dynamics when compared to the traditional site preparation method, mounding. Exposed mineral soil patches in Norway spruce (Picea abies) dominated clear-cut stands were sampled 1–5 years after the treatments. The extent of the exposed mineral soil surface was significantly larger at the stump removal sites when compared to the mounding sites. No differences were found in soil pH, organic matter content or total concentration of soil C between the treatments or treatment years. Total concentration of soil N was consistently higher and C:N ratio lower in the stump removal plots than in the mounded plots. Further, both net N mineralisation and nitrification were clearly increased in the stump removal plots one year after the treatments. Soil microbial activity (CO₂ production) was higher in the stump removal plots but similar difference was not found in sieved soil samples incubated in the laboratory. Fluxes of other important greenhouse gases (CH₄ and N₂O) did not seem to be affected by stump removal. The differences between the stump removal and mounding procedures were most obviously attributed to more substantial soil disturbance by stump pulling and/or differences in the microbial communities and quality of soil organic matter in the differently treated soil.

Kataja-aho, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland E-mail: saana.m.kataja-aho@jyu.fi
Smolander, Finnish Forest Research Institute, Vantaa, Finland E-mail: as@nn.fi
Fritze, Finnish Forest Research Institute, Vantaa, Finland E-mail: hf@nn.fi
Norrgård, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland E-mail: sn@nn.fi
Haimi, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland E-mail: jh@nn.fi

article id 66, category Research article

Monika Strömgren, Kristina Mjöfors, Björn Holmström, Achim Grelle. (2012). Soil CO2 flux during the first years after stump harvesting in two Swedish forests. Silva Fennica vol. 46 no. 1 article id 66. https://doi.org/10.14214/sf.66

Keywords: stump removal; Picea abies; C stock; site preparation; soil C; soil disturbance; soil respiration

Abstract | View details | Full text in PDF | Author Info

One way of increasing the supply of renewable energy, thereby decreasing the use of fossil fuels, is to extract the stumps that remain after final stem harvesting. However, little is known about the environmental consequences of stump harvesting, and how ecosystem services, such as carbon sequestration, are affected by the practice. In the present paper, the effects on the soil carbon pool during the first months and years after stump harvesting in former Norway spruce stands are presented. The study was performed at two sites in mid- and southern Sweden. At both sites, the soil CO₂ flux was measured on several occasions with a portable respiration system, to compare plots on which stump harvesting had occurred, with reference plots. At one of the sites, CO₂ exchange was also followed continuously by means of eddy-covariance measurements before and after stump harvesting. Since there was no vegetation at the beginning of the study, almost all emitted CO₂ could be assumed to come from heterotrophic sources, and the soil CO₂ flux was measured. This study shows that the effect of stump harvesting on CO₂ flux or soil decomposition processes is small or absent compared to site preparation such as mounding in a short-term perspective of months and years. The long-term consequences of stump harvesting are, however, still uncertain.

Strömgren, Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden E-mail: monika.stromgren@slu.se
Mjöfors, Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden E-mail: km@nn.se
Holmström, Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden E-mail: bh@nn.fi
Grelle, Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden E-mail: ag@nn.se

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