Volatile organic compounds from leaf litter decomposition alter soil microbial communities and carbon dynamics

Abstract

Investigations into the transfer of carbon from plant litter to underlying soil horizons have primarily focused on the leaching of soluble carbon from litter belowground or the mixing of litter directly into soil. However, previous work has largely ignored the role of volatile organic compounds (VOCs) released during litter decomposition. Unlike most leaf carbon, these litter-derived VOCs are able to diffuse directly into the soil matrix. Here, we used a 99-d microcosm experiment to track VOCs produced during microbial decomposition of 13 Clabeled leaf litter into soil carbon fractions where the decomposing litters were only sharing headspace with the soil samples, thus preventing direct contact and aqueous movement of litter carbon. We also determined the effects of these litter-derived VOCs on soil microbial community structure. We demonstrated that the litter VOCs contributed to all measured soil carbon pools. Specifically, VOC-derived carbon accounted for 2.0, 0.61, 0.18, and 0.08% of carbon in the microbial biomass, dissolved organic matter, mineral-associated organic matter, and particulate organic matter pools, respectively. We also show that litter-derived VOCs can affect soil bacterial and fungal community diversity and composition. These findings highlight the importance of an underappreciated pathway where VOCs alter soil microbial communities and carbon dynamics.

The Chemistry of Stress: Understanding the ‘Cry for Help’ of Plant Roots

“…Root VOCs can act as both signaling molecules and nutrient sources for soil microbes [68], and hence might influence the assembly and proliferation of root-associated microbiome. A microcosm experiment showed that VOC-derived carbon released (in the headspace) during decomposition of 13 C-labelled leaf litter accounted for fractions in microbial biomass (located separately from the decomposition site), suggesting that VOCs can be carbon sources for soil microbes [69]. In another study, gaseous ethylene produced by peanut roots (as a response to cyanide released by neighboring cassava plants) altered microbial composition of peanut rhizosphere by shifting the abundance of actinobacterial species, resulting in improved seed production [60].…”

Reviews and syntheses: VOC emissions from soil cover in boreal and temperate natural ecosystems of the Northern Hemisphere

“…CC BY 4.0 License. dynamics (McBride et al, 2020). However, it should be noted that this is not the only process linking deciduous litter and soil biota.…”

Volatile and Dissolved Organic Carbon Sources Have Distinct Effects on Microbial Activity, Nitrogen Content, and Bacterial Communities in Soil

“…Like LMW-DOC, VOCs, including methanol and monoterpenes, function as microbial C substrates (Madyastha et al, 1977;Radajewski et al, 2002. ), drive microbial activity (Asensio et al, 2012;McBride et al, 2019), alter N transformations (Paavolainen et al, 1998;McBride et al, 2019), and alter microbial community composition (McBride et al, 2020). VOCs can enter the soil through a variety of mechanisms including root emission, organic matter decomposition, and soil-atmosphere exchange, (Asensio et al, 2007;Leff and Fierer, 2008;Wenke et al, 2010;Peñuelas et al, 2014).…”