IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-29 DOI: 10.1016/j.catena.2024.108584

Chaogui Lei

Understanding the critical source areas (CSAs) of pollution and their key relationships with land use is essential for efficient water quality improvement. Despite much efforts to examine their influences on water quality, the role of topographic characteristics in land use processes acting on water quality in lowland regions remains unclear. Therefore, taking a typical rural lowland catchment-the Stör catchment (in northern Germany) as the study area, the influences of different land use types with varying slopes on sediment, total phosphorus (TP), and total nitrogen (TN) loads, as well as on the relevant CSAs of a single or combined index (I_j) were determined using an integrated approach that applies hydrologic model SWAT_3s (Soil and Water Assessment Tool, adapted with three groundwater aquifers) and multivariate statistical techniques. The results indicated: (1) sediment and nutrients have markedly declined from 1990 to 1991 over 2009–2011 to 2018–2019, particularly in summer and in comparatively steeper areas with slopes above 5%; (2) the subbasins in the southwest or northeast of the catchment dominated by larger arable fields with slope > 5% and urban areas were identified as CSAs; (3) the spatial heterogeneity of overall water quality was more explained in summer (75% on average) and particularly by croplands (50% on average); (4) water quality indicators were mostly and positively affected by cropland and pasture with relatively steeper slope (>5%). In particular, cropland with slopes > 5% was among those land use indicators producing the highest values of sediment, TP, TN, and I_j. This study demonstrates that the identification of seasonal CSAs could provide insights into the seasonal targeting of conservation practices. Furthermore, communicating model outputs to cause-effect analysis can help formulate slope-adaptability measures for water quality protection.

了解污染的关键来源区域及其与土地利用的关键关系对于有效改善水质至关重要。尽管为检查地形特征对水质的影响作出了许多努力，但地形特征在土地利用过程中对低地地区水质的作用仍不清楚。因此，以典型的农村低地流域- Stör流域（位于德国北部）为研究区，采用综合方法，应用水文模型SWAT3s （Soil and Water Assessment Tool，土壤和水评估工具），确定了不同土地利用类型和不同坡度对泥沙、总磷（TP）和总氮（TN）负荷的影响，以及对单个或组合指数（Ij）的相关csa的影响。适用于三个地下水含水层)和多元统计技术。结果表明：(1)2009-2011年至2018-2019年，1990 - 1991年泥沙和养分显著减少，特别是夏季和坡度大于5%的相对陡峭地区；(2)集水区西南或东北的子盆地以坡度较大的耕地为主；5%和城市地区被确定为CSAs；(3)总体水质的空间异质性主要体现在夏季（平均75%），尤其是农田（平均50%）；(4)坡度较大的农田和牧场对水质指标的影响最大，且正相关（>5%）。特别是有斜坡的农田。5%是产生沉积物、TP、TN和Ij值最高的土地利用指标。该研究表明，季节性csa的确定可以为保护措施的季节性目标提供见解。此外，将模型输出传递到因果分析中，有助于制定水质保护的坡面适应性措施。

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引用次数: 0

Pleistocene pedogenic carbonates from alluvial paleosols in eastern Sudan reveal a semi-arid and seasonal climate, similar to today 来自苏丹东部冲积古土壤的更新世成土碳酸盐揭示了与今天类似的半干旱和季节性气候

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-29 DOI: 10.1016/j.catena.2024.108583

Mosab Mohammednoor , Faysal Bibi , Ulrich Struck , Ali Eisawi , Robert Bussert

Pedogenic carbonates can provide important information regarding paleoclimatic conditions. Compared with East Africa, Pleistocene pedogenic carbonates in Sudan, particularly calcretes, have received very little attention, particularly with regard to local paleoclimatic reconstructions. Pleistocene alluvial sediments aged from ∼230 to <17 ka were deposited along the middle Atbara River in eastern Sudan. Intercalated in these alluvial deposits are paleosols in which different types of pedogenic carbonates occur. Petrographic, mineralogical and isotopic analyses were performed to reconstruct the regional paleoenvironmental conditions. The investigated pedogenic carbonates are appropriate for paleoclimatic reconstruction because they are free of inherited carbonate and diagenetic modification. The paleosols identified in a previous study as Aridisols/Calcisols contain calcrete horizons that consist of an orthic nodular horizon, sometimes overlain by a laminar horizon. Paleosols identified as Vertisols contain slickensides, and disorthic and septaric nodules. The paleosols show stable carbon and oxygen isotope values ranging between −9.12 and −5.12 ‰, and between −7.25 and −4.09 ‰, respectively. Supporting the previous study, the inferred climatic conditions were arid to semi‐arid, with a mixture of C₃ and C₄ vegetation cover, and paleoprecipitation greater than 350 mm/yr, similar to that of the present-day, with likely higher rainfall during the formation of Vertisols than Aridisols/Calcisols. The thickness and morphology of Pleistocene calcretes in eastern Sudan are similar to those in East Africa, suggesting similar climatic conditions during their formation. Well-and weakly-developed calcretes in Aridisols formed in distal and proximal floodplains, respectively, whereas well-developed vertic horizon in Vertisols formed in distal floodplains.

成土碳酸盐可以提供有关古气候条件的重要信息。与东非相比，苏丹更新世成壤碳酸盐岩，特别是钙质碳酸盐岩，在当地古气候重建方面受到的关注很少。苏丹东部沿阿特巴拉河中部沉积了年龄为~ 230 ~ 17ka的更新世冲积沉积物。在这些冲积矿床中穿插着各种类型的成土碳酸盐的古土壤。通过岩石学、矿物学和同位素分析，重建了该区的古环境条件。研究的成土碳酸盐不受继承碳酸盐和成岩作用的影响，适合古气候重建。在先前的研究中被确定为干粉土/钙质土的古土壤含有钙质层，钙质层由一个斜块状层组成，有时被层流层覆盖。被确定为垂直土层的古土壤含有滑溜苷，以及不规则和分离的结核。古土壤碳、氧同位素稳定值分别在- 9.12 ~ - 5.12‰和- 7.25 ~ - 4.09‰之间。支持先前的研究，推断出的气候条件为干旱至半干旱，C3和C4植被覆盖混合，古降水量大于350毫米/年，与当今相似，在垂直土壤形成期间的降雨量可能高于干旱区/钙化区。苏丹东部更新世钙质岩石的厚度和形态与东非相似，表明它们形成时的气候条件相似。干旱区发育良好和发育较弱的钙质层分别形成于远端和近端洪泛平原，而发育良好的垂直层形成于远端洪泛平原。

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引用次数: 0

Source and degradation of soil organic matter in different vegetations along a salinity gradient in the Yellow River Delta wetland 黄河三角洲湿地盐度梯度下不同植被土壤有机质来源与退化

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-29 DOI: 10.1016/j.catena.2024.108603

Xin Ni , Guangming Zhao , John R. White , Peng Yao , Kehui Xu , Yadav Sapkota , Jiancong Liu , Hao Zheng , Dapeng Su , Lei He , Qiang Liu , Shixiong Yang , Hongming Yuan , Xigui Ding , Yao Zhang , Siyuan Ye

Salt marsh wetlands exhibit high carbon capture and storage capabilities, which are crucial for mitigating climate change. However, the mechanisms of soil organic carbon (SOC) sequestration in coastal deltaic salt marsh wetlands are not well understood. To bridge this gap, we present new findings on the distribution, sources, and decomposition of SOC in the Yellow River Delta wetland, focusing on four vegetation types along a salinity gradient: Phragmites australis, Tamarix chinensis, Suaeda salsa, and Spartina alterniflora. The input of litter was found to be the primary factor affecting SOC at the depth from 20 to 100 cm, while microbial degradation and clay content were the main factors in the deeper soil layers between 20 and 100 cm. The SOC in all four communities was predominantly derived from recalcitrant organic carbon (81 %–99 %). A Monte Carlo model revealed that terrestrial sources accounted for 61 % of SOC, plant sources for 31 %, and marine sources for 8 %. The vertical distribution of δ¹³C profiles in Phragmites australis and Spartina alterniflora communities was influenced by preferential utilization of ¹²C and substrate, with SOC degradation rate constants of 0.28 and 1.02 per annum (a⁻¹), respectively. The invasion of Spartina alterniflora has led to a significant increase in the easily oxidizable carbon (EOC) to SOC ratio, thus reducing SOC stability, which underscores the importance of mitigating Spartina alterniflora invasion. SOC stability was increased by evaluated salinity in the Yellow River Delta wetland, which was higher than that in Chinese coastal wetlands.

盐沼湿地具有较高的碳捕获和储存能力，这对减缓气候变化至关重要。然而，滨海三角洲盐沼湿地土壤有机碳固存机制尚不清楚。为了弥补这一空白，我们提出了黄河三角洲湿地有机碳的分布、来源和分解的新发现，重点研究了沿盐度梯度的四种植被类型：芦苇、柽柳、沙豆叶和互花米草。在20 ~ 100 cm土层中，凋落物的输入是影响土壤有机碳的主要因素，而在20 ~ 100 cm土层中，微生物降解和粘土含量是影响土壤有机碳的主要因素。4个群落的有机碳主要来自顽固性有机碳（81% ~ 99%）。蒙特卡罗模型显示，陆地碳源占61%，植物碳源占31%，海洋碳源占8%。芦苇和互花米草群落δ13C剖面垂直分布受12C和底物优先利用的影响，有机碳降解速率常数分别为0.28和1.02 /年（a−1）。互花米草的入侵导致互花米草易氧化碳（EOC）与有机碳（SOC）之比显著升高，从而降低了SOC的稳定性，这凸显了减少互花米草入侵的重要性。评价盐度提高了黄河三角洲湿地的有机碳稳定性，高于中国滨海湿地。

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引用次数: 0

Key factors driving soil diazotrophic community assembly and nitrogenase activity in Qinghai-Tibet alpine meadows 青藏高寒草甸土壤重氮营养群落组合及氮酶活性的关键驱动因素

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-29 DOI: 10.1016/j.catena.2024.108600

Qun Wang , Changting Wang , Li Lei , Yiming Jing , Nan Lan , Xiangzhen Li , Jiabao Li

Biological nitrogen (N) fixation by soil diazotrophs is the primary source of nitrogen for natural grasslands, especially at high altitudes such as alpine meadow ecosystems. However, the mechanisms shaping the compositions and assembly processes of diazotrophic communities, as well as soil nitrogenase activity in alpine meadows remain poorly understood. In this study, 241 soil samples were collected from alpine meadows on the Qinghai-Tibet Plateau to investigate the distribution patterns and driving factors of diazotrophic communities and nitrogenase activities. Our results showed that soil N fixation potential across all samples ranged from 28.8 to 110 nmol C₂H₄ g^-1h^-¹, and Nitrospirillum and Bradyrhizobium were the most dominant diazotrophic genera. The composition and diversity of soil diazotrophic communities were mainly influenced by soil pH, and to a lesser extent by aridity index and mean annual precipitation. The abundance of nifH gene decreased linearly with soil pH, whereas the ɑ-diversity increased linearly with soil total phosphorus. Null model analysis indicated that deterministic processes governed diazotrophic community assembly, and more acidic soil conditions led to more phylogenetically clustered diazotrophic communities. Partial least squares path modeling and linear regression analyses identified diazotrophic community composition, followed by climatic factors, nifH gene abundance and total phosphorus, as the dominant regulators of soil N fixation potential in alpine meadows. Unexpectedly, soil N fixation potential was not closely related to dominant diazotrophic genera, diversity, or assembly, but highly related to the less abundant diazotrophs. This study provides a novel insight into the ecological mechanisms shaping soil biological nitrogen fixation in alpine meadow ecosystems.

土壤重氮营养体的生物固氮是天然草地氮的主要来源，特别是在高寒草甸生态系统中。然而，对高寒草甸重氮营养群落组成和组装过程的形成机制以及土壤氮酶活性的了解仍然很少。本研究以青藏高原高寒草甸为研究对象，收集了241份土壤样品，探讨了重氮营养群落和氮酶活性的分布格局及其驱动因素。结果表明：土壤固氮势在28.8 ~ 110 nmol C2H4 g-1h-1之间，氮螺旋菌和慢生根瘤菌是重氮营养菌属中最具优势的。土壤重氮营养群落的组成和多样性主要受土壤pH值的影响，其次受干旱指数和年平均降水量的影响。nifH基因丰度随土壤pH值呈线性下降，而nifH基因多样性随土壤全磷呈线性增加。零模型分析表明，确定性过程控制重氮营养群落的聚集，酸性土壤条件越强，重氮营养群落在系统发育上聚集越多。偏最小二乘路径模型和线性回归分析表明，重氮营养群落组成是高寒草甸土壤固氮潜力的主要调节因子，其次是气候因子、氮肥基因丰度和全磷。出乎意料的是，土壤固氮势与重氮营养菌的优势属、多样性或组合关系并不密切，而与重氮营养菌数量较少的重氮营养菌高度相关。本研究为高寒草甸生态系统土壤生物固氮形成的生态机制提供了新的视角。

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引用次数: 0

Assessment and correction of representational bias in phytoliths from modern soil in the Dongting Lake Basin, China 洞庭湖盆地现代土壤植物岩代表性偏差评价与校正

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-29 DOI: 10.1016/j.catena.2024.108591

Lidan Liu

Understanding how well topsoil phytoliths represent their aboveground plant communities, and then correcting for any representational bias, is the basis for the accurate phytolith-based reconstruction of past vegetation. We evaluated the representational bias in topsoil phytoliths at 39 sampling sites in forest, shrub, and herb communities in the Dongting Lake Basin, China. We compared the types, concentrations, and percentages of topsoil phytoliths and corresponding plant community phytoliths within the same plant community and quantified the relationships. We observed significant representational biases. Combined with the representation indices of phytoliths, we quantitatively defined the vegetation representativeness of different phytolith types in the topsoil samples. We defined four categories of representation: Associated types, Over-represented types, Under-represented types, and “Special” types. We observed differences in the vegetation representativeness of different topsoil phytolith types, and the same phytolith type also showed significant differences in vegetation representativeness between different plant communities. Additionally, using the preservation index (R-value), we corrected the representational bias of topsoil phytoliths between the different plant communities. After validation, we found that the corrected topsoil phytoliths more accurately represented quantitative changes in the aboveground plant communities. Therefore, the preservation index (R value) is an effective means of correcting the representational bias of topsoil phytoliths, and it can provide the basis for more accurate phytolith-based reconstructions of past vegetation.

了解表土植物岩如何很好地代表其地上植物群落，然后纠正任何代表性偏差，是基于植物岩准确重建过去植被的基础。我们对洞庭湖流域森林、灌木和草本群落的39个采样点的表层土壤植物岩的代表性偏差进行了评估。我们比较了同一植物群落中表层土壤植物岩与相应植物群落植物岩的类型、浓度和百分比，并量化了它们之间的关系。我们观察到显著的代表性偏差。结合植物岩代表性指标，定量界定了不同类型植物岩在表土样品中的植被代表性。我们定义了四种表示类型：关联类型、过度表示类型、未充分表示类型和“特殊”类型。我们观察到不同表层土壤植物岩类型的植被代表性存在差异，同一植物岩类型在不同植物群落之间的植被代表性也存在显著差异。此外，利用保存指数（r值），我们纠正了不同植物群落间表层土壤植物岩的代表性偏差。经过验证，我们发现修正后的表层土壤植物岩更准确地反映了地上植物群落的数量变化。因此，保存指数（R值）是纠正表土植物岩代表性偏差的有效手段，可以为更准确地重建过去植被提供依据。

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引用次数: 0

Bulk density and coarse fragment content of the French soil monitoring network for better assessment of changes of soil organic carbon stocks 法国土壤监测网络的容重和粗粒含量，以便更好地评估土壤有机碳储量的变化

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-29 DOI: 10.1016/j.catena.2024.108609

José-Luis Munera-Echeverri, Line Boulonne, Dominique Arrouays, Nicolas Saby, Nicolas Soler-Dominguez, Céline Ratié, Claudy Jolivet, Manuel P. Martin

Bulk density (BD) and coarse fragments (CF) are often missing in soil monitoring networks. In the French Soil Quality Monitoring Network BD and CF have been measured in two campaigns in sites distributed in a grid over mainland France. The objective of this work is to evaluate i) how BD and CF have changed, ii) how volumetric methods and land use affect the observed trends, and iii) to simulate the impact of BD and CF changes on the estimations of changes of soil organic carbon stocks (SOCS). The results showed no significant change of (Δ) CF between campaigns in either the topsoil or subsoil, while there was a significant decrease of BD only in the topsoil (−3.1 ± 0.9 %). When methods were constant in both campaigns, BD decreased in croplands and grasslands topsoil and it did not change in forests. We could explain a rather low part of the ΔBD variance (R² = 0.21), mostly linked to the within-site variability of CF and to changes in some methodological aspects between campaigns. We simulated changes in topsoil SOCS, assuming SOC content constant over time; we found negative estimates that were the largest in soils with low CF content (−0.2 ± 0.06 % yr⁻¹ an^-1) as well as differences between using site-specific average CF values over both campaigns and using site-specific values of each campaign [-0.17 ± 0.04 % yr⁻¹ vs −0.05 ± 0.06 % yr⁻¹, respectively]. These differences were caused by rocky soils, and were not significant when using only sites with low CF content. Our work highlights some limitations in assessing BD changes using broad-scale soil monitoring networks. These findings have important consequences on the methods used to assess changes in SOCS and their uncertainties at broad-scale. They are timely and relevant given the current proposals to implement soil health monitoring at national, continental and global scale.

土体容重（BD）和粗粒（CF）在土壤监测网络中经常缺失。在法国土壤质量监测网络中，BD和CF在法国大陆网格分布的两个地点进行了测量。本研究的目的是评估1)土壤有机质含量和土壤有机质含量是如何变化的；2)体积方法和土地利用对观测趋势的影响；3)模拟土壤有机质含量和土壤有机质含量变化对土壤有机碳储量（SOCS）变化估算的影响。结果显示，（Δ） CF在运动期间表土和底土均无显著变化，而BD仅在表土中显著降低（- 3.1±0.9%）。在两种运动方法不变的情况下，农田和草地表层土壤的生物量均有所下降，森林的生物量没有变化。我们可以解释ΔBD方差的一个相当低的部分（R2 = 0.21），主要与CF的站点内变异性和运动之间的一些方法学方面的变化有关。我们模拟了表层土壤SOC的变化，假设SOC含量随时间不变；我们发现，在低CF含量的土壤中，负估计最大（- 0.2±0.06% yr -1 an-1），以及在两个运动中使用特定地点的平均CF值与使用每个运动的特定地点值之间的差异[分别为-0.17±0.04% yr -1 vs - 0.05±0.06% yr -1]。这些差异主要是由岩石土壤引起的，而仅使用低CF含量的场地时差异不显著。我们的工作强调了使用大规模土壤监测网络评估BD变化的一些局限性。这些发现对用于评估SOCS变化及其在大尺度上的不确定性的方法具有重要影响。鉴于目前在国家、大陆和全球范围内实施土壤健康监测的建议，这些建议是及时和相关的。

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引用次数: 0

Changes in accumulation of land-based organic matter under recent climate change and anthropogenic impact: A tropical coastal perspective 近期气候变化和人为影响下陆基有机质积累的变化：热带沿海视角

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-29 DOI: 10.1016/j.catena.2024.108611

Ming Liu , Yazhi Bai , Li Jiang , Limin Hu , Bin Wu , Shuqing Qiao , Weini Chong , Narumol Kornkanitnan , Somkiat Khokiattiwong , Xuefa Shi

Tropical continental shelves play an important role in the global carbon cycle especially in the context of increased anthropogenic interference and climate change. However, the long-term fate and response of sedimentary organic carbon (OC) in these regions remain poorly understood. In this study, we analyzed bulk OC and molecular biomarkers in a sediment core collected from the lower Gulf of Thailand, and compiled with several published records of sedimentary organic matter (OM) from other tropical Asian margins. Our results reveal a dramatic ∼ 40 % increase in terrestrial OC inputs since the 1980s, likely driven by the effects of accelerated coastal erosion from rising sea levels and the degradation of mangrove ecosystems. In addition, shifts in regional human activities, including changes in energy consumption patterns, have altered the sources of pyrogenic OM, contributing to the observed spatial and temporal variability of anthropogenic OM across tropical coastal margins. Molecular fingerprints highlight recent changes in the accumulation of land-based OM, showing an increased presence of erosion-derived and degraded OC, along with pyrogenic OM. This shift is linked to the combined effects of coastal retreat and basin-wide emissions, influenced by both natural climate forces and anthropogenic activities.

热带大陆架在全球碳循环中发挥着重要作用，特别是在人为干扰和气候变化加剧的背景下。然而，这些地区沉积有机碳（OC）的长期去向和响应尚不清楚。在这项研究中，我们分析了在泰国湾下游收集的沉积物岩心中的大块OC和分子生物标志物，并与其他热带亚洲边缘的沉积有机质（OM）记录进行了汇编。我们的研究结果显示，自20世纪80年代以来，陆地OC输入急剧增加了40%，这可能是由于海平面上升和红树林生态系统退化加速海岸侵蚀的影响。此外，区域人类活动的变化，包括能源消费模式的变化，已经改变了热源性有机质的来源，导致观测到的热带沿海边缘人为有机质的时空变化。分子指纹图谱强调了陆基有机质积累的近期变化，表明侵蚀性和降解性有机质以及热原性有机质的存在增加。这种转变与海岸退缩和全流域排放的综合影响有关，受到自然气候力量和人为活动的影响。

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引用次数: 0

Late holocene vegetation succession and climate change in the Central Plains of China: Evidence from a high-resolution pollen record 中国中原地区晚全新世植被演替与气候变化：来自高分辨率花粉记录的证据

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-28 DOI: 10.1016/j.catena.2024.108589

Peng Chen , Xuewen Zhou , Liran Hu , Chang Liu , Zhengchuang Hui

Changes in the East Asian summer monsoon precipitation will have a significant impact on China’s politics, economy, and social development. To explore the controls and drivers of the Late Holocene (∼3350–2560 cal. yr. BP) vegetation succession and East Asian summer monsoon precipitation changes in the Central Plains of China, we conducted pollen analysis of the Pu Tian core collected from Zhengzhou, China. The results showed three periods of vegetation and East Asian summer monsoon variation: coniferous and broad-leaved mixed forest between ∼3350–3025 cal. yr. BP, increasing forest vegetation dominated by broadleaf Betula between ∼3025–2930 cal. yr. BP, decreasing forest vegetation and increasing herbaceous plants dominated by Artemisia and Poaceae between ∼2930–2560 cal. yr. BP. Weighted Averaging Partial Least Squares Regression was used to quantitatively reconstruct the average annual precipitation variation in the Central Plains of China. Our precipitation reconstruction and its comparison to other reconstructions and forcing show that it was influenced by internal (intertropical convergence zone and El Niño-Southern Oscillation) and external (Northern Hemisphere Summer Insolation) forcing. Specifically, average annual precipitation decreased significantly between ∼2980–2680 cal. yr. BP, and tree pollen (such as Betula) also decreased significantly during this period, possibly related to the “2.8 ka” event (a weak monsoon event in the Holocene). Our comparison of the published climate and environmental records of the East Asian monsoon region suggests that the 2.8 ka event exhibiting a “W” structure of “dry-wet-dry” and may have been caused by the weakening of solar activity, which affected the climate of the East Asian monsoon region through oceanic and terrestrial atmospheric circulation such as El Niño-Southern Oscillation.

东亚夏季风降水的变化将对中国的政治、经济和社会发展产生重大影响。为了探讨中国中原地区晚全新世（~ 3350 ~ 2560 cal.yr . BP）植被演替和东亚夏季风降水变化的控制因素和驱动因素，我们对郑州浦田岩心进行了花粉分析。结果表明，植被和东亚夏季风的变化有3个时期：在~ 3350 ~ 3025 cal. yr. BP之间，针叶阔叶混交林增加；在~ 3025 ~ 2930 cal. yr. BP之间，以阔叶桦树为主的森林植被增加；在~ 2930 ~ 2560 cal. yr. BP之间，以蒿科和禾科为主的森林植被减少，草本植物增加。采用加权平均偏最小二乘回归定量重建了中国中原地区年平均降水变化。我们的降水重建及其与其他重建和强迫的比较表明，它受到内部（热带辐合带和El Niño-Southern振荡）和外部（北半球夏季日照）强迫的影响。具体来说，年平均降水量在~ 2980 ~ 2680 cal. yr. BP之间显著减少，树木花粉（如桦树）在此期间也显著减少，这可能与“2.8 ka”事件（全新世的弱季风事件）有关。对比已发表的东亚季风区气候环境记录，认为2.8 ka事件表现为“干-湿-干”的“W”型结构，可能是太阳活动减弱引起的，太阳活动减弱通过El Niño-Southern涛动等海洋和陆地大气环流影响了东亚季风区气候。

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引用次数: 0

Spatiotemporal variations and driving factors of buried organic carbon in mangrove sediments of China: Based on δ13C values 中国红树林沉积物中埋藏有机碳的时空变化及其驱动因素——基于δ13C值

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-28 DOI: 10.1016/j.catena.2024.108571

Bingshuai Liu , Peng Xia , Yao Zhang , Jun Du , Xianen Luo

Mangroves, as significant coastal carbon reservoirs, play a pivotal role in the global carbon cycle. However, the detailed data on mangrove organic carbon (OC) burial is patchy in China, owing to regional discrepancies in spatiotemporal variations and driving factors. To fill this gap, the end-member mixing models based on δ¹³C and C/N values were used to calculate the relative contributions of terrestrial, mangrove, and marine OC, based on 28 sediment cores collected from five typical mangroves in China. The organic carbon burial flux (OCBF) and stocks (OCS) were calculated to be 133.93 ± 106.56 (n = 28) g C m⁻² yr⁻¹ and 126.91 ± 52.45 (n = 28) Mg C ha⁻¹, respectively, which were lower than the global averages. The study indicated that there were no significant latitudinal variations in mangrove OCS. The reason was that these sampling sites in high latitudes were mostly located at estuaries, exhibiting relatively higher sedimentation rates. The increase in terrestrial OC derived from river inputs effectively offset the decline in mangrove productivity. Therefore, sedimentation rates should be the main driving factor for spatiotemporal variations of mangrove OC burial in China.

红树林作为重要的沿海碳库，在全球碳循环中发挥着关键作用。然而，由于时空变化和驱动因素的区域差异，中国红树林有机碳埋藏的详细数据并不完整。为了填补这一空白，采用基于δ13C和C/N值的端元混合模型，基于中国5个典型红树林的28个沉积物岩心，计算了陆地、红树林和海洋OC的相对贡献。有机碳埋藏通量（OCBF）和储量（OCS）分别为133.93±106.56 (n = 28) g C m−2 yr−1和126.91±52.45 (n = 28) Mg C ha−1，均低于全球平均水平。研究表明，红树林OCS的纬向变化不显著。原因是这些高纬度采样点大多位于河口，沉积速率相对较高。河流输入带来的陆地OC的增加有效地抵消了红树林生产力的下降。因此，沉积速率应该是中国红树林OC埋藏时空变化的主要驱动因素。

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引用次数: 0

Bacterial and fungal diversity, community composition, functional groups, and co-occurrence network succession in dryland and paddy soils along a 3000-year chronosequence 3000年来旱地和水田土壤细菌和真菌多样性、群落组成、功能群和共现网络演替

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena

Pub Date : 2024-11-28 DOI: 10.1016/j.catena.2024.108582

He Jiao , Mingxu Xu , Jiachen Ji , Yonghong Wang , Yalu Zhang , Baowei Su , Huan Zhang , Chao Gao

There is a limited understanding of soil microbial community successional trajectories during dryland and paddy soil long-term management after wetland reclamation. We examined the effects of long-term reclamation on the microbial diversity, community composition, functional groups, and co-occurrence network in dryland and paddy soils using a 3000-year soil chronosequence established in the floodplain of the middle and lower Yangtze River, employing the “space-for-time” method and 16S rRNA and ITS amplicon sequencing. Over time, reclaimed land experienced varying losses in microbial richness and diversity, with paddy soils exhibiting higher alpha diversity than drylands due to greater resources and ecological niches. Proteobacteria dominated drylands, Chloroflexi prevailed in paddy soils, and fungal communities in both land-use types were primarily Ascomycota and Basidiomycota. Functional predictions showed higher chemoheterotrophy and aerobic_chemoheterotrophy in dryland soils and more animal_parasites_or_symbionts and dung_saprotrophs in paddy soils. During the 2000–3000 year reclamation, the abundance of pathogens increased, posing risks to agricultural production. Co-occurrence network analysis indicated that, compared to paddy soils, dryland soils may form a more complex and stable microbial cooperative network. Soil organic carbon and pH influenced microbial communities in drylands, while bulk density and cation exchange capacity were crucial in paddy soils. Partial least squares path modeling indicated that reclamation duration impacts microbial network complexity and diversity, with soil properties regulating paddy soil microbial networks. These findings broaden our understanding of microbial community succession in dryland and paddy soils after long-term wetland reclamation, supporting soil health and sustainable agriculture.

对湿地复垦后旱地和水田土壤长期管理过程中土壤微生物群落演替轨迹的认识有限。利用长江中下游河漫滩建立的3000年土壤时间序列，采用16S rRNA和ITS扩增子测序方法，研究了长期垦殖对旱地和水稻土微生物多样性、群落组成、功能群和共生网络的影响。随着时间的推移，复垦土地的微生物丰富度和多样性发生了不同程度的损失，由于资源和生态位的增加，水稻土比旱地表现出更高的α多样性。干旱地以变形菌门为主，水稻土以绿菌门为主，两种土地利用类型真菌群落均以子囊菌门和担子菌门为主。功能预测表明，旱地土壤具有较高的化学异养性和好氧化学异养性，而水田土壤具有较高的动物寄生共生体和粪养体。在2000-3000年的垦殖过程中，病原菌数量增加，对农业生产构成威胁。共生网络分析表明，与水稻土相比，旱地土壤可能形成一个更复杂、更稳定的微生物协同网络。土壤有机碳和pH值影响旱地微生物群落，而容重和阳离子交换量对水稻土微生物群落影响较大。偏最小二乘路径模型表明，垦殖时间影响水稻土微生物网络的复杂性和多样性，土壤性质对水稻土微生物网络具有调节作用。这些发现拓宽了我们对长期湿地复垦后旱地和水稻土微生物群落演替的认识，为土壤健康和农业可持续发展提供了支持。

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引用次数: 0

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