Soil disturbance and early vegetation response to varying intensity of energy wood harvest

• Published in: Forest ecology and management Vol. 348; pp. 153 - 163
• Main Authors: Tarvainen, Oili, Hekkala, Anne-Maarit, Kubin, Eero, Tamminen, Pekka, Murto, Tanja, Tolvanen, Anne
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2015
• Subjects: Betula; Disturbances; Energy harvesting; Forest soil; Harvesting; Logging industry; Logging residue; Patch mounding; Residues; Site preparation; Soil (material); Stump removal; Understory vegetation; Vegetation; Wood; ANE, Europe; Patch mounding; Understory vegetation; Site preparation; Forest soil; Logging residue; Stump removal
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2015.04.001

•Tree stump removal after clear-felling increased the open mineral soil cover.•Removing all stumps had no additional effects compared to 95% stump removal.•Stump removal had little impact on vegetation compared to other methods.•Effects of stump removal on soil and vegetation showed high site-dependency.•Betula spp. benefited from energy wood harvesting indicating need for tending.
Forest biomass plays an important role in the production of renewable energy, particularly in northern Europe. During recent decades, tree stumps have also been increasingly used for energy production. The environmental impacts of stump removal on the functioning of forest ecosystems, for example on soil processes and biodiversity, are still inadequately understood. To investigate the separate impacts of tree stump and logging residue removal on soil and plant variables, we conducted a large-scale replicated experiment in clear-felled stands in three geographical areas. Four energy wood harvesting levels were combined with patch mounding (organic and mineral soil layer turned upside down) as a site preparation method. The harvesting treatments were: (1) no energy wood harvesting, (2) 70% logging residue removal, (3) 25 stumps per hectare left at site and 70% logging residue removal (maximum level in official recommendations), (4) complete stump and 100% logging residue removal. Soil disturbance in terms of mineral and organic soil cover increased with the increasing harvesting level, but complete stump removal did not increase the mineral soil cover more than partial stump removal (on average 95% removed). Despite the increase in soil disturbance, stump removal did not have an overall impact on plant species richness or vegetation composition in the second growing season after harvesting. However, an increasing trend in Betula spp. biomass with increasing harvesting intensity was seen in two of three study areas in four years. Our results underscored the high site-dependency of the effects of stump removal on ecological variables, thus the initial stand structure and vegetation type need to be considered when planning harvesting treatments.