Abstract
Biochar is an environmental soil application tool used for climate change mitigation and carbon (C) sequestration that can be used in forest soils. Soil physical and chemical properties can be altered by biochar amendment, which can affect soil microbial communities. A limited number of forest soil studies have shown biochar can affect soil microbial communities, but few studies exist in temperate, northwestern USA forests. We investigated the effects of biochar amendment to soil in three western USA managed forest sites. Sites were amended with 0, 2.5, or 25 Mg ha-1 biochar, applied to the soil surface. DNA was extracted from soil samples collected from two depths, three to five years following amendment (dependent on site). Double-barcoded 16S rRNA (bacteria) and LSU rRNA (fungi) amplicons were sequenced on an Illumina MiSeq platform. Resulting sequencing data was analyzed for community richness, diversity, phyla relative abundance, and composition. For fungi, sequencing data represented six phyla. Biochar amendment did not affect fungal community measures, but site and sampling depth or their interaction did. Bacterial sequencing data represented 33 phyla. Biochar did not affect richness or diversity measures. However biochar did affect Bacteroidetes and Acidobacteria phyla relative abundance either alone, or when dependent on site or sampling depth. As with fungi, site and sampling depth or their interaction influenced richness, diversity, phyla relative abundance, and community composition. Results indicate that biochar amendment to northwestern USA forests is not detrimental to soil microbial community composition.