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A) Sterile microcosm containing Pinus sylvestris ectomycorrhizal with Paxillus involutus, with plastic wells containing 10% (w/w) apatite in quartz sand (top left and bottom right) and two wells with quartz sand only (top right, bottom left). (B) Detail of an apatite containing well, colonized by Paxillus involutus.
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Ectomycorrhizal (EcM) fungi are increasingly recognized as important agents of mineral weathering and soil development, with far-reaching impacts on biogeochemical cycles. Because EcM fungi live in a symbiotic relationship with trees and in close contact with bacteria and archaea, it is difficult to distinguish between the weathering effects of the...
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... either with or without ortho- phosphate (+P, )P, see Table S1). The agar was covered with a sheet of cellophane, and on the top, an extra 20 mL of the nutrient agar was added to immobilize a monolayer of acid- washed sieved (2.0 < 2.4 mm) perlite grains that were inserted into four polypropylene wells that provided discrete weathering arenas (Fig. 1). The tree seedlings were trans- planted with their roots on the perlite and shoots emerging outside through a slot cut in the side of the dishes, sealed around the stem with sterile lanolin, and the lid and base of the dishes held together and sealed with strips of parafilm to maintain axenic ...
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... the second experiment ('C-allocation experiment'), two of the four wells were filled with 10% (w ⁄ w) apatite amended quartz sand, and the two other wells with quartz sand only (see Fig. 1). Four replicated microcosms were set up with )P nutrient ...
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... fungus developed networks extending from the dichoto- mously branched, fungal-sheathed root tips, to form multicel- lular hyphal cords that grew over almost the entire perlite layer, dividing down into individual hyphae (Fig. 1A,B), reflecting the natural growth of EcM fungi in soils (Smith & Read, 2008). Fungal hyphal growth was especially intense in wells containing apatite grains, and the EcM root tips closest to these locations often showed a very high frequency of branching (Fig. 1B). Within the first 5 weeks, more than 30% of the wells were colonized by the ...
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... that grew over almost the entire perlite layer, dividing down into individual hyphae (Fig. 1A,B), reflecting the natural growth of EcM fungi in soils (Smith & Read, 2008). Fungal hyphal growth was especially intense in wells containing apatite grains, and the EcM root tips closest to these locations often showed a very high frequency of branching (Fig. 1B). Within the first 5 weeks, more than 30% of the wells were colonized by the fungus, increasing to 95% by week 20 of the experiment (Fig. S1). On average, it took 9.8 (±3.2) weeks from the start of the experiment, before a well became colonized. Neither the presence of apatite in the well nor the absence of P in the nutrient solution ...
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... in soils (Smith & Read, 2008). Fungal hyphal growth was especially intense in wells containing apatite grains, and the EcM root tips closest to these locations often showed a very high frequency of branching (Fig. 1B). Within the first 5 weeks, more than 30% of the wells were colonized by the fungus, increasing to 95% by week 20 of the experiment (Fig. S1). On average, it took 9.8 (±3.2) weeks from the start of the experiment, before a well became colonized. Neither the presence of apatite in the well nor the absence of P in the nutrient solution affected the time taken for the fungus to first grow into a well (ANOVA, F (3,9) = 0.67, P = ...
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... 14 C labelling experiment (Fig. 5A) permitted the visuali- zation of the role of EcM fungi in connecting plant photosyn- thetic energy to the weathering of nutrient-rich minerals. The presence of apatite wells not only shaped the fungal biomass distribution and activity (Figs 1 and 5A), but also the EcM root tip distribution and the whole root architecture as well. Localized patches of apatite grains supplying P to the fungal partner stimulate the proliferation of EcM root tips near to the resource, shortening the distance required for fungal transport of P to the plant in return for photosynthate-derived carbon. ...
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... for weathering studies comprised square Petri dishes (10 · 10 cm) that were filled with 100 mL of 1% agar, containing inorganic nutrients either with or without ortho- phosphate (+P, )P, see Table S1). The agar was covered with a sheet of cellophane, and on the top, an extra 20 mL of the nutrient agar was added to immobilize a monolayer of acid- washed sieved (2.0 < 2.4 mm) perlite grains that were inserted into four polypropylene wells that provided discrete weathering arenas (Fig. 1). The tree seedlings were trans- planted with their roots on the perlite and shoots emerging outside through a slot cut in the side of the dishes, sealed around the stem with sterile lanolin, and the lid and base of the dishes held together and sealed with strips of parafilm to maintain axenic ...
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... the second experiment ('C-allocation experiment'), two of the four wells were filled with 10% (w ⁄ w) apatite amended quartz sand, and the two other wells with quartz sand only (see Fig. 1). Four replicated microcosms were set up with )P nutrient ...
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... fungus developed networks extending from the dichoto- mously branched, fungal-sheathed root tips, to form multicel- lular hyphal cords that grew over almost the entire perlite layer, dividing down into individual hyphae (Fig. 1A,B), reflecting the natural growth of EcM fungi in soils (Smith & Read, 2008). Fungal hyphal growth was especially intense in wells containing apatite grains, and the EcM root tips closest to these locations often showed a very high frequency of branching (Fig. 1B). Within the first 5 weeks, more than 30% of the wells were colonized by the fungus, increasing to 95% by week 20 of the experiment (Fig. S1). On average, it took 9.8 (±3.2) weeks from the start of the experiment, before a well became colonized. Neither the presence of apatite in the well nor the absence of P in the nutrient solution affected the time taken for the fungus to first grow into a well (ANOVA, F (3,9) = 0.67, P = ...
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... fungus developed networks extending from the dichoto- mously branched, fungal-sheathed root tips, to form multicel- lular hyphal cords that grew over almost the entire perlite layer, dividing down into individual hyphae (Fig. 1A,B), reflecting the natural growth of EcM fungi in soils (Smith & Read, 2008). Fungal hyphal growth was especially intense in wells containing apatite grains, and the EcM root tips closest to these locations often showed a very high frequency of branching (Fig. 1B). Within the first 5 weeks, more than 30% of the wells were colonized by the fungus, increasing to 95% by week 20 of the experiment (Fig. S1). On average, it took 9.8 (±3.2) weeks from the start of the experiment, before a well became colonized. Neither the presence of apatite in the well nor the absence of P in the nutrient solution affected the time taken for the fungus to first grow into a well (ANOVA, F (3,9) = 0.67, P = ...
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... fungus developed networks extending from the dichoto- mously branched, fungal-sheathed root tips, to form multicel- lular hyphal cords that grew over almost the entire perlite layer, dividing down into individual hyphae (Fig. 1A,B), reflecting the natural growth of EcM fungi in soils (Smith & Read, 2008). Fungal hyphal growth was especially intense in wells containing apatite grains, and the EcM root tips closest to these locations often showed a very high frequency of branching (Fig. 1B). Within the first 5 weeks, more than 30% of the wells were colonized by the fungus, increasing to 95% by week 20 of the experiment (Fig. S1). On average, it took 9.8 (±3.2) weeks from the start of the experiment, before a well became colonized. Neither the presence of apatite in the well nor the absence of P in the nutrient solution affected the time taken for the fungus to first grow into a well (ANOVA, F (3,9) = 0.67, P = ...
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... 14 C labelling experiment (Fig. 5A) permitted the visuali- zation of the role of EcM fungi in connecting plant photosyn- thetic energy to the weathering of nutrient-rich minerals. The presence of apatite wells not only shaped the fungal biomass distribution and activity (Figs 1 and 5A), but also the EcM root tip distribution and the whole root architecture as well. Localized patches of apatite grains supplying P to the fungal partner stimulate the proliferation of EcM root tips near to the resource, shortening the distance required for fungal transport of P to the plant in return for photosynthate-derived carbon. Such increased EcM root tip growth has also been observed on the surface of mesh bags containing apatite bur- ied in forest soils ( Hagerberg et al., ...
Citations
... Ectomycorrhizal fungi play an important role in mobilising N from organic substrates and our results support the well-established idea that photosynthetically derived C transferred to the ectomycorrhizal fungal symbionts drives this process (Bending & Read, 1995;Rineau et al., 2013;Shah et al., 2016;Nicol as et al., 2018). Selective allocation of photosynthetically derived C through ectomycorrhizal fungal networks to patches of added minerals has been shown in experimental microcosms inoculated with single fungal species (Rosling et al., 2004;Smits et al., 2012) and shown to increase the weathering of apatite and subsequent uptake of P by plants (Smits et al., 2012). However, there are few mechanistic studies of mycorrhizal weathering in natural soils. ...
... Ectomycorrhizal fungi play an important role in mobilising N from organic substrates and our results support the well-established idea that photosynthetically derived C transferred to the ectomycorrhizal fungal symbionts drives this process (Bending & Read, 1995;Rineau et al., 2013;Shah et al., 2016;Nicol as et al., 2018). Selective allocation of photosynthetically derived C through ectomycorrhizal fungal networks to patches of added minerals has been shown in experimental microcosms inoculated with single fungal species (Rosling et al., 2004;Smits et al., 2012) and shown to increase the weathering of apatite and subsequent uptake of P by plants (Smits et al., 2012). However, there are few mechanistic studies of mycorrhizal weathering in natural soils. ...
... Microcosm studies with added minerals and microscopic investigation of mineral surfaces suggest that ectomycorrhizal fungi can modify mineral surfaces (Quirk et al., 2012) and that allocation of C to the fungal mycelium colonising in-growth cores filled with basalt is related to the rate of calcium silicate dissolution from the basalt (Quirk et al., 2014). The fungi in the latter experiment were not identified but enhanced weathering of added apatite patches and uptake of mobilised P have been shown in microcosms using P. sylvestris seedlings inoculated with the ectomycorrhizal fungus Paxillus involutus and growing under axenic conditions (Smits et al., 2012). In our study, we found that high availability of N from OM increased plant C allocation to mycorrhizal mycelial biomass in deeper mineral horizons, resulting in increased mobilisation of Mg, Ca, K and P, and we identified the fungal communities involved, but we did not quantify long-term C sequestration. ...
Tree growth in boreal forests is driven by ectomycorrhizal fungal mobilisation of organic nitrogen and mineral nutrients in soils with discrete organic and mineral horizons. However, there are no studies of how ectomycorrhizal mineral weathering and organic nitrogen mobilisation processes are integrated across the soil profile.
We studied effects of organic matter (OM) availability on ectomycorrhizal functioning by altering the proportions of natural organic and mineral soil in reconstructed podzol profiles containing Pinus sylvestris plants, using ¹³CO2 pulse labelling, patterns of naturally occurring stable isotopes (²⁶Mg and ¹⁵N) and high‐throughput DNA sequencing of fungal amplicons.
Reduction in OM resulted in nitrogen limitation of plant growth and decreased allocation of photosynthetically derived carbon and mycelial growth in mineral horizons. Fractionation patterns of ²⁶Mg indicated that magnesium mobilisation and uptake occurred primarily in the deeper mineral horizon and was driven by carbon allocation to ectomycorrhizal mycelium. In this horizon, relative abundance of ectomycorrhizal fungi, carbon allocation and base cation mobilisation all increased with increased OM availability.
Allocation of carbon through ectomycorrhizal fungi integrates organic nitrogen mobilisation and mineral weathering across soil horizons, improving the efficiency of plant nutrient acquisition. Our findings have fundamental implications for sustainable forest management and belowground carbon sequestration.
... Of these, solubilization is often assumed to be the chief means through which AM or the AM-hyphosphere-associated microbiome (Faghihinia et al. 2022;Zhang et al. 2022) aids in crop utilization of insoluble or low solubility P forms such as rock phosphates (RP), presumably through AM-mediated secretion of organic acids (e.g., maleic, citric, acetic acid) (Andrino et al. 2021;Tawaraya et al. 2006;Zhang et al. 2022). However, reports of P solubilization from insoluble inorganic P forms have been largely limited to ectomycorrhiza and ericoid mycorrhiza species (Blum et al. 2002;Landeweert et al. 2001;Smits et al. 2012;Van Schöll et al. 2006), rather than for AM that are more common mutualists with crop species (Plassard and Dell 2010). In some cases, crop utilization of RP is not improved by AM as compared to soluble phosphates (SP) such as superphosphate (e.g., Dann et al. 1996). ...
Arbuscular mycorrhizae (AM) are thought to improve crop growth by enhancing phosphorus (P) uptake via scavenging and enhancing dissolution. However, AM-mediated crop growth responses to P forms of varying solubility are often crop-species and soil-context dependent. The relative importance of AM associations and P source solubility on crop growth is not conclusively understood, and requires controlled factorial experiments to test their relative and interactive effects. We conducted a meta-analysis to evaluate how AM impact crop growth responses to rock phosphate relative to soluble phosphates across diverse crop species and soil characteristics. A total of 83 observations utilizing a 2 × 2 factorial design of relative presence or absence of AM and fertilization with rock phosphate vs. soluble phosphates were identified. We found that AM similarly improved crop growth with rock phosphate and soluble phosphates. A distinguishable crop growth benefit from AM coupled with rock phosphate was observed for soils with a low degree of weathering, at soil pH < 6.5 and > 7.5, and when soils were heat-sterilized prior to inoculation with AM. Shoot biomass of legumes was uniquely greater than non-legumes with rock phosphates and AM as compared to soluble phosphates and AM. However, crop growth under rock phosphate fertilization relative to soluble phosphates was still lower irrespective of AM. This meta-analysis reveals that crop growth is more dependent on P fertilizer solubility than AM. Moreover, AM do not appear to close the solubility gap of rock phosphate vs. soluble phosphate fertilizers to support similar crop growth under rock phosphate relative to soluble phosphates. Studies assessing crop growth responses to AM-crop associations effect on contrasting solubility P fertilizers should expand to the field, and greenhouse experiments should be conducted under realistic field growing conditions, such as agronomically appropriate P application rates.
... Both nutrient amendments (urea and apatite) increased EMF production in comparison with the quartz-only mesh bags in the control plots. This is consistent with mesocosm experiments that have shown that when organic (Wallander and Pallon, 2005;Leake et al., 2001;Bending and Read, 1995) and mineral nutrient patches (Smits et al., 2012;Leake et al., 2008) are colonized by EMF, mycelial branching and proliferation increase to explore the nutrient patch. In support of our second hypothesis, apatite amendment increased EMF production in comparison with the quartz-only bags but only in the control plots. ...
Ectomycorrhizal fungi (EMF) are important components of soil microbial communities, and EMF biomass can potentially increase carbon (C) stocks by accumulating in the soils as necromass and producing recalcitrant structures. EMF growth depends on the C allocated belowground by the host trees, and the nutrient limitation on tree growth is expected to influence this allocation. Therefore, studying EMF production and understanding the factors that regulates it in natural soils are important to understand C cycling in forests. Fungal mycelium collected from ingrowth mesh bags is commonly used to estimate EMF biomass, but these measurements might not reflect the total EMF production since turnover rates of the hyphae are not considered. Here we estimated EMF production and turnover in response to P fertilization (applied as superphosphate) in a Norway spruce forest where nitrogen (N) deposition has resulted in phosphorus (P) limitation of plant production by using a combination of mesh bags with different incubation periods and with Bayesian inferences. To test how localized patches of N and P influence EMF production and turnover we amended some bags with a nitrogen source (methylene urea) or P source (apatite). Additionally, the Bayesian model tested the effect of seasonality (time of mesh-bag harvesting) on EMF production and turnover. We found that turnover of EMF was not affected by P fertilization or mesh-bag amendment. P fertilization had a negative effect on EMF production in all the mesh-bag amendments, suggesting a reduced belowground C allocation to the EMF when P limitation is alleviated. Apatite amendment significantly increased EMF biomass production in comparison with the pure quartz bags in the control plots but not in the P-fertilized plots. This indicates that P-rich patches enhance EMF production in P-limited forests, but not when P is not limiting. Urea amendment had a generally positive effect on EMF production, but this was significantly reduced by P fertilization, suggesting that a decrease in EMF production due to the alleviated P limitation will affect N foraging. Seasonality had a significant effect on EMF production, and the differences registered between the treatments were higher during the warmer months and disappeared at the end of the growing season. Many studies highlight the importance of N for regulating belowground C allocation to EMF in northern coniferous forests, but here we show that the P status of the forest can be equally important for belowground carbon allocation to EMF production in areas with high N deposition.
... Thus, there is a need to study BW in soil environments under those conditions. The above-mentioned limitations were partly overcome in recent studies where minerals were either exposed to more complex microbial communities 122,185 or to air and mycorrhizal consortia 86,87,90,91,186,187 . Nevertheless, reproducing close-to-natural conditions in the laboratory remains challenging for many environments, and this also concerns the properties of the mineral surfaces used. ...
... Current models incompletely account for the specific weathering processes occurring at the interface and in close vicinity of hyphae in contact with the mineral surface (see previous sections for a detailed review on those processes). In addition, it was shown that surface-bound mycorrhiza were able to alter minerals in a humid environment, yet with no free water present 87,187 , which shifts the way mineral weathering may need to be conceptualized and studied, with free water not being the sole media controlling mineral-weathering reactions. Moving forward, evaluation of the spatial heterogeneity related to, for example, mineral surface coverage by microorganisms and its temporal evolution represent key steps in the formulation, parameterization, and validation of future "microbially informed" reactive transport models 217 . ...
... Arbuscular mycorrhiza colonization of crop culture is indeed primarily controlled by the plant nutrient status 239 . Usually, as nutrient limitation sets in, plants tend to invest more energy into mycorrhizal networks to mitigate nutrient shortage 187 . Conversely when nutrient (especially P) supply is large as in soils subjected to fertilization, plants invest less into arbuscular mycorrhizal symbiosis 187 . ...
Rock weathering is a key process in global elemental cycling. Life participates in this process with tangible consequences observed from the mineral interface to the planetary scale. Multiple lines of evidence show that microorganisms may play a pivotal—yet overlooked—role in weathering. This topic is reviewed here with an emphasis on the following questions that remain unanswered: What is the quantitative contribution of bacteria and fungi to weathering? What are the associated mechanisms and do they leave characteristic imprints on mineral surfaces or in the geological record? Does biogenic weathering fulfill an ecological function, or does it occur as a side effect of unrelated metabolic functions and biological processes? An overview of efforts to integrate the contribution of living organisms into reactive transport models is provided. We also highlight prospective opportunities to harness microbial weathering in order to support sustainable agroforestry practices and mining activities, soil remediation, and carbon sequestration.
... The vertical distribution of exchangeable K, with 10 times more exchangeable K + than Na + ions in the topsoil (Fig. 3), indicated that K is uplifted by plants from deeper soil horizons in longer terms and accumulates within the topsoil in the arid shrubland Jackson, 2004, 2001). Especially in extremely water-limited areas as under arid conditions, the acquisition of rock--derived elements from depth can be an important component of the nutrient acquisition strategy of plants (Smits et al., 2012). Contrary to our expectations, plants recovered the K analogs in short terms not dominantly from depth, but uniformly from topsoil to saprolite (Fig. 2). ...
Nutrient acquisition strategies of plants regulate water flow and mass transport within ecosystems, shaping earth surface processes. Understanding plant strategies under current conditions is important to assess and predict responses of natural ecosystems to future climate and environmental changes. Nitrogen (N) and potassium (K) (re-)utilization from topsoil and their acquisition from subsoil and saprolite were evaluated in a continental transect, encompassing three study sites – an arid shrubland, a mediterranean woodland, and a temperate rainforest – on similar granitoid parent material in the Chilean Coastal Cordillera. The short-term (<1 year) plant N and K acquisition was traced with ¹⁵N and the K analogs rubidium and cesium. To do so, the tracers were either injected into topsoil, subsoil, or saprolite, in the immediate vicinity of eight individual plants per study site and injection depth. The long-term (>decades) K uplift by plants was investigated by the vertical distribution of exchangeable K⁺ and Na⁺. Recoveries of ¹⁵N and K analogs by arid shrubland plants were similar from topsoil, subsoil, and saprolite. Mediterranean woodland shrubs recovered the tracers primarily from topsoil (i.e., 89 % of recovered ¹⁵N and 84 % of recovered K analogs). Forest plants recovered the tracers from topsoil (¹⁵N = 49 %, K analogs = 57 %) and partially from greater depth: 38 % of recovered ¹⁵N and 43 % of recovered K analogs were acquired from subsoil and saprolite, respectively. Low nutrient accessibility in the topsoil (e.g., because of frequent droughts) drives shrubland plants to expand their N and K uptake to deeper and moister soil and saprolite. Woodland and forest plants dominantly recycled nutrients from topsoil. In the forest, this strategy was complemented by short-term uplift of N and K from depth. The vertical distribution of exchangeable K indicated long-term uplift of K by roots in all three sites. This highlighted that long-term K uplift from depth complements the nutrient budget across the continental transect.
... In ectomycorrhiza, a symbiotic association of fungi with the feeder roots of higher plants, essential plant nutrients are mobilized directly from insoluble mineral sources through excretion of oxalic acid. For instance, apatite dissolution by oxalic acid is linked to phosphorus acquisition and calcium oxalate sequestration (Wallander 2000;Smits et al. 2012;Schmalenberger et al. 2015). ...
Microorganisms inhabit almost every natural environment on Earth. Since the beginning of life, microorganisms have played a fundamental role in the geochemical cycling of elements and shaped our current environments. Microorganisms that form minerals, a process known as biomineralization, contribute substantially to these processes. Over half of the essential elements required by living organisms are incorporated into biominerals. More than 60 different biominerals are known in nature, including oxides and hydroxides, carbonates, phosphates, sulfates and sulfides, silicates, and organic crystals.Biominerals are composite materials that often exhibit superior properties when compared to their abiotically formed counterparts. Their well-designed architectures and hierarchical structures offer structural support and protection, but also fulfill a wide variety of other functions. Biominerals often reflect the physicochemical properties of the environment the biomineral was formed in. Fossilized biominerals are therefore useful tools for paleoceanographic and paleoclimate reconstructions. Biomineralization not only fascinates biologists, it also provides sophisticated models for functional materials in materials science and affects the global aspects of the earth sciences.The chapter gives an overview over non-siliceous biominerals formed by microorganisms and lists them in tabular form ordered by taxonomic criteria. It features carbonates, oxides and hydroxides, phosphates, sulfur-containing biominerals, and organic crystals.KeywordsBiomineralization ∙ Microorganisms ∙ Carbonates ∙ Oxides ∙ Sulfate ∙ Sulfides ∙ Phosphates ∙ Organic crystals ∙ Microalgae ∙ Bacteria
... Benefits of these mycorrhizal structures to the plant host include increased absorption of mineral nutrients that are present in low concentrations and are relatively immobile in soil, improved water-use efficiency, and disease resistance (Zeng, 2006;Allen, 2007;Bonfante and Genre, 2010;Behie and Bidochka, 2014). Smits et al. (2012) found that Pinus sylvestris seedlings inoculated with Agaricales (Paxillus involutus) showed a significant increase of available P in rhizosphere soil and promote seedling growth. Our results indicate that long-term overgrazing resulted in a significant decrease in SOC, and led to the lack of TP and SAP (Table 1). ...
Overgrazing directly and indirectly affects soil microorganisms, which can have feedback effects on plant growth. Little is known about the root metabolites plants produce and whether they recruit beneficial microbes in response to overgrazing. Here, we used the dominant grassland species Leymus chinensis to explore correlations between root metabolites and the rhizosphere microbiome shaped by long-term overgrazing, which was determined by using LC-MS technology and high-throughput sequencing. In total, 839 metabolites were detected, with 41 significantly higher and 3 significantly lower in overgrazing versus grazing exclusion plots. The rhizosphere bacterial community was changed, but the fungal community was not altered. Moreover, 11 bacterial orders were found only in the overgrazed samples, and these showed close relationships to root metabolites and certain soil properties. Of these, Latescibacterales, B10-SB3A, and Nitrosococcales are known to be involved in growth promotion, C and N metabolism, respectively. In addition, root metabolites play an important role in mediating root-fungi interactions. The beneficial fungal orders Agaricales and Sordariales have a tread to be higher maybe due to root metabolites, mainly facilitate nutrient absorption and protect organic carbon in the soil, respectively. Our results indicate that grassland plants send metabolic signals to recruit key beneficial bacteria and stabilize fungal communities to alleviate grazing-induced stress in typical grassland ecosystems.
... It is well known that biological factors also affect soil development (Arocena et al., 2012;Föllmi et al., 2009;Kolo & Claeys, 2005;Smits et al., 2012). With the increase of vegetation coverage, dissolved Si can protect the soil from erosion (F. ...
... Plants can destroy mineral particles through root growth and accelerate weathering rate and soil development (Föllmi et al., 2009). In addition, many studies have found that arbuscular mycorrhizal fungi can dissolve minerals and accelerate mineral weathering (Arocena et al., 2012;Kolo & Claeys, 2005;Smits et al., 2012). As the mineral weathering, especially silicate minerals, is the initial source of different liable Si fractions (Conley & Carey, 2015;Cornelis & Delvaux, 2016;Derry et al., 2005), factors promoting mineral weathering will eventually affect soil development and health during the vegetation evolution after glacier retreat. ...
The biogeochemical cycle of Si plays an important role in maintaining the function and stability of ecosystems. Although there have been many studies on long‐term silicate weathering, there are few reports on Si fractions and cycling in early ecosystem development. Using optimized sequential chemical extraction processes, this study quantified soil Si fractions of the eluvial horizon and deposition layers in Hailuogou Glacier Retreat Area of Gongga Mountain, Southwest China. The results showed that plant‐available Si (NaAc–Si) content decreased significantly from 33.40 to 2.16 mg kg⁻¹ with the increase of soil age. There was a significantly positive correlation (p < .01) between soil pH and NaAc–Si. Within the labile Si fractions, the largest fraction was amorphous Si (Na2CO3–Si) (165.35 ± 81.50 mg kg⁻¹), followed by pedogenic oxides/hydroxides chemisorbed Si (Oxalate–Si) (135.13 ± 66.83 mg kg⁻¹), Si adsorbed on the surface of inorganic soil particles (Acetic–Si) (9.66 ± 4.27 mg kg⁻¹), and soluble Si (CaCl2–Si) (4.89 ± 1.68 mg kg⁻¹). Compared with Stage 1 (i.e., a variety of pioneer species symbiosis stage) after glacier retreat, the storage of these four labile Si fractions in Stage 3 (i.e., climax species stage) decreased by 45.95% (CaCl2–Si), 42.98% (Acetic–Si), 67.34% (Oxalate–Si), and 75.24% (Na2CO3–Si), respectively, due to the absorption and utilization of Si by plants. Our study implies that the multiple transformations of different Si fractions in soils and the absorption and return of Si by plants can keep the CaCl2–Si pool in dynamic equilibrium, which provides a basis for the stability of ecosystem functions during the vegetation evolution after glacier retreat.
... Exchanges between bones or teeth and sediment or soil are more difficult to detect and to estimate. The interrelations between apatite, fungi and soil are complex [112,113]. Sometimes, filaments or small granules are assigned to fungi or bacteria [108], but the molecular exchanges need the extraction of the organic components to be revealed. A model trying to explain the diagenesis of proteins has been proposed by Bada et al. [114], but lipids and sugars also exist. ...
Biominerals are recorders of evolution and palaeoenvironments. Predation is one of the most frequent modes leading to the concentration of small vertebrates in fossil assemblages. Consumption by predators produces damages on bones and teeth from prey species, and one of the greatest challenges to taphonomists is differentiating original biological and secondary, geologically altered attributes of fossils. Excellent morphological preservation is often used to assume that the structure and composition of fossils are not modified. Nevertheless, during predation and fossilization, both the physical structure and chemical composition of enamel, dentine and bone are altered, the degree and extent of which varies from site to site, depending on the nature of the burial environment. A relationship between the surficial alterations and the compositional changes which take place during fossilization has yet to be established. Herein, I present a review of old and recent taphonomic studies that collectively reveal the wide diversity of microstructural and chemical changes that typically take place during fossilization of vertebrate remains, including common taphonomic biases and the challenges inherent to reconstructing the history of vertebrate fossil assemblages.
... These results strongly suggest that the reactivity of aged minerals can be restored by fungal hyphae, at least for aged minerals with an altered layer of a few tens of nanometers after a relatively short treatment period, i.e., weeks in a strong acidic solution in a laboratory setting or few years under natural conditions. Long-term coevolution of mycorrhizal fungi and plants (Brundrett, 2002) have established cooperation in which the fungi provide inorganic nutrients to the host plants through the weathering of minerals (Landeweert et al., 2001;Blum et al., 2002;Smits et al., 2012). It is thus reasonable to speculate that fungi play an important role in promoting the weathering of aging minerals. ...
Fungi actively enhance the local dissolution of nutrient-bearing minerals through the combined biomechanical and biochemical actions of their hyphal tips to obtain mineral-bound inorganic nutrients (MINs). However, little is known about the dynamic processes underlying hyphal tip-mineral interactions. Here, we assess the adhesive force between a single hypha of the common fungus Talaromyces flavus and the Fe-bearing silicate lizardite and quartz (as a control), as well as hyphal tip-induced lizardite weathering and hyphal Fe uptake. We showed that T. flavus hyphae formed their maximal adhesive force with lizardite at the growing tips, reaching 6.11 ± 0.69 nN after a contact time of one minute. The adhesive forces of the tip-lizardite interface within two minutes were > 2.65 times stronger than those of the tip-quartz interface. Examination of the hyphal tip-lizardite interface after 18 h indicated the formation of dissolution channels with a depth of 27.7 ± 8.0 nm. Furthermore, the hyphal tips resulted in an altered lizardite up to 46 nm. The thickness of the altered lizardite increased to ∼130 nm after contact with the mature regions of the hyphae for ∼173 min. And the altered lizardite was found to have depleted Fe levels that increased with increasing contact time. The total content of Fe in T. flavus associated with the lizardite surface after 18 h was 52.98 ± 12.20 nmol mg⁻¹, which was 6 times greater than the total amount of Fe in quartz surface-associated T. flavus after 24 h of culture. These results demonstrate that fungi access MINs by the active development of a strong adhesive force with target minerals through their hyphal tips, effectively enabling fungi to flourish in heterogeneous environments and be major geological agents for biogeochemical transformation.
