Biochar and high-carbon wood ash effects on soil and vegetation in a boreal clearcut

Abstract

Additions of fire residues in the form of charcoal and wood ash may better emulate natural disturbance processes in managed boreal forests. We examined the effects of a poplar (Populus) wood biochar and a high-carbon wood ash on soil and vegetation in a 3-year experiment in northwestern Ontario, Canada. Both soil amendments increased soil pH and soil Ca levels; high-carbon wood ash also increased soil Cu, Zn, B, S, and Pb. Amendments had large effects on plant community composition, favoring a subset of ruderal species including raspberry (Rubus idaeus L.) and goldenrod (Solidago canadensis L.). The addition of high-carbon wood ash resulted in declines in growth of planted white spruce (Picea glauca (Moench) Voss); a path analysis suggests that this was due to the effects of toxic elements rather than the indirect effects of competition. We conclude that high-carbon wood ash, while qualifying as a type of biochar and having some beneficial effects on soil properties, can enhance toxic metals in boreal forest soils, with negative consequences to early tree growth. Differences in plant species responses to biochars and the potential for toxicity effects and indirect effects mediated by plant competition will require screening and field trials of potential biochars prior to their use in operational forestry and forest restoration.

Spatial heterogeneity in soil pyrogenic carbon mediates tree growth and physiology following wildfire

“…Fire-adapted species, including P. banksiana, might be expected to show the most significant positive responses to fire residues. The large positive responses observed in the present study contrast dramatically with neutral to negative growth responses to biochar and wood ash additions observed in a field trial with Picea glauca, also conducted in northern Ontario (Bieser & Thomas, 2019).…”

Short‐term growth response of jack pine and spruce spp. to wood ash amendment across Canada

“…In contrast, results on upland forests have been less consistent. For example, individual wood ash amendment studies of coniferous species on mineral soils have reported positive (Hallenbarter, Landolt, Bucher, & Schutz, ; Omil, Piñeiro, & Merino, ; Saarsalmi, Smolander, Kukkola, & Arola, ; Saarsalmi, Smolander, Moilanen, & Kukkola, ; Solla‐Gullón, Santalla, Pérez‐Cruzado, Merino, & Rodríguez‐Soalleiro, ; Solla‐Gullón, Santalla, Rodríguez‐Soalleiro, & Merino, ), negative (Bieser & Thomas, ; Brais, Bélanger, & Guillemette, ; Prescott & Brown, ; Shepard, ; Staples & Van Rees, ), and neutral (Jacobson, Lundström, Nordlund, Sikström, & Pettersson, ; Mandre, Pärn, & Ots, ; Saarsalmi, Derome, & Levula, ; Saarsalmi, Mälkönen, & Kukkola, ; Wang, Olsson, & Lundkvist, ) tree growth response. Although wood ash is typically enriched in calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P; Demeyer, Voundi Nkana, & Verloo, ), inconsistencies in tree growth responses to wood ash amendment have been attributed to the lack of nitrogen (N) in wood ash at sites with N limitations (e.g., Jacobson et al, ).…”

Expansive soil-biochar-root-water-bacteria interaction: Investigation on crack development, water management and plant growth in green infrastructure

“…Fitted curves of 10% and 15% BAS are almost same, and LSPs and LCPs of them are remarkably declining as compared to 5% BAS or even BS. In a 3-year experiment conducted in Ontario, Canada, carbon-rich wood biochar increased soil pH value and heavy mental (such as Cu, Zn and Pb) levels (Bieser and Thomas, 2019). Toxic heavy metal induced by biochar in soil resulted in reduction in growth of white spruce.…”