Soil fauna diversity increases CO₂ but suppresses N₂O emissions from soil

Abstract

Soil faunal activity can be a major control of greenhouse gas (GHG) emissions from soil. Effects of single faunal species, genera or families have been investigated, but it is unknown how soil fauna diversity may influence emissions of both carbon dioxide (CO2, end product of decomposition of organic matter) and nitrous oxide (N2O, an intermediate product of N transformation processes, in particular denitrification). Here, we studied how CO2 and N2O emissions are affected by species and species mixtures of up to eight species of detritivorous/fungivorous soil fauna from four different taxonomic groups (earthworms, potworms, mites, springtails) using a microcosm set‐up. We found that higher species richness and increased functional dissimilarity of species mixtures led to increased faunal‐induced CO2 emission (up to 10%), but decreased N2O emission (up to 62%). Large ecosystem engineers such as earthworms were key drivers of both CO2 and N2O emissions. Interestingly, increased biodiversity of other soil fauna in the presence of earthworms decreased faunal‐induced N2O emission despite enhanced C cycling. We conclude that higher soil fauna functional diversity enhanced the intensity of belowground processes, leading to more complete litter decomposition and increased CO2 emission, but concurrently also resulting in more complete denitrification and reduced N2O emission. Our results suggest that increased soil fauna species diversity has the potential to mitigate emissions of N2O from soil ecosystems. Given the loss of soil biodiversity in managed soils, our findings call for adoption of management practices that enhance soil biodiversity and stimulate a functionally diverse faunal community to reduce N2O emissions from managed soils.

Identifying potential threats to soil biodiversity

“…Hamidov et al (2018) Lavelle et al (2014) (continued on next page) Hagvar (1998) & ''soil biodiversity''. However, with the removal of the word 'threat' from the search references are being returned that not only report the impacts of climate change on soil biodiversity, but also the ecosystem services provided by soil biodiversity in terms of climate change mitigation (e.g., Lubbers et al, 2019). From this broader bibliographic analysis, we concluded that threats to soil biodiversity was the appropriate focus of this review, and the use of the search term threat* ''soil biodiversity'' was therefore rational in this instance.…”

Precipitation‐drainage cycles lead to hot moments in soil carbon dioxide dynamics in a Neotropical wet forest

“…However, after this initial increase, the damage in the canopy may lead to the opposite effect, and may open the soil to drying and to large diurnal variations in soil CO 2 respiration (Vargas & Allen, 2008a); this is a major driver of the nitrogen cycling and belowground carbon dynamics (Hasselquist, Santiago, & Allen, 2010). Regardless of mechanisms, short‐term fluctuations in soil CO 2 concentrations (and other greenhouse gases) lead to variability in soil emissions (Barcellos et al., 2018; Fernandez‐Bou, Dierick, & Harmon, 2020; Fernandez‐Bou et al, 2018; Harms & Grimm, 2008; Haverd, Ahlström, Smith, & Canadell, 2017; Kuzyakov & Blagodatskaya, 2015; Leon et al., 2014; Lubbers, Berg, Deyn, van der Putten, & van Groenigen, 2019; Soper et al., 2019; Swanson et al., 2019; Vargas et al., 2018). In this work, we monitor soil CO 2 concentration over multiple years to better understand its short‐term dynamics and potential influence on tropical soil CO 2 emissions.…”

Preferential degradation of leaf- vs. root-derived organic carbon in earthworm-affected soil

“…Their role in soil organic matter (SOM) dynamics, though, is often neglected despite their presence in many ecosystems worldwide (Hendrix et al, 2008). Earthworms affect SOM dynamics in two principal ways: (1) they stimulate soil microbial activity and biomass and, thus, enhance the mineralization of SOM (i.e., the release of CO 2 into the atmosphere; Ferlian et al, 2018;Groffman et al, 2015;Lubbers et al, 2019;McLean et al, 2006) and (2) they promote the formation of macro-and microaggregates, transferring SOM into a more stabilized form (Bossuyt et al, 2005;Pulleman et al, 2005). The net effect of these processes on the storage of soil organic C (SOC), though, is still subject to debate likely due to a focus on coarse-scale measures, such as the SOC contents of bulk soil.…”