Abstract The South Brazilian grasslands (Campos Sulinos) form the dominant vegetation in southern Brazil. They are species-rich ecosystems that occur under distinct geomorphological and climatic conditions but spatial variation of plant species diversity remains understudied. Here, we present a detailed description of plant communities across the region. Our data were obtained in 1080 plots, representing well-preserved grasslands in different ecological systems. Apart from describing alpha and beta diversity, we investigated the relations of plant communities with environmental features. We identified 759 plant species and found clear differences in community composition across the region. Northern and Southern highland grasslands, humid and dry coastal grasslands and the mesic Pampa grassland were clearly distinct, related to climatic and edaphic features. While species abundance distribution was markedly uneven, local species richness was high, above 20 species/m2, especially in the highlands and in mesic Pampa sites, on shallow soils. The predominant component of beta diversity was species turnover, which suggests that a network of well-conserved grasslands distributed across the region would be the best strategy to protect plant diversity. Our results establish regionalized reference values for richness and diversity that can be useful for initiatives of restoration and conservation of these grasslands.

Mapas convencionais de solos têm adquirido importância crescente como entrada para diversas aplicações, muitas vezes sem levar em conta a sua qualidade deles. O objetivo deste estudo foi descrever e comparar mapas de solos usando indicadores quantitativos de fácil determinação. Foram utilizados nove mapas elaborados em diferentes escalas no Rio Grande do Sul e o software ArcGIS. Calcularam-se a escala efetiva, o número de polígonos menores que a área mínima mapeável e um índice de complexidade de forma, e quantificaram-se o número de classes taxonômicas, de tipos de solos e de unidades de mapeamento e a fração da área com dados não uniformes. Os resultados evidenciaram que a qualidade de mapas de solos tende a ser inferior ao presumido para sua escala de apresentação, o que demonstra a importância e a necessidade de avaliações prévias ao seu uso. Indicadores computados a partir dos polígonos e da legenda possibilitam avaliação rápida e objetiva, com potencial de aplicação na sistematização e documentação de dados legados de solos no Brasil.

Conventional soil maps have acquired increasing importance as inputs for various applications, often without regard to their quality. The aim of this study was to assess and compare soil maps using easily determinable quantitative indicators. Nine soil maps (at different scales, from Rio Grande do Sul) and ArcGIS software were used. Effective scale number (NSN), polygons smaller than the minimum legible delineation (MLD), shape complexity index (S), number of taxonomic classes, soil types, mapping units, and proportion of areas with non-uniform data (PND) were computed. Results showed that the quality of legacy soil maps tends to be lower than presumed for their presentation scale, what shows the importance and need for quality assessments prior to using them. Indicators computed from polygons and map legend enable quick and objective assessment, with potential application in systematizing and documenting legacy soil data in Brazil.

O objetivo deste trabalho foi avaliar a redução do vigor vegetativo da cobertura vegetal do Pampa do Brasil e do Uruguai, por meio da identificação de tendências negativas em séries temporais de imagens. Utilizaram-se séries temporais de imagens de NDVI/EVI do sensor Modis, de 2000 a 2011; imagens de índices de umidade do solo do "climate forecast system reanalysis"; e dados de precipitação pluvial de estações meteorológicas. O estudo quantificou tendências lineares e não lineares nas séries de NDVI e EVI, em áreas de campos. Na tendência monotônica de Mann-Kendall, a 5% de probabilidade, 81,9% da área total estudada foi significativa com o NDVI, e 74,8%, com o EVI; no entanto, o EVI apresentou contraste superior na estimativa dos parâmetros. Os resultados mostraram maior sinal negativo a oeste, com valores médios de R²>0,15, r<-0,3 e τ <-0,15 na tendência dos índices de vegetação, e tendência decrescente para NDVI, EVI e precipitação pluvial, com menores valores médios de umidade do solo. A tendência negativa dos índices de vegetação, relacionada à combinação da ocorrência de deficit hídrico em solos rasos com o sobrepastoreio, indica alterações no padrão de cobertura vegetal do Pampa, com redução do vigor vegetativo.

The objective of this work was to evaluate the reduction in the vegetative vigor of Pampa vegetation cover in Brazil and Uruguay, by identifying negative trends in images time series. The following were used: time series of NDVI/EVI images from the Modis sensor, from 2000 to 2011; images from soil moisture indices from the climate forecast system reanalysis; and precipitation data from meteorological stations. The study quantified linear and nonlinear trends in the NDVI and EVI series in grassland areas. With the Mann-Kendall monotonic trend, at 5% probability, 81.9% of the total area studied was significant with NDVI, and 74.8% with EVI; however, EVI showed superior contrast in the estimation of parameters. The results showed: highest negative signal in the west, with average values of R²>0.15, r<-0.3, and τ <-0.15 in the tendency of the vegetation indices; and decreasing tendency for NDVI, EVI, and rainfall, with lower mean soil moisture values. The negative trend of the vegetation indices, related to the combination of drought occurrence in surface soils with excessive grazing, indicates changes in the pattern of Pampa vegetation cover, with reduction in vegetative vigor.

O objetivo deste trabalho foi avaliar a densidade de amostragem na acurácia de predição de ordens de solos, com alta resolução espacial, em área vitícola da Serra Gaúcha. Para isso, utilizou-se modelo digital de elevação (MDE) do terreno, base cartográfica, mapa convencional de solos e o programa Idrisi. Sete variáveis preditoras foram calculadas e lidas junto com as classes de solo, em pontos aleatoriamente distribuídos, nas densidades de 0,5, 1, 1,5, 2 e 4 pontos por hectare. Os dados foram usados para treinar uma árvore de decisão (Gini) e três redes neurais artificiais: teoria da ressonância adaptativa, fuzzy ARTMap; mapa auto‑organizável, SOM; e perceptron de múltiplas camadas, MLP. Os mapas estimados foram comparados com o mapa de solos convencional para calcular erros de omissão e de inclusão, exatidão geral, e erros de quantidade e de alocação. A árvore de decisão foi menos sensível à densidade de amostragem e apresentou maior acurácia e consistência. O SOM foi a rede neural com menor sensibilidade e maior consistência. O MLP apresentou mínimo crítico e maior inconsistência, enquanto fuzzy ARTMap apresentou maior sensibilidade e menor acurácia. Os resultados indicam que densidades de amostragem usadas em levantamentos convencionais podem servir de referência para estimar ordens de solos na Serra Gaúcha.

The objective of this work was to evaluate sampling density on the prediction accuracy of soil orders, with high spatial resolution, in a viticultural zone of Serra Gaúcha, Southern Brazil. A digital elevation model (DEM), a cartographic base, a conventional soil map, and the Idrisi software were used. Seven predictor variables were calculated and read along with soil classes in randomly distributed points, with sampling densities of 0.5, 1, 1.5, 2, and 4 points per hectare. Data were used to train a decision tree (Gini) and three artificial neural networks: adaptive resonance theory, fuzzy ARTMap; self‑organizing map, SOM; and multi‑layer perceptron, MLP. Estimated maps were compared with the conventional soil map to calculate omission and commission errors, overall accuracy, and quantity and allocation disagreement. The decision tree was less sensitive to sampling density and had the highest accuracy and consistence. The SOM was the less sensitive and most consistent network. The MLP had a critical minimum and showed high inconsistency, whereas fuzzy ARTMap was more sensitive and less accurate. Results indicate that sampling densities used in conventional soil surveys can serve as a reference to predict soil orders in Serra Gaúcha.

Quando levantamentos de solos não estão disponíveis para atividades de planejamento de uso das terras, técnicas de mapeamento digital de solos podem ser úteis. Mapeadores de solos podem processar as informações espaciais rapidamente, auxiliando na execução de levantamentos de solos tradicionais ou prevendo a ocorrência de classes de solos na paisagem. Avaliaram-se técnicas de análise de decisão na predição da ocorrência de classes de solos em áreas de encostas basálticas no Sul do Brasil. Várias combinações de tipos de algoritmos de árvore de decisão e quantidade de elementos nos nós terminais das árvores de decisão foram testadas usando mapas de solos com a legenda original e com legenda simplificada. Em geral, o uso de árvores de decisão foi eficaz na predição de ocorrência de unidades de mapeamento de solos. Menor número de elementos no nó terminal das árvores de decisão produziu acurácias mais altas e a simplificação da legenda (agregação) reduziu a precisão das predições. O algoritmo J48 teve melhor desempenho que BF Tree, RepTree, Random Tree, e Simple Chart.

When soil surveys are not available for land use planning activities, digital soil mapping techniques can be of assistance. Soil surveyors can process spatial information faster, to assist in the execution of traditional soil survey or predict the occurrence of soil classes across landscapes. Decision tree techniques were evaluated as tools for predicting the ocurrence of soil classes in basaltic steeplands in South Brazil. Several combinations of types of decicion tree algorithms and number of elements on terminal nodes of trees were compared using soil maps with both original and simplified legends. In general, decision tree analysis was useful for predicting occurrence of soil mapping units. Decision trees with fewer elements on terminal nodes yield higher accuracies, and legend simplification (aggregation) reduced the precision of predictions. Algorithm J48 had better performance than BF Tree, RepTree, Random Tree, and Simple Chart.

The present study aimed to evaluate the composition of mixed-species bird flocks in a fragmented landscape of the Atlantic Forest in southern Brazil. We recorded 117 species in 218 mixed-species flocks. The correspondence analysis showed two distinct groups of fragments according to degree of connectivity with other fragments. The percentage of original cover surrounding a sampled fragment area up to a ratio of 2.5 and 1 km was the variable that presented highest correlation with the formation of different composition of mixed-species bird flocks, followed by altitude. Based on these results, we concluded that, in landscapes with low levels of fragmentation, the composition of mixed flocks reflects the local species pool. Thus, future studies comparing composition of mixed-specie flocks should concentrate their efforts in areas where some of these variables remain constant, as for example where fragments are at similar altitudes.

O presente trabalho propõe o emprego de geotécnicas no apoio a um levantamento detalhado de solos, desde a coleta de dados em campo até à delimitação das unidades de solo e, posteriormente, a elaboração de um mapa final. A área de estudo corresponde a uma carta topográfica na escala 1:5.000 do Vale dos Vinhedos, na região da Serra Gaúcha, Rio Grande do Sul, Brasil. O material utilizado consiste em dados planialtimétricos de um levantamento aerofotogramétrico, receptores GPS (Global Posigioning System) e softwares de SIG (Sistemas de Informação Geográfica). Os softwares de SIG foram utilizados para integrar os dados de campo com as informações cartográficas e para analisar o relevo por meio de um MNT (Modelo Numérico do Terreno). Os resultados mostraram que o método permite a obtenção de um mapa digital georreferenciado, em que as unidades de mapeamento estão fortemente associadas com as fases de relevo, melhorando sua consistência e confiabilidade e facilitando seu uso futuro para outras aplicações.

This study proposes the use of geotechnologies to support detailed soil surveys, from field surveys to the delimitation of mapping units and later the drawing of the final map. The study area corresponds to a topographic map on a scale of 1:5,000 of the Vale dos Vinhedos, in the Serra Gaúcha region, State of Rio Grande do Sul, Brazil. The material used consists of planialtimetric data derived from aerial photographs, navigation GPS (Global Positioning System), and GIS (Geographical Information System) software. The GIS program was used to integrate field data with cartographic information and with a DTM (Digital Terrain Model). Results show that the methodology can generate a georreferenced digital map in which soil mapping units are strongly associated with relief phases, improving the consistency and reliability as well as making the use in further applications easier.

A survey of carnivore mammals was accomplished in Aparados da Serra National Park from February 1998 to March 2000. The park has 10,250 ha and is considered a biodiversity core area of the Atlantic Forest Biosphere Reserve in the Rio Grande do Sul State, Brazil. The landscape is characterized by relatively well preserved relicts of Araucaria angustifolia (Bertol.) Kuntze forest, grasslands and Atlantic Forest, which have contributed for the survival of endangered carnivore mammals. The National Park was divided in a grid of 16 km² cells using a 1:50,000 scale map. The animals were recorded using indirect methods, by identifying signs (scats, tracks) and direct observation in 2.5 km long and 5 m wide transects, with 10 replicates in each grid cell. Interviews with local people were also used to confirm the animal presence. A total of 13 species was recorded: Procyon cancrivorus (Cuvier, 1798), Pseudalopex gymnocercus (G. Fischer, 1814), Leopardus pardalis (Linnaeus, 1758) and Cerdocyon thous (Linnaeus, 1766) were the most frequent species registered. Nasua nasua (Linnaeus 1766), Herpailurus yaguarondi (Lacépède, 1809), Chrysocyon brachyurus (Illiger, 1815), Eira barbara (Linnaeus, 1758), Leopardus sp., Puma concolor (Linnaeus, 1771), Galictis cuja (Molina, 1782), Conepatus chinga (Molina, 1892) and Lontra longicaudis (Olfers, 1818) showed lower frequencies. The Park presented areas with significant differences (Mantel Test, P< 0.05) in species richness and composition related to habitat classes. Areas with high habitat richness presented high species richness. The Araucaria forest was the habitat that presented the higher carnivore richness. The border areas of the Park are influenced by several environmental degradation factors that could be affecting the distribution of carnivores.