ABSTRACT 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.

ABSTRACT Grazing is an important determinant for the composition and structure of grasslands; however, soil seed bank (SSB) response to grazing intensity is poorly investigated. We analyzed SSB richness and density in a subtropical grassland in southern Brazil with different forage offers (low, intermediate, high and very high), that is, contrasting grazing intensities. The SSB was evaluated by the seedling emergence method. We collected ten SSB samples at two layers (0-5 and 5-10 cm) in spring and autumn in each of grazing intensity treatments. We surveyed the established vegetation to assess its similarity with the SSB. Treatment effects were analyzed by Poisson regression while compositional differences were visualized by ordination. We found 103 species in the SSB, of which 71 were also found in established vegetation. We found a positive correlation between SSB density and grazing intensity. High grazing intensity influences patterns of composition and dominance in the SSB, while no strong differences were found among the other treatments. The SSB was characterized by low participation of dominant grasses in the vegetation and the dominance of ruderal species, indicating that recovery from the SSB after total removal of vegetation (severe disturbance) may be limited in grasslands in the region.

ABSTRACT Land-use change is the main cause of biodiversity losses, and for grasslands includes changes in management. The last 10 years has seen afforestation of traditionally grazed grasslands increase considerably in the understudied Serra do Sudeste region of the Brazilian Pampa, turning the region into a mosaic of tree plantations, natural ecosystems (partly in conservation areas without grazing management) and other land uses. We evaluated grassland plant community structure and composition in conservation areas considering two distinct types of land-use history and compared them to grasslands under traditional management. The study was carried out at 58 sites. Per site, three plots were established to sample the plant composition of the herbaceous and shrub layers. We used ordination techniques and indicator species analysis to describe patterns of community composition. We recorded a total of 516 species, thus confirming the high biodiversity of the region. We detected differences in vegetation structure and composition between primary and secondary grasslands. Our study emphasizes the need to increase conservation efforts in the region and points out that current conservation approaches should be evaluated critically regarding their effects for biodiversity conservation and that adequate grazing management is key for grassland biodiversity conservation.

ABSTRACT A functional perspective of tree communities is helpful for understanding forest dynamics, especially vegetation recovery after other land uses. Knowledge about ecological filters and survival strategies of trees are also important for the restoration of degraded areas. This study aimed to evaluate the functional composition and structure of adult and regenerative components of natural Araucaria forests, Araucaria plantations and plantations of exotic Pinus in subtropical southern Brazil. Differences in functional diversity and functional richness, and in community weighted mean trait values, including leaf traits and reproductive traits, were analyzed. RLQ analysis was used to assess the association between community structure, plant traits and environmental variables. Clear differences were found for most traits and for functional richness for the regenerative component, while the adult component was more similar among forest types. A clear separation in RLQ ordination associated with trait variation, for the adult component but not for regenerative trees, also indicates that communities are becoming functionally more similar with time. Plantations were shown to function as environmental filters by directly influencing species recruitment, richness and functional diversity. We conclude that passive restoration may be the best strategy for restoration of Araucaria forests.

ABSTRACT Grassland and savanna ecosystems are the original vegetation types of more than 30% of the Brazilian territory, but conservation and training of future professionals has largely focused on forests. In fact, no standard protocols exist for sampling grassland vegetation for environmental planning or licensing. Neglecting non-forest ecosystems may have deleterious consequences for the maintenance of biodiversity and the provisioning of ecosystem services. Herein, we provide practical guidelines on how to conceive and develop ecological studies of grassland vegetation for scientific, monitoring or technical purposes. Using examples mostly from southern Brazil, we explain and discuss the various components of the research process, from the question to be investigated to defining and implementing the sampling design, performing data analyses and presenting the results. Our guidelines should prove useful for training technicians and researchers working on grassland ecosystems and other non-forest ecosystems in Brazil and surrounding regions.

ABSTRACT Subtropical Campos Sulinos grasslands, in South Brazil, are among the most biodiverse grasslands of the world. As climatic conditions lead to high productivity, disturbance are critical to maintain their diversity. Long-term exclusion, on the other hand, leads to plant species losses and changes in composition. No studies on the restoration of these grasslands after abandonment exist to date. We tested combinations of restoration techniques with the aim of increasing plant diversity in an abandoned and species-poor grassland in the South Brazilian highland region. In a bi-factorial experiment, we tested the effects of two different frequencies of mowing and of hay transfer. Mowing reduced plant cover, vegetation height, and abundance of erect grasses and shrubs, and increased species richness, diversity (Shannon diversity index) and prostrate forb and grass cover. No differences were found between mowing frequencies. Hay transfer was not effective at reintroducing species. The results of the present study provide further evidence that the reintroduction of plants is a major challenge in the restoration of subtropical and tropical grasslands. The study shows that mowing is a fast way to increase plant diversity in Campos Sulinos after long periods of abandonment.

RESUMO Áreas ribeirinhas são foco recorrente de restauração ecológica, devido a sua importância para a manutenção de serviços ecossistêmicos. Entretanto, poucos estudos têm de fato avaliado o sucesso de intervenções ativas em restaurar funções ou processos ecossistêmicos. A regeneração natural é um processo sucessional, cuja avaliação pode indicar o estado e o potencial de resiliência do ecossistema em áreas sob restauração. O presente estudo comparou padrões de regeneração natural de uma área de restauração ecológica (com plantio de mudas nativas há 10 anos) com a mata ciliar de referência, em Cachoeirinha, Rio Grande do Sul, Brasil. Para tanto, foi realizado o levantamento das espécies arbóreas e arbustivas presentes no estrato superior (DAP ≥ 5 cm) e inferior (altura > 30 cm e DAP < 5 cm), em 40 parcelas de 100 m² cada, considerando o plantio (restauração) e a mata ciliar remanescente (referência). Cada estrato e tratamento (referência vs. restauração) foi avaliado quanto aos descritores fitossociológicos, padrões de estrutura e composição, riqueza e similaridade entre as comunidades. Os resultados demonstraram que a área de restauração apresenta composição de espécies e estrutura diferenciada com relação à referência, especialmente para o estrato superior. No estrato inferior (regeneração natural), o número de indivíduos, a altura média e a riqueza de espécies já não diferiram da referência. A composição de espécies em regeneração ainda foi distinta, porém, esta foi mais similar entre si do que as demais comparações entre estratos, indicando que espécies não plantadas foram capazes de se estabelecer nas áreas de restauração.

ABSTRACT Riparian areas are a recurrent focus of ecological restoration due to their importance for the maintenance of ecosystem services. However, few studies have evaluated the success of active interventions in restoring ecosystem functions and processes. The natural regeneration is a successional process and its evaluation might reveal the state and the potential of the ecosystem resilience in forest areas undergoing restoration. The present study aimed to compare natural regeneration of a riparian area that is undergoing restoration (planting of native trees, 10 years ago) with a reference forest area, in Cachoeirinha, Rio Grande do Sul state, Brazil. We conducted a survey of trees and shrubs in the upper stratum (DBH ≥ 5 cm) and the lower stratum (> 30 cm in height and DBH > 5 cm) in a total of 40 plots (100 m2 each), within the planting (restoration) and the remnant forest (reference). For each stratum and treatment (reference vs. restoration) we analyzed phytosociological parameters, patterns of structure and composition, and similarity among plots. The results showed significant differences in relation to structure and species composition, especially for the upper stratum. For the lower stratum (natural regeneration), abundance, height, and species richness were similar between the restoration and the reference areas. Species composition in regeneration remained distinct. However, its similarity value was higher than any other comparison among strata, indicating that species that were not planted were able to establish in the planted areas.

The expansion of land use for agriculture is among the main reasons for the reduction of natural grasslands around the world, and little is known about the recovery potential of original native grassland vegetation from seed banks. The aim of this study was to assess the seed bank potential of grassland areas with or without history of cultivation in southern Brazil. Specifically, we aimed at evaluating if agricultural use allowed for the persistence of species typical of natural grasslands in soil seed banks. We analyzed seed banks in two areas with a history of cultivation and in two natural grasslands. Samples were collected in spring and autumn in order to assess transient and persistent components, and were characterized by density, richness, presence of exotic species and relationship between seed bank and established vegetation. Both richness and density were high; we found a total of 114 species and a mean density of 61,796 seedlings/m2 for all four areas in the spring sampling. In the natural grasslands, the dominant species of established vegetation were mostly absent from the soil seed bank. Our study indicates that the seed bank is of little relevance for the recovery of typical grassland vegetation after disturbance.

Restinga forests are commonly known to be plant communities rather poor in tree species. This study aimed to describe and explain the association between the floristic-structural similarities and the environmental conditions in three Swamp Restinga Forest communities in southern Brazil. In 13 plots of 100 m2 each, we sampled all individual trees (circumference at breast height >12 cm and height ≥3 m). We collected soil samples in each plot for chemical and textural analyses. Phytosociological parameters were calculated and different structural variables were compared between areas. The density of individuals did not differ between areas; however, the maximum height and abundance of species differed between the site with Histosols and the other two sites with Gleysols. Further, a canonical correspondence analysis based on a matrix of vegetation and that of environmental characteristics explained 31.5% of the total variation. The high floristic and environmental heterogeneity indicate that swamp-forests can shelter many species with low frequency. Most species were generalists that were not exclusive to this type of forest. Overall, our study showed that swamp-forests within the same region can show considerable differences in composition and structure and can include species-rich communities, mostly due to the presence of species with a broader distribution in the Atlantic Rainforest domain on sites with less stressful environmental conditions and without waterlogged conditions.

A passagem do fogo pode quebrar a dormência de sementes de muitas espécies em ecossistemas suscetíveis ao fogo. Essa resposta ao fogo é especialmente bem conhecida para espécies da família Fabaceae, mas tem sido pouco estudado no Sul do Brasil. Coletamos sementes de quatro espécies de Fabaceae presentes em mosaicos de campo-florestas do Sul do Brasil: Mimosa bimucronata, Desmodium barbatum, Sesbania virgata e Collaea stenophylla. As sementes foram expostas a diferentes tratamentos de calor (60 °C e 80 °C, ambos por 5 minutos, e 100° C por 2 minutos, mais controle sem tratamento de calor). Nem todas as espécies foram submetidas a todos os tratamentos. Após o tratamento, as sementes foram mantidas em câmara de germinação com fotoperíodo 12/12 horas e temperatura de 25 °C. A porcentagem de sementes germinadas foi contada a cada 2 dias. Os resultados foram analisados por teste de aleatorização. A taxa de germinação de D. barbatum e S. virgata aumentou quando expostas a altas temperaturas (80 °C e 60 °C, respectivamente), enquanto M. bimucronata mostrou redução e C. stenophylla nenhuma resposta aos tratamentos. Esse estudo foi o primeiro para o Sul do Brasil a mostrar uma resposta positiva na germinação de espécies campestres expostas a altas temperaturas, simulando os efeitos do fogo. Como o estudo apresentou respostas distintas, é importante conduzir trabalhos com outras espécies da família a fim de detectar padrões gerais.

Passage of a fire can break dormancy of the seeds of many plant species in fire-prone ecosystems. This response to fire is especially well known for the Fabaceae family, but has been poorly studied in Southern Brazil. We collected seeds of four Fabaceae species present in grasslands-forest mosaics of Southern Brazil: Mimosa bimucronata, Desmodium barbatum, Sesbania virgata and Collaea stenophylla. Seeds were exposed to different heat treatments (exposure to 60° and 80 °C for 5 minutes, to 100 °C for 2 minutes, control without heat treatment); not all species were tested in all treatments. After the treatment, the seeds were kept in a germination chamber with a light period of 12/12 hours and temperature of 25 °C. Germinated seeds were counted every 2 days. The results were analyzed by randomization testing. Germination of D. barbatum and S. virgata was increased after exposure to high temperatures (80° and 60 °C, respectively), while M. bimucronata showed reduced germination after temperatures of 80 °C and C. stenophylla no response. This study is the first for Southern Brazil to show a positive response of germination for grassland species exposed to high temperatures, simulating fire effects. As the study presented distinct responses of species to the heat treatment, it seems important to conduct more works with other species from the family, in order to be able to detect more general patterns.