Brazilian Plateau Research Articles

Multiproxy analysis (phytoliths, stable isotopes, and C/N) as indicators of paleoenvironmental changes in a Cerrado Site, Southern Brazil

Cerrado vegetation is associated with the semi-humid climate of the Central Brazil highlands. The presence of this vegetation in small and sparse areas in Parana, Southern Brazil, can be associated with its past climate conditions. Paleoenvironmental changes of Cerrado vegetation in the Campo Mourao region (24o06’S - 52o23’W) are discussed in this study. The environmental changes were characterized using proxy data that includes stable isotopes and phytolith analyses in peaty sediments. Two drill cores obtained in alluvial plains were analyzed. Results were compared with the isotopic record (δ 13 C) from a trench in the Cerrado Ecological Station. Based on the results, we can infer that in ~48,800±270 yrs BP, the vegetation was mainly composed of grasses and at ~42,280 cal yrs BP a wetter climate allowed the expansion of arboreal vegetation. During the Middle Holocene (~7280 cal yrs BP), a drier period is also reported. Current climatic conditions (wet) were established since ~3280 cal yrs BP, after which the data suggests the expansion of subtropical forests over the Cerrado.

Diversity and life-forms of a woody-herbaceous community on the quartzite rocky complexes in the Brazilian Iron Quadrangle

Although campos rupestres are iconic rock outcrops with a high biogeographic value in Brazilian highlands, little is known about the drivers responsible for the plant community pattern. We studied the diversity and life forms of the woody and herbaceous components occurring along different phytophysiognomies of the quartzite rocky complexes in highlands of the Quadrangle, Minas Gerais State, Brazil. A total of 130 plots were allocated in three phytophysiognomies along the pedogeomorphological gradient: i) herbaceous campo rupestre; ii) upper and lower strata of montane forest (capao florestal) and iii) scrub. Overall, 4 446 individuals were sampled, distributed among 218 species, especially from families: Asteraceae, in general; Myrtaceae, in the woody community; and Poaceae and Cyperaceae, in the herbaceous community. Species diversity, life forms, and abundance showed differences between phytophysiognomies. The most frequent life form was phanerophyte (montane forest and scrub), followed by hemicryptophyte (herbaceous campo rupestre). Our study reveals marked differences in the floristic composition, species richness, and life form spectrum among phytophysiognomies on a local scale. Such differences probably indicate that there is a high environmental heterogeneity at a small spatial scale.

Physiognomic and Multivariate Phytosociological Analyses of a Subtropical Peat Bog Located on the Eastern Plateau in Southern Brazil

Subtropical peat bog vegetation in southern Brazil was examined using physiognomic and phytosociological approaches. The analysis included vascular (angiosperms, pteridophytes) and non-vascular species (bryophytes, mat-forming algae, lichens, macroscopic fungi). The breadth of this approach is novel among wetland studies in southern Brazil. The study examined the Banhado Amarelo peat bog (29°19′05″S, 50°08′18″W), which is located in the Brazilian highlands of Rio Grande do Sul (RS) state. Plant cover data extracted from 125 plots distributed among 13 physiognomically recognizable vegetation patches were analyzed using the Braun-Blanquet procedure. In total, 165 species were identified. Multivariate analysis distinguished four groups of patches. The distinctions among groups were particularly evident when all floristic elements were included, i.e., vascular + non-vascular species. When the peat soil in these 13 vegetation patches was analyzed, the proportional clay content of the soil was related to the distribution of patches. The integrated analysis of the Banhado Amarelo bog demonstrated the relevance of physiognomic studies to support phytosociological analyses and the importance of including all floristic elements and soil composition data in a comprehensive approach. These findings can be extended to other studies of subtropical bogs of southern Brazilian highlands that aim to conserve these important South American ecosystems.

The hunter-gatherer site BES II (Jacaré-Guaçu River low terraces, central Sao Paulo state, Brazil): Interface with geomorphical and environmental fluctuations of the Pleistocene-Holocene transition

The lithic site Boa Esperança II (BES II), in the São Paulo segment of the Brazilian Plateau, next to the boundary between the cities of Araraquara (SP) and Boa Esperança do Sul (SP), presents a collection of almost 2,000 lithic artifacts (predominantly chert and sandstone), being interpreted as a settlement of diversified functions with possibly continuous or successive occupation. In this work, we approach the site based on interface of its insertion in the regional physical-environmental context - with emphasis on the interface with relief frames, surface structure study and estimated geomorphic sequences of the alluvial plain of Jacaré-Guaçu river - and techno-typological analysis. It was verified that the BES II artifacts are distributed along vertical profiles and relief pictures lined by records that mark the transition from semi-arid conditions to others of increasing humidity, successive oscillations of base levels and modifications of fluvial regimes (ephemeral channels passing to perennial channels of different hydrological meandrings patterns), indicating that human occupation has dealt with conditions of quite distinct landscapes between the Late Pleistocene and the Holocene. Local lithic industry would have taken advantage of attributes derived from these modifications in the landscape over time - in particular the exposure of gravels of large river pebbles deposited by torrential ephemeral channels. The past abundance of raw material of fluvial origin would have contributed to the location of the site in the regional geomorphological context, as well as for a lithic assemblage based on the production of large unipolar flakes. We observed in the correlations between the position of artifacts, geomorphical and pedological data, OSL and Carbone-14 dates at archaeological levels, elements that allow us to discuss considering BES II as an archaeological site to integrate the interval of the Pleistocene-Holocene transition and to had interfaces with the geomorphological and environmental changes of such time. The archaeological implications of the issue and the fact that only one dating of photoluminescence has been reported from the deepest level of the site (basal gravel layer) emphasize the need for new, denser and more diversified studies.

Reconstruction of Holocene coupling between the South American Monsoon System and local moisture variability from speleothem δ18O and 87Sr/86Sr records

Investigating controls on past variability of South American hydroclimate is critical to assessing its response to future warming scenarios. δ18O records from South America offer insight into past variability of the South American Monsoon System (SAMS). The controls, however, on precipitation δ18O values can be decoupled from precipitation amount at a given site and, thereby, limit local moisture condition reconstructions. Here we use a principal components analysis to assess the coherence of speleothem and lake core Holocene δ18O records in tropical and subtropical South America to evaluate the extent to which δ18O variability reflects changes in SAMS intensity at different sites across the region. The main mode of variability across Holocene δ18O records (PC1) closely tracks austral summertime insolation, consistent with existing work. Sites towards the periphery of the continent are heavily weighted on PC1, whereas interior sites as not. Further δ18O variability at interior sites bear little similarity to each other and implicate controls, beyond regional monsoon intensity, on these δ18O records. Further, we develop speleothem 87Sr/86Sr records spanning the Holocene from Tamboril Cave (Brazilian Highlands), Paraíso Cave (eastern Amazon Basin), Jaraguá Cave (Mato Grosso do Sul Plateau), and Botuverá Cave (Atlantic coastal plain) to investigate coupling between reconstructed monsoon variability (reflected by PC1) and local moisture conditions (interpreted from 87Sr/86Sr records). We interpret speleothem 87Sr/86Sr variability as a proxy of local moisture conditions, reflecting the degree of water-rock interaction with the cave host rock as driven by variations in water residence time. Speleothem 87Sr/86Sr records from all the sites, except Botuverá cave, do not co-vary with PC1, suggesting that local moisture conditions do not necessarily follow variations in regional monsoon intensity at these interior sites. These speleothem 87Sr/86Sr records generally suggest dry mid-Holocene conditions relative to the early- and late-Holocene, consistent with interpretations of other paleo-moisture records in the region, but timing of wet-dry transitions varies between sites. These results highlight that controls, in addition to SAMS variability, might influence δ18O variability. Further, our results suggest spatially variable local moisture conditions at interior sites that do not uniformly respond to regional monsoon intensity, and stress the need for δ18O-independent reconstructions of moisture conditions.

Classification of South Brazilian grasslands: Implications for conservation

AbstractAimsWe offer a first classification of South Brazilian grasslands (Campos Sulinos) based on quantitative vegetation data and describing grassland types in terms of dominant and indicator species.LocationSouth Brazilian grasslands (Paraná, Santa Catarina, Rio Grande do Sul states).MethodsWe described vegetation plots in 167 sampling units throughout the region using a stratified nested design, totalizing 1,502 1 m² quadrats. We classified vegetation using cluster analysis based on Bray–Curtis dissimilarities, establishing three vegetation types and ten subtypes. We conducted indicator species analysis within the resulting subtypes, and for all possible combinations of subtypes.ResultsIn the cluster analyses, a clear separation of poorly drained grasslands from the drier sites appeared. Further, a clear distinction between grasslands in the South Brazilian highland region, situated in the Atlantic Forest biome, and the grasslands of the Pampa biome, to the south, emerged, reflecting climatic and management differences. Highland grasslands showed lower species cover dominance, while in the Pampa, Paspalum notatum clearly was the most important species and the abundance of exotic species was higher.ConclusionsOur study provides the first classification of South Brazilian grasslands based on quantitative vegetation data recorded in a standardized sampling design. The data support the division of grasslands into the main phytogeographic units of the region (Brazilian biome classification). Grasslands in these two regions also differ in terms of species dominance pattern (higher dominance in Pampa grasslands, likely also due to higher grazing levels) and in terms of conservation state (low presence of exotic species in highland grasslands). Our results are important for conservation policies, which can now consider the presence of different grassland types in different region, but more data will be necessary for a more detailed classification that considers different abiotic features in more detail.

Seasonal variation in the composition of ground-dwelling anuran (Amphibia) assemblages in southern Brazil

Climate seasonality may differently influence habitat quality and heterogeneity depending on habitat type. We examined whether the taxonomic, functional and phylogenetic composition of ground-dwelling anuran assemblages from grassland and forest habitats vary seasonally. We tested the hypothesis that the forest anuran assemblage varies less seasonally than the grassland assemblage. We monitored anurans using pitfall trap arrays in two areas, sampled across four seasons over a two-year period. For the functional composition, we acquired information on species morphology, reproduction, and habitat use to represent the anuran niche. For the phylogenetic composition, we used the most comprehensive anuran phylogeny. We used Principal Coordinate Analysis and Analysis of Variance to evaluate seasonal variations in assemblage composition along the study period. Our data revealed significant seasonal variation in the taxonomic and phylogenetic composition of anuran assemblages. Variation in taxonomic composition was higher in the grassland than in the forest assemblage, while variation in phylogenetic composition was higher in the spring-summer than in the autumn-winter seasons. We did not identify seasonal variation in functional composition. Seasonal variations in taxonomic and phylogenetic composition, but not in functional composition, indicate that the species with a fluctuating seasonal abundance have similar life-history traits, but belong to different lineages. Keywords: anuran traits, Brazilian highland grasslands, habitat variability, temporal beta diversity, temporal turnover.

Diversification of the widespread neotropical frog Physalaemus cuvieri in response to Neogene-Quaternary geological events and climate dynamics

Here we reconstructed the demographical history and the dispersal dynamics of Physalemus cuvieri through the Neogene-Quaternary periods by coupling DNA regions with different mutation rates, ecological niche modelling, reconstruction of spatio-temporal lineage dispersal and coalescent simulations. Still, to test alternative diversification scenarios we used approximate Bayesian computation. Molecular phylogenetic analysis recovered four deep and strongly supported clades, which we interpret as population lineages. The ancestral location reconstruction placed the root in southcentral Amazonia, and the dispersal events indicate that spatial displacement was widespread early in the diversification of this species. The demographical scenario of “Multiple Refugia” with recent lineage admixture was the most likely hypothesis to predict the observed genetic parameters of P. cuvieri. Our results revealed that Neogene orogenic events might have played a prominent role in the early diversification of P. cuvieri. The species shows deep divergences with strong regional population structure, despite its widespread distribution. Final uplift of the central Brazilian Plateau and formation of the river basins in Central South America played an important role in the origin, diversification and the maintenance of P. cuvieri lineages.

Interaction of land management and araucaria trees in the maintenance of landscape diversity in the highlands of southern Brazil.

In the southern Brazilian highlands, pre-Columbian societies created domesticated landscapes through the use and management of forests, including nurse Araucaria angustifolia trees, a common conifer in these regions. Nowadays, local smallholders still use traditional practices, such as burning, to promote vegetation for cattle grazing in highland grasslands. Even though burning is normally of small extent and low frequency, such management can slow down natural forest expansion and contribute to the maintenance of grasslands, by opposing the facilitative effect of nurse araucaria trees. To comprehend the interplay between human cultural management, species interactions and the environment, it is important to better understand how these relations affect diversity and composition. Our goal was to investigate how land management, biotic interactions and abiotic factors affect saplings species richness, abundance and composition. We hypothesized that (1) land management would decrease sapling richness and abundance and change sapling composition, (2) nurse araucaria trees would increase species richness and abundance and change sapling composition, and (3) the interactive effect between land management and nurse araucaria trees would shape sapling richness, abundance and composition. Data were collected in unmanaged and managed conditions, both beneath araucaria crowns and in nearby treeless areas. Our results indicate that abundance and species composition are affected by land management and araucaria crown influence. The highest values of sapling abundance were found beneath crowns in unmanaged areas. Species composition changed between all assessed combinations of land management and crown influence. Our study demonstrates the major roles of land management and facilitation in structuring communities, despite the effects of rock and grass cover. Moreover, our results clarify patterns and processes that may emerge in natural highland grasslands, such as the conversion of grasslands into forests and the loss of cultural landscapes when the main local management actions are excluded.

Influence of plant habitat types and the presence of fish predators on macroinvertebrate assemblages in southern Brazilian highland wetlands

Influence of plant habitat types and the presence of fish predators on macroinvertebrate assemblages in southern Brazilian highland wetlands

Humans and climate as designers of the landscape in Serra da Bocaina National Park, southeastern Brazil, over the last seven centuries

Abstract Campos de altitude and Araucaria forest are unique and highly diverse ecosystems and focus areas for conservation and restoration in southeastern Brazil. This paper reports a high-resolution paleoecological study of an approximately 700-year Late Holocene core, a period that includes the influence of two highly distinct civilizations and the transition between them: Amerindian/pre-Columbian and European/post-Columbian. Results highlight the interworkings of regional climate change and local human agency in “designing” the Late Holocene forest-grassland mosaic in the Serra da Bocaina. Amerindians maintained more open highland habitats probably through slash and burn agriculture. The depopulation of the study region after European arrival in the 1500s plus increasing precipitation led to a marked and rapid rebound in forest cover. After 1720 CE, establishment of permanent European communities and farming in the study area led to forest loss and a renewed expansion of grassland. Based on current knowledge about forest-grassland relationships, and in light of projections for warmer and wetter conditions in southeast Brazil, we provide suggestions for management strategies that might better maintain the mosaic of Araucaria forest and campos de altitude in the southeastern Brazilian highlands.

Raleio de cachos próximo ao ‘véraison’ nas variedades ‘Montepulciano’ e ‘Cabernet Franc’ em região de elevada altitude do sul do Brasil

The objective of this study was to evaluate the effects of pre- and post-veraison cluster thinning on the physicochemical characteristics of Montepulciano and Cabernet Franc grape varieties grown in regions 900 m above sea level (ASL) in Santa Catarina, southern region of Brazil. The experiment was conducted in two commercial vineyards, Montepulciano vineyard located at 28o12'58''S, 50o06'45''W, 1,185 m ASL during the 2007, 2008 and 2009 vintages; and Cabernet Franc vineyard located at 28°15'20S, 49°56'60W, 1,284 m ASL, during the 2010 and 2011 vintages. Treatments consisted on cluster thinning at three distinct moments for both varieties: during veraison, about 15 days pre-veraison and 15 days post-veraison. For Montepulciano, when cluster thinning is performed post-veraison, there is a reduction in cluster mass and a slight reduction on the acidity of grapes. For Cabernet Franc, when cluster thinning is performed during veraison, there is an increase in total soluble solids of grapes. In general, cluster thinning is recommended two weeks pre- or post-veraison for Montepulciano and Cabernet Franc wine grapes produced in southern Brazilian highlands.

Phylogeography of Muller's termite frog suggests the vicariant role of the Central Brazilian Plateau

AbstractAimTo test three different scenarios to account for the geographic distribution of genetic variation inDermatonotus muelleri, a fossorial frog endemic of the South American diagonal of open formations (DOF) formed by Chaco, Cerrado, and Caatinga biomes: (a) The pan‐DOFhypothesis, where these biomes behave as a single biogeographical unit andDOFspecies lack population structure; (b) the southwest‐northeast (SW‐NE) hypothesis, where structured populations along theDOFhave either asymmetric or unidirectional gene flow in the northeast direction; (c) the vicariance hypothesis, where a pattern of population structure with no or reduced gene flow is observed.LocationCaatinga, Cerrado, and Chaco in South America.MethodsWe sampled 179 individuals across the species distribution and sequenced one mitochondrial and two nuclear markers. We evaluated population structure, the presence, direction, and asymmetry of gene flow, and demographic changes to test three different phylogeographic hypotheses forD. muelleriusing a model‐based simulation approach.ResultsWe found two geographically structured lineages with no gene flow, refuting pan‐DOFhypothesis. The Southwest lineage occurs in Chaco and western Cerrado and the Northeast lineage in eastern Cerrado and Caatinga. Our results support the model with demographic change for the Northeast lineage and constant size for Southwest lineage. The vicariance model with divergence time estimated around 4 Ma was preferred.Main conclusionsVicariance was the best explanation for the geographic distribution of genetic variation inDermatonotus. Divergence time supports the role of Neogene orogeny in central Brazil for the splitting ofDermatonotuslineages. The influence of Pleistocene climatic fluctuations seems restricted to changes in one lineage's population size. Therefore, both ancient and recent events shaped the phylogeography ofDermatonotus. Genetic divergence, lack of gene flow, and the presence of a geographic barrier between lineages indicate the existence of a cryptic, undescribed species in northeastern Brazil.

Rethinking households, communities and status in the southern Brazilian highlands

Disparities in domestic architecture are a potential correlate of emergent status inequality between households. In the southern Brazilian highlands, pit house settlements exhibit significant variations in structure size and site layout. Particularly relevant are the oversized structures whose function has been debated but remained unresolved. Here, I present data from Baggio 1, a large site including an oversized structure (cal CE 1365–1790). I show how the oversized pit house emerged earlier and was distinguished not only by its dimensions, but also by its privileged hilltop position and practices of floor renewal. When the settlement expanded with the addition of smaller pits, some of which were small houses, whereas others were specialized facilities, the precinct around the oversized structure continued to be the focus of activities of the settlement. Based on ethnography of the Jê peoples of Brazil and cross-cultural relationships between household size and status, I argue that the dwellers of the oversized pit house could have derived a higher status from their more numerous kin and connection to the founders of the site. Finally, the appearance of oversized pit houses must be understood in a broader context of landscape and social transformations in southern Brazil after the turn of the second millennium AD, which was also reflected in other material signs of emergent status inequalities.

Endemic plants from the Southern Brazilian Highland Grasslands

Abstract The flora of the subtropical highland grasslands in Southern Brazil, locally known as Campos de Cima da Serra, is within the Atlantic Forest hotspot, and has being highlighted by its richness, having around 25% of endemic plants. Those formations require specific studies to estimate its species richness and to protect its natural resources. This study aimed to map and to analyze the distribution of endemic taxa from these grasslands based on available herbarium collections databases as sources for highlighting important taxonomic groups for future studies. We verified how much of those endemic taxa are inside protected areas, and recognized the most important taxa and areas for future studies. All the data about each endemic taxon was obtained through visiting herbaria, online databases, collecting expeditions and published references. Distribution maps for endemic species were prepared. As the main result, we describe and map the distribution of the endemic flora of this species rich vegetation formation and highlight the threatened taxa as priority for future taxonomic and conservation studies. Our results also point out the central-west of Santa Catarina and central Paraná states as priority areas for future studies considering its high diversity of taxa.

Future hydroclimatological changes in South America based on an ensemble of regional climate models

Changes between two time slices (1961–1990 and 2071–2100) in hydroclimatological conditions for South America have been examined using an ensemble of regional climate models. Annual mean precipitation (P), evapotranspiration (E) and potential evapotranspiration (EP) are jointly considered through the balances of land water and energy. Drying or wetting conditions, associated with changes in land water availability and atmospheric demand, are analysed in the Budyko space. The water supply limit (E limited by P) is exceeded at about 2% of the grid points, while the energy limit to evapotranspiration (E = EP) is overall valid. Most of the continent, except for the southeast and some coastal areas, presents a shift toward drier conditions related to a decrease in water availability (the evaporation rate E/P increases) and, mostly over much of Brazil, to an increase in the aridity index (Ф = EP/P). These changes suggest less humid conditions with decreasing surface runoff over Amazonia and the Brazilian Highlands. In contrast, Argentina and the coasts of Ecuador and Peru are characterized by a tendency toward wetter conditions associated with an increase of water availability and a decrease of aridity index, primarily due to P increasing faster than both E and EP. This trend towards wetter soil conditions suggest that the chances of having larger periods of flooding and enhanced river discharges would increase over parts of southeastern South America. Interannual variability increases with Ф (for a given time slice) and with climate change (for a given aridity regimen). There are opposite interannual variability responses to the cliamte change in Argentina and Brazil by which the variability increases over the Brazilian Highlands and decreases in central-eastern Argentina.

Podonomus amarali n. sp., a new species of the albinervis group (Diptera: Chironomidae: Podonominae) from Atlantic Forest, southern Brazil.

Podonomus amarali sp. n. is described from male, female, larva and pupa collected in the Brazilian Atlantic Highlands. The new species belongs to the albinervis group, which comprises eight Andean species.

Diversification patterns of the grasshopper genus Zoniopoda Stål (Romaleidae, Acridoidea, Orthoptera) in open vegetation biomes of South America

AbstractThe open vegetation biomes, within the limits of the Chacoan subregion, occur along a diagonal in eastern South America covering a large range of environmental conditions. In order to contribute to the knowledge on the biodiversity of these open biomes, we analysed the phylogenetic relationships of the grasshopper genus Zoniopoda to the remaining South American Romaleinae, and examined the biogeographical patterns of diversification of the genus. The study is based on morphological and molecular (COI and H3) evidence, including 12 species of Zoniopoda and 17 species of four tribes of South American Romaleinae. We describe a new species of Zoniopoda, and test its taxonomic placement within the group. Results of our phylogenetic analyses recovered Zoniopoda as a monophyletic group with high support values. According to the dispersion–vicariance analysis, the ancestor of Zoniopoda may have been distributed in an area corresponding to the Chacoan and Cerrado provinces. A vicariant event, that could be explained by the uplift of the Brazilian Plateau and the subsidence of the Chaco, is hypothesized to have occurred splitting the ancestral distribution of Zoniopoda, resulting in the independent evolution of the Tarsata group within the Cerrado and the Iheringi group in the Chacoan subregion.This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:act:FCFB4C5D-1741-46F1-8E25-B37ED2B9D872.

Peopling Central Brazilian Plateau at the onset of the Holocene: Building territorial histories

In this paper we discuss the occupation process of Central Brazilian Plateau during the end of the Pleistocene and the early Holocene calling attention on two main issues: technology and mobility. We work in two spatial scales, local and regional, in order to indicate some long-term processes during the period between 13,000–7000 BP. Based on site distribution, archaeological remains and chronology we propose four distinct periods that should correspond to different phases of the peopling process of this region. Finally, we discuss hypotheses that might explain these changes and we emphasize the importance of integrating practical and symbolic aspects in order to interpret the archaeological record and construct territorial histories.

Hydropedology of a High Tableland with Cerrado, Brazilian Central Plateau: the Frutal Catchment Case Study

ABSTRACT: Currently, the Brazilian savanna (Cerrado) represents the main agricultural area of the country, comprising a great variety of landscapes and soils, geological formations and vegetation patterns, as well as the major watershed. We studied the hydropedology and morphometry of a representative catchment (Frutal river), on a high tableland (Chapada) in the Triângulo Mineiro region, Brazil, describing the soil-water-landscape relationships to understand land use and water resources. To this end, we applied physical, chemical, micromorphological, and morphometric methods. When dry, [...]