Sammanfattning

The growing demand for renewable energy sources in Sweden has resulted in an increased use of forest biomass that now includes logging residues. However, concern has been raised that the moderate increase in biomass removal associated with whole-tree harvesting results in a significant increase in nutrient removal, which in turn has a negative effect on future forest growth. Productivity over 31 years in planted Norway spruce (Picea abies (L.) Karst) in northern Sweden following three different harvest intensities is reported from a field experiment with exceptionally large growth reductions following whole-tree harvest. The three harvest intensities were applied in a randomized block design with four blocks: (i) conventional stem-wood harvest up to a top diameter of 5 cm (CH); (ii) whole-tree harvest of all above-stump biomass (WTH); (iii) branch and stem harvest with needles left on site (BSH). Recovery rate of biomass was almost 100% and the logging residues left were evenly spread over the 25-by 25-m experimental plots. Stand growth was negatively affected by WTH: basal area after 31 years was significantly lower following WTH (10.5 m(2) ha(-1)) as compared to CH (14.0 m(2) ha(-1), p = 0.005) and BSH (14.2 m(2) ha(-1) p = 0.003). Annual height growth of a sub-sample of trees (10 undamaged trees per plot, or 40 per treatment) was used to estimate and compare long-term effects on site productivity. This showed that stand growth loss resulted from a significant but temporary reduction in site productivity on WTH plots over a 5-year period (years 8-12, 1984-1988). Nitrogen is the major growth-limiting nutrient in boreal Swedish forests, and the N-content of needles during that period suggests that the temporal reduction in site productivity (i.e., stand growth) was primarily due to increased nitrogen loss with WTH. (C) 2010 Elsevier B.V. All rights reserved.

Nyckelord

Slash removal; Slash retention; Brash; Full-tree harvest; Soil productivity

Publicerad i

Forest Ecology and Management
2011, Volym: 261, nummer: 1, sidor: 148-153
Utgivare: ELSEVIER SCIENCE BV

SLU författare

• Egnell, Gustaf

  • Institutionen för skogens ekologi och skötsel, Sveriges lantbruksuniversitet
    

Associerade SLU-program

SLU Future Forests


Globala målen

Säkerställa tillgång till ekonomiskt överkomlig, tillförlitlig, hållbar och modern energi för alla


UKÄ forskningsämne

Skogsvetenskap
Ekologi


Publikationens identifierare

DOI: https://doi.org/10.1016/j.foreco.2010.09.045

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/60491