Biochar effects on NTFP-enriched secondary forest growth and soil properties in Amazonian Ecuador

Pedro Damián Ríos Guayasamín; Sandy M Smith; Sean C Thomas

doi:10.1016/j.jenvman.2023.119068

Biochar effects on NTFP-enriched secondary forest growth and soil properties in Amazonian Ecuador

J Environ Manage. 2024 Jan 15:350:119068. doi: 10.1016/j.jenvman.2023.119068. Epub 2023 Oct 10.

Authors

Pedro Damián Ríos Guayasamín¹, Sandy M Smith², Sean C Thomas²

Affiliations

¹ Institute of Forestry and Conservation, John H. Daniels, Faculty of Architecture, Landscape and Design, University of Toronto, 33 Willcocks St., Toronto, ON, M5S3B3, Canada; Facultad de Ciencias de la Vida, Universidad Estatal Amazónica - UEA, Campus Principal Km 2.1/2 vía a Napo (Paso Lateral) Puyo, Pastaza, Ecuador; Laboratorio de Ecología Tropical Natural y Aplicada - LETNA, CEIPA, UEA, Km 44, Santa Clara, Pastaza - Arosemena Tola, Napo, Ecuador. Electronic address: ppedro83@gmail.com.
² Institute of Forestry and Conservation, John H. Daniels, Faculty of Architecture, Landscape and Design, University of Toronto, 33 Willcocks St., Toronto, ON, M5S3B3, Canada.

PMID: 37821334
DOI: 10.1016/j.jenvman.2023.119068

Abstract

Deforestation in the Amazon has resulted in large areas of depleted soils on abandoned pastures and agricultural sites that present a restoration challenge central to protecting biodiversity and ecosystem function in the region. Biochar - charcoal made from waste materials - can improve soil physical, chemical, and biological properties, but the few tropical field trials to date do not give consistent results regarding tree growth. This study presents three years of soil performance and tree growth of a secondary forest shading nontimber forest product (NTFP) plantations of Ocotea quixos (Lauraceae), Myroxylon balsamum (Fabaceae), and their mixture. Open kiln and traditional mound biochars were added at 10 t ha^-1 at two sites with contrasting soil types. Biochar additions resulted in pronounced effects on soil properties that varied over time and with depth in the soil profile. Biochar additions generally increased soil organic matter, electrical conductivity, and plant nutrients (in particular K, Ca, and N), but there were interactive effects of NTFP treatments, and stronger responses on the poorer soil type. Biochar amendments resulted in increased tree growth, with a 29 ± 12% increase in aboveground biomass (AGB) on plots amended with kiln biochar and a 23 ± 9% increase in plots with mound biochar compared to controls. Tree species also varied in growth responses to biochar additions, with the largest increases observed in Jaccaranda copaia and Piptocoma discolor. Significant interactions between biochar and NTFP treatments were also seen for tree growth responses, such as Cecropia spp., which only showed increased biomass on mound biochar plots planted with Ocotea quixos. Overall, our results demonstrate a stronger effect of biochar in less favorable soil conditions, and an overriding effect of the legume NTFP in richer soils, and suggest that additions of biochar and legumes are important options to increase productivity and ecological resilience in tropical forest restoration.

Keywords: Above-ground biomass; Aluminum; Forest ecology; Nontimber forest products; Organic matter; Tropical forest.

MeSH terms

Charcoal / chemistry
Ecosystem
Ecuador
Fabaceae*
Forests
Soil* / chemistry
Trees
Vegetables

Substances

Soil
biochar
Charcoal