Carbon dynamics and pathways in soil density fractions across different land-use types over 3000 years: Insights from 13C natural abundance

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena Pub Date : 2025-03-24 DOI:10.1016/j.catena.2025.108968

Mingxu Xu , He Jiao , Yalu Zhang , Baowei Su , Shuangwen Yi , Huan Zhang , Chao Gao

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引用次数: 0

Abstract

Carbon (C) flow pathways, as identified through stable C isotopes(¹³C), provide insights into C dynamics within terrestrial ecosystems. However, how C pathways change in response to varying combinations of chronosequence, land use, and soil depth remains uncertain. To fill this gap and further elucidate stability mechanisms and functional disparities in soil organic carbon (SOC) pools, we establish a 3000-year sequence for four land types using space-for-time substitution and sample five soil profiles from serial plots along the Yangtze River. We also use soil density fractions (fLF, free light fraction; oLF, occluded light fraction; DF, dense fraction; and MF, mineral fraction) and δ¹³C natural abundance to deepen our understanding of biogeochemical processes related to C transformation. Consistent chronosequence dynamics in SOC content are revealed across bulk soil and three fractions (fLF, DF, and MF), with an initial increase and then a decrease occurring after 2000a. Similar dynamics observed in fLF and bulk soil highlight the importance of plant-derived C input in C accumulation. The oLF continuously increases and has the lowest δ¹³C value, reflecting the role of a physical occlusion stabilization mechanism. Chronosequence stability and the mass ratio (proportion > 95 %) of MF reveal its superior C stabilization capacity compared with other fractions. Through decreased C accessibility and C flows between MF and other fractions, paddy–dryland rotation accumulates the most C within the MF. The overall C pathway is from light (oLF and fLF) to heavy (DF and MF) fractions (oLF → fLF → DF → MF), flowing to the deeper subsoil. With increasing depth, the trend in δ¹³C enrichment of heavy fractions is more pronounced than for light fractions, potentially because of their distinct sources and constituents. We provide insights into C dynamics through δ¹³C and C pathways in more finely subdivided, representative SOC pools.

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来源期刊

Catena 环境科学-地球科学综合

CiteScore

10.50

自引率

9.70%

发文量

816

审稿时长

54 days

期刊介绍： Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment. Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.