South Brazilian Grasslands Research Articles

The potential of hay for graminoid introduction in the restoration of subtropical grasslands: Results from a greenhouse experiment

IntroductionSubtropical grasslands have been severely impacted. Due to their low resilience after degradation, active restoration is necessary; however, knowledge still is incipient. Hay transfer is a successfully employed technique to restore other grassland ecosystems and its use is promising in subtropical grasslands. We evaluated the potential of hay transfer for the restoration of the subtropical grasslands in Southern Brazil by assessing the effects of (1) the date of hay harvest and (2) the amount of dry hay used. MethodsIn two protected areas in South Brazilian grasslands, we harvested hay on three dates (mid-Spring, early-Summer, and mid-Summer) and placed it into a greenhouse for seeds in the hay to germinate. Two different amounts of dry hay (375 g/m² and 750 g/m²) were used for each date. We assessed the number of emerging seedlings, species richness, and seedling species composition in each treatment, separately for each site. Emerging forbs were identified as soil seed bank contamination, and only data for graminoids (grasses and sedges) are presented. ResultsThe number of seedlings varied among harvest dates, with mid-Spring and early-Summer resulting in more emergencies in both sites. No common pattern to both sites regarding the effect of the amount of dry hay on seedling emergence was found for the two sites, but interaction with the harvest date is important. Species composition and richness also varied across harvest dates, and, independent of the donor site, more hay resulted in more species. Nevertheless, few species were transferred overall. ConclusionsHay transfer has the potential to introduce seeds of graminoids and appears to be a promising tool for the restoration of South Brazilian grasslands. There is not a single optimal time for hay harvest nor a pattern regarding hay amount. Few species are established from hay and more than one harvest should be done to increase species richness.

Phytotoxicity of Hesperozygis ringens (Benth.) Epling essential oil on Eragrostis plana Nees

Natural products derived from native plant species may be an alternative for the control of invasive exotic plants, thus reducing the use of synthetic herbicides. The present study evaluated the phytotoxicity of the essential oil of Hesperozygis ringens (Benth.) Epling, a native plant to the Pampa Biome, as an alternative for the control of Eragrostis plana Nees, an invasive exotic plant from the South Brazilian grasslands. The effect of the essential oil and pulegone, its major component, on germination and initial plant growth was evaluated at concentrations 0 (control), 0.001%, 0.0025%, 0.005%, 0.01%, and 0.02% (v/v). Furthermore, chlorophyll concentration, hydrogen peroxide accumulation, and loss of plasma membrane integrity were evaluated in adult plants at concentrations of 0 (control) and 0.02% for 48 and 60 h. Germination and root/shoot development were negatively affected starting at the concentration of 0.001%, with the most evident results at higher essential oil concentrations. Reduced chlorophyll concentration and tissue damage, due to hydrogen peroxide accumulation as well as loss of plasma membrane integrity, were also observed, thus showing the potential for this essential oil to control E. plana. Pulegone also had inhibitory effects during E. plana germination and seedling formation. Field studies must be conducted to check potential toxic effects on the environment and to determine its applicability as a natural herbicide.

Reference values and drivers of diversity for South Brazilian grassland plant communities.

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.

Are we ready to restore South Brazilian grasslands? Plant material and legal requirements for restoration and plant production

The need for grassland restoration in the State of Rio Grande do Sul (RS), Brazil, has become evident in the last two decades, when more than 1 million hectares were converted to other uses only in the Pampa region. Since then, studies have started to verify the most suitable ways to restore subtropical grasslands. Around the world, species introduction is one of the principal restoration techniques. We investigated the availability of seedlings and seeds of native grassland species in the local market and the legal framework regarding the restoration of grassland vegetation in RS. We found, in total, only seven companies that sold seedlings or seeds of nine native species from grasslands, a very limited number given the great biodiversity of South Brazilian grasslands. In addition to that, we found no criteria and procedures for grassland conversion or obligatory replacement established in legal norms for grasslands to Pampa region, as there are for forest vegetation. Without legal requirement, a market for seeds and seedlings likely will not develop and, without a market, there will be no producers, and restoration will remain limited. Our results support the need to create initiates and legislation with basic guidelines for the grassland conversion and restoration in RS.

Influence of land use on the diversity of pond-breeding anurans in South Brazilian grasslands

Influence of land use on the diversity of pond-breeding anurans in South Brazilian grasslands

Elucidating plant-pollinator interactions in South Brazilian grasslands: What do we know and where are we going?

Grassland ecosystems present patterns of plant-pollinator interactions that may be linked to habitat heterogeneity, plant composition and disturbances. Most studies about plant-pollinator interactions in the Neotropics were conducted in forest, savanna-like, or Andean vegetation. However, the current increase in the number of studies about interactions in grassland vegetation promises a better understanding of the pollination ecology of these landscapes. In this systematic review, we summarised information from 24 articles about plant-pollinator interactions in South Brazilian grasslands. We highlighted patterns of plant-pollinator interactions, indicating their particularities compared to other grassland communities in South America. Bees are important pollinators of many plant species in these grasslands and most plants are visited by more than one group of pollinators. Among the plant species visited by a single pollinator group, most were visited by bees. However, many types of pollinators, plant species, habitats, and regions have, thus far, received little sampling effort. Pollination by groups other than bees, such as nocturnal pollinators, flies, beetles, and birds, is particularly understudied. The information provided in this review summarizes data that could be used to foster more detailed pollination studies to understand the diversification and maintenance of grassland floras of South Brazil.

Climate and land-use changes coupled with low coverage of protected areas threaten palm species in South Brazilian grasslands

South Brazilian grasslands are at risk due to climate change and activities that convert native vegetation into agricultural lands. We used 12 native palm species as ecological indicators of these ecosystems to evaluate the impact of climate and land-use changes on their geographical distribution. We estimated the potential distribution of species for current and future (year 2050; RCP 4.5 and 8.5) climate and land-use conditions considering two dispersal scenarios. We also assessed the coverage of protected areas (PAs) for current and future species distribution. Our results indicated that the future distribution of all species will decrease under scenarios with no dispersal and increase under scenarios with dispersal; however, a dispersal scenario might be unlikely considering species dispersal ability and the increased pressure on grasslands. A comprehensive strategy is fundamental to ensure species conservation and recovery since the current PAs network covers less than 2% of the current distribution for nine out of the 12 species. Assessing the synergy of trends in climate and land-use changes is essential to improve conservation strategies for these emblematic species.

Seed traits of species from South Brazilian grasslands with contrasting distribution

ABSTRACT South Brazilian grasslands are among the most species-rich grasslands worldwide yet they have been suffering ongoing degradation due to land-use. Little is known about the reproductive ecology of the native species of these grasslands. Thus, our goal was to characterize seed traits and germination requirements of three native species of the tribe Tigridieae (Iridaceae, Iridoideae) due to its richness in the Pampa biome and the contrasting morphology, cytogenetics, and geographic distributions of its representatives. We tested if closely related species possess similar seed traits and whether species with wider distributions have broader germination requirements. Seed production and mass were estimated, and morphological analyses, germination experiments and viability tests were performed. Principal component analysis (PCA) was used to describe correlations between seed traits and species’ distributions. Germination was assessed using time-to-event analysis and the Cox model. All seed traits differed among the analyzed species/cytotypes. Final germination percentage (FGP) averaged 39.1 % and with overall viability of 89.9 %. Germination tests showed that seeds benefit from negative photoblasty. Species/cytotypes with wider distributions and heavier and larger seeds generally had better germination performances than narrower distributed species/cytotypes with lighter and smaller seeds.

The interplay between local and landscape scales on the density of pond‐dwelling anurans in subtropical grasslands

AbstractWe investigated the role of local and landscape environmental variables on anurans density classified as habitat specialists and generalists in grassland landscapes, known as South Brazilian grasslands (SBG). In this region, we surveyed 187 ponds distributed over 40 landscape sampling units. For each pond, 31 local environmental variables were measured. Each landscape sampling unit was embedded within a larger regional sampling unit with different landscape properties. For each landscape and regional sampling units, 16 landscape metrics were extracted from a land cover and use map. We recorded 35 species, eleven of which are specialists in the SBG. The specialists were affected by 11 local and 2 landscape environmental variables, while generalists were affected by 14 local and one landscape environmental variable. Thus, specialists and generalists presented different relationships with local and landscape variables, but in general local variables had a greater influence on the density of anurans than the landscape variables. However, the landscape indirectly influenced local variables because higher quality ponds were in landscapes with higher percentages of natural habitat. In conclusion, reproductive sites with higher local quality and located within landscapes with higher percentages of natural grasslands are essential to conserve anurans in this habitat. Effective conservation of such sites would benefit from further studies that assess effects of land use and biotic integrity of ponds, which can help to determine (a) the relative effects of local habitat quality of ponds and (b) the effectiveness of protecting ponds and their local surroundings for anuran conservation in SBG.Abstract in Portuguese is available with online material.

Variation of benthic macroinvertebrate communities in streams of three landscapes of South Brazilian grasslands

Introduction: Aquatic ecosystems in southern Brazil are presently under great environmental pressure. Changes in land use result in negative impacts on the ecosystem, affecting the functioning of stream communities. Objective: To compare the benthic macroinvertebrate community richness, abundances and compositions in streams of three South Brazilian grassland landscapes and correlate community patterns with environmental and spatial variables. Methods: Fifteen streams along riparian forests were selected in three landscapes (mean geographical distance of 285.1 km) inserted in the Paraná and Uruguai river basins. Of the three landscapes, two are inserted in conservation units (State Park of Guartelá and Palmas Wildlife Refuge). Invertebrates were collected in 20 kick net points along 150 m of the streams between June and November 2015. Invertebrates were sorted in the laboratory with three sieves and were identified to the lowest taxonomic level possible. The taxa were classified in functional feeding groups of shredders/detritivores, predators, scrapers, collectors/filters and gatherers/collectors. For each stream, we measured the environmental variables width and velocity, pH, dissolved oxygen, and temperature; and the relative cover of forest, grassland, plantation and silviculture in the catchments. Results: We found a total of 1 058 individuals, divided in 53 morphospecies and 34 families. Lower abundance of benthic macroinvertebrates was found in the northernmost landscape with higher temperature, and forest in the catchment. These streams were described mainly by predator groups, while streams inserted in the other two landscapes showed a more diverse guild composition of shredders/detritivores, gatherers/collectors, collectors/filterers, and scrapers. Geographical distance was the main factor influencing differences in community compositions among landscapes. Conclusions: Lower abundance of the northernmost landscape may be explained by (i) the low habitat heterogeneity due to dominance of sandy substrates, and by (ii) the anthropogenic land use of agriculture and extensive cattle breeding in the region that is ongoing and started before the creation of the conservation unit. Additionally, composition of macroinvertebrates may be correlated with environmental differences among landscapes that, in turn, are related to the geographical distance. Therefore, macroinvertebrate community responses may reflect different biota biogeographical histories that can also be associated with historical land use practices.

Changes in land use affect anuran helminths in the South Brazilian grasslands

Degradation and habitat loss of natural grasslands in Southern Brazil has a negative impact on native organisms, potentially including the composition of anuran helminth communities. Here, we characterized the richness, abundance, taxonomic composition, prevalence and intensity of helminth infection in four anuran species. Host anurans were collected in 34 ponds (19 in native grasslands with livestock and 15 in agricultural cultivation) from the highland grasslands in the Brazilian states of Santa Catarina and Paraná. Our results showed a significant difference between native grasslands with livestock and agricultural cultivation regarding the structure of helminth communities for the hosts Aplastodiscus perviridis and Pseudis cardosoi. We also found a greater prevalence and intensity of infection in anurans in areas of agricultural cultivation than in native grasslands with livestock. We found that the environmental descriptors (local and landscape) seem to explain most of the differences in anuran parasitism recorded between native grasslands with livestock and agricultural areas. Thus, we emphasized that the loss of grassy habitat due to conversion to agricultural cultivation can alter helminth communities in anurans, with further work needed to understand the mechanisms involved.

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.

Plant species richness record in Brazilian Pampa grasslands and implications

Species richness remains one of the most valuable type of information for biodiversity conservation. Here, we report a plant richness record in the Brazilian Pampa. We found 56 vascular plant species in a single plot of 1 × 1 m in a privately owned grazed grassland in a region with shallow soils. This number is considerably higher than common species numbers in similar surveys and highlights the high plant diversity in South Brazilian grasslands. We take our record as an opportunity to reflect on some issues of high importance if we wish to reach conservation goals: much of the biodiversity is inside private lands, and these should be more in the focus of conservation efforts; field research, especially quantitative sampling, continues to be essential to improve knowledge on biodiversity and its distribution patterns; training biologists to be able to carry out biodiversity assessments and to interpret the results should be a key issue for universities. We hope that the communication of this record will encourage new scientific discoveries and raise social interest about the conservation of grasslands in South Brazil.

Negative effects of an invasive grass, but not of native grasses, on plant species richness along a cover gradient

AbstractImpacts of invasive plants on plant communities are not universal, and effects may differ depending on the life form of the invading species. At three sites in the Brazilian Pampa region, we assessed the effects of invasion by Eragrostis plana Nees, considered to be the most problematic invasive plant in South Brazilian grasslands, on local plant communities. Specifically, we evaluated effects on species richness, community evenness and richness of principal functional groups along an invasion gradient. Based on plant community data, we also evaluated the effects of dominant native species on the same plant community features, thus being able to assess the relative impacts of an invasive species compared to abundant native species. Eragrostis plana invasion reduced total plant richness, with some distinct effects regarding plant functional groups, and differently from other coexisting native species that did not show the same effects even when of high abundance. Grasses were the most affected plant group when E. plana cover increased, consistent with the limiting similarity hypothesis. Overall, our results indicate clear negative effects of this invasive plant on the grassland communities. Comparing the effects of an invasive species to those of coexisting natives is crucial for disentangling the real impact of an invader. Our results demonstrate that effects are consequence of species identity, and not only of high abundances.

Local biodiversity erosion in south Brazilian grasslands under moderate levels of landscape habitat loss

Abstract Habitat loss is one of the greatest threats to biodiversity, exerting negative effects on the ecological viability of natural vegetation remnants. The south Brazilian grasslands belong to one of the largest temperate grassland regions in the world, but have lost 50% of their natural extent in the past 35 years. To date, there is no empirical evidence for the effects of habitat loss on these grasslands' biological diversity, undermining their conservation. Using data from a large‐scale biodiversity survey, we asked if local plant communities respond to levels of habitat loss representative of the entire region (≤50%). Vegetation in grassland remnants was sampled in 24 landscapes at three localities each, using nine plots per locality. To investigate whether species losses were a consequence of stochastic or nonrandom local extinctions and whether plant communities became more homogenized, we evaluated species richness, beta‐diversity components (spatial turnover and nestedness), and phylogenetic diversity, in respect to landscape change. In part of the landscapes, arthropods were sampled to investigate if loss of plant diversity had a cascading effect on other trophic levels. We evaluated generic richness of ants, an omnivore group with high levels of plant associations, in respect to a plant community's phylogenetic diversity. Local plant communities in landscapes with less grassland cover had fewer species, less spatial turnover, increased nestedness and lower phylogenetic diversity. Our results suggest that the observed species loss can be linked to taxonomic homogenization and is nonrandom, decreasing evolutionary diversity within the community. Furthermore, ant richness declined by 50% in plant communities with the lowest phylogenetic diversity, suggesting that effects of habitat loss propagate to higher trophic levels. Policy implications. We conclude that the biological diversity of south Brazilian grasslands, at the producer and consumer level, is at risk under the current rate of land‐use conversion, even at habitat losses below 50%. To avoid substantial biodiversity loss, conservation and more restrictive policies for conversion of native grasslands to different land uses in South Brazil are urgently needed.

The South Brazilian grasslands – A South American tallgrass prairie? Parallels and implications of fire dependency

Fire has long been recognized as an important driver of vegetation patterns, and is of particular importance for biodiversity maintenance in many grassland systems, including the North American tallgrass prairie. Here, it has been successfully used as a conservation and restoration tool. In southern Brazil, grasslands appear to present many similarities to tallgrass prairie in terms of composition and ecology, but the role of fire has been poorly studied and it is not usually used in conservation. Here, we compare plant genera and family composition of tallgrass prairie and South Brazilian grassland sites. We find striking similarities in terms of dominant families, genera, and functional types. The similarities between plant communities suggest similarities in ecological processes and should lead to a re-thinking of conservation strategies in South Brazilian grasslands. Research on the role of fire is needed, and comparative North–South studies on grasslands in the Americas likely will provide important insights for grassland ecology and management.

Flowering phenology and plant-pollinator interactions in a grassland community of Southern Brazil

Synchrony of phenological events at the community level is a critical aspect for plants. Distinct phenological patterns, such as aggregated and segregated, act in the establishment of plant-pollinator interactions and can play a fundamental role in plant community structure. Working in grazed subtropical grasslands in southern Brazil, our goals were to describe the plant-pollinator interactions in the grassland community and investigate the phenological patterns. The study was performed in a grassland community of Southern Brazil. In 12 sample plots (100m2 each) all flowering plant species with visually attractive flowers were recorded monthly during the period of six months. We used the Pianka index to estimate the flowering overlap, by comparison with 1000 pseudo-communities and a synchrony index to evaluate the phenological community pattern. All 82 flowering species present in the 12 study plots were observed monthly between six months. We observed that the community presented aggregated and non-synchronized flowering periods, which should reduce pollinator competition. We found no significant relationship between flowering synchrony and similarity of pollinators, that is, plant species that flower for a long time or together with many species did not share more pollinators than plants that flower for short time and alone. Some guilds of flowers visitors preferred flowers with a particular color, which indicated the important role of visual traits in plant-pollinator interactions. This study reports that flowering phenology could be structured by biotic components more than by random processes in these species-rich South Brazilian grasslands.

Revealing the pathways by which agricultural land‐use affects stream fish communities in South Brazilian grasslands

Summary Understanding mechanisms by which agricultural practices affect freshwater ecosystems helps to inform land‐use policies and management strategies aimed at mitigating effects of agriculture on biodiversity. Land‐use activities in the catchment, riparian and local scales likely influence stream fish communities via multiple pathways, for instance, by modifying the instream habitat. We investigated the mechanisms driving local stream fish taxonomic richness and functional diversity in South Brazilian grasslands by testing a theoretical path model in which we specified a priori relationships predicting how land use at multiple scales affects instream habitat and fish communities. Agricultural activities adjacent to streams (i.e. local impact on the streambank) and catchment‐scale cropland area were positively related to macrophyte cover and negatively associated with coarse particulate organic matter (CPOM, i.e. woody debris and leaf litter). Local impact also increased substrate siltation and homogenisation. Riparian vegetation in the upstream buffer ameliorated instream habitat condition by dampening macrophyte proliferation and providing CPOM. Fish species richness increased with both macrophyte cover and CPOM, revealing multiple pathways of agricultural influence. However, functional diversity decreased only with substrate siltation, revealing a response to agricultural activities adjacent to sample sites. Agricultural streams showed a replacement of benthic and lithophilic species by a larger number of morphologically similar and macrophyte‐associated nektonic fish. Our study indicates that land‐use adjacent to streams and upstream riparian zones is critical for maintaining taxonomically and functionally diverse fish communities due to their strong effects on instream habitat. Protection and recovery of riparian zones from land‐use change can mitigate the effects of agriculture on fish communities in South Brazilian grasslands.

Taxonomic and Functional Resilience of Grasshoppers (Orthoptera, Caelifera) to Fire in South Brazilian Grasslands.

Fire is a frequent disturbance in grassland ecosystems enabling variability in habitat characteristics and creating important environmental filters for community assembly. Changes in vegetation have a large influence on herbivore insect assemblages. Here, we explored the responses of grasshoppers to disturbance by fire in grasslands of southern Brazil through a small-scale experiment based in paired control and burned plots. The resilience of grasshoppers was assessed by monitoring changes to their abundance, taxonomic, and functional parameters along time. Burned patches have been already recolonized by grasshoppers 1month after fire and did not differ in terms of abundance and richness from control areas in any evaluated time within 1year. Simpson diversity decreased 1month after fire due to the increased dominance of Dichroplus misionensis (Carbonell) and Orphulella punctata (De Geer). In this period, grasshoppers presented in average a smaller body and a larger relative head size; these are typically nymph characteristics, which are possibly indicating a preference of juveniles for the young high-quality vegetation, or a diminished vulnerability to predation in open areas. Further, at 6months after fire grasshoppers with smaller relative hind femur and thus lower dispersal ability seemed to be benefitted in burned patches. Finally, 1year after fire grasshoppers became more similar to each other in relation to their set of traits. This study demonstrates how taxonomic and functional aspects of grasshopper assemblages can be complementary tools to understand their responses to environmental change.

Grassland degradation and restoration: a conceptual framework of stages and thresholds illustrated by southern Brazilian grasslands

Land degradation is a complex concept that integrates different aspects, including changes in soil conditions, biodiversity, productivity and socio-economic implications, compared to a reference state. We propose a new conceptual framework to analyze degradation stages and restoration thresholds in species-rich natural grasslands. The framework integrates different degradation stages with their respective thresholds and describes key processes of land-use change that lead to certain stages and thresholds. Specifically, we discuss two scenarios of grassland degradation, i.e. unsuitable grassland management and complete change of land use, sometimes followed by spontaneous recovery. We illustrate the framework with the case of south Brazilian grasslands, which are rich in biodiversity, but suffer from a series of degradation processes and are poorly considered from a conservation perspective. The conceptual framework can be applied by studies on degradation and restorability of tropical and subtropical grasslands after changes in management or transition to other land use; it will facilitate decisions on alternative management and conservation.