Canadian Forest Service Publications
Developing and validating indicators of site suitability for forest harvesting residue removal. 2014. Thiffault, E.; Barrette, J.; Paré, D.; Titus, B.D.; Keys, K.; Morris, D.M.; Hope, G. Ecol. Indicators 43:1-18.
Issued by: Laurentian Forestry Centre
Catalog ID: 35461
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The increasing demand for forest biomass, notably from primary residues of harvested trees for the production of bioenergy, has raised concerns because of potential adverse effects on forest soil productivity. Our aim was to develop and validate spatially explicit planning indicators of site suitability for harvesting residue removal based on mapped forest site properties for four large case study areas located across Canada, each containing field studies on the impact of harvesting residue removal. Sustainability was assessed relative to the baseline scenario of conventional stem-only harvesting, to investigate the incremental effects of the removal of residues associated with whole-tree harvesting in typical operationalconditions in Canada. Using information from scientific literature and guidelines from various jurisdictions, eleven planning indicators were developed, from which nine were related to the loss of soil fertility risk and two to erosion risk. Planning indicators were tested for redundancy and validated using response indicators of stand growth and nutrition from field studies. Several relationships between mapped soil properties and the empirical response of stands to harvesting residue removal were found. Planning indicators based on concentrations of organic C, total N and total P in the top 30 cm of the mineral soil best explained stand responses to harvesting residue removal. Despite caveats, the methodology used here demonstrates an approach for developing and empirically testing planning indicators of site suitability for harvesting residue removal. As more information on the impact of this practice becomes available from field studies, it can be used to refine and further validate the indicators.
Plain Language Summary
The development of bioenergy, particularly bioenergy produced from forest biomass, has sparked greater interest in the use of forest harvest residues. In the case of traditional forest products, these residues consist mainly of the crowns and branches of harvested trees. This increased demand for forest biomass has also prompted a debate on the impact of residue harvesting on the productivity of forest soils and stands.
In countries around the world, there are many guidelines for protecting soil fertility where harvest residues are collected, but few of these recommendations are based on empirical data. The objective of this study was to develop and validate indicators that can be used to predict the sensitivity of sites to residue harvesting, based on field studies conducted across Canada.
Once these indicators have been determined, they will be used to identify in advance, either in the field or on maps, vulnerable sites that are at risk of reduced growth following residue harvesting.
In the course of this work, researchers were able to determine two indicators that provide the best information on site sensitivity: total nitrogen concentrations and organic carbon concentrations in the mineral soil. These data can usually be found on soil maps.