首页期刊导航|Geoderma: An International Journal of Soil Science
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Geoderma: An International Journal of Soil Science
Elsevier Science Publishers
Geoderma: An International Journal of Soil Science

Elsevier Science Publishers

0016-7061

Geoderma: An International Journal of Soil Science/Journal Geoderma: An International Journal of Soil Science
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    Humipedon dynamics in lowland Amazonian forests: are there Amphi humus forms even in tropical rain forests?

    Cesario, Fernando VieiraBalieiro, Fabiano de CarvalhoMazzei, Lucas
    12页
    查看更多>>摘要：Understanding humipedon dynamics is crucial to capture forest ecological processes. However, studies disentangling humipedon dynamics in tropical forests are scarce. The humipedon structure classification is important because it shows how forest ecosystems interact and react with (a)biotic factors. Here, we used the humus morpho-functional approach to investigate how soil texture and reduced impact-logging affect forest humipedon structure and dynamics in the eastern Amazon. We used a morpho-functional classification of humus forms as the foundation to visualize, classify, and code 133 soil profiles in two contrasting soil textures and different postlogging practices, to identify litter leaching, fragmentation, and humification processes coupled with soil aggregation and root dynamics. The classification of humus forms resulted in the identification of three humus systems: Mull, Moder and Amphi. Sandy and clayey textures differ statistically (chi 2 = 51.83; p < 0.001), with sandy texture predominating in Moder system, while clayey texture exhibits Amphi or Mull systems. Sandy textures presented a weak soil aggregation, but strong association with root (rhiOF) and humification (OH) horizons, leading to a clear transition between organic and mineral pools. In contrast, clayey textures show a strong carbon storage and soil aggregation. The humipedon horizons differ significantly (p = 0.009; stress = 0.1142 and R2 = 0.987) and their dynamics clearly evolve towards an opposite direction. The classification framework introduced here supports environmental management by promoting speed and viability in diagnosing forest ecosystem soils towards forest protection or use in the landscape, and specific climate mitigation goals both in local and regional planning.
      原文链接:
    • NSTL
    • Elsevier

    Iron speciation in soil size fractions under different land uses

    Giannetta, BeatricePlaza, CesarThompson, AaronPlante, Alain F....
    10页
    查看更多>>摘要：Iron (Fe) (oxyhydr)oxides represent a significant phase for the organic carbon (OC) stabilization. Due to their high surface areas, short-range-ordered Fe minerals, like ferrihydrite, show a higher ability to stabilize OC than crystalline secondary minerals, like lepidocrocite, goethite, and magnetite. However, how Fe phases and their crystallinity relate to soil organic matter (SOM) composition is still not completely known. We investigated Fe solid phase speciation in two soil particle size fractions (i.e., fine sand - FSa - and fine silt and clay - FSi + Cl -), isolated from coniferous (CF) and broadleaved forest soils (BF), grassland soils (GL), and technosols (TS). All samples were characterized by Fe K-edge extended X-ray absorption fine structure (EXAFS) and X-ray diffraction, and a subset by 57Fe Mo & BULL;ssbauer spectroscopy. Further, ramped combustion thermal analyses (coupled differential scanning calorimetry (DSC) and CO2 evolved gas analysis (CO2-EGA)) were used to evaluated SOM stability. With the only exception of TS, goethite was the main Fe phase in FSa fractions, whereas less crystalline phases (i.e., ferrihydrite, based on EXAFS) dominated the FSi + Cl fractions. The proportion of goethite and ferrihydrite in both fractions decreased with increasing OC content, while that of Fe(III)-SOM in FSa increased with increasing OC content. Mo & BULL;ssbauer and EXAFS data clearly indicated a presence of hematite in GL soils. Our data suggest that more crystalline Fe forms, like goethite and hematite, may be important for OC abundance in the FSa fraction and in soils with high OC contents, like GL. Thermal analysis showed the dominance of mineral associated organic matter in low-OC soils, and of plant residues in high-OC soils. As a whole, we posit that the FSi + Cl fractions contain Fe phases of less crystallinity because of presumed association with SOM, and that SOM in the FSi + Cl fraction is also more thermodynamically stable than in FSa, although differences are observed across land uses. Our observations suggest that the nature of Fe-SOM interactions can vary substantially with soil particle size and land use, which has important implication for SOM persistence.
      原文链接:
    • NSTL
    • Elsevier

    Do morphological traits of ground-dwelling ants respond to land use changes in a neotropical landscape?

    Sanabria, CatalinaBarot, SebastienFonte, Steven J.Dubs, Florence...
    9页
    查看更多>>摘要：Analyzing the impacts of agricultural activities on biodiversity requires a full knowledge of the ecology of the studied species. Using a trait-based approach may improve our ability to understand land use impacts on less well-studied species in order to establish general trends that will facilitate the prediction of these impacts. In this study, we applied a trait-based approach to understand the impact of land use change on ant communities in the Colombian Llanos region. Five common land uses were considered (annual crops, rubber plantations, oil palm plantations, improved pastures and semi-natural savannas) to test whether some morphological traits respond to soil properties and land uses. An RLQ analysis shows a significant common structure between species distribution, environmental factors, and morphological ant traits. This indicates that morphological traits could be used to predict the response of ant communities in different land uses since they respond to environmental characteristics as vegetation complexity, composition and management. Based on the selected morphological ant traits, three groups of land uses were differentiated: grazing-based systems, agroforestry plantations and annual crops. Agroforestry plantations, especially rubber plantations tend to host larger and specialized ant species, while grazing-based systems (i.e. improved pastures) mainly host small and generalist ants, and annual crops host more pigmented ants. These findings suggest that certain morphological traits can reflect the ability of ant species to settle down and survive in a given land use system. Our study shows that improving knowledge about trait environment associations could be a useful way to better understand how ecological filtering shape neotropical ant communities and how they respond to landscape transformation and land use changes.
      原文链接:
    • NSTL
    • Elsevier

    Land use-land cover gradient demonstrates the importance of perennial grasslands with intact soils for building soil carbon in the fertile Mollisols of the North Central US

    Sanford, Gregg R.Jackson, Randall D.Rui, YichaoKucharik, Christopher J....
    11页
    查看更多>>摘要：The impact of land use change and agricultural management on the cycling of soil organic carbon (SOC) is not well understood, limiting our ability to manage for, and accurately model, soil carbon changes at both local and regional scales. To address this issue, we combined long-term soil incubations with acid-hydrolysis and dry combustion to parse total SOC (Ct) into three operationally defined SOC pools (active, slow, and recalcitrant) from 9 long-term sites with varying land uses on current and former tallgrass prairie soil. Land uses represented a gradient of soil disturbance histories including remnant prairie, restored prairie, grazed pasture, annual crop rotations, and continuous maize. Dry combustion was used to estimate total carbon (Ct, physical), while acid hydrolysis of both the active (Ca) and slow (Cs) pools was used to estimate a recalcitrant carbon pool (Cr, chemical). Non-linear modeling of CO2 efflux data from the long-term incubations was then used to estimate Ca, and the decomposition rates of both Ca and Cs (ka and kr, biological). The size of the slow pools Cs was then defined mathematically as Ct-(Ca + Cr). Remnant prairie had the highest Ct, while cool-season pasture and a 35-yold restored prairie had higher Ct than the other agricultural systems. All agricultural systems, including pasture, had the highest fraction of Ct as Cr (~50%), whose mean residence time (MRT) in these soils is >= 500 years (Paul et al., 2001a) demonstrating that this fraction persists, while the more labile fractions were lost over the course of a few months (Ca) to a few decades (Cs) as a result of tillage-intensive agriculture. The two- to four-decade MRT time of Cs indicated a pool likely to be more responsive to the 20 to 40 years of land-use practices used at some of the sites. The Cs pool was largest in the remnant- and 35-y-old prairies indicating significant C accrual and stabilization compared to the agricultural ecosystems. Interestingly, the remnant prairie maintained the highest Ca pool as well, demonstrating the strong connection between the quantity of fresh C inputs and the potential for long-term C stabilization and accrual. The accumulation of C in active (approximate to labile) pools as a first step toward longterm stabilization highlights the tenuous nature of early carbon gains, which can be quickly lost in response to climate change or poor management.
      原文链接:
    • NSTL
    • Elsevier

    Aluminum mobilization as influenced by soil organic matter during soil and mineral acidification: A constant pH study

    Li, Ke-weiLu, Hai-longNkoh, Jackson NkohHong, Zhi-neng...
    9页
    查看更多>>摘要：Soil acidification is an increasing challenge to food security due to the production of free aluminum ion (Al3+) that is toxic to crops. The production of exchangeable Al3+ in soils during acidification is a complex process and its specific mechanism is not clear. In this study, kaolinite, montmorillonite, and three acidic soils (two Ultisols and one Alfisol) were used to investigate the changes in exchangeable and soluble Al with pH using a constant pH automatic potentiometric titrator. The effect of soil organic matter (SOM) on soil pH and Al change was also investigated. The results showed that montmorillonite consumed more acid than kaolinite under the same conditions, which were consistent with the larger cation exchange capacity (CEC) of montmorillonite than kaolinite. When the pH was adjusted from 4.8 to 4.3, the exchangeable Al of montmorillonite was significantly higher than that of kaolinite. This was consistent with their CEC and indicated that montmorillonite adsorbed more H+ than kaolinite at the same pH, resulting in more exchangeable Al on its surface. Besides CEC, SOM shows a significant effect on acid buffering capacity and Al activation of acid soils. When acidified to the same pH, the content of exchangeable Al in Alfisol was larger than that in Ultisols. This observation was consistent with the larger CEC and smaller organic matter content of Alfisol. The presence of more organic matter in the Ultisols not only improved their acid buffering performance, but also inhibited the production of exchangeable and soluble Al. In conclusion, CEC of soils and minerals play an important role in soil acid buffering performance. While, SOM not only improves soil acid buffering performance, but also inhibits the mobilization of soil Al.
      原文链接:
    • NSTL
    • Elsevier

    Microbial habitat specificity largely affects microbial co-occurrence patterns and functional profiles in wetland soils

    Liu, ChiLi, XiangzhenMansoldo, Felipe R. P.An, Jiaxing...
    15页
    查看更多>>摘要：Microbial species have different niche breadth, leading to distinct habitat ranges. Specialists have narrow niche breadth and high habitat specificity in comparison with the generalists, which possess extensive habitat ranges. Since specialists have low probabilities to occur in various habitats at a specific spatio-temporal scale, communities with different ratios of specialists and generalists may exhibit different species co-occurrence patterns and functional characteristics. However, it is still not clear how the assemblages of specialists and generalists can affect microbial co-occurrence and functional potential at a large biogeographical scale. In this study, we explored the relationship between microbial habitat specificity and the co-occurrence patterns of prokaryotic communities in Chinese wetland soils and the contribution of functional profiles to this relationship. We first identified some specialists and generalists which hold significant roles in the co-occurrence network. Then, we found that communities with more specialists have more simple co-occurrence patterns (fewer linkages in network) than those with more generalists. Soil electrical conductivity was the most significant abiotic factor in structuring this relationship. The biological mechanisms that contribute to this relationship were closely associated with functional differences of taxa. With the increase of specialists in communities, aerobic ammonia oxidation and cellulolysis guilds decreased, and photoautotrophy and sulfate/sulfide respiration populations increased. Furthermore, the abundances of metabolic pathways altered along with the abiotic gradients (e.g., conductivity and pH), including carbohydrate degradation, fermentation, inorganic nutrient metabolism and stress resistance-related pathways. Especially, there were higher abundances of metabolism-related pathways in communities with more specialists compared to those with more generalists. Functional differences at traits, genes, and metabolic pathways reflected the characteristics of microbial co-occurrence patterns and biogeochemical cycles of habitats. In summary, microbial habitat-specificity can modulate the co-occurrence patterns of prokaryotic communities along the environmental gradients in wetland soils. Our findings provide a mechanistic understanding on how microbial niche breadth can affect microbial co-occurrence in wetland soils.
      原文链接:
    • NSTL
    • Elsevier

    Spatio-temporal characterization of microbial heat production on undisturbed soil samples combining infrared thermography and zymography

    Schwarz, KatharinaReinersmann, TheresaHeil, JannisMarschner, Bernd...
    15页
    查看更多>>摘要：Passive infrared thermography (IRT) has already been applied in several approaches for high-resolution and non-contact imaging of microbial hot spots and hot moments on soil sample surfaces. The technique has only been used on homogenized disturbed samples to characterize the in-situ heterogeneity of heat development. In this study, undisturbed top-and subsoils samples from two forest sites were used in a substrate-induced approach to capture surface heat production using passive IRT with homogeneously applied glucose and water. The soil sample surface temperature was measured at 10-minute intervals and a spatial resolution of 0.17 mm per pixel. The soil samples were incubated for five days during passive IRT measurements under controlled ambient conditions with a relative air humidity > 95% and constant ambient air temperature of 20 ?. Soil sample surface characterization was done by using active IRT for soil moisture approximation and surface structure, digital photography to estimate soil organic carbon (SOC) contents from soil color parameters, and zymography to get an indicator of initial microbial activity. In a first step, surface temperature dynamics were characterized using mathematical and geostatistical methods concerning microbial hot spots and hot moments. The characterization of hot moments was performed using a Gaussian curve fit. The spatial information of the hot spots was described using geostatistical semivariance. In a second step, a stepwise forward regression using sample surface properties was performed to find explanatory variables for surface heat production. Finally, a hierarchical k-means clus-tering was applied to the sequential thermal images and transferred to the other spatial datasets for deeper insights into small-scale variations in heat production and to also consider the temporal perspective. With an ANOVA combined with Tukey's HSD post hoc test, significant differences between the cluster groups were calculated. This study showed that the temperature difference between averaged glucose-and water-treated sample surface temperature increased up to 0.2 K with a maximum hot moment duration of nearly 46 h. The variance in the samples could not be mapped, since the maximum spatial variability of the sample surface temperature could not be represented in the sample sections. The regression analysis revealed significant in-fluences by soil moisture content, approximated SOC content, as well as initial beta-glucosidase activity in the subsoil, which could be confirmed by the k-means cluster analysis. There was an indication that soil brightness (SOC contents) was influencing heat production due to the varying soil-borne substrate availability. The initial beta-glucosidase activity showed that the initial biotic state of the soil contributed to the temperature increase concerning the provision of energy for microbial activity. In conclusion, passive IRT is a helpful mapping tool for the spatio-temporal characterization of hot spots and hot moments. In this context, additional mapping tech-niques such as zymography help to gain insights into the process level of heat generation by microbial activity.
      原文链接:
    • NSTL
    • Elsevier

    Valuable phosphorus retained by ironstone gravels can be measured as bicarbonate extractable P

    Weaver, DavidSummers, RobertSchweizer, SteffenLeopold, Matthias...
    11页
    查看更多>>摘要：The > 2 mm fraction of soils is often excluded from laboratory analysis and glasshouse experiments, but is known to influence whole soil physical, chemical and biological properties. The historical focus on the < 2 mm fraction has led to a knowledge gap in analytical procedures and flow-on effect for agronomic response and advice when the > 2 mm fraction is present, especially when it is porous and chemically reactive.An ironstone gravel soil (Endopetric Pisoplinthic Plinthosol (Arenic)) from south west Western Australia was separated into < 2, 2-4, 4-6, 6-8 and 8-10 mm fractions. Physical analysis included specific surface area (SSA), optical mineralogy, XRD and SEM. Chemical analysis included phosphorus (P) sorption, P retention index (PRI), P buffering index (PBI) and sodium bicarbonate extractable P (Cowell P) on intact and ground samples, and intact mixtures of the < 2 mm and > 2 mm fractions. Delta NaF pH was used as a surrogate P retention measure on intact mixtures of the < 2 mm and > 2 mm fractions.P adsorbed onto the > 2 mm fraction can be measured as Colwell P, suggesting this fraction can provide P to plants. Colwell P determined on ground samples was correlated 1:1 with Colwell P on intact counterparts. Grinding of samples resulted in large increases in PRI and PBI, and is not a supported sample preparation, neither is the use of end over end shakers due to surface abrasion of the > 2 mm fraction increasing P sorption, however the use of Delta NaF pH as a surrogate measure of P sorption offers some potential.Phosphorus adsorption decreased with increasing particle size but adsorption by the > 2 mm fraction is likely significant in the context of an entire unsieved soil and was influenced by SSA. The > 2 mm fraction had higher SSA than their physical size would imply, possibly influenced by the thickness and mineralogy of the exterior coating (rind). Our results show that the > 2 mm fraction contains reactive surfaces that can contribute to the nutrient holding capacity and plant available P of soils.
      原文链接:
    • NSTL
    • Elsevier

    Resilient Andisols under silvopastoral systems

    Gomez, Federicovon Muller, AxelTarabini, ManuelaLa Manna, Ludmila...
    15页
    查看更多>>摘要：Livestock can affect physical and chemical soil properties, depending on both stocking rates, and intrinsic soil properties. This study aimed to analyze changes in physicochemical properties in volcanic soils under silvo-pastoral systems. Two contrasting study sites were selected in Patagonia, Argentina, where Nothofagus antarctica silvopastoral systems develop on volcanic soils with different moisture regimes: Udands and Xerands. In each site, four treatments were considered according to canopy openness and accessibility for livestock: closed forests (control), open forests, 5-year exclosures in open forests, and finally, degraded areas affected by large-scale disturbances (i.e., grazing + clear cutting + fire). Localized stocking rate was estimated, and soil properties were analyzed at two depths (0-10 and 10-20 cm). Results showed that physicochemical properties were slightly modified by silvopastoral use, with no critical values found, except for penetration resistance. Soil types behaved differently: while Udands were more fertile and resilient, Xerands were more susceptible to livestock impact, and localized stocking rate was a good short-scale soil degradation indicator for these soils. Although grazing negatively affected soil fertility, increments in carbon stock, nitrogen, and phosphorus were found in Xerands. Besides, an evident improvement in physical soil properties in the short term (5 years) was found in Udands when livestock was excluded. Despite the high resilience of udic volcanic soils under silvopastoral use, total organic matter and organic matter associated with macroaggregates severely decreased. Such decrease occurred especially when grazing was overlapped with other impacts, leading to the loss of forest cover, regardless the soil moisture regime. Nothofagus antarctica forests on volcanic soils seem to form a system capable of sustaining silvopastoral use with controlled stocking rate, but they are highly vulnerable to major impacts.
      原文链接:
    • NSTL
    • Elsevier

    Depth-differentiated, multivariate control of biopore number under different land-use practices

    Stolze, KatharinaEisenhauer, NicoTotsche, Kai U.Barnes, Andrew D....
    13页
    查看更多>>摘要：Earthworms and (tap-)roots impact the soil structure by creating large biopores, affecting infiltration capacity, seepage, nutrient cycling, and soil aeration. Despite the importance of biopores for the functions of soils and the fact that several hundreds of biopores >2 mm in diameter may occur on one square meter of soil, knowledge on the interdependence of soil properties, land-use intensity, and biopore number is still rudimentary. In this study, we investigate the linkage of the number of biopores (>2 mm i.d.) with the earthworm community, root biomass, and soil properties, including pH, water content, soil organic carbon (SOC), as well as the land-use intensity (pasture vs. cropland) as a function of the soil depth (15, 30 and 50 cm). Hypothesized causal relationships among these factors were analyzed by piecewise structural equation modelling (SEM). We found various and novel linkages between roots, earthworms, biopores, and soil properties depending on soil depth. In topsoil (at 15 cm depth), roots directly affected the number of small-sized biopores, and anecic earthworms were related to medium-sized biopores. These effects diminished with depth. We identified land-use intensity as the factor preponderating the relations between biopores, root biomass, and earthworm number in the topsoil horizons, thereby masking other interactions among variables. This appeared as high multicollinearity among variables in the SEM of the topsoil. Land-use intensity effects were found to impact the whole soil profile but decreased with soil depth. To further elucidate the single effects of soil properties on biopore-forming biota and number of biopores in the topsoil, we excluded land-use intensity as a variable in subsequent analyses. Biopores increased with soil pH and soil water content but decreased with increasing SOC. Based on our SEM analysis, we conclude that the occurrence, frequency, and persistence of biopores are the consequence of intricate interdependencies between earthworm communities, roots, and site-specific soil properties, governed by land-use intensity.
      原文链接:
    • NSTL
    • Elsevier