A meta-analysis of soil biodiversity impacts on the carbon cycle

Abstract

Abstract. Loss of biodiversity impacts ecosystem functions, such as carbon (C) cycling. Soils are the largest terrestrial C reservoir, containing more C globally than the biotic and atmospheric pools together. As such, soil C cycling, and the processes controlling it, has the potential to affect atmospheric CO 2 concentrations and subsequent climate change. Despite the growing evidence of links between plant diversity and soil C cycling, there is a dearth of information on whether similar relationships exist between soil biodiversity and C cycling. This knowledge gap occurs even though there has been increased recognition that soil communities display high levels of both taxonomic and functional diversity and are key drivers of fluxes of C between the atmosphere and terrestrial ecosystems. Here, we used meta-analysis and regression analysis to quantitatively assess how soil biodiversity affects soil C cycling pools and processes (i.e., soil C respiration, litter decomposition, and plant biomass). We compared the response of process variables to changes in diversity both within and across groups of soil organisms that differed in body size, a grouping that typically correlates with ecological function. When studies that manipulated both within-and across-body size group diversity were included in the meta-analysis, loss of diversity significantly reduced soil C respiration (−27.5 %) and plant tissue decomposition (−18 %) but did not affect above-or belowground plant biomass. The loss of within-group diversity significantly reduced soil C respiration, while loss of across-group diversity did not. Decomposition was negatively affected both by loss of within-group and across-group diversity. Furthermore, loss of microbial diversity strongly reduced soil C respiration (−41 %). In contrast, plant tissue decomposition was negatively affected by loss of soil faunal diversity but was unaffected by loss of microbial diversity. Taken together, our findings show that loss of soil biodiversity strongly impacts on soil C cycling processes, and highlight the importance of diversity across groups of organisms (e.g., primary consumers and secondary decomposers) for maintaining full functionality of C cycle processes. However, our understanding of the complex relationships between soil biodiversity and C cycling processes is currently limited by the sheer number of methodological concerns associated with these studies, which can greatly overestimate or underestimate the impact of soil biodiversity on soil C cycling, challenging extrapolation to natural field settings. Future studies should attempt to further elucidate the relative importance of taxonomic diversity (species numbers) versus functional diversity.

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

“…Such research gaps are particularly wide for soil animals, which is at odds with a growing number of studies on how their body size determines ecosystem processes or responses to global change (de Graaff, Adkins, Kardol, & Throop, 2015;Knox et al, 2017;Lindo, 2015;Moretti et al, 2016). Body size varies enormously in soil fauna, as reflected by the conventional sorting of soil invertebrates in microfauna, mesofauna and macrofauna, of demonstrated functional importance (Cole, Bradford, Shaw, & Bardgett, 2006;de Graaff et al, 2015). What this classification conceals is the large variation that occurs also within each size class.…”

Long‐Term Durum Wheat‐Based Cropping Systems Result in the Rapid Saturation of Soil Carbon in the Mediterranean Semi‐arid Environment

“…Land degradation is related to the soil quality and health and he degradation of the soil system will change the hydrological, biological, and geochemical cycles in the Earth and the service the soils offers to the human societies (Keesstra et al, 2012;Berendse et al, 2015). Within the Earth System cycles the carbon is one that is more influenced by the human use of the land (de Graaff et al, 2015;Köchy et al, 2015;Ping et al, 2015). Agriculture and intensive tillage have caused a 30 to 50% decrease in the carbon (C) content of many soils that have been cultivated for more than 100 years (Schlesinger, 1986;Lal & Kimble, 1997;Smith et al, 2000;de Moraes Sá et al, 2013).…”

Are There Arid Land Soilscapes in Southwestern Europe?

“…Soils are self-organized heterogeneous porous media essential for supporting life within the Earth system, as they control the hydrological and biogeochemical cycles, among other biospherical services (Keesstra et al, 2012;Billings et al, 2015;Brevik et al, 2015b;de Graaff et al, 2015;Köchy et al, 2015;van Groenigen et al, 2015). The Iberian Peninsula has a long history of soil use.…”