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Guo Z, Zhang X, Dungait JAJ, Green SM, Wen X, Quine TA. Contribution of soil microbial necromass to SOC stocks during vegetation recovery in a subtropical karst ecosystem. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 761:143945. [PMID: 33360125 DOI: 10.1016/j.scitotenv.2020.143945] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/12/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
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.
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Affiliation(s)
- Zhiming Guo
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Xinyu Zhang
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China.
| | - Jennifer A J Dungait
- Geography, College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK; Sustainable Agriculture Sciences, Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, UK
| | - Sophie M Green
- Geography, College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK
| | - Xuefa Wen
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Timothy A Quine
- Geography, College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK
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Laurén A, Lappalainen M, Kieloaho AJ, Karhu K, Palviainen M. Temperature sensitivity patterns of carbon and nitrogen processes in decomposition of boreal organic soils - Quantification in different compounds and molecule sizes based on a multifactorial experiment. PLoS One 2019; 14:e0223446. [PMID: 31600246 PMCID: PMC6786529 DOI: 10.1371/journal.pone.0223446] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 09/20/2019] [Indexed: 11/18/2022] Open
Abstract
Climate warming and organic matter decomposition are connected in a recursive manner; this recursion can be described by temperature sensitivity. We conducted a multifactorial laboratory experiment to quantify the temperature sensitivity of organic carbon (C) and nitrogen (N) decomposition processes of common boreal organic soils. We incubated 36 mor and 36 slightly decomposed Carex-Sphagnum peat samples in a constant moisture and ambient temperature for 6 months. The experiment included three temperature and two moisture levels and two food web manipulations (samples with and without fungivore enchytraeid worms). We determined the release of carbon dioxide (CO2) and dissolved organic carbon (DOC) in seven molecular size classes together with ammonium N and dissolved organic N in low molecular weight and high molecular weight fractions. The temperature sensitivity function Q10 was fit to the data. The C and N release rate was almost an order of magnitude higher in mor than in peat. Soil fauna increased the temperature sensitivity of C release. Soil fauna played a key role in N release; when fauna was absent in peat, the N release was ceased. The wide range of the studied C and N compounds and treatments (68 Q10 datasets) allowed us to recognize five different temperature sensitivity patterns. The most common pattern (37 out of 68) was a positive upwards temperature response, which was observed for CO2 and DOC release. A negative downward pattern was observed for extractable organic nitrogen and microbial C. Sixteen temperature sensitivity patterns represented a mixed type, where the Q10function was not applicable, as this does not allow changing the sign storage change rate with increasing or decreasing temperature. The mixed pattern was typically connected to intermediate decomposition products, where input and output fluxes with different temperature sensitivities may simultaneously change the storage. Mixed type was typical for N processes. Our results provide useful parameterization for ecosystem models that describe the feedback loop between climate warming, organic matter decomposition, and productivity of N-limited vegetation.
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Affiliation(s)
- Ari Laurén
- School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, Joensuu, Finland
- * E-mail:
| | - Mari Lappalainen
- School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, Joensuu, Finland
| | | | - Kristiina Karhu
- Department of Forest Sciences, University of Helsinki, Helsinki, Finland
| | - Marjo Palviainen
- Department of Forest Sciences, University of Helsinki, Helsinki, Finland
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Jiang T, Kaal J, Liang J, Zhang Y, Wei S, Wang D, Green NW. Composition of dissolved organic matter (DOM) from periodically submerged soils in the Three Gorges Reservoir areas as determined by elemental and optical analysis, infrared spectroscopy, pyrolysis-GC-MS and thermally assisted hydrolysis and methylation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017. [PMID: 28641186 DOI: 10.1016/j.scitotenv.2017.06.114] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Soil-derived dissolved organic matter (DOM) has a major influence in biogeochemical processes related to contaminant dynamics and greenhouse gas emissions, due to its reactivity and its bridging role between the soil and aquatic systems. Within the Three Gorges Reservoir (TGR, China) area, an extensive water-fluctuation zone periodically submerges the surrounding soils. Here we report a characterization study of soil-derived DOM across the TGR areas, using elemental and optical analysis, infrared spectroscopy (FTIR), pyrolysis-GC-MS (Py-GC-MS) and thermally assisted hydrolysis and methylation (THM-GC-MS). The results showed that the soil DOM from the TGR area is a mixture of "allochthonous" (i.e., plant-derived/terrigenous) and "autochthonous" (i.e., microbial) origins. The terrigenous DOM is composed primarily of phenolic and aliphatic structures from lignin and aliphatic biopolymers (i.e. cutin, suberin), respectively. Multivariate statistics differentiated between two fractions of the microbial DOM, i.e. chitin-derived, perhaps from fungi and arthropods in soil, and protein-derived, partially sourced from algal or aquatic organisms. Molecular proxies of source and degradation state were in good agreement with optical parameters such as SUVA254, the fluorescence index (FI) and the humification index (HIX). The combined use of elemental analysis, fluorescence spectroscopy, and Py-GC-MS provides rigorous and detailed DOM characterization, whereas THM-GC-MS is useful for more precise but qualitative identification of the different phenolic (cinnamyl, p-hydroxyphenyl, guaiacyl, syringyl and tannin-derived) and aliphatic materials. With the multi-methodological approach used in this study, FTIR was the least informative, in part, because of the interference of inorganic matter in the soil DOM samples. The soil DOM from the TGR's water fluctuation zone exhibited considerable compositional diversity, mainly related to the balance between DOM source (microbial- or plant-derived), local vegetation and anthropogenic activities (e.g., agriculture). Finally, the relationship between DOM composition and its potential reactivity with substances of environmental concerns in the TGR area are also discussed.
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Affiliation(s)
- Tao Jiang
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå SE-90183, Sweden.
| | - Joeri Kaal
- Ciencia do Sistema Terra, Departamento de Edafoloxía e Química Agrícola, Universidade de Santiago de Compostela, Campus Sur s/n, Santiago de Compostela 15782, Spain; Instituto de Ciencias del Patrimonio (Incipit), Consejo Superior de Investigaciones Científicas (CSIC), Avda. de Vigo sn, 15705 Santiago de Compostela, Spain
| | - Jian Liang
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Yaoling Zhang
- Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China
| | - Shiqiang Wei
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Dingyong Wang
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Nelson W Green
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
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