DOI: 10.5061/dryad.g1jwstqx5
title: Microbial traits dictate soil neromass accumulation coefficient: A global synthesis

description: The accumulation of microbial necromass carbon has drawn mounting
 attention due to the slow decomposition. However, it remains unclear what
 determines the microbial necromass carbon accumulation via reiterated
 community turnover on large spatial scales. This study aimed to explore
 the characteristics of soil necromass carbon accumulation in terrestrial
 ecosystems. A dataset was compiled with 993 observations on the
 coefficient of microbial carbon accumulation in the equilibrium from 82
 peer-reviewed papers. The linear mixed-effect models and structural
 equation models were used to ascertain the controlling factors of NAC on a
 global scale. The average NAC was higher in croplands (28.2) and forests
 (26.8) than that in grasslands (21.1). Although the edaphic factors
 seemingly affect the NAC whereby the NAC lowered in soils with high levels
 of pH and clay content on a global scale, the biotic factors, particularly
 for the living microorganism abundance and microbial biomass nitrogen
 content, were the pivotal drivers of NAC that accounted for approximately
 42.5% of the geographic variances in NAC. More organic carbon was likely
 to be preserved in soil with a higher NAC regardless of ecosystem types.
 Novel findings on the overriding controls from the living microorganism
 abundance and microbial biomass nitrogen in driving NAC raise an urgent
 need for viable strategies in manipulating microbial characteristics for
 carbon sequestrations.
description: # Readme **Title** Microbial necromass carbon accumulation coefficients
 (NAC) dataset **Author** Bingbing Han, Yanzhong Yao, Yini Wang, Xiaoxuan
 Su, Lihua Ma, Xinping Chen, Zhaolei Li \* **Corresponding author:**
 Zhaolei Li, Professor E-mail: lizhaolei@swu.edu.cn **Correspondence
 address:** College of Resources and Environment, and Academy of
 Agricultural Sciences, Southwest University, Chongqing 400715, China
 **Data abstract** The accumulation of microbial necromass carbon has drawn
 mounting attention due to the slow decomposition. However, it remains
 unclear what determines the microbial necromass carbon accumulation via
 reiterated community turnover on large spatial scales. This study aimed to
 explore the characteristics of soil necromass carbon accumulation in
 terrestrial ecosystems. A dataset was compiled with 993 observations on
 the coefficient of microbial carbon accumulation in the equilibrium from
 82 peer-reviewed papers. The linear mixed-effect models and structural
 equation models were used to ascertain the controlling factors of NAC on a
 global scale. The average NAC was higher in croplands (28.2) and forests
 (26.8) than that in grasslands (21.1). Although the edaphic factors
 seemingly affect the NAC whereby the NAC lowered in soils with high levels
 of pH and clay content on a global scale, the biotic factors, particularly
 for the living microorganism abundance and microbial biomass nitrogen
 content, were the pivotal drivers of NAC that accounted for approximately
 42.5% of the geographic variances in NAC. More organic carbon was likely
 to be preserved in soil with a higher NAC regardless of ecosystem types.
 Novel findings on the overriding controls from the living microorganism
 abundance and microbial biomass nitrogen in driving NAC raise an urgent
 need for viable strategies in manipulating microbial characteristics for
 carbon sequestrations. **Data collect** The NACs dataset was compiled from
 peer-reviewed papers. These peer-reviewed papers were obtained by means of
 two platforms: the Web of Science
 ([http://apps.webofkonwledge.com](http://apps.webofkonwledge.com)) and the
 China National Knowledge Infrastructure Database
 ([http://www.cnki.net](http://www.cnki.net)). At the same time, the papers
 were supplemented by Google Scholar. The keywords used to search papers
 are soil microbial biomass AND microbial necromass AND microbial residue\*
 AND amino sugar\* AND PLFAs. The publishing date for the peer-reviewed
 paper was up to January 20, 2023. The eligible peer-reviewed papers
 matched the following criteria: (1) Soil microbial necromass was measured
 using amino sugars as markers; (2) The living microorganisms were
 determined by phospholipid fatty acid (PLFAs). Finally, the NAC dataset
 was constructed based on the 82 peer-reviewed papers. The details of the
 experimental site were also extracted from papers, including the
 geographic information of the experiment site (i.e., latitude and
 longitude), climate conditions (i.e., mean annual temperature and mean
 annual precipitation), and ecosystem types (i.e., grasslands, forests, and
 croplands). Additionally, soil physicochemical properties [soil pH, the
 ratio of carbon to nitrogen (soil C: N), total nitrogen (TN), bulk density
 (BD), clay content, and ammonium content (NH4+)] and the number of
 replicates were also extracted from the articles. Additionally, in the NAC
 dataset, the empty cells are representing the data scarcity (i.e., NA
 values). You should know that not every article will contain all the
 metrics. **Data analysis** The content of fungal and bacterial necromass
 carbon was calculated based on the concentrations of amino sugar in
 microbial cell walls: glucosamine and muramic acid. The bacterial
 necromass carbon and fungal necromass carbon were calculated using
 equations (1) and (2). where, MurA is muramic acid and GlcN is
 glucosamine. In equation (1), 45 is the conversion factor from MurA to
 bacterial necromass carbon; in equation (2), 9 is the conversion factor
 from GlcN to fungal necromass carbon; while 179.17 and 251.23 are the
 molecule weights of GlcN and MurA, respectively. Total microbial necromass
 carbon was the sum of fungal necromass carbon and bacterial necromass
 carbon. For the absence of microbial biomass carbon (MBC) in some
 experimental sites. The NAC functions as the ratio of the microbial
 necromass carbon to microbial biomass carbon: where MBC is soil microbial
 biomass carbon. The linear mixed-effect models were used to test the
 bivariate relationship between the NAC and environmental factor by means
 of *lme4* packages in R (version 4.2.2., R Core Team). The equation (4)
 was: where NAC refers to the microbial necromass carbon accumulation
 coefficient, lnX is the logarithm of each edaphic and climatic factor
 (except for soil pH and fungi: bacteria ratio), refers to the intercept of
 this model, refers to the slope value, refers to the random effect of
 study, refers to the sampling error. **Document Type** We will upload it
 in data\_NAC\_2023.csv format to the Dryad database. The main variables
 collected in the data form were muramic acid (MurA) and glucosamine
 (GlcN). We perform the calculation of NAC based on equations 1, 2, and 3
 above. Total biomass represents the abundance of living microorganisms.
 Fungal biomass represents the abundance of fungi. Bacterial biomass
 represents the abundance of bacteria. MBC is microbial biomass nitrogen.
 SOC is soil organic carbon. **Data processing software** We processed the
 entire set of data by utilizing the R language, version 4.2.2., R Core
 Team. **Contact Information** **Corresponding author:** Zhaolei Li,
 Professor **E-mail:** [lizhaolei@swu.edu.cn](mailto:lizhaolei@swu.edu.cn)
 **ORCID:**
 [https://orcid.org/0000-0001-8767-1277](https://orcid.org/0000-0001-8767-1277)