Dissolved Organic Matter Drives Soil Carbon Mineralization Efficiency and Indirectly Affects Stocks After Converting Forest Swamps to Cropland

IF 3.7 2区农林科学 Q2 ENVIRONMENTAL SCIENCES

Land Degradation & Development Pub Date : 2025-09-06 DOI:10.1002/ldr.70183

Wei Wang, Gaoxiang Li, Jianwei Li, Yixinfei Lin, Bian Hongfeng, Yong Wang, Chunguang He

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Abstract

Forest swamps, unique ecosystems with large amounts of organic matter, are seriously threatened by agricultural cultivation. As the most active component of soil, dissolved organic matter (DOM) is susceptible to environmental changes. However, the carbon dynamics of forest swamps after agricultural cultivation and the role of DOM in this process remain unclear. We collected topsoil (0–20 cm) and subsoil (20–40 cm) across forest swamps and post‐cultivation paddy and maize fields to investigate the DOM characteristics and carbon mineralization efficiency (CME). The results indicated that CME increased (from 0.08 ± 0.004 to 0.15 ± 0.004 g CO2‐C/g SOC in topsoil; from 0.03 ± 0.001 to 0.11 ± 0.002 g CO2‐C/g SOC in subsoil), and carbon stocks significantly decreased (from 87.71 ± 1.98 to 36.21 ± 0.65 Mg/ha in topsoil; from 57.38 ± 1.44 to 25.26 ± 0.72 Mg/ha in subsoil) after the conversion of forest swamps to cropland. The conversion significantly reduced the relative proportion of humic‐like components and humification degree (p < 0.01), while significantly increasing the ligninase:cellulase ratio (p < 0.01). Linear regression analyses revealed that microbial enzymatic strategies reduced the relative proportions of recalcitrant DOM components (R2 = 0.67, p < 0.01), with changes in DOM composition being the major driver of increased CME (R2 = 0.88, p < 0.01), resulting in carbon loss indirectly after cultivation. Our study emphasizes the vital role of DOM in the soil carbon dynamics and provides new insights into carbon cycling under agricultural encroachment.

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森林沼泽还田后溶解有机质驱动土壤碳矿化效率并间接影响储量

森林沼泽是具有大量有机物质的独特生态系统，受到农业耕作的严重威胁。溶解有机质（DOM）是土壤中最活跃的成分，易受环境变化的影响。然而，农业开垦后森林沼泽的碳动态以及DOM在这一过程中的作用尚不清楚。本研究收集了森林沼泽、稻田和玉米地表层土壤（0 ~ 20 cm）和底土（20 ~ 40 cm），研究了土壤DOM特征和碳矿化效率（CME）。结果表明：森林沼泽还田后，表层土壤碳排放总量从0.08±0.004 g CO2‐C/g SOC增加到0.15±0.004 g，下层土壤碳排放总量从0.03±0.001 g增加到0.11±0.002 g CO2‐C/g SOC)，碳储量显著减少（表层土壤碳排放总量从87.71±1.98 Mg/ha减少到36.21±0.65 Mg/ha，下层土壤碳排放总量从57.38±1.44 Mg/ha减少到25.26±0.72 Mg/ha）。转化显著降低了腐殖质样组分的相对比例和腐殖质化程度（p < 0.01），显著提高了木质素酶与纤维素酶的比值（p < 0.01）。线性回归分析显示，微生物酶促策略降低了顽固性DOM成分的相对比例（R2 = 0.67, p < 0.01）， DOM成分的变化是CME增加的主要驱动因素（R2 = 0.88, p < 0.01），间接导致了培养后碳的损失。我们的研究强调了DOM在土壤碳动态中的重要作用，并为农业侵蚀下的碳循环提供了新的见解。

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来源期刊

Land Degradation & Development 农林科学-环境科学

CiteScore

7.70

自引率

8.50%

发文量

379

审稿时长

5.5 months

期刊介绍： Land Degradation & Development is an international journal which seeks to promote rational study of the recognition, monitoring, control and rehabilitation of degradation in terrestrial environments. The journal focuses on: - what land degradation is; - what causes land degradation; - the impacts of land degradation - the scale of land degradation; - the history, current status or future trends of land degradation; - avoidance, mitigation and control of land degradation; - remedial actions to rehabilitate or restore degraded land; - sustainable land management.