Changes in the Soil Bacterial Communities in a Cedar Plantation Invaded by Moso Bamboo

Moso bamboo is fast-growing and negatively allelopathic to neighboring plants. However, there is little information on the effects of its establishment and expansion to adjacent forest soil communities. To better understand the impacts of bamboo invasion on soil communities, the phylogenetic structure and diversity of the soil bacterial communities in moso bamboo forest, adjacent Japanese cedar plantation, and bamboo-invaded transition zone were examined using a combination of 16S rRNA gene clone libraries and bar-coded pyrosequencing techniques. Based on the number of operational taxonomic units (OTUs), Shannon diversity index, Chao1 estimator, and rarefaction analysis of both techniques, the bamboo soil bacterial community was the most diverse, followed by the transition zone, with the cedar plantation possessing the lowest diversity. The results from both techniques revealed that the Acidobacteria and Proteobacteria predominated in the three communities, though the relative abundance was different. The 250 most abundant OTUs represented about 70 % of the total sequences found by pyrosequencing. Most of these OTUs were found in all three soil communities, demonstrating the overall similarity among the bacterial communities. Nonmetric multidimensional scaling analysis showed further that the bamboo and transition soil communities were more similar with each other than the cedar soils. These results suggest that bamboo invasion to the adjacent cedar plantation gradually increased the bacterial diversity and changed the soil community. In addition, while the 10 most abundant OTUs were distributed worldwide, related sequences were not abundant in soils from outside the forest studied here. This result may be an indication of the uniqueness of this region.     

The Impact of Selective-Logging and Forest Clearance for Oil Palm on Fungal Communities in Borneo

Tropical forests are being rapidly altered by logging, and cleared for agriculture. Understanding the effects of these land use changes on soil fungi, which play vital roles in the soil ecosystem functioning and services, is a major conservation frontier. Using 454-pyrosequencing of the ITS1 region of extracted soil DNA, we compared communities of soil fungi between unlogged, once-logged, and twice-logged rainforest, and areas cleared for oil palm, in Sabah, Malaysia. Overall fungal community composition differed significantly between forest and oil palm plantation. The OTU richness and Chao 1 were higher in forest, compared to oil palm plantation. As a proportion of total reads, Basidiomycota were more abundant in forest soil, compared to oil palm plantation soil. The turnover of fungal OTUs across space, true β-diversity, was also higher in forest than oil palm plantation. Ectomycorrhizal (EcM) fungal abundance was significantly different between land uses, with highest relative abundance (out of total fungal reads) observed in unlogged forest soil, lower abundance in logged forest, and lowest in oil palm. In their entirety, these results indicate a pervasive effect of conversion to oil palm on fungal community structure. Such wholesale changes in fungal communities might impact the long-term sustainability of oil palm agriculture. Logging also has more subtle long term effects, on relative abundance of EcM fungi, which might affect tree recruitment and nutrient cycling. However, in general the logged forest retains most of the diversity and community composition of unlogged forest.     

Pyrosequencing Reveals Changes in Soil Bacterial Communities after Conversion of Yungas Forests to Agriculture

The Southern Andean Yungas in Northwest Argentina constitute one of the main biodiversity hotspots in the world. Considerable changes in land use have taken place in this ecoregion, predominantly related to forest conversion to croplands, inducing losses in above-ground biodiversity and with potential impact on soil microbial communities. In this study, we used high-throughput pyrosequencing of the 16S ribosomal RNA gene to assess whether land-use change and time under agriculture affect the composition and diversity of soil bacterial communities. We selected two areas dedicated to sugarcane and soybean production, comprising both short- and long-term agricultural sites, and used the adjacent native forest soils as a reference. Land-use change altered the composition of bacterial communities, with differences between productive areas despite the similarities between both forests. At the phylum level, only Verrucomicrobia and Firmicutes changed in abundance after deforestation for sugarcane and soybean cropping, respectively. In cultivated soils, Verrucomicrobia decreased sharply (~80%), while Firmicutes were more abundant. Despite the fact that local diversity was increased in sugarcane systems and was not altered by soybean cropping, phylogenetic beta diversity declined along both chronosequences, evidencing a homogenization of soil bacterial communities over time. In spite of the detected alteration in composition and diversity, we found a core microbiome resistant to the disturbances caused by the conversion of forests to cultivated lands and few or none exclusive OTUs for each land-use type. The overall changes in the relative abundance of copiotrophic and oligotrophic taxa may have an impact in soil ecosystem functionality. However, communities with many taxa in common may also share many functional attributes, allowing to maintain at least some soil ecosystem services after forest conversion to croplands.     

Characterization of fungal soil communities by F-RISA and arbuscular mycorrhizal fungi fromAraucaria angustifolia forest soils after replanting and wildfire disturbances

The Fungal Ribosomallntergenic Spacer Analysis (F-RlSA) was used to characterize soil fungal communities from three Cecosystems ofAraucaria angustifolia from Brazil: a native forest and two replanted forest ecosystems, one of them with a past history of wildfire. The arbuscular mycorrhizal fungi (AMF) infection was evaluated inAraucaria roots of 18-monthold axenic plants previously inoculated with soils collected from those areas in a greenhouse experiment. The principal componentanalysis of F-RISA profiles showed different soil fungal community betweenthe three studied areas. Sixty three percent of F-RISA fragments amplified in the soil and the substrate samples presented lengths between 500 and 700 bp. The number of Operational Taxonomic Units (OTUs) was 34 for soil and 38 for substrate, however, more fragments were detected in soil (214) than in substrate (163). Anin silico F-RISA analysis to compare our data with ITSI-5.8S-ITS2 sequences from NCBI database showed the presence of Ascomycota, Basidiomycota and Glomeromycota among the soil and substrate fungal communities. AMF infection was higher in plants inoculated with soil from the native forest and the replanted forest with wildfire, both presenting similar chemical characteristics but with different disturbance levels. These results indicate that soil chemical composition may influence the soil fungal community structures rather than the anthropogenicor fire disturbances.     

Effect of Sugarcane Burning or Green Harvest Methods on the Brazilian Cerrado Soil Bacterial Community Structure

Background

The Brazilian Cerrado is one of the most important biodiversity reservoirs in the world. The sugarcane cultivation is expanding in this biome and necessitates the study of how it may impact the soil properties of the Cerrado. There is a lack of information especially about the impacts of different sugarcane management on the native bacterial communities of Cerrado soil. Therefore, our objective was to evaluate and compare the soil bacterial community structure of the Cerrado vegetation with two sugarcane systems.

Methods

We evaluated samples under native vegetation and the impact of the two most commonly used management strategies for sugarcane cultivation (burnt cane and green cane) on this diversity using pyrosequencing and quantitative PCR of the rrs gene (16S rRNA).

Results and Conclusions

Nineteen different phyla were identified, with Acidobacteria (≈35%), Proteobacteria (≈24%) and Actinobacteria (≈21%) being the most abundant. Many of the sequences were represented by few operational taxonomic units (OTUs, 3% of dissimilarity), which were found in all treatments. In contrast, there were very strong patterns of local selection, with many OTUs occurring only in one sample. Our results reveal a complex bacterial diversity, with a large fraction of microorganisms not yet described, reinforcing the importance of this biome. As possible sign of threat, the qPCR detected a reduction of the bacterial population in agricultural soils compared with native Cerrado soil communities. We conclude that sugarcane cultivation promoted significant structural changes in the soil bacterial community, with Firmicutes phylum and Acidobacteria classes being the groups most affected.     

Distinct bacterial communities across a gradient of vegetation from a preserved Brazilian Cerrado

The Cerrado biome in the Sete Cidades National Park, an Ecological Reserve in Northeastern Brazil, has conserved its native biodiversity and presents a variety of plants found in other savannas in Brazil. Despite this finding the soil microbial diversity and community structure are poorly understood. Therefore, we described soil bacterial diversity and distribution along a savanna vegetation gradient taking into account the prevailing environmental factors. The bacterial composition was retrieved by sequencing a fragment of the 16S ribosomal RNA gene. The bacterial operational taxonomic units (OTUs) were assigned to 37 different phyla, 96 classes, and 83 genera. At the phylum level, a core comprised by Proteobacteria, Acidobacteria, Actinobacteria, Firmicutes, Verrucomicrobia and Planctomycetes, was detected in all areas of Cerrado. ‘Cerrado stricto sensu’ and ‘Cerradao’ share more similarities between edaphic properties and vegetation and also present more similar bacterial communities, while ‘Floresta decidual’ and ‘Campo graminoide’ show the largest environmental differences and also more distinct bacterial communities. Proteobacteria (26%), Acidobacteria (21%) and Actinobacteria (21%) were the most abundant phyla within the four areas. All the samples present similar bacteria richness (alpha diversity) and the observed differences among them (beta diversity) were more related to the abundance of specific taxon OTUs compared to their presence or absence. Total organic C, N and P are the main abiotic factors structuring the bacterial communities. In summary, our findings show the bacterial community structure was clearly different across the Cerrado gradient, but that these environments share a bacterial phylum-core comprising Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia and Planctomycetes with other Brazilian savannas.     

不同植被恢复模式下矿区复垦土壤真菌群落组成及多样性

本研究利用Illumina MiSeq高通量测序技术,分析安太堡露天煤矿生态复垦区4种植被恢复模式(刺槐Robinia pseudoacacia、油松Pinus tabulaeformis、沙棘Hippophae rhamnoides和柠条锦鸡儿Caragana korshinskii)土壤真菌群落组成及多样性,并探究其与土壤环境因子的相关性。高通量测序结果共获得821 508条有效序列和1 841个OTUs,子囊菌门Ascomycota和担子菌门Basidiomycota为优势菌门,序列数占真菌总数的88.43%,此外还含有3.72%未被分类学鉴定的真菌。真菌α多样性分析结果表明：刺槐模式、沙棘模式和柠条锦鸡儿模式的Sobs指数、Chao1指数、Ace指数和Shannon指数均显著高于油松模式(P<0.01),而油松模式的Simpson指数显著高于其余3种植被恢复模式(P<0.05)。真菌β多样性分析结果显示：OTU水平下4种植被恢复模式土壤真菌群落组成差异显著(R=0.709 9,P=0.005),其中,油松模式的土壤真菌群落与其他3种模式距离较远,差异显著(P<0.01),而其余3种植被恢复模式之间两两组成相近,差异不显著(P>0.05)。通过土壤理化性质的测定、典范对应分析、冗余分析以及Spearman相关性分析,结果发现土壤有机质、全氮和有效磷是显著影响4种植被恢复模式土壤真菌群落组成的环境因子。综上所述,在矿区生态复垦过程中刺槐模式是物种相对多度最高的植被恢复模式,油松模式是优势菌群含量最高的植被恢复模式。研究结果可为植被修复煤矿复垦区土壤及真菌资源的开发利用提供理论依据。     

Molecular phylogenetic diversity of bacteria associated with soil of the savanna-like Cerrado vegetation

The Brazilian savanna-like vegetation of Cerrado is rapidly being converted to pasture and agricultural fields. A 16S rDNA-based approach was taken to study the bacterial community associated with the soil of a native cerrado area (sensu stricto) and an area that has been converted to pasture. The bacterial group most abundantly identified in cerrado sensu stricto soil was the alpha-Proteobacteria while in cerrado converted to pasture the Actinobacteria were the most abundant. Rarefaction curves indicate that the species richness of cerrado sensu stricto is greater than that of cerrado converted to pasture. Furthermore, lineage-through-time plots show that the expected richness of species present in cerrado sensu stricto soil is approximately 10 times greater than that of cerrado converted to pasture.     

Diversity and distribution of soil fungal communities in a semiarid grassland

The fungal loop model of semiarid ecosystems integrates microtopographic structures and pulse dynamics with key microbial processes. However limited data exist about the composition and structure of fungal communities in these ecosystems. The goal of this study was to characterize diversity and structure of soil fungal communities in a semiarid grassland. The effect of long-term nitrogen fertilization on fungi also was evaluated. Samples of rhizosphere (soil surrounding plant roots) and biological soil crust (BSC) were collected in central New Mexico, USA. DNA was amplified from the samples with fungal specific primers. Twelve clone libraries were generated with a total of 307 (78 operational taxonomic units, OTUs) and 324 sequences (67 OTUs) for BSC and rhizosphere respectively. Approximately 40% of soil OTUs were considered novel (less than 97% identity when compared to other sequences in NCBI using BLAST). The dominant organisms were dark-septate (melanized fungi) ascomycetes belonging to Pleosporales. Effects of N enrichment on fungi were not evident at the community level; however the abundance of unique sequences, sampling intensity and temporal variations may be uncovering the effect of N in composition and diversity of fungal communities. The fungal communities of rhizosphere soil and BSC overlapped substantially in composition, with a Jaccard abundance similarity index of 0.75. Further analyses are required to explore possible functions of the dominant species colonizing zones of semiarid grassland soils.     

广西喀斯特地区毛唇芋兰根内与根际土壤真菌群落组成分析

为探索兰科(Orchidaceae)植物毛唇芋兰(Nervilia fordii)根内和根际土壤真菌群落多样性，该研究采用Illumina MiSeq高通量测序技术，分析了大新(DX)和龙州(LZ)两个样地(简称两地)毛唇芋兰根内和根际土壤的真菌组成。结果表明：(1)两地的毛唇芋兰根内和根际土壤真菌多样性很丰富，根际土壤真菌多样性均高于根内，主根的真菌多样性高于走茎。(2)通过测序共获得有效序列118 040条，207个可操作分类单元(OTUs)涉及8门19纲42目86科123属。(3)担子菌门(Basidiomycota)真菌是两地毛唇芋兰根内真菌的共同优势菌群，涉及胶膜菌科(Tulasnellaceae)、Trimorphomycetaceae、角担菌科(Ceratobasidiaceae)、马拉色菌科(Malasseziaceae)和小皮伞科(Marasmiaceae)等，其中优势科和优势属分别是胶膜菌科(75%)和瘤菌根菌属(Epulorhiza)(56%),而土壤中的优势菌属则是镰刀菌属(Fusarium)。综上认为，毛唇芋兰根内与根际土壤中的优势菌群既差异显著也存在一些共同...     

Changes in Diversity, Abundance, and Structure of Soil Bacterial Communities in Brazilian Savanna Under Different Land Use Systems

The Brazilian Savanna, also known as “Cerrado”, is the richest and most diverse savanna in the world and has been ranked as one of the main hotspots of biodiversity. The Cerrado is a representative biome in Central Brazil and the second largest biome in species diversity of South America. Nevertheless, large areas of native vegetation have been converted to agricultural land including grain production, livestock, and forestry. In this view, understanding how land use affects microbial communities is fundamental for the sustainable management of agricultural ecosystems. The aim of this work was to analyze and compare the soil bacterial communities from the Brazilian Cerrado associated with different land use systems using high throughput pyrosequencing of 16S rRNA genes. Relevant differences were observed in the abundance and structure of bacterial communities in soils under different land use systems. On the other hand, the diversity of bacterial communities was not relevantly changed among the sites studied. Land use systems had also an important impact on specific bacterial groups in soil, which might change the soil function and the ecological processes. Acidobacteria, Proteobacteria, and Actinobacteria were the most abundant groups in the Brazilian Cerrado. These findings suggest that more important than analyzing the general diversity is to analyze the composition of the communities. Since soil type was the same among the sites, we might assume that land use was the main factor defining the abundance and structure of bacterial communities.     

Fungal soil communities in a young transgenic poplar plantation form a rich reservoir for fungal root communities

Fungal communities play a key role in ecosystem functioning. However, only little is known about their composition in plant roots and the soil of biomass plantations. The goal of this study was to analyze fungal biodiversity in their belowground habitats and to gain information on the strategies by which ectomycorrhizal (ECM) fungi form colonies. In a 2-year-old plantation, fungal communities in the soil and roots of three different poplar genotypes (Populus × canescens, wildtype and two transgenic lines with suppressed cinnamyl alcohol dehydrogenase activity) were analyzed by 454 pyrosequencing targeting the rDNA internal transcribed spacer 1 (ITS) region. The results were compared with the dynamics of the root-associated ECM community studied by morphotyping/Sanger sequencing in two subsequent years. Fungal species and family richness in the soil were surprisingly high in this simple plantation ecosystem, with 5944 operational taxonomic units (OTUs) and 186 described fungal families. These findings indicate the importance that fungal species are already available for colonization of plant roots (2399 OTUs and 115 families). The transgenic modification of poplar plants had no influence on fungal root or soil communities. Fungal families and OTUs were more evenly distributed in the soil than in roots, probably as a result of soil plowing before the establishment of the plantation. Saprophytic, pathogenic, and endophytic fungi were the dominating groups in soil, whereas ECMs were dominant in roots (87%). Arbuscular mycorrhizal diversity was higher in soil than in roots. Species richness of the root-associated ECM community, which was low compared with ECM fungi detected by 454 analyses, increased after 1 year. This increase was mainly caused by ECM fungal species already traced in the preceding year in roots. This result supports the priority concept that ECMs present on roots have a competitive advantage over soil-localized ECM fungi.     

Fungal diversity within the phyllosphere of Pinus massoniana and the possible involvement of phyllospheric fungi in litter decomposition

Fungi play key roles in forest ecosystems and help to shape the forest’s diverse functions. However, little is known about the diversity of phyllospheric fungi or their possible relationships with fungal communities residing in different micro-environments of Pinus massoniana forests. We investigated seven different sample types: mature needles (NM), dead needles (ND), needles falling as litter (L), fermenting needles (F), humus (H), top soil (0–20 cm) (TS), and secondary soil (20–40 cm) (SS). These seven fungal communities were examined and compared with ITS amplicons using a high-throughput sequencing technique. A total of 1213 fungal operational taxonomic units (OTUs) were obtained at a 97% sequence similarity level. Distinct fungal communities were associated with different sample types. A greater number of OTUs were present in both NM and F samples than those shared by both NM and TS samples, indicating that phyllospheric fungi may play crucial roles in litter decomposition. Sixty OTUs (the core microbiome) were found in all sample types, and they may probably play different ecological roles in different sample types. These findings extend our knowledge of the fungal diversity of the phyllosphere and its possible interactions with fungal communities found in distinct forest micro-habitats.     

Environmental Controls on Fungal Community Composition and Abundance Over 3 Years in Native and Degraded Shrublands

Soil fungal communities have high local diversity and turnover, but the relative contribution of environmental and regional drivers to those patterns remains poorly understood. Local factors that contribute to fungal diversity include soil properties and the plant community, but there is also evidence for regional dispersal limitation in some fungal communities. We used different plant communities with different soil conditions and experimental manipulations of both vegetation and dispersal to distinguish among these factors. Specifically, we compared native shrublands with former native shrublands that had been disturbed or converted to pasture, resulting in soils progressively more enriched in carbon and nutrients. We tested the role of vegetation via active removal, and we manipulated dispersal by adding living soil inoculum from undisturbed native sites. Soil fungi were tracked for 3 years, with samples taken at ten time points from June 2006 to June 2009. We found that soil fungal abundance, richness, and community composition responded primarily to soil properties, which in this case were a legacy of plant community degradation. In contrast, dispersal had no effect on soil fungi. Temporal variation in soil fungi was partly related to drought status, yet it was much broader in native sites compared to pastures, suggesting some buffering due to the increased soil resources in the pasture sites. The persistence of soil fungal communities over 3 years in this study suggests that soil properties can act as a strong local environmental filter. Largely persistent soil fungal communities also indicate the potential for strong biotic resistance and soil legacies, which presents a challenge for both the prediction of how fungi respond to environmental change and our ability to manipulate fungi in efforts such as ecosystem restoration.     

Fungal diversity in soils across a gradient of preserved Brazilian Cerrado

The preserved Cerrado from Northeastern Brazil presents different physicochemical properties and plant diversity, which can influence the fungal communities. Therefore, we evaluated the fungal diversity in preserved sites, at Sete Cidades National Park, across a gradient of vegetation that included Campo graminoide, Cerrado stricto sensu, Cerradao, and Floresta decidual. Of all of the operational taxonomic units (OTUs) obtained, the Floresta decidual presented the highest richness. Ascomycota were the most abundant phylum (45%), followed by Basidiomycota (32%). Basal fungi and other phyla accounted for 23% of the total dataset. Agaricomycetes, Eurotiomycetes, Lecanoromycetes, Basidiobolus, Dothideomycetes, and Taphrinomycetes were the most abundant classes of fungi found across the gradient of Cerrado vegetation. In conclusion, our study suggests that the Brazilian Cerrado from Sete Cidades National Park presents a high fungal diversity and includes sources of new fungal species for biotechnological purposes.     

Unravelling soil fungal communities from different Mediterranean land-use backgrounds

Background

Fungi strongly influence ecosystem structure and functioning, playing a key role in many ecological services as decomposers, plant mutualists and pathogens. The Mediterranean area is a biodiversity hotspot that is increasingly threatened by intense land use. Therefore, to achieve a balance between conservation and human development, a better understanding of the impact of land use on the underlying fungal communities is needed.

Methodology/Principal Findings

We used parallel pyrosequencing of the nuclear ribosomal ITS regions to characterize the fungal communities in five soils subjected to different anthropogenic impact in a typical Mediterranean landscape: a natural cork-oak forest, a pasture, a managed meadow, and two vineyards. Marked differences in the distribution of taxon assemblages among the different sites and communities were found. Data analyses consistently indicated a sharp distinction of the fungal community of the cork oak forest soil from those described in the other soils. Each soil showed features of the fungal assemblages retrieved which can be easily related to the above-ground settings: ectomycorrhizal phylotypes were numerous in natural sites covered by trees, but were nearly completely missing from the anthropogenic and grass-covered sites; similarly, coprophilous fungi were common in grazed sites.

Conclusions/Significance

Data suggest that investigation on the below-ground fungal community may provide useful elements on the above-ground features such as vegetation coverage and agronomic procedures, allowing to assess the cost of anthropogenic land use to hidden diversity in soil. Datasets provided in this study may contribute to future searches for fungal bio-indicators as biodiversity markers of a specific site or a land-use degree.     

Disclosing arbuscular mycorrhizal fungal biodiversity in soil through a land-use gradient using a pyrosequencing approach

The biodiversity of arbuscular mycorrhizal fungi (AMF) communities present in five Sardinian soils (Italy) subjected to different land-use (tilled vineyard, covered vineyard, pasture, managed meadow and cork-oak formation) was analysed using a pyrosequencing-based approach for the first time. Two regions of the 18S ribosomal RNA gene were considered as molecular target. The pyrosequencing produced a total of 10924 sequences: 6799 from the first and 4125 from the second target region. Among these sequences, 3189 and 1003 were selected to generate operational taxonomic units (OTUs) and to evaluate the AMF community richness and similarity: 117 (37 of which were singletons) and 28 (nine of which were singletons) unique AMF OTUs were detected respectively. Within the Glomeromycota OTUs, those belonging to the Glomerales order were dominant in all the soils. Diversisporales OTUs were always detected, even though less frequently, while Archaeosporales and Paraglomerales OTUs were exclusive of the pasture soil. Eleven OTUs were shared by all the soils, but each of the five AMF communities showed particular features, suggesting a meaningful dissimilarity among the Glomeromycota populations. The environments with low inputs (pasture and covered vineyard) showed a higher AMF biodiversity than those subjected to human input (managed meadow and tilled vineyard). A reduction in AMF was found in the cork-oak formation because other mycorrhizal fungal species, more likely associated to trees and shrubs, were detected. These findings reinforce the view that AMF biodiversity is influenced by both human input and ecological traits, illustrating a gradient of AMF communities which mirror the land-use gradient. The high number of sequences obtained by the pyrosequencing strategy has provided detailed information on the soil AMF assemblages, thus offering a source of light to shine on this crucial soil microbial group.     

Diversity of Archaea in Brazilian savanna soils

Although the richness of Bacteria and Fungi in Cerrado’ soils has been reported, here we report, for the first time, the archaeal community in Cerrado’s soils. DNA extracted from soil of two distinct vegetation types, a dense subtype of sensu strict (cerrado denso) and riverbank forest (mata de galeria), was used to amplify Archaea-specific 16S rRNA gene. All of the fragments sequenced were classified as Archaea into the phylum Thaumarchaeota, predominantly affiliated to groups I.1b and I.1c. Sequences affiliated to the group I.1a were found only in the soil from riverbank forest. Soils from ‘cerrado denso’ had greater Archaea richness than those from ‘mata de galeria’ based on the richness indexes and on the rarefaction curve. β-Diversity analysis showed significant differences between the sequences from the two soil areas studied because of their different thaumarchaeal group composition. These results provide information about the third domain of life from Cerrado soils.     

Ecosystem Disturbances and Diversity Increase: Implications for Invertebrate Conservation

The Pantanal is one of the faunistic provinces considered as a priority area for invertebrate conservation. However, it is one of the areas in Brazil where the local fauna is less assessed, thus needing more scientific information that could allow political decisions to be made regarding conservation. The continuous pressure for new pasture areas leads to improper habitat occupation and destruction, like fragmentation of forest areas in the region. Such alterations can cause different impacts on the local fauna, including the soil arthropods. The main objective of this work was to compare the morphospecies composition, diversity and density of the soil arthropod fauna between a secondary single species forest (Cambarazal) and a cultivated pasture with exotic and native grass species, using only pitfall traps as sampling method. We found a great variation on the vegetal cover among environments. A higher humidity in the forest soil was observed, as well as a greater compaction of the soil in the cultivated pasture. A total of 3635 individuals were collected, belonging to 214 different morphospecies. 139 morphospecies were collected in the forest (37% exclusive to this environment), while 134 morphospecies were collected in the cultivated pasture (35% exclusive). The diversity was higher in the forest (H′ = 1.634) than in the cultivated pasture (H′ = 1.253). However, considering the area as a whole (forest and pasture) the global diversity was increased. In this paper we discuss about the effects of environmental changes on soil arthropod diversity and propose a hypothetical model for invertebrate management in mosaic ecosystems.     

Characterization of Soil Bacterial Assemblies in Brazilian Savanna-Like Vegetation Reveals Acidobacteria Dominance

The Brazilian Cerrado is the second largest biome in Brazil and is considered a biodiversity hotspot. In this work, we compared the bacterial communities in Cerrado soil associated with four types of native vegetation (Cerrado Denso, Cerrado sensu stricto, Campo Sujo, and Mata de Galeria) by ribosomal RNA intergenic spacer analysis, terminal fragment restriction length polymorphism and pyrosequencing. The fingerprinting results were very similar. The bacterial communities of Cerrado Denso and Cerrado sensu stricto grouped together and were distinct from those in Campo Sujo and Mata de Galeria. Pyrosequencing generated approximately 40,000 16S rRNA gene sequences per sample and allowed the identification of 17 phyla in soil samples under Cerrado vegetation. Acidobacteria were dominant in all areas studied with a relative frequency of 40-47?%, followed closely by Proteobacteria accounting for 34-40?% of the sequences. Results from all molecular techniques used suggested that the bacterial communities of Cerrado sensu stricto and Cerrado Denso are very similar to each other, while Campo Sujo forms a separate group, and Mata de Galeria is the most distinct with higher species richness. This is the first extensive study of native Cerrado soil microbiota, an important but endangered biome.