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Arbuscular mycorrhizal fungi (AMF) are important symbionts of many plant species, facilitating the acquisition of soil nutrients by roots. We hypothesized that AMF root colonization is strongly influenced by the composition of the soil microbiome. Here, we evaluated mycorrhizal colonization of two plants, the grass Urochloa brizantha (Brachiaria) and the legume Crotalaria juncea (Crotalaria). These were cultivated in the same soil but hosting eight distinct microbiomes: natural soil (i); soil exposed to heat treatments for 1 h at 50 ºC (ii), 80 ºC (iii), or 100 ºC (iv); sterilized soil by autoclaving (AS) followed by re-inoculation of dilutions of the natural soil community at 10-1 (v), 10-3 (vi), and 10-6 (vii); and AS without re-inoculation (viii). Microbial diversity (bacteria and fungi) was assessed through 16S rDNA and ITS1 metabarcoding, respectively, and the soil acid phosphatase activity (APASE) was measured. Sequencing results showed the formation of distinct microbial communities according to the soil manipulations, which also correlated with the decline of APASE. Subsequently, seedlings of Brachiaria and Crotalaria were grown in those soils inoculated separately with three AMF (Acaulospora colombiana, Rhizophagus clarus, and Dentiscutata heterogama) which were compared to an AMF-free control treatment. Brachiaria showed higher colonization in natural soil when compared to the microbial community manipulations, regardless of the AMF species inoculated. In contrast, two mycorrhiza species were able to colonize Crotalaria under modified microbial communities at similar rates to natural soil. Furthermore, Brachiaria showed a possible inverse relationship between APASE and mycorrhization, but this trend was absent for Crotalaria. We conclude that mycorrhizal root colonization and soil acid phosphatase activity were associated with the structure of the soil microbiome, depending on the plant species evaluated.

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Terrestrial plants establish symbiosis with arbuscular mycorrhizal fungi (AMF) to exchange water and nutrients. However, the extent to which soil biodiversity influences such association remains still unclear. Here, we manipulated the soil microbial diversity using a "dilution-to-extinction" approach in a controlled pot microcosm system and quantified the root length colonization of maize plants by the AMF Rhizophagus clarus. The experiment was performed by manipulating the soil microbiome within a native and foreign soil having distinct physicochemical properties. Overall, our data revealed significant positive correlations between the soil microbial diversity and AMF colonization. Most importantly, this finding opposes the diversity-invasibility hypothesis and highlights for a potential overall helper effect of the soil biodiversity on plant-AMF symbiosis.

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Introducción: La macrofauna del suelo cumple un rol clave en los procesos del suelo, por lo tanto, regula la oferta se servicios ecosistémicos; sin embargo, su nivel de actividad depende en gran parte de las condiciones edafoclimáticas. Objetivo: El presente trabajo evaluó el efecto del gradiente de altitud sobre comunidades de macrofauna del suelo y propiedades edafoclimáticas en zonas cafeteras del Norte del Huila. Métodos: El estudio incluyó 12 lotes de café separados en dos gradientes de altitud: bajo (1 300-1 600 m.s.n.m) y alto (1 600-1 900 m.s.n.m), se recolectó la macrofauna del suelo mediante monolitos (25 x 25 cm a 30 cm de profundidad) y se estudiaron las condiciones edafoclimáticas. Resultados: En total se registró 9 520 individuos m-2 y una riqueza específica de 14 táxones. Las condiciones edafoclimáticas con mayor diferencia estadística entre los gradientes de altitud, fue la temperatura ambiente y humedad relativa con diferencias de 4.9 °C y 10.4 %, respectivamente. Conclusiones: La mayor abundancia de Coleoptera, Hemiptera, Isoptera y Lepidoptera se presentó en sitios más cálidos, es decir a un gradiente de altitud entre 1 300-1 600 m.s.n.m, mientras que Chilopoda y Diplopoda se adaptaron mejor a sitios más fríos en el gradiente altitudinal entre 1 600-1 900 m.s.n.m.

Introduction: Soil macrofauna plays a key role in soil processes and therefore regulates the supply of ecosystem services; however, its level of activity depends largely of the edaphoclimatic conditions. Objective: This work evaluated the effect of altitude gradient on soil macrofauna communities and edafoclimatic properties in coffee zones of North Huila. Methods: The study included 12 coffee lots separated in two altitude gradients: low (1 300-1 600 masl) and high (1 600-1 900 masl). Soil macrofauna was collected by means of monoliths (25 x 25 cm with 30 cm depth) and edaphoclimatic conditions were studied. Results: A total of 9 520 individuals m-2 and a specific richness of 14 taxa were registered. The edaphoclimatic conditions with the greatest statistical difference between altitude gradients were the environmental temperature and relative humidity with differences of 4.9 °C and 10.4 %, respectively. Conclusions: The highest abundance of Coleoptera, Hemiptera, Isoptera, Lepidoptera was presented in warmer sites, that is, altitude gradient 1 300-1 600 masl, while Chilopoda and Diplopoda adapted better to colder sites in altitude gradient 1 600-1 900 m.a.s.l.

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Spiders are part of the soil biodiversity, considered fundamental to the food chain hierarchy, directly and indirectly influencing several services in agricultural and forest ecosystems. The present study aimed to evaluate the biodiversity of soil spider families and identify which soil properties influence their presence, as well as proposing families as potential bioindicators. Native forest (NF) and reforested sites (RF) with Araucaria angustifolia (Bertol.) Kuntze were evaluated in three regions of the state São Paulo, both in the winter and summer. Fifteen soil samples were collected from each forest to evaluate the biological (spiders and microbiological), chemical and physical soil properties, in addition to properties of the litter (dry matter and C, N and S contents). For soil spiders, two sampling methods were used: pitfall traps and soil monoliths. In total, 591 individuals were collected, and distributed in 30 families, of which 306 individuals (22 families) came from pitfall traps and 285 individuals (26 families) from monoliths. Only samples obtained by the monolith method revealed seasonal differences in the mean density and richness of spiders between NF and RF. Canonical discriminant analysis showed the separation of these forests of Araucaria. Principal Component Analysis demonstrated the correlation of a number of spider families with certain soil properties (organic carbon, basal respiration, metabolic quotient, litter carbon, total porosity, bulk density and soil moisture). We identified 10 families (Anapidae, Corinnidae, Dipluridae, Hahniidae, Linyphiidae, Lycosidae, Nemesiidae, Palpimanidae, Salticidae, Scytodidae) that contributed most to separating native forest from the replanted forest, indicating the possibility of the spiders being used as bioindicators.(AU)

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Spiders are part of the soil biodiversity, considered fundamental to the food chain hierarchy, directly and indirectly influencing several services in agricultural and forest ecosystems. The present study aimed to evaluate the biodiversity of soil spider families and identify which soil properties influence their presence, as well as proposing families as potential bioindicators. Native forest (NF) and reforested sites (RF) with Araucaria angustifolia (Bertol.) Kuntze were evaluated in three regions of the state São Paulo, both in the winter and summer. Fifteen soil samples were collected from each forest to evaluate the biological (spiders and microbiological), chemical and physical soil properties, in addition to properties of the litter (dry matter and C, N and S contents). For soil spiders, two sampling methods were used: pitfall traps and soil monoliths. In total, 591 individuals were collected, and distributed in 30 families, of which 306 individuals (22 families) came from pitfall traps and 285 individuals (26 families) from monoliths. Only samples obtained by the monolith method revealed seasonal differences in the mean density and richness of spiders between NF and RF. Canonical discriminant analysis showed the separation of these forests of Araucaria. Principal Component Analysis demonstrated the correlation of a number of spider families with certain soil properties (organic carbon, basal respiration, metabolic quotient, litter carbon, total porosity, bulk density and soil moisture). We identified 10 families (Anapidae, Corinnidae, Dipluridae, Hahniidae, Linyphiidae, Lycosidae, Nemesiidae, Palpimanidae, Salticidae, Scytodidae) that contributed most to separating native forest from the replanted forest, indicating the possibility of the spiders being used as bioindicators.

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Spiders are part of the soil biodiversity, considered fundamental to the food chain hierarchy, directly and indirectly influencing several services in agricultural and forest ecosystems. The present study aimed to evaluate the biodiversity of soil spider families and identify which soil properties influence their presence, as well as proposing families as potential bioindicators. Native forest (NF) and reforested sites (RF) with Araucaria angustifolia (Bertol.) Kuntze were evaluated in three regions of the state São Paulo, both in the winter and summer. Fifteen soil samples were collected from each forest to evaluate the biological (spiders and microbiological), chemical and physical soil properties, in addition to properties of the litter (dry matter and C, N and S contents). For soil spiders, two sampling methods were used: pitfall traps and soil monoliths. In total, 591 individuals were collected, and distributed in 30 families, of which 306 individuals (22 families) came from pitfall traps and 285 individuals (26 families) from monoliths. Only samples obtained by the monolith method revealed seasonal differences in the mean density and richness of spiders between NF and RF. Canonical discriminant analysis showed the separation of these forests of Araucaria. Principal Component Analysis demonstrated the correlation of a number of spider families with certain soil properties (organic carbon, basal respiration, metabolic quotient, litter carbon, total porosity, bulk density and soil moisture). We identified 10 families (Anapidae, Corinnidae, Dipluridae, Hahniidae, Linyphiidae, Lycosidae, Nemesiidae, Palpimanidae, Salticidae, Scytodidae) that contributed most to separating native forest from the replanted forest, indicating the possibility of the spiders being used as bioindicators.

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The amount of nanoparticles (NP), such as TiO2, has increased substantially in the environment. It is still largely unknown, however, how NP might interact with earthworms and organic material and how this might affect the bacterial community structure and their functionality. Therefore, an arable soil was amended with TiO2 NP at 0, 150 or 300 mg kg-1 and subjected to different treatments. Treatments were soil amended with ten earthworms (Eisenia fetida (Savigny, 1826)) with fully developed clitellum and an average fresh mass of 0.5 to 500 g dry soil, 1.75 g tyndallized Quaker® oat seeds Avena sativa (L.) kg-1, or earthworms plus oat seeds, or left unamended. The bacterial community structure was monitored throughout the incubation period. The bacterial community in the unamended soil changed over time and application of oats, earthworm and a combination of both even further, with the largest change found in the latter. Application of NP to the unamended soil and the earthworm-amended soil altered the bacterial community, but combining it by adding oats negated that effect. It was found that the application of organic material, that is, oats, reduced the effect of the NP applied to soil. However, as the organic material applied was mineralized by the soil microorganisms, the effect of NP increased again over time.

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Changes in land use management in agricultural areas can affect the biodiversity of spider families. This study aimed to evaluate spider diversity in different land use systems with capture by two sampling methods, and to identify soil properties that can modulate the occurrence of spiders. Five land use systems, representative of traditional agricultural areas, were evaluated in the west of Santa Catarina, Brazil, to establish a scale of land use intensity: native forest, eucalyptus reforestation areas, pastures, crop-livestock integration areas, and annual crops under no-tillage. The collection methods were manual from soil monoliths and soil traps. Altogether 479 individuals were captured, which were distributed among 20 families, 40 genera, and 8 species. Principal component analysis separated the land use systems and showed an association of spider families with land use in the two sampling methods. There was reduction in spider diversity as the intensity of land use increased. The manual collection method was more efficient for families of soil spiders, whereas traps were more efficient for epigeic spiders. The Lycosidae family was more resistant to environmental pressures, while Oonopidae and Amaurobiidae were more sensitive to environmental modifications. The differences in the spider communities were explained by the following soil properties: organic matter, mean weight-diameter of soil aggregates, and resistance to penetration, which were associated with the degree of anthropic intervention in the land use systems.

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Land use changes (LUC) from pasture to sugarcane (Saccharum spp.) crop are expected to add 6.4Mha of new sugarcane land by 2021 in the Brazilian Cerrado and Atlantic Forest biomes. We assessed the effects of these LUC on the abundance and community structure of animals that inhabit soils belowground through a field survey using chronosequences of land uses comprising native vegetation, pasture, and sugarcane along a 1000-km-long transect across these two major tropical biomes in Brazil. Macrofauna community composition differed among land uses. While most groups were associated with samples taken in native vegetation, high abundance of termites and earthworms appeared associated with pasture soils. Linear mixed effects analysis showed that LUC affected total abundance (X(2)(1)=6.79, p=0.03) and taxa richness (X(2)(1)=6.08, p=0.04) of soil macrofauna. Abundance increased from 411±70individualsm(-2) in native vegetation to 1111±202individualsm(-2) in pasture, but decreased sharply to 106±24individualsm(-2) in sugarcane soils. Diversity decreased 24% from native vegetation to pasture, and 39% from pasture to sugarcane. Thus, a reduction of ~90% in soil macrofauna abundance, besides a loss of ~40% in the diversity of macrofauna groups, can be expected when sugarcane crops replace pasture in Brazilian tropical soils. In general, higher abundances of major macrofauna groups (ants, coleopterans, earthworms, and termites) were associated with higher acidity and low contents of macronutrients and organic matter in soil. This study draws attention for a significant biodiversity loss belowground due to tropical LUC in sugarcane expansion areas. Given that many groups of soil macrofauna are recognized as key mediators of ecosystem processes such as soil aggregation, nutrients cycling and soil carbon storage, our results warrant further efforts to understand the impacts of altering belowground biodiversity and composition on soil functioning and agriculture performance across LUC in the tropics.

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The consequences of deforestation for aboveground biodiversity have been a scientific and political concern for decades. In contrast, despite being a dominant component of biodiversity that is essential to the functioning of ecosystems, the responses of belowground biodiversity to forest removal have received less attention. Single-site studies suggest that soil microbes can be highly responsive to forest removal, but responses are highly variable, with negligible effects in some regions. Using high throughput sequencing, we characterize the effects of deforestation on microbial communities across multiple biomes and explore what determines the vulnerability of microbial communities to this vegetative change. We reveal consistent directional trends in the microbial community response, yet the magnitude of this vegetation effect varied between sites, and was explained strongly by soil texture. In sandy sites, the difference in vegetation type caused shifts in a suite of edaphic characteristics, driving substantial differences in microbial community composition. In contrast, fine-textured soil buffered microbes against these effects and there were minimal differences between communities in forest and grassland soil. These microbial community changes were associated with distinct changes in the microbial catabolic profile, placing community changes in an ecosystem functioning context. The universal nature of these patterns allows us to predict where deforestation will have the strongest effects on soil biodiversity, and how these effects could be mitigated.

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Analysis of bacterial diversity in soils along the banks of the Solimões and Negro rivers, state of Amazonas, Brazil, was by partial sequencing of the genes codifying the rDNA16S region. Diversity of operational taxonomic units (OTU) and of the divergent sequences obtained were applied in comparative analysis of microbiological diversity in the two environments, based on richness estimators and OTU diversity indices. The higher OTU diversity in the Solimões was based on the higher number of parameters that evoke this. The interaction between the nucleotide sequences of bacteria inhabiting the two riverine environments indicated that the two microrganism communities are similar in composition.

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Analysis of bacterial diversity in soils along the banks of the Solimões and Negro rivers, state of Amazonas, Brazil, was by partial sequencing of the genes codifying the rDNA16S region. Diversity of operational taxonomic units (OTU) and of the divergent sequences obtained were applied in comparative analysis of microbiological diversity in the two environments, based on richness estimators and OTU diversity indices. The higher OTU diversity in the Solimões was based on the higher number of parameters that evoke this. The interaction between the nucleotide sequences of bacteria inhabiting the two riverine environments indicated that the two microrganism communities are similar in composition.

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