A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems

Abstract

Aim To estimate the concentrations, stoichiometry and storage of soil microbial biomass carbon (C), nitrogen (N) and phosphorus (P) at biome and global scales. Location Global. Method We collected 3422 data points to summarize the concentrations and stoichiometry of C, N and P in soils, soil microbial biomass at global and biome levels, and to estimate the global storage of soil microbial biomass C and N. Results The results show that concentrations of C, N and P in soils and soil microbial biomass vary substantially across biomes; the fractions of soil elements C, N and P in soil microbial biomass are 1.2, 2.6 and 8.0%, respectively. The best estimates of C:N:P stoichiometry for soil elements and soil microbial biomass are 287:17:1 and 42:6:1, respectively, at global scale, and they vary in a wide range among biomes. The vertical distribution of soil microbial biomass follows the distribution of roots up to 1 m depth. Main conclusions The global storage of soil microbial biomass C and N were estimated to be 16.7 Pg C and 2.6 Pg N in the 0–30 cm soil profiles, and 23.2 Pg C and 3.7 Pg N in the 0–100 cm soil profiles. We did not estimate P in soil microbial biomass due to insufficient data and insignificant correlation between soil total P and climate variables used for spatial extrapolation. The spatial patterns of soil microbial biomass C and N were consistent with those of soil organic C and total N, i.e. high density in northern high latitude, and low density in low latitudes and the Southern Hemisphere.

Spatial variability of soil microbial biomass and its relationships with edaphic, vegetational and climatic factors in the Three-River Headwaters region on Qinghai-Tibetan Plateau

“…This study showed that soil MBC and MBN in TRH (0-10 cm in depth) averaged at 30.95 mmol C/kg dry soil and 5.84 mmol N/kg dry soil, are much lower than the global means in the same soil depth (0-10 cm) (72.12 mmol C/kg dry soil and 9.24 mmol N/kg dry soil) (Table 2), as well as the global means (56.7 mmol C/kg dry soil and 7.5 mmol N/kg dry soil) at 0-30 cm soil depth (Xu et al, 2013) although soil microbial C and N concentrations normally decrease with soil depth (Fierer et al, 2003;Peng et al, 2005;Yu and Steinberger, 2012). We acknowledged that soil microbial properties feature high temporal variability in addition to spatial variations and the synthesized study of Xu et al (2013) included global datasets with soil microbial biomass measured in different seasons.…”

“…These large-scale studies examined microbial biomass storage and the mechanisms determining its spatial patterns. For example, a recent study (Xu et al, 2013) found that soil MB showed substantial variation across various biomes at global scale and the spatial patterns of MBC and MBN were in line with those of soil C and N with higher densities in northern high latitudes and lower densities in low latitudes and the Southern Hemisphere. Serna-Chavez et al (2013) suggested that the global pattern of soil MB was driven by moisture and soil nutrient contents, not temperature.…”

“…To compare the level of MB in TRH with published results for other parts of the world, we also selected the measurements for the same soil depth (0-10 cm) from the microbial biomass database in Xu et al (2013), the most comprehensive microbial biomass database in the world. Within the total 3422 measurements in the database, we chose 373 measurements which were also reported in the top layer of 10 cm in depth.…”

“…Many studies on soil MB have been conducted in the past few decades (Dempster et al, 2012;Kaschuk et al, 2010;Xu et al, 2013), and the focus has recently changed from site/ecosystem level Wright and Coleman, 2000;Zak et al, 1994) to regional (Dequiedt et al, 2011;Drenovsky et al, 2010) and global scales (Serna-Chavez et al, 2013;Xu et al, 2013). These large-scale studies examined microbial biomass storage and the mechanisms determining its spatial patterns.…”

“…Using meta-analysis, Fierer et al (2009) showed that soil MB was highly correlated with soil organic C and belowground plant NPP across global biomes. Nevertheless, MB studies have rarely been conducted above 3000 m in elevation, therefore, previous studies estimating the global soil MB pattern and its dominant factors lack support from high elevation sites (Serna-Chavez et al, 2013;Wardle, 1992;Xu et al, 2013).…”