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Natural grasslands in southern Brazil are ecosystems that are naturally adapted to grazing. Despite the productivity and ecological relevance of these ecosystems, the effects of grazing intensity on their soil quality are still underexplored. This work aimed to determine whether increasing the grazing intensity would jeopardize the soil structure in a natural highland grassland in southern Brazil. Pastures were evaluated at four pregrazing canopy heights, 0.12, 0.20, 0.28 and 0.36 m, with Andropogon lateralis Nees as the reference species, and in one ungrazed control area. The pastures were intermittently stocked, and the postgrazing heights corresponded to 60% of the pregrazing targets (i.e., the postgrazing heights were 0.072, 0.12, 0.168 and 0.216 m). The experiment started in 2015 and was conducted for three years, with evaluations of soil physical properties performed in the final year. Forage growth and grazing were concentrated from October to May; during the winter, no grazing occurred for a period of approximately 4 months. The soil structure was evaluated at two points: after the end of the 2017/2018 grazing season, in June, and after the winter period, in October. Regardless of the canopy height, the presence of grazing animals increased the degree of compaction at the soil surface (0.0–0.05 m) to an intermediate level immediately after grazing, did not disaggregate the soil or change its carbon and nitrogen stocks, and increased soil macroporosity and water infiltration compared to those in the exclusion area (control). Increasing the grazing intensity (i.e., increasing the grazing frequency, corresponding to lower pregrazing canopy heights) increased the soil macroporosity and water infiltration rate, decreased the soil moisture and increased the soil penetration resistance. Except at the 0.12 m canopy height, the exclusion of grazing for 4 months allowed the soil water infiltration in the grazed plots to return to a level similar to that in the exclusion area. We conclude that there are a wide range of grazing intensities (corresponding to canopy heights of 0.12–0.36 m) that do not jeopardize the soil structural quality in highland grasslands. Furthermore, it was not possible to determine whether canopy heights below 0.12 m would disrupt the synergism at the soil-plant-animal interface in these natural ecosystems. • Natural grasslands are global resources that have been threatened by human activity. • We assessed the effects of cattle grazing on soil structure in highland grasslands. • The soil water infiltration rate increased in grazed compared to ungrazed areas. • The soil structure was not jeopardized across a wide range of grazing intensities. [ABSTRACT FROM AUTHOR]

Changes in land use are considered the main factor in the degradation of ecosystems, especially in continental aquatic environments. In this study, we evaluated the genotoxicity potential of the environmental matrix using tadpoles from three anuran species as a model, to test whether more genetic damage and changes in oxidative stress biomarkers occur in ponds on farms than in native grasslands. Tadpoles were sampled from ponds in the subtropical highland grassland region of southern Brazil. We quantified DNA damage in tadpoles of Scinax squalirostris, Ololygon aromothyella and Odontophrynus asper using the comet assay and oxidative stress changes using glutathione as a biomarker. Our results demonstrated that the tadpoles of the three anuran species collected in agricultural ponds accumulated greater DNA damage and alterations in biomarkers of oxidative stress when compared with those collected in ponds in the native grassland, corroborating our initial hypothesis. The DNA damage detected in tadpoles from farm ponds suggests that these populations are suffering impacts from environmental contamination, mainly from heavy metals and fertilizers, as indicated by our complementary data. Our results highlight the importance of grassland remnants for the conservation of amphibians in the subtropical region, which are under severe threat due to the replacement of natural areas by agriculture. Moreover, we emphasize the importance of monitoring and quantifying agrochemicals in habitats and organisms to ensure the viability of populations and support adequate management and conservation strategies for the species of pond-breeding anurans in the region of subtropical grasslands in southern Brazil. [ABSTRACT FROM AUTHOR]

Southern Brazil's highland Araucaria Forest-Campos grassland mosaic is an ancient and iconic landscape in the globally important Atlantic Forest biodiversity hotspot. Human land use has inflicted significant losses on the region's natural vegetation since the late 19th Century, but these have not been effectively quantified. This study uses land cover maps and forest survey data to assess how much of the mosaic's natural vegetation remains, the quality of this remnant vegetation, how it has changed since 1985, and the extent to which it is protected. Natural vegetation covers 13.9–37.3 % of the Araucaria Forest-Campos mosaic's core regions and 13.0–38.0 % of the whole area, depending on the dataset. Most remnant areas are degraded and remaining forests have low average integrity. In only minorities of forest plots are the landscape's characteristic Araucaria angustifolia trees still present (23.5 % in the Araucaria Forest region), moderately abundant (11.4 %), or >50 % of the canopy (0.5 %). Major expansions in cropland and forest plantations between 1985 and 2018 drove net/absolute losses of 12.7 %/24.1 % in the mosaic's natural forest and 38.1 %/43.2 % in its natural grasslands. Protected Areas and Indigenous Territories cover 4.6 % of the core mosaic and 6.5 % of the whole region. These conserve important remnant vegetation, though grasslands are under-protected. By analysing and integrating diverse and complementary data sources, we significantly improve on and add nuance to previous estimates of the quantity and quality of Araucaria Forest remnants. This study also provides the first robust, quantitative estimate of remaining highland grassland across southern Brazil. [Display omitted] • Brazil's highland Araucaria Forest-Campos grassland mosaic is highly threatened. • Combining datasets gives key insights into both vegetation coverage and quality. • Natural vegetation covers 13–38 % of the whole mosaic and 14–37 % of its core regions. • Most remnant areas are degraded and remaining forests have low average integrity. • Campos grasslands are less protected and declining even more steeply than forests. [ABSTRACT FROM AUTHOR]

Pastures are of central importance in food production and provide multiple ecosystem services. The objective of this paper was to determine whether the intensification of pasture-based animal production systems, through practices such as fertilization and improved pasture species, has a higher capacity in the short-term (five years) to sequester carbon in the soil compared to (1) natural grassland without anthropogenic interactions, (2) natural grassland fertilized and overseeded with exotic species, and (3) annual pastures with frequent soil disturbance. The study assessed the organic carbon stock (OCS), total organic carbon (TOC), particle size, porosity, and density at different soil strata, as well as the root system and forage production. Forage dry matter (DM) production varied significantly with means ranging from 6615 to 13,000 kg ha–1 year–1 for natural grassland (NG) and permanent pasture (PP), respectively. Improved natural grassland (ING) and NG presented a higher density and root diameter than PP and annual pasture (AP). Forage systems significantly influenced soil porosity and density, with NG and ING showing lower soil densities and higher soil porosities. The OCS (0–100 cm) was similar between NG (270 Mg ha–1), ING (255 Mg ha–1), PP (274 Mg ha–1), and AP systems (256 Mg ha–1). Over a period of five years, the intensification of pasture-based animal production systems did not have a significant impact on OCS in the soils of a Brazilian subtropical highland. [ABSTRACT FROM AUTHOR]

Grasslands are one of the vegetation types most widely affected by wildfires in southern Brazil. It is a fire-dependent ecosystem and it is necessary to know the hourly fuel moisture variation for its management. The objective of this work is to fit Grass Fuel Moisture Code (GFMC) models to estimate the moisture content for the grassland of the State Park of Vila Velha, Paraná, Brazil. Data sampling to determine the hourly moisture content was performed during the winter of 2018 and divided into two campaigns of five days with stable weather conditions. Destructive samples were taken out for the sorption tests on climatic chambers to obtain the equilibrium moisture content and the time lag values. The fitted equilibrium moisture and time lag models were evaluated by residual distribution analysis, mean absolute error (MAE), root mean square error (RSME) and coefficient of determination (R2). The fitted model performed better than the original GFMC model due to the obtained MAE, RSME and R2 values. The results showed that the fitted GFMC model is better to predict the fine fuel moisture for the region. [ABSTRACT FROM AUTHOR]

Population genetic structure results from the interaction between historical events, current ecological conditions and life traits. The genetic structure and gene flow between populations are important to species dynamics, mainly for rare and endangered species that are more vulnerable to landscape changes and fragmentation. Here we evaluated the genetic diversity, population structure and gene exchange in Petunia bonjardinensis , P. reitzii and P. saxicola , three rare species endemic to subtropical highland grasslands in southern South America. We analysed the genetic diversity and structure considering historical events, such as founder effect and climate changes, and biological traits of each species. We also estimated the conservation status for these three species. We collected samples from all adult individuals and occurrence sites that could be found at the same flowering season and genotyped them for 13 nuclear microsatellite markers. Our results indicate that rarity is probably historical for these species, given that we found no genetic evidence for recent bottlenecks. Petunia bonjardinensis , with the largest occurrence area and population sizes, displayed the higher diversity indices. The other two showed lower genetic diversity and are geographically most restricted. Gene exchange among these species was low, although they share some ancestral genetic polymorphism. Historical migration, founder effects and Pleistocene climate cycles ae the main factors explaining genetic diversity, and this was also influenced by reproductive biology and recent habitat loss, whereas the landscape influences the structure. Based on IUCN criteria, the three species are endangered, and the main risk for their survival is probably anthropic activity in the occurrence area. We recommend an urgent programme for the preservation of these species in situ and ex situ. [ABSTRACT FROM AUTHOR]

Question: Grazing is an important disturbance for maintenance of structure and functioning of the plant communities in grassy ecosystems. Functional characteristics of plants, which are responsible for their response to grazing, vary at inter‐ and intraspecific levels. Here, we assessed: (1) the extent of intraspecific trait variation when compared to interspecific variability; and (2) how grazing regime affects intraspecific trait variation in leaf functional traits of species with different leaf economics strategies. Location: A multisite grazing experiment in subtropical grasslands, southern Brazil. Methods: For 30 dominant grassland plant species we measured functional traits related to resource acquisition strategy and grazing response (SLA, specific leaf area; LDMC, leaf dry matter content; LA, leaf area; and FT, leaf resistance to traction) under three grazing treatments (grazing exclusion, traditional, or deferred grazing) arranged in a randomized block design. We quantified the overall proportion of intra‐ and interspecific variation and, for each species, we tested for the grazing treatment effects on intraspecific trait variation through Bayesian analysis of variance. Results: The overall contribution of intraspecific variation was up to 37% of the total variation. For most grass species, grazing exclusion led to lower values of SLA and higher values of LA, while no effect of grazing treatments was detected on intraspecific variation of LDMC and FT. Altogether, the effect of grazing management on intraspecific trait variation was more prevalent in species presenting a conservative strategy than in species with an acquisitive strategy. Conclusion: The expression of leaf traits is variable within species, especially for those species with a conservative strategy of resource acquisition. The extent of intraspecific trait variation in response to grazing depends on the considered traits and the resource acquisition strategy of the studied species. [ABSTRACT FROM AUTHOR]

Copyright of Rodriguésia is the property of Revista Rodriguesia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aim: We evaluated different facets of beta diversity (taxonomic, phylogenetic and functional), and its components (spatial turnover and nestedness), of a stream macroalgal metacommunity, as well as the effect of local environmental variables, types of biome and spatial factors on these facets and components. Location: Ten natural areas of southern Brazil, covering the main biomes represented in the region. Taxon: Stream macroalgae. Methods: We analysed a macroalgal data set collected in 105 stream segments using a dissimilarity partitioning approach to decompose total beta diversity into spatial turnover and nestedness components. Furthermore, we assessed the effects of local environmental variables, biome type and spatial factors on beta diversity components by performing distance‐based redundancy analysis (db‐RDA), and its partial version (db‐pRDA). Taxonomic data were tabulated considering four different species incidence matrices: total macroalgae; only green algae; only red algae and only cyanobacteria. Results: For taxonomic and phylogenetic facets, very high values of total beta diversity were found for all species incidence matrices, with spatial turnover (species replacement) accounting for almost all this diversity; nestedness had extremely low values. For functional diversity, total beta diversity was again high and spatial turnover was greater than nestedness, but nestedness (the tendency for less diverse locations to contain a subset of those in higher diversity locations) was considerably higher than that observed for taxonomic and phylogenetic facets. In regard to taxonomic and phylogenetic facets, total beta diversity and spatial turnover were, in general, significantly related to local environmental variables, biome type and spatial factors for total macroalgae and green algae, whereas they were significantly related to types of biome and space for red algae, and only to local environment for cyanobacteria. Main conclusions: Our results showed that spatial turnover was the main component of beta diversity, regardless of the facet and macroalgal species incidence matrix, and that the relative influence of local environmental variables, types of biome and spatial factors on the total beta diversity and its spatial turnover component can vary according to the facet considered and by algal group. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the last three decades, several studies have suggested that the structure of stream macroalgal communities is shaped by local environmental variables, but some recent papers have shown that the relevance of the environment on these communities may be overestimated. Using Partial Redundancy Analysis (pRDA), we analyzed macroalgal communities (considering all macroalgae and Phyla Chlorophyta, Cyanobacteria, and Rhodophyta individually) from 105 streams in southern Brazil to test the hypothesis that the relative contributions of the environment and space on the taxonomic composition of these communities is mainly determined by the biological traits and dispersal mechanisms typical for each group. The pRDA showed that the taxonomic composition of the entire community and green algae were explained by both space and environment, whereas for cyanobacteria, only the environment was significant, and for red algae, only space was significant. These divergences in the relative contribution among algal phyla were consistent with our initial hypothesis and can be ascribed to the differences in the ecological features of each group. Our results also support the idea that the community structure of organisms with low dispersal is influenced more significantly by spatial processes, whereas for organisms with high dispersal the local environmental variables are more influential. [ABSTRACT FROM AUTHOR]

The Brazilian high altitude grasslands are important biodiversity centers that contribute to human well‐being far outside their boundaries. They host many vulnerable species that may go locally extinct as a result of small changes in the environment. Performing studies on local species distribution is important to guide biodiversity conservation in these areas. This study aimed to characterize a high altitude grassland plant community along an elevation gradient in southeastern Brazil. Simple logistic regression, chi‐squared tests and indicator species analysis were performed to investigate respectively whether: 1) the occurrence of botanical families was related to the altitude; 2) the richness and abundance of life forms varied along the gradient and 3) there were populations associated with specific altitudinal belts. Rubiaceae and Polygalaceae had higher occurrence probability at higher altitudes. Hemicryptophytes and chamaephytes seem to be the most favored life forms under local extreme conditions such as low temperatures and drought. The vegetation spectra varied significantly along the gradient, highlighting the major role of the turnover of habitats on a local scale for the underlying patterns of species distribution. Upper elevations encompassed a high number of indicator species, and further analyses of indicator species of high altitude grasslands will provide clues about adaptability of local species, important to consider in ecosystem management and conservation. [ABSTRACT FROM AUTHOR]

The taxonomic status of a disjunctive population of Phyllomedusa from southern Brazil was diagnosed using molecular, chromosomal, and morphological approaches, which resulted in the recognition of a new species of the P. hypochondrialis group. Here, we describe P. rustica sp. n. from the Atlantic Forest biome, found in natural highland grassland formations on a plateau in the south of Brazil. Phylogenetic inferences placed P. rustica sp. n. in a subclade that includes P. rhodei + all the highland species of the clade. Chromosomal morphology is conservative, supporting the inference of homologies among the karyotypes of the species of this genus. Phyllomedusa rustica is apparently restricted to its type-locality, and we discuss the potential impact on the strategies applied to the conservation of the natural grassland formations found within the Brazilian Atlantic Forest biome in southern Brazil. We suggest that conservation strategies should be modified to guarantee the preservation of this species.