Veredas are humid tropical ecosystems, generally associated to hydromorphic soils and a shallow water table. The soils of these ecosystems are affected by the use of the areas around these veredas. The objective of this study was to determine soil organic matter (SOM) fractions in veredas adjacent to preserved (native savanna) and disturbed environments (agricultural areas and pastures) in the Cerrado biome. Soil samples were collected from the 0-10 and 10-20 cm layers along reference lines drawn along the relief following the upper, middle and lower positions of one of the slopes, in the direction of the draining line of the vereda. The soil analysis determined: total soil OC, total nitrogen and C:N ratio; C and N contents and C:N ratio in particulate and mineral-associated fractions (of SOM); fulvic acids, humic acids and humin fractions and ratio between humic and fulvic acids. The agricultural use around the veredas induced changes in the SOM fractions, more pronounced in the lower part of the slope. In the soil surface of this part, the OC levels in the humic substances and the particulate fraction of SOM, as well as total soil OC were reduced in the vereda next to crop fields. Keywords

RESUMOAs veredas são ecossistemas úmidos, geralmente associados a solos hidromórficos e ao afloramento do lençol freático, ocorrendo com frequência nas proximidades das nascentes e cursos d'água da região do Cerrado. Este trabalho objetivou estudar os solos de veredas situadas no bioma Cerrado, em ambientes conservados e antropizados (em áreas agrícolas e de pecuária), por meio da determinação da textura e da matéria orgânica do solo. Três veredas foram selecionadas para amostragem de solo, sendo: uma conservada, circundada por vegetação natural; uma área antropizada, com pastagem em seu entorno e uma outra, também antropizada, com culturas anuais (agricultura) em seu entorno. As amostras de solo foram coletadas em diferentes profundidades, ao longo de linhas de referência dispostas segundo sua posição no relevo, nos terços superior, médio e inferior de uma das vertentes, acompanhando de modo aproximado o sentido da linha de drenagem da vereda. Verificou-se que os teores de argila na região inferior do relevo são maiores em ambientes antropizados e os teores de silte são maiores na vereda adjacente à área agrícola. No terço inferior das vertentes os teores de matéria orgânica são menores em veredas adjacentes às áreas com pastagens e agricultura.Palavras-chave: áreas úmidas, propriedades do solo, solos hidromórficos, uso da terra Organic matter and texture of the soil in conserved and altered wetlands in the Cerrado biome ABSTRACT Veredas (a type of wetland) are humid ecosystems, generally associated to hydromorphic soils and shallow water table, which occur frequently in the neighborhood of the springs and watercourses in the Cerrado region. The objective of this work was to study wetland soils located in undisturbed (native forest) and disturbed (agriculture and pasture) environments by means of determination of the soil texture and organic matter contents. Three wetlands were selected for this study: undisturbed wetland, surrounded by natural vegetation; disturbed wetland, surrounded by pasture areas; and disturbed wetland, surrounded by cultivated areas. Soil samples were collected at three different depths, following reference leveled lines defined, according to their positions in the relief, i.e., upper, middle and lower slope positions. The reference lines were approximately parallel to the direction of the wetland fluvial channel. It was verified that the clay contents in the lower portion of the slope were higher for the disturbed environments and the contents of silt were higher for the disturbed wetland surrounded by agricultural areas. The organic matter contents in the lower portion of the slope were lower for the disturbed wetlands.

ABSTRACT:The veredas (a type of wetlands) are wet ecosystems usually associated with the presence of hydromorphic soils, which often occur in the vicinity of springs and watercourses of the Cerrado region in Brazil. This study aimed to assess microbiological and biochemical soil properties in wetlands (veredas) located in preserved and disturbed environments (in farming and grazing areas) in the Cerrado biome. Soil samples were collected at depths of 0-10 cm and 10-20 cm, along reference lines arranged according to their position in the landscape, in the upper, middle and lower positions of one of the slopes. The total soil organic carbon, microbial biomass carbon and nitrogen (C mic and N mic ), microbial biomass C:N ratio, microbial quotient, basal respiration, metabolic quotient and fluorescein diacetate (FDA) hydrolytic activities in soil (as total soil heterotrophic enzymatic activity) were determined. The soils of veredas adjacent to agricultural and livestock environments showed changes in their biological properties compared to preserved ecosystems. Increased microbial biomass (C mic and N mic ) is reported in veredas located nearby grazing areas under intensive and technified management, on the soil surface layer (0-10 cm), especially in the lower slope position, while in agricultural environments, under the same conditions of relief and depth, there is a relative decrease in microbial biomass carbon.

No abstract