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{"title":"Changes in soil multifunctional properties in semi-arid environments are dependent on ecosystem health","authors":"Atefeh Shah Piri ,&nbsp;Yahya Kooch ,&nbsp;Seyed Mohammad Hojjati","doi":"10.1016/j.catena.2025.108978","DOIUrl":"10.1016/j.catena.2025.108978","url":null,"abstract":"<div><div>Mountainous and semi-arid habitats are considered very sensitive and fragile, due to their climatic conditions. Soil has different functions, and its physicochemical and biological characteristics can be indicators that affect these functions. In recent years due to human intervention, most of these areas have been destroyed and now some areas are either bare or have sparse vegetation. The presence of different percentages of vegetation coverage can be an indicator of ecosystem health, especially in areas affected by the human intervention. <em>Carpinus orientalis</em> Miller. <em>− Quercus macranthera</em> Fisch &amp; C.A. Mey and <em>Crataegus melanocarpa</em> M.B. <em>and Crataegus microphylla</em> C. Koch. <em>− Berberis integerrima</em> Bunge. are the dominant vegetation types found in the forest and rangelands of semi-arid areas in Iran. This study aimed to investigate the impact of different intensities of vegetation cover degradation, ranging from heavy (0–10 % coverage) to moderate (30–40 % coverage) and light (60–70 % coverage) in comparison to undisturbed sites (control group with 90–100 % coverage) in northern Iran. A total of 15 soil samples from forest and rangeland habitats with four degradation intensities were collected from each site, within an area of 30 × 30 cm at the depth intervals of 0–10 cm, 10–20 cm, and 20–30 cm, with a total of 360 samples that were subsequently analyzed in the laboratory. Degradation of vegetation reduced soil moisture by 5 to 10 %. In general, increasing the intensity of degradation caused an increase in soil temperature in the studied habitats. The values of pH and EC decreased by about 0.5 units with the increase of degradation intensity in both the vegetation types, and showed a decreasing trend with depth. Soil fertility characteristics, including N, P, Ca, K and Mg, showed a significant decrease (about 3 to 5 %) with the increase habitat degradation in forest and rangeland covers. Furthermore, in the studied sites, soil fauna including earthworms, acarina, collembola, nematodes, protozoa (about 1–2 %) and soil microflora including fungi, bacteria (about 1 %) decreased with the increase in the intensity of degradation. The highest effect of degradation was found in the topsoil of the studied habitats. From the point of view of soil multifunctional indicators, results showed that high and moderate degradation intensities are clearly different compared with light and non-degradation intensities. In addition, the intensity of degradation in light degraded and non degraded sites did not show a significant difference, thus ecosystem restoration is associated with fewer challenges.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108978"},"PeriodicalIF":5.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancing soil texture and organic carbon spatial variability assessment: Integrating proximal γ-ray spectroscopy and electromagnetic induction via data fusion for site-independent analysis","authors":"Angelica De Ros ,&nbsp;Ilaria Piccoli ,&nbsp;Luigi Sartori ,&nbsp;Beatrice Portelli ,&nbsp;Giuseppe Serra ,&nbsp;Nicola Dal Ferro ,&nbsp;Francesco Morari","doi":"10.1016/j.catena.2025.108980","DOIUrl":"10.1016/j.catena.2025.108980","url":null,"abstract":"<div><div>In this study we tested the combination of two proximal sensors –an electromagnetic conductivity meter (EMI) and a gamma(γ)-ray detector– to estimate the variability of some soil properties. The hypothesis was that the employment of data fusion techniques would provide a more comprehensive description of soil texture and soil organic carbon (SOC) content compared to using single sensors alone. This approach aimed to capture a spectrum of characteristics across various mineral and organic alluvial soils. Field surveys covering more than 60 ha were conducted in 2019 on five agricultural experimental sites, whose texture ranged from silty-clay to silty- and sandy-loam and SOC from 0.5 % to 21.9 %. A total of 354 undisturbed soil samples (0–30 cm) was collected and soil properties such as granulometry, bulk density and SOC concentration and stock determined. The fusion of proximal sensing data of apparent electrical conductivity (EC_a) and γ-ray radionuclides (total counts –TC–, ²³⁸U, ²³²Th, ⁴⁰K) combined with multivariate analysis was applied to describe soil spatial variability. Partial leas square regression (PLSR) and artificial neural network (ANN) models were trained and tested to predict the variability in soil properties within and between sites. Results showed that data fusion captured the soil spatial variability within and between fields, with a predictive ability (test set) to explain up to 88 % of clay and 74 % of SOC stock variability when all mineral soils were embedded in the ANN model. The combination of TC and EC_a was particularly effective in explaining texture and SOC heterogeneity within and across fields. In contrast, different responses were observed for single radionuclides, either ²³⁸U, ²³²Th, ⁴⁰K, or their ratios, within each field, that likely identified site-specific radioisotope enrichment and/or depletion processes. In conclusion, data fusion of EMI and γ-ray detectors accurately predicted soil texture and SOC across soils from alluvial origin.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108980"},"PeriodicalIF":5.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fire severity and its induced permafrost degradation drive vegetation recovery and succession in the permafrost region in the northern Da Xing’anling Mountains, NE China","authors":"Xiaoying Li ,&nbsp;Jingtao Li ,&nbsp;Huijun Jin ,&nbsp;Zhi Wen ,&nbsp;Tao Xu ,&nbsp;Kui Chen ,&nbsp;Ruixia He ,&nbsp;Hongwei Wang","doi":"10.1016/j.catena.2025.108970","DOIUrl":"10.1016/j.catena.2025.108970","url":null,"abstract":"<div><div>Under a warming climate, forest fires are becoming more severe and prolonged, leading to permafrost degradation and alterations in soil properties, vegetation composition, and community dynamics. The Da Xing’anling Mountains in Northeast China is the only mid-high latitude permafrost region in China, and a critical region of boreal forests disturbed by forest fires. However, studies on the effects of forest fires on the vegetation of boreal permafrost regions are lacking. This study investigated post-fire soil and vegetation characteristics in larch forests through field surveys and chronosequence approaches. The results revealed that: forest fires decreased organic layer thickness, moss layer thickness (MLT), and soil nutrients, while increased pH, depth of seasonal thawing (DST), and soil temperature. After fires, the dominant shrub species shifted from <em>Vaccinium vitis-idaea</em> and <em>Betula fruticosa</em> to these two and <em>Ledum palustre</em> species; the importance values of <em>Deyeuxia purpurea</em> increased, with a shift in dominant herbs species from <em>Carex bohemica</em> to <em>Deyeuxia purpurea, Carex cespitosa</em> and <em>Carex bohemica.</em> Forest fires promoted the growth of tall shrubs and high growth herbs. As time progressed after fires, the height of herbs and the aboveground biomass of trees gradually recovered, the aboveground biomass and cover of shrubs initially decreased before subsequently increasing. Notably, the changes in aboveground biomass and cover of herbs were exactly the opposite of those observed in shrubs. Eight years after fire, species diversity increased, but decreased with increasing fire severity 14 years after fire. In the early post-fire period, NH₄⁺-N and total nitrogen (TN) were the most important factor affecting the characteristics of understory vegetation; as time progressed after fires, the DST, TN and MLT became the main influencing factor. Overall, vegetation recovered gradually with increasing time post-fire, with light burns facilitating faster recovery than severe burns. This study provides valuable insights for ecological restoration in boreal permafrost region.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108970"},"PeriodicalIF":5.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate change impact on peatland dynamics during the Holocene in Latvia, Northeastern Europe","authors":"N. Stivrins ,&nbsp;L. Kalnina ,&nbsp;A. Cerina ,&nbsp;E. Reire ,&nbsp;S. Kreslina ,&nbsp;I. Ozola ,&nbsp;J. Soms ,&nbsp;S. Veski","doi":"10.1016/j.catena.2025.108965","DOIUrl":"10.1016/j.catena.2025.108965","url":null,"abstract":"<div><div>Peatlands are essential ecosystems for climate regulation and biodiversity yet they face increasing threats from human activities and climate change. The geological record of Northeastern Europe, including Latvia, reveals periods of warmer-than-present climatic conditions during the Holocene, offering valuable insights into historical peatland dynamics under changing climates. This study aims to evaluate the initiation and development of peatlands in Latvia during the Holocene, an epoch characterised by distinct long-term climate patterns. We analysed published and unpublished data – including radiocarbon dating, lithology and loss-on-ignition – from fen and raised bog sites in Latvia to assess their characteristics and responses to past climate conditions. Our findings indicate that the earliest peatlands, established approximately 11,000 years ago, were fens. Over the course of the Holocene, Latvian peatlands accumulated an average 4 m of peat, with maximum depths exceeding 8 m. Peat accumulation was most pronounced during the Early Holocene (11,700–8,200 years ago) and the Late Holocene (the last 4,200 years), coinciding with cool and moist hydroclimatic conditions. The highest rates of peat and carbon accumulation were observed during the Late Holocene, whereas peatland establishment was lowest during the Middle Holocene (8,200–4,200 years ago), when the climate was warmer and drier than today. These findings suggest that prolonged warming and drying – similar to Middle Holocene conditions – could significantly slow peat formation and carbon sequestration in Latvian peatlands under future climate warming scenarios.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108965"},"PeriodicalIF":5.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydro-sedimentological interactions between a tropical fluviokarst system and surface waters in the Brazilian Savannah","authors":"André Silva Tavares ,&nbsp;Joaquim Ernesto Bernardes Ayer ,&nbsp;Rogério Elias Soares Uagoda","doi":"10.1016/j.catena.2025.108966","DOIUrl":"10.1016/j.catena.2025.108966","url":null,"abstract":"<div><div>Karst environments are fragile. Their hydro-sedimentologic flows transport materials from various sources, and their hydrogeological recharge areas are diverse. They also suffer directly from the effects of surface water and soil degradation. In tropical regions, these flows intensify, accelerating hydro-sedimentological dynamics and degradation. This study assessed the hydro-sedimentological interactions between land use, surface water, and the fluviokarst system in the Extrema cave. The karstic system in the Lagoa do Jacaré Formation presents the main land uses and soil management of the Cerrado Biome and karst formations like caves, dolines, sinkholes, and springs. Data collection platforms were installed at the cave’s entrance and exit, recording level, turbidity, physicochemical variables, and sediment during floods, and a three-dimensional model of the area was created to evaluate structural and lithological dispositions. The Extrema cave has a perennial flow transporting materials from distinct sources. The solid discharge ranged from 1,082 Mg per day at the sinkhole to 1,630 Mg per day at the resurgence, indicating that approximately one-third of the material is transported through the karst conduit. This process primarily involves older upper layers of the Tarimba cave and adjacent dolines. Water samples revealed seasonal variations in basicity, indicating contributions of low mineralization water from sandstones of the upper aquifer and dilution processes in carbonate formations in the rainy season. The model indicated flows originate from different areas, elevating contamination susceptibility through sinkholes, caves, and karst fissures, common given the area’s hydrological regime. Thus, priorities were considered for the conservation of these karst systems, their uses, and management with high susceptibility to erosion, and the absence of riparian forests in the streams and surroundings of the sinkholes, given their capacity to affect the hydro-sedimentological dynamics in the Extrema cave.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108966"},"PeriodicalIF":5.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil organic carbon formation from plant and microbial residual carbon: Effects of home-field advantage and root litter quality","authors":"Huijun Li ,&nbsp;Baorong Wang ,&nbsp;Yue Zhou ,&nbsp;Haolin Zhang ,&nbsp;Chunhui Liu ,&nbsp;Xuan Yang ,&nbsp;Zhaolong Zhu ,&nbsp;Xuejuan Bai ,&nbsp;Gurpal S. Toor ,&nbsp;Shaoshan An","doi":"10.1016/j.catena.2025.108985","DOIUrl":"10.1016/j.catena.2025.108985","url":null,"abstract":"<div><div>Home-Field Advantage (HFA) hypothesis states that microorganisms specialized in decomposing local litter result in faster <em>in situ</em> decomposition compared to <em>ex situ</em>, enhancing soil organic carbon (SOC) formation <em>in situ</em> soils. Short-term litter decomposition (e.g., &lt; 3 years) typically exhibits the HFA effect. However, it remains unclear whether long-term (e.g., &gt; 5 years) microbial adaptation to substrates <em>in situ</em> or <em>ex situ</em> leads to a loss of HFA and how this impacts SOC accumulation from plant and microbial sources. To address this issue, we conducted a 7-year <em>in situ</em> and <em>ex situ</em> decomposition experiment using three typical root litters with different quality: <em>Stipa bungeana</em> (C/N = 81.7), <em>Thymus mongolicus</em> (C/N = 56.6), and <em>Artemisia sacrorum</em> (C/N = 43.2). Our findings challenge the conventional perspective by showing that HFA declines over time, likely due to long-term microbial adaptation to <em>ex situ</em> soil. This suggests that microorganisms can eventually acclimate to new environments, thereby reducing initial advantages observed <em>in situ</em>. Despite this, a pre-existing strong HFA accelerated root litter decomposition and SOC formation, increasing SOC by 19.9–152.7 % under <em>in situ</em>. This acceleration was primarily due to enhanced <em>in situ</em> microbial “<em>in vivo turnover</em>,” as evidenced by significant increases in fungal necromass C (294.6–312.1 %) and extracellular polymeric substances protein (EPS-protein, 4.8–92.1 %). Conversely, plant residual C contributed more to SOC in <em>ex situ</em> (14.3–17.8 %) than <em>in situ</em> (2.5–9.0 %), indicating stronger physical migration of plant residual in <em>ex situ</em>. Low-quality litter facilitated fungal residual C, EPS-protein, and SOC accumulation both <em>in situ</em> and <em>ex situ</em>, suggesting its suitability for biomass synthesis and microbial residual pool formation. This study clarifies the weakening of the HFA over time and the significant contribution of low-quality litter in increasing SOC. This study elucidates the mechanisms by which root decomposition enhances SOC accumulation, highlighting the critical role of HFA in root litter decomposition dynamics.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108985"},"PeriodicalIF":5.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid and significant lithium isotope response to afforestation in Icelandic topsoils","authors":"Xianyi Liu ,&nbsp;David J. Wilson ,&nbsp;Kevin W. Burton ,&nbsp;Bjarni Diðrik Sigurdsson ,&nbsp;Julia C. Bos ,&nbsp;Wesley T. Fraser ,&nbsp;Philip A.E. Pogge von Strandmann","doi":"10.1016/j.catena.2025.108967","DOIUrl":"10.1016/j.catena.2025.108967","url":null,"abstract":"<div><div>Silicate weathering plays an important role in pedogenesis and the carbon cycle. Lithium (Li) isotopes are an effective tracer for the silicate weathering intensity and have been employed extensively to quantify both modern and past silicate weathering processes. The presence of vascular plants is believed to significantly influence weathering processes and pedogenesis, but how exactly plants and their ecosystems influence the behaviour of silicate weathering and Li isotopes in soils is poorly constrained. Here, we explored this question by measuring plant organs and sequentially leached fractions from soil chronosequences in Iceland spanning 25–63 years following afforestation. We found that Li isotopes were significantly fractionated within the plants during Li transport from the roots towards the leaves, and propose that ⁶Li preferentially crosses vacuole membranes in cells, while ⁷Li is enriched in the vascular system and accumulates in the leaves. This intra-plant fractionation could be most pronounced during plant growth when plants are subject to an excess nutrient supply. The Li isotope compositions in the exchangeable, carbonate, and oxide minerals of the afforested soils were ∼ 10 ‰ higher than in those of the heathland soils, and such differences can be attributed to both the input of heavy Li isotopes from litterfall decomposition and the effect of afforestation-mediated secondary mineral formation. Overall, this study suggests that silicate weathering processes traced by Li isotopes can respond significantly and rapidly (&lt;25 years) to forest establishment, with important implications for paleoenvironmental reconstructions and the evolution of the critical zone.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108967"},"PeriodicalIF":5.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measuring water ponding time, location and connectivity on soil surfaces using time-lapse images and deep learning","authors":"Pedro Zamboni ,&nbsp;Mikesch Blümlein ,&nbsp;Jonas Lenz ,&nbsp;Wesley Nunes Gonçalves ,&nbsp;Jose Marcato Junior ,&nbsp;Thomas Wöhling ,&nbsp;Anette Eltner","doi":"10.1016/j.catena.2025.108919","DOIUrl":"10.1016/j.catena.2025.108919","url":null,"abstract":"<div><div>Rainfall simulations are an established method to gain knowledge on small-scale hydrological processes like infiltration, ponding and the formation of surface runoff. Due to limitations in measuring methods, these processes must usually be understood to happen homogeneously within the bounded plot area while it is well known that they actually vary on a subplot scale. Within this study we took high resolution time-lapse images of several plots to observe and quantify the subplot processes of ponding and the formation of connectivity and surface runoff.</div><div>We investigated the potential of deep learning in the segmentation of water ponding areas in time-lapse images during rainfall simulations and to estimate the ponding time. We trained three different Convolutional Neural Networks (CNNs), considering classification uncertainty and imbalance of the ground-truth data (water pixels) as well as ensemble modeling and spatial correlation between samples. Our findings suggest that addressing ground-truth annotation uncertainty and imbalance was more important in our study than the choice of the CNNs itself, and ensemble models increase the model performance leading to more robust predictions. Overall, our results suggest that CNNs have great potential to segment ponding areas, and thus it is possible to observe their spatio-temporal evolution.</div><div>When comparing the evolution of water ponding areas to runoff, different behaviors across the plots were observable, which could be related to differences in initial soil moisture and infiltration behaviors. Further, our image-based deep learning approach allows for direct measurement of the ponding time and can be considered a first step to spatially and temporally resolved mapping of infiltration rates.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108919"},"PeriodicalIF":5.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impacts of repeated forest fires and agriculture on soil organic matter and health in southern Amazonia","authors":"Mario Lucas Medeiros Naval ,&nbsp;Wanderlei Bieluczyk ,&nbsp;Facundo Alvarez ,&nbsp;Lidiany Camila da Silva Carvalho ,&nbsp;Leonardo Maracahipes-Santos ,&nbsp;Edmar Almeida de Oliveira ,&nbsp;Karina Gonçalves da Silva ,&nbsp;Maurivan Barros Pereira ,&nbsp;Paulo Monteiro Brando ,&nbsp;Ben Hur Marimon Junior ,&nbsp;Plínio Barbosa de Camargo ,&nbsp;Ted R. Feldpausch","doi":"10.1016/j.catena.2025.108924","DOIUrl":"10.1016/j.catena.2025.108924","url":null,"abstract":"<div><div>The Arc of Deforestation, a Cerrado-Amazon transition region, faces large-scale agricultural expansion and land degradation, fostering fire spread and recurrence, particularly during extreme droughts driven by climate change. While previous research has focused on aboveground changes, the impacts of fires on soil functions, such as carbon (C) storage and nutrient cycling, remain understudied. This study investigated how forest-to-agriculture conversion and fire frequency in standing forests affect soil C and nitrogen (N) in the Arc of Deforestation. We also examined the effects of these disturbances on stable isotopes (δ¹³C and δ¹⁵N) and how the changes in Soil Organic Matter (SOM) influence other soil health indicators. Four treatments were considered: (i) annual forest burns; (ii) forest burning every 3 years; (iii) undisturbed forest; and (iv) long-term agriculture. Annual burns depleted soil C stocks (0-30 cm) by 16 %, triennial burns by 19 %, and long-term agriculture by 38 %, compared to the undisturbed forest. Annual and triennial burns reduced aboveground C stocks by 40 % and 60 %, respectively, showing that fire impacts on soil and vegetation differed. In burned forests, δ¹³C indicated no grass invasion, remaining below −27 ‰ and rising slightly (∼ 2 ‰) with depth. In agricultural areas, the δ¹³C was uniform (−24 ‰) due to C₄ plants’ influence and soil mixing from tillage. The relationships between soil C and health indicators suggested that SOM depletion from fire and agriculture disrupted soil structure and negatively affected nutrient cycling. Our findings revealed long-lasting fire legacies in tropical forest soils, with SOM loss and harmful effects on soil health persisting nearly a decade after the fire, but no evident effect of fire frequency was found. Soil degradation was less severe when the forest was repeatedly burned than when converted to agriculture. Conservation and management practices prioritizing forest protection, wildfire prevention, and halting agricultural expansion are needed to preserve soil health in the Amazon.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108924"},"PeriodicalIF":5.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon dynamics and pathways in soil density fractions across different land-use types over 3000 years: Insights from 13C natural abundance","authors":"Mingxu Xu ,&nbsp;He Jiao ,&nbsp;Yalu Zhang ,&nbsp;Baowei Su ,&nbsp;Shuangwen Yi ,&nbsp;Huan Zhang ,&nbsp;Chao Gao","doi":"10.1016/j.catena.2025.108968","DOIUrl":"10.1016/j.catena.2025.108968","url":null,"abstract":"<div><div>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 &gt; 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.</div></div>","PeriodicalId":9801,"journal":{"name":"Catena","volume":"254 ","pages":"Article 108968"},"PeriodicalIF":5.4,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143679955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}