The biogeography of relative abundance of soil fungi and bacteria in top surface soil

Abstract

Abstract. Fungi and bacteria are the two dominant groups of soil microbial communities worldwide. By controlling the turnover of soil organic matter, these organisms directly regulate the exchange of carbon between the soil and the atmosphere. Fundamental differences in the physiology and life history of bacteria and fungi suggest that variation in the biogeography of soil fungal and bacterial relative abundance could drive striking differences in carbon decomposition and soil organic matter formation across different biomes. However, a lack of global and predictive information on the distribution of these organisms in terrestrial ecosystems has prevented the inclusion of soil fungal and bacterial relative abundance and the associated processes into global biogeochemical models. Here, we used a global scale dataset in the top soil surface (>3000 distinct observations of soil fungal and bacterial abundance) to generate the first quantitative and spatially high resolution (1 km) explicit map of soil fungal proportion, defined as fungi/fungi + bacteria, across terrestrial ecosystems. We reveal striking latitudinal trends where fungal dominance increases in cold and high latitude environments with large soil carbon stocks. There was strong non-linear response of fungal dominance to environmental gradient, i.e., mean annual temperature (MAT) and net primary productivity (NPP). Fungi and bacteria dominated in regions with low and high MAT and NPP, respectively, thus representing slow vs. fast soil energy channels, a concept with a long history in soil ecology. These high-resolution models provide the first steps towards representing the major soil microbial groups and their functional differences in global biogeochemical models to improve predictions of soil organic matter turnover under current and future climate scenarios. Raw datasets and global maps generated in this study are available at https://doi.org/10.6084/m9.figshare.19556419 (Yu, 2022).

Soil water status shapes nutrient cycling in agroecosystems from micrometer to landscape scales

“…Waring et al (2013) have discussed how changes in soil conditions across biomes and land use affect the ratio of fungal to bacterial biomass, as differences in physiology affect the biogeographic distributions of these two groups. A recent study (Yu et al, 2022) showed that fungi with their generally slower growth and turnover rates (Rousk & Bååth, 2007), greater carbon to nutrient stoichiometry (Waring et al, 2013), and greater capacity to degrade more recalcitrant substrates (Strickland & Rousk, 2010) dominate in high latitudes with low mean annual temperature and high net primary productivity relative to soil bacteria that dominate in the tropical regions and in arable lands with frequent tillage disturbances.…”