Coupled effects of elevated CO2 and biochar on microbial communities of vegetated soil

Abstract

<p>Soil <a href="https://www.sciencedirect.com/topics/engineering/microbial-community" title="Learn more about microbial communities from ScienceDirect's AI-generated Topic Pages">microbial communities</a> are important for <a href="https://www.sciencedirect.com/topics/social-sciences/plant-physiology" title="Learn more about plant growth from ScienceDirect's AI-generated Topic Pages">plant growth</a> and establishing healthy ecosystems. Although biochar is widely adopted as a sustainable fertilizer, its influence on soil ecological functions is still unclear, especially under climate change such as elevated <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/carbon-dioxide-concentration" title="Learn more about carbon dioxide concentration from ScienceDirect's AI-generated Topic Pages">carbon dioxide concentration</a> (eCO2). This study explores the coupled effects between eCO2 and biochar on <a href="https://www.sciencedirect.com/topics/engineering/microbial-community" title="Learn more about microbial communities from ScienceDirect's AI-generated Topic Pages">microbial communities</a> in soil planted with tree seedlings of <em>Schefflera heptaphylla</em>. Root characteristics and soil microbial communities were examined and interpreted with statistical analysis. Results show that biochar application at ambient <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/carbon-dioxide-concentration" title="Learn more about carbon dioxide concentration from ScienceDirect's AI-generated Topic Pages">carbon dioxide concentration</a> (aCO2) always improves <a href="https://www.sciencedirect.com/topics/social-sciences/plant-physiology" title="Learn more about plant growth from ScienceDirect's AI-generated Topic Pages">plant growth</a>, which is further promoted under eCO2. Similarly, β-glucosidase, urease and <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/phosphatase" title="Learn more about phosphatase from ScienceDirect's AI-generated Topic Pages">phosphatase</a> activities are enhanced by biochar at aCO2 (<em>p</em> < 0.05). In contrast, only urease activity increases with biochar added at eCO2 (<em>p</em> < 0.05). The beneficial effects of biochar on soil <a href="https://www.sciencedirect.com/topics/engineering/enzymatic-activity" title="Learn more about enzyme activities from ScienceDirect's AI-generated Topic Pages">enzyme activities</a> become less significant at eCO2. Depending on biochar type, biochar can increase bacterial diversity and fungal richness at aCO2. However, at eCO2, biochar does not significantly affect microbial richness (<em>p</em> > 0.05) while microbial diversity is reduced by peanut shell biochar (<em>p</em> < 0.05). Owing to better plant growth under biochar application and eCO2, plants are likely to become more dominant in specializing the microbial communities that are favourable to them. In such community, the abundance of <em>Proteobacteria</em> is the greatest and increases after biochar addition at eCO2. The most abundant fungus also shifts from <em>Rozellomycota</em> to <em>Ascomycota</em> and <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/basidiomycete" title="Learn more about Basidiomycota from ScienceDirect's AI-generated Topic Pages">Basidiomycota</a>. These microbes can improve <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/soil-fertility" title="Learn more about soil fertility from ScienceDirect's AI-generated Topic Pages">soil fertility</a>. Even though the microbial diversity is reduced, using biochar at eCO2 can further promote plant growth, which in turn enhances <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/carbon-sequestration" title="Learn more about carbon sequestration from ScienceDirect's AI-generated Topic Pages">carbon sequestration</a>. Thus, biochar application can be an effective strategy to facilitate ecological restoration under climate change and relieve the problem of eCO2.<br></p>