Contribution of soil microbial necromass to SOC stocks during vegetation recovery in a subtropical karst ecosystem

A - Papers appearing in refereed journals

Guo, Z., Zhang, X., Dungait, J. A. J., Green, S. M., Wen, X. and Quine, T. A. 2020. Contribution of soil microbial necromass to SOC stocks during vegetation recovery in a subtropical karst ecosystem. Science of the Total Environment. 761 (article), p. 143945. https://doi.org/10.1016/j.scitotenv.2020.143945

AuthorsGuo, Z., Zhang, X., Dungait, J. A. J., Green, S. M., Wen, X. and Quine, T. A.
Abstract

Carbon sequestration is a key soil function, and an increase in soil organic carbon (SOC) is an indicator of ecosystem recovery because it underpins other ecosystem services by acting as a substrate for the soil microbial community. The soil microbial community constitutes the active pool of SOC, and its necromass (microbial residue carbon, MRC) contributes strongly to the stable SOC pool. Therefore, we propose that the potential for restoration of degraded karst ecosystems lies in the abundance of soil microbial community and the persistence of its necromass, and may be measured by changes in its contribution to the active and stable SOC pools during recovery. We investigated changes in SOC stocks using an established space-for-time chronosequence along a perturbation gradient in the subtropical karst ecosystem: sloping cropland < abandoned cropland < shrubland < secondary forest < primary forest. Microbial biomarkers were extracted from soil profiles from surface to bedrock and used to measure the contributions of the soil microbial community composition (using phospholipid fatty acids, PLFAs) and MRC (using amino sugars) to SOC stocks at each recovery stage. The results showed that the SOC stocks ranged from 10.53 to 31.77 kg m−2 and increased with recovery stage, with total MRC accounting for 17–28% of SOC. Increasing PLFAs and MRC abundances were positively correlated with improved soil structure (decreased bulk density) and organic carbon, nitrogen and phosphorus nutrient. Bacterial MRC contributes more to SOC stocks than fungal residue carbon during vegetation recovery. The PLFA analysis indicated that Gram positive bacteria were the largest microbial group and were relatively more abundant in deeper soils, and biomarkers for saprophytic and ectomycorrhizal fungi were more abundant in soils under woody vegetation. In conclusion, this study suggests that the soil microbial community in karst soils have the potential to adapt to changing soil conditions and contribute substantially to building SOC stocks after abandonment of agriculture in degraded karst landscapes.

KeywordsMicrobial residue carbon; Phospholipid fatty acid; Cropland; Shrubland; Forest; Soil degradation; Karst Critical Zone
Year of Publication2020
JournalScience of the Total Environment
Journal citation761 (article), p. 143945
Digital Object Identifier (DOI)https://doi.org/10.1016/j.scitotenv.2020.143945
Web address (URL)https://www.sciencedirect.com/science/article/abs/pii/S0048969720374763?via%3Dihub
Open accessPublished as non-open access
FunderNational Key Research and Development Program of China
National Natural Science Foundation of China
National Environmental Research Council
Funder project or code31988102 - Science Centre Project
41877091
41830860
2017YFC0503904
41571130043
NE/N007603/1
Output statusPublished
Publication dates
Print20 Mar 2021
Online04 Dec 2020
Publication process dates
Accepted16 Nov 2020
PublisherElsevier Science Bv
ISSN0048-9697

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