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Research article - Peer-reviewed, 2021

Biochar increases tree biomass in a managed boreal forest, but does not alter N2O, CH4, and CO2 emissions

Grau-Andres, Roger; Pingree, Melissa R. A.; Oquist, Mats G.; Wardle, David A.; Nilsson, Marie-Charlotte; Gundale, Michael J.;

Abstract

Biochar soil amendment may provide the forestry sector with a formidable tool to simultaneously sequester carbon (C) in the soil and aboveground by enhancing plant productivity, yet several key uncertainties remain. Crucially, empirical evidence of long-term effects of biochar management on vegetation and on greenhouse gas emissions in forest ecosystems is scarce. Using a large field experiment in a young managed boreal forest in northern Sweden, we investigated the effects of biochar (applied either on the soil surface or mixed in the soil 8-9 years prior to this study) on supply rates of soil nutrients, on survival and growth of planted Pinus sylvestris, on community composition of the understory vegetation, and on forest floor fluxes of N2O, CH4, and CO2. We found that biochar promoted P. sylvestris survival only when biochar was applied on the soil surface. Conversely, biochar enhanced P. sylvestris growth overall, resulting in a 19% increase in C stored in biomass. Biochar also altered the composition of the understory vegetation, especially when mixed into the soil, and promoted a more resource-conservative community (i.e., with more ericaceous shrubs and less graminoids and forbs). Meanwhile, supply rates of the main soil nutrients were largely unaffected by biochar. Finally, we found that biochar did not alter overall N2O and CO2 emissions and CH4 uptake from the forest floor. Our findings show that biochar amendment increased the net C input to the system, since, besides directly increasing soil C stocks, biochar enhanced biomass growth without increasing soil C losses. Therefore, our study suggests that biochar could potentially be used for emissions abatement in intensively managed boreal forests.

Keywords

carbon sequestration; charcoal; forest management; greenhouse gas emission; Pinus sylvestris; plant community composition; soil nutrient supply; tree growth; tree survival; understory vegetation

Published in

GCB Bioenergy

2021, volume: 13, number: 8, pages: 1329-1342
Publisher: WILEY

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Pingree, Melissa
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Nanyang Technological University (NTU)
Nilsson, Marie-Charlotte (Nilsson Hegethorn, Marie-Charlotte)
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management

UKÄ Subject classification

Forest Science

Publication Identifiers

DOI: https://doi.org/10.1111/gcbb.12864

URI (permanent link to this page)

https://res.slu.se/id/publ/112574