SUMMARYMorphologically differentiated Spodosols usually occur in the Coastal Plain of the South of Bahia and North of Espírito Santo. They are found in profiles known as "muçungas", i.e. sandy soils that accumulate water. In these areas, two kinds of Spodosols, different from those in the Restinga area, can be found: Spodosols with E albic horizon (white muçunungas) and without this horizon (black muçunungas). Eight soil profiles with spodic characteristics were collected and described in order to evaluate differences in the formation process of Barreiras and Restinga Spodosols in the South of Bahia. The soil profiles were also characterized chemically, physically and mineralogically. Additionally, texture and chemical analysis, Fe and Al extraction by sodium dithionite-citrate-bicarbonate (DBC), acid ammonium oxalate and sodium pyrophosphate, ammonium oxalate extract optic density (DOox), sulphuric acid attack, and X ray difractometry of the clay fraction were performed. In the Spodosols of the Barreiras area, fragipan was found the spodic layers. Cemented B spodic horizon were observed in the white muçunungas, and granular structure and dark color from the surface in the black muçunungas. There was no fragipan or hard spodic horizon in the Restinga Spodosol. This soil is acid, dystrophic and alic, with sandy texture and high clay percentages in the spodic horizons. The CEC, based on H + Al, is predominantly represented by the organic matter. The most representative components of the mineral phase of the clay fraction are kaolinite and possibly vermiculite traces with interlayered hydroxy.

-The objective of this work was to present an approach to evaluate soil functions in agroecosystems and their impact on environmental services (ES). An approach with case studies was proposed to assess the relationship between the establishment and management of agroecosystems, in three Brazilian biomes (Atlantic Forest, Cerrado, and Caatinga), and their environmental services provision, considering the specificities of each area. A set of soil parameters that can be used as indicators to monitor changes in the agroecosystem was also proposed. The environmental services types most affected by the establishment and management of the agroecosystems were the supporting and provisioning services, showing the potential of agricultural management in providing multiple services, besides food, fiber, and energy. "No fire use" and "agricultural consortium" were the criteria for the establishment and management of agroecosystems with greater potential to increase environmental services provision, whereas biomass stock in soil and litter was the most appropriate soil parameter to be used as an indicator to monitor the impact of agroecosystems in environmental services provision.Index terms: environmental services indicators, multifunctional agriculture, public policies, soil management, sustainable agriculture. Uma abordagem para avaliar o potencial de agroecossistemas em prover serviços ambientaisResumo -O objetivo deste trabalho foi apresentar uma abordagem para avaliar as funções do solo em agroecossistemas e seus impactos sobre os serviços ambientais (SA). Uma abordagem com estudo de casos foi proposta para analisar a relação entre o estabelecimento e o manejo de agroecossistemas, em três biomas brasileiros (Floresta Atlântica, Cerrado e Caatinga), e a sua correlação com a prestação de serviços ambientais, tendo-se levado em consideração as especificidades de cada área. Também foi proposto um conjunto de parâmetros do solo que possam ser utilizados como indicadores para monitorar as alterações no agroecossistema. Observou-se que os tipos de serviços ambientais mais afetados pela implantação e pela gestão dos agroecossistemas são os de suporte e provisão, o que mostra o potencial que o manejo agrícola tem de fornecer múltiplos serviços, além de alimentos, fibras e energia. "Sem uso de fogo" e "consórcios agrícolas" foram os critérios usados na implantação e a gestão de agroecossistemas com maior potencial em aumentar a prestação de serviços ambientais, enquanto o estoque de biomassa no solo e na serapilheira foi o parâmetro do solo mais adequado para uso como indicador no monitoramento do impacto do agroecossistema na prestação de serviços ambientais.Termos para indexação: indicadores de serviços ambientais, agricultura multifuncional, políticas públicas, manejo do solo, agricultura sustentável.

As iniciativas de Pagamento por Serviços Ambientais com foco na água (PSA hídrico) estão se expandindo em toda a América Latina e no Brasil, sobretudo a partir da criação do Programa Produtor de Água, em 2006, pela Agência Nacional de Águas (ANA). Este estudo objetivou traçar o perfil da evolução dos PSAs hídricos no período de 2011 a 2014 no Brasil. As iniciativas de PSAs hídricos foram identificadas, classificadas e mapeadas quanto a seu estágio de atuação, com base em dados obtidos em páginas eletrônicas e entrevistas a organizações não governamentais e governamentais (federais, estaduais e municipais), relacionadas a essas iniciativas. O número de iniciativas de PSAs hídricos aumentou de 42, em 2011, para 52 em 2014. De modo geral, elas estão evoluindo em termos de estágio de atuação, mas muitas têm enfrentado dificuldades, principalmente pela descontinuidade da fonte de recursos para o pagamento. Concluiu-se que as informações sobre as iniciativas de PSA hídrico no Brasil, quando existentes, são difusas, e que elas estão evoluindo progressivamente no Brasil e se expandindo para outros biomas além da Mata Atlântica, mas ainda com diversas lacunas que precisam ser supridas.

Advancing extensive cattle production shifts the forest landscape and is considered one of the main drivers against biodiversity conservation in the Brazilian Amazonia. Considering soil as an ecosystem it becomes vital to identify the effects of land-use changes on soil microbial communities, structure, as well as its ecological functions and services. Herein, we explored relationships between land-use, soil types and forest floor (i.e., association between litter, root layer and bulk soil) on the prokaryotic metacommunity structuring in the Western Amazonia. Sites under high anthropogenic pressure were evaluated along a gradient of ± 800 km. Prokaryotic metacommunity are synergistically affected by soil types and land-use systems. Especially, the gradient of soil fertility and land-use shapes the structuring of the metacommunity and determines its composition. Forest-to-pasture conversion increases alpha, beta, and gamma diversities when considering only the prokaryotes from the bulk soil. Beta diversity was significantly higher in all forests when the litter and root layer were taken into account with the bulk soil. Our argumentation is that the forest floor harbors a prokaryotic metacommunity that adds at the regional scale of diversity a spatial turnover hitherto underestimated. Our findings highlight the risks of biodiversity loss and, consequently, the soil microbial diversity maintenance in tropical forests.

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Advancing extensive cattle production is a major threat to biodiversity conservation in Amazonia. The dominant vegetation cover has a drastic impact on soil microbial communities, affecting their composition, structure, and ecological services. Herein, we explored relationships between land-use, soil types, and forest floor compartments on the prokaryotic metacommunity structuring in Western Amazonia. Soil samples were taken in sites under high anthropogenic pressure and distributed along a ±800 km gradient. Additionally, the litter and a root layer, characteristic of the forest environment, were sampled. DNA was extracted, and metacommunity composition and structure were assessed through 16S rRNA gene sequencing. Prokaryotic metacommunities in the bulk soil were strongly affected by pH, base and aluminum saturation, Ca + Mg concentration, the sum of bases, and silt percentage, due to land-use management and natural differences among the soil types. Higher alpha, beta, and gamma diversities were observed in sites with higher soil pH and fertility, such as pasture soils or fertile soils of the state of Acre. When taking litter and root layer communities into account, the beta diversity was significantly higher in the forest floor than in pasture bulk soil for all study regions. Our results show that the forest floor’s prokaryotic metacommunity performs a spatial turnover hitherto underestimated to the regional scale of diversity.

This study investigated the contribution of soil organic layers to bacterial diversity evaluations. We used a forest in the eastern Amazon and an adjacent pasture as model systems. Distinct organic and organo-mineral layers were identified in the forest and pasture floors, including the litter, partially and wholly decomposed organic material, and the mineral and rhizospheric soils. DNA was extracted, and 16S rRNA gene sequencing and qPCR were performed to assess bacterial community structure and the abundance of critical groups of the N cycle. We observed a clear vertical gradient in bacterial community composition. Species followed a log-normal distribution, with the highest richness and diversity observed in transitional organic layers of both land uses. Generally, critical groups of the N cycle were more abundant in these transitional layers, especially in the pasture’s fragmented litter and in the forest’s partially decomposed organic material. Considering the organic layers increased diversity estimates significantly, with the highest alpha and gamma bacterial diversity observed on the pasture floor and the highest beta diversity on the forest floor. The results show that organic layers harbor significant bacterial diversity in natural and anthropized systems and suggest that they can be crucial for maintaining the N cycle in these ecosystems, highlighting the need to consider them when studying soil bacterial diversity.

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