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Research article - Peer-reviewed, 2021

Critical biomass harvesting indicator for whole-tree extraction does not reflect the sensitivity of Swedish forest soils

Lofgren, Stefan; Stendahl, Johan; Karltun, Erik

Abstract

There is a growing societal demand to increase the use of forest biomass for substitution of fossil fuels. The production of this biomass must be sustainable and an indicator for critical biomass harvesting (CBH) has been suggested in order to sustain forest soil fertility and mitigate soil acidification at whole-tree harvesting. The CBH indicator is based on an acidity mass balance approach in line with the critical load of acid deposition (CL) concept. Countries like Sweden, the Netherlands and the state of Quebec, Canada apply such mass balance approaches for developing forest biomass harvesting guidelines. The implementation of this type of policy instrument may restrict the use of harvest residues for bioenergy and thereby the substitution of fossil fuels. It may as well affect the forestry sector revenue negatively. To maintain credibility for enforced limitations, it is important that the risk assessment and suggested policy implications are based on solid scientific methods and assumptions. The mass balance approach have been criticized for being too uncertain and not sufficiently validated for being used to guide ecosystem management. In this paper we use published Swedish data on soils, acid deposition, forest production and information from international scientific literature to critically examine the CBH indicator. We conclude that the CBH indicator 1) does not account for all relevant processes 2) it exaggerates the sensitivity and correlates poorly to actual forest soil acid-base status and edaphic conditions and 3) data availability does not allow the indicator to be calculated at a high enough spatial resolution for advice on management for forest owners. The concerns for the mass-balance approach and CBH indicator are discussed in an international perspective.

Keywords

Acidity mass-balance; Forest biomass harvesting; Soil acidity; Soil nutrient depletion; Critical biomass harvest

Published in

Ecological Indicators
2021, volume: 132, article number: 108310
Publisher: ELSEVIER

Authors' information

Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Swedish University of Agricultural Sciences, Department of Soil and Environment
Swedish University of Agricultural Sciences, Department of Soil and Environment

Sustainable Development Goals

SDG7 Affordable and clean energy
SDG15 Life on land

UKÄ Subject classification

Soil Science
Forest Science

Publication Identifiers

DOI: https://doi.org/10.1016/j.ecolind.2021.108310

URI (permanent link to this page)

https://res.slu.se/id/publ/114505