Contribution of litter-derived carbon to soil organic carbon fractions and its response to freezing-thaw cycling in a subalpine forest

doi:10.17521/cjpe.2023.0278

Abstract

Abstract:

Aims The impact of global warming on soil freeze-thaw cycling in high-altitude area is increasing. However, the contribution of litter-derived carbon to various soil organic carbon fractions and its response to freeze-thaw cycling remains unclear.

Methods The study utilized an indoor simulated freeze-thaw cycling experiment and stable isotope tracing technique, using ¹³C-labeled Picea asperate litter (root, twig, leaf), to explore the contribution of litter-derived carbon to dissolved organic carbon (DOC), microbial biomass carbon (MBC), humus carbon (HC), particulate organic carbon (POC) and mineral associated organic carbon (MAOC) in soil under freeze-thaw cycles.

Important findings The results showed that: after 30 days of incubation, litter-derived carbon significantly contributed to soil POC and MBC, accounting for 13.1% and 9.0%, respectively. The contribution of litter to different soil organic carbon fractions varied among different organs, with roots exhibiting a significantly lower contribution rate to POC, MAOC, and HC compared to twigs and leaves. Under freeze-thaw cycles, litter carbon contributed more to soil DOC and MBC, while showing a lower contribution rate to soil POC, MAOC, and HC. Correlation analysis revealed a significant positive relationship between soil carbon acquisition-related activity enzymes and the contribution of litter-derived carbon to soil organic carbon. These findings indicate that freeze-thaw processes facilitate the accumulation of litter-derived carbon in active organic carbon fractions such as soil DOC and MBC, but inhibit the sequestration of plant-derived carbon in stable soil organic carbon during the initial litter decomposition period in subalpine forests. The research findings contribute to a deeper understanding of the contribution of forest litter return to soil organic carbon fractions, providing a scientific basis for the management and operation of soil carbon pools in subalpine forests under the backdrop of climate change.

Key words: freeze-thaw cycle, litter decomposition, soil organic carbon, δ¹³C

ZHANG Yu, DU Ting, CHEN Yu-Lian, ZHU He-Meng, TAN Bo, YOU Cheng-Ming, ZHANG Li, XU Zhen-Feng, LI Han. Contribution of litter-derived carbon to soil organic carbon fractions and its response to freezing-thaw cycling in a subalpine forest[J]. Chin J Plant Ecol, 2024, 48(11): 1422-1433.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2023.0278

https://www.plant-ecology.com/EN/Y2024/V48/I11/1422

Figures/Tables 7

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分类 Classification	胞外酶 Extracellular enzyme	酶底物浓度 Enzyme substrate concentration
水解酶 Hydrolase	酸性磷酸酶 Acid phosphatase	5 mmol·L^-1 pNP-phosphate
	β-葡萄糖苷酶 β-glucosidase	5 mmol·L^-1 pNP-β-glucopyranoside
	纤维二糖水解酶 Cellobiohydrolase	5 mmol·L^-1 pNP-cellobioside
	β-N-乙酰氨基葡萄糖苷酶 β-N-acetylglucosaminidase	5 mmol·L^-1 pNP-β-N-acetylglucosaminide
	亮氨酸氨基肽酶 Leucine aminopeptidase	5 mmol·L^-1 Leucine p-nitroanilide
氧化酶 Oxidase	多酚氧化酶 Polyphenol oxidase	5 mmol·L^-1 Dihydroxy-phenylalanine
氧化酶 Oxidase	过氧化物酶 Peroxidase	5 mmol·L^-1 Dihydroxy-phenylalanine + 0.3% H₂O₂

分类 Classification	胞外酶 Extracellular enzyme	酶底物浓度 Enzyme substrate concentration
水解酶 Hydrolase	酸性磷酸酶 Acid phosphatase	5 mmol·L^-1 pNP-phosphate
	β-葡萄糖苷酶 β-glucosidase	5 mmol·L^-1 pNP-β-glucopyranoside
	纤维二糖水解酶 Cellobiohydrolase	5 mmol·L^-1 pNP-cellobioside
	β-N-乙酰氨基葡萄糖苷酶 β-N-acetylglucosaminidase	5 mmol·L^-1 pNP-β-N-acetylglucosaminide
	亮氨酸氨基肽酶 Leucine aminopeptidase	5 mmol·L^-1 Leucine p-nitroanilide
氧化酶 Oxidase	多酚氧化酶 Polyphenol oxidase	5 mmol·L^-1 Dihydroxy-phenylalanine
氧化酶 Oxidase	过氧化物酶 Peroxidase	5 mmol·L^-1 Dihydroxy-phenylalanine + 0.3% H₂O₂

变异来源 Source of variance	δ¹³C-DOC (‰)		δ¹³C-MBC (‰)		δ¹³C-POC (‰)		δ¹³C-MAOC (‰)		δ¹³C-HC (‰)
变异来源 Source of variance	F	p	F	p	F	p	F	p	F	p
冻融 Freeze-thaw	2 076.98	0.000	79.32	0.000	4.97	0.035	6.82	0.015	16.67	0.000
器官 Organ	1 156.73	0.000	286.93	0.000	1.39	0.267	0.32	0.728	1.58	0.226
培养时间 Period	0.38	0.542	1.24	0.277	27.79	0.000	3.83	0.062	59.67	0.000
冻融×器官 Freeze-thaw × organ	674.11	0.000	10.36	0.001	4.10	0.029	14.55	0.000	12.85	0.000
冻融×培养时间 Freeze-thaw × period	1 460.01	0.000	85.15	0.000	1.26	0.273	95.91	0.000	2.62	0.119
器官×培养时间 Organ × period	636.85	0.000	22.63	0.000	1.24	0.306	21.60	0.000	2.78	0.082
冻融×器官×培养时间 Freeze-thaw × organ × period	353.77	0.000	14.85	0.000	1.76	0.194	2.61	0.094	0.34	0.716

变异来源 Source of variance	δ¹³C-DOC (‰)		δ¹³C-MBC (‰)		δ¹³C-POC (‰)		δ¹³C-MAOC (‰)		δ¹³C-HC (‰)
变异来源 Source of variance	F	p	F	p	F	p	F	p	F	p
冻融 Freeze-thaw	2 076.98	0.000	79.32	0.000	4.97	0.035	6.82	0.015	16.67	0.000
器官 Organ	1 156.73	0.000	286.93	0.000	1.39	0.267	0.32	0.728	1.58	0.226
培养时间 Period	0.38	0.542	1.24	0.277	27.79	0.000	3.83	0.062	59.67	0.000
冻融×器官 Freeze-thaw × organ	674.11	0.000	10.36	0.001	4.10	0.029	14.55	0.000	12.85	0.000
冻融×培养时间 Freeze-thaw × period	1 460.01	0.000	85.15	0.000	1.26	0.273	95.91	0.000	2.62	0.119
器官×培养时间 Organ × period	636.85	0.000	22.63	0.000	1.24	0.306	21.60	0.000	2.78	0.082
冻融×器官×培养时间 Freeze-thaw × organ × period	353.77	0.000	14.85	0.000	1.76	0.194	2.61	0.094	0.34	0.716

变异来源 Source of variance	DOC贡献率 Contribution to DOC (%)		MBC贡献率 Contribution to MBC (%)		POC贡献率 Contribution to POC (%)		MAOC贡献率 Contribution to MAOC (%)		HC贡献率 Contribution to HC (%)
变异来源 Source of variance	F	p	F	p	F	p	F	p	F	p
冻融 Freeze-thaw	5 119.84	0.000	931.05	0.000	120.60	0.000	3.76	0.132	96.44	0.000
器官 Organ	229.66	0.000	848.32	0.000	110.39	0.000	190.35	0.000	87.50	0.000
培养时间 Period	462.55	0.000	4.11	0.054	5.75	0.025	42.83	0.000	8.03	0.011
冻融×器官 Freeze-thaw × organ	940.69	0.000	77.77	0.000	23.01	0.000	44.47	0.000	56.92	0.000
冻融×培养时间 Freeze-thaw × period	7 860.27	0.000	127.08	0.000	75.22	0.000	165.64	0.000	6.56	0.006
器官×培养时间 Organ × period	1 601.80	0.000	677.13	0.000	5.60	0.010	58.45	0.000	7.67	0.003
冻融×器官×培养时间 Freeze-thaw × organ × period	57.48	0.000	133.02	0.000	24.35	0.000	26.40	0.000	2.80	0.074