Restoration of abandoned subtropical highland grasslands in Brazil: mowing produces fast effects, but hay transfer does not

Thomas, Pedro Augusto; Overbeck, Gerhard Ernst; Müller, Sandra Cristina

doi:10.1590/0102-33062018abb0377

Cited by 15 publications

(8 citation statements)

References 37 publications

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“…Current evidence points out that southern Brazil grasslands are resilient enough to return to their speciesrich state after years of overgrazing [14]. Similarly, after many years of management-exclusion, species-poor grasslands from the south Brazilian highlands showed positive responses (i.e., increased plant species richness and diversity) to mowing as a restoration technique [81].…”

Section: Plant Taxonomic Diversitymentioning

confidence: 99%

Long-term ecological research in southern Brazil grasslands: Effects of grazing exclusion and deferred grazing on plant and arthropod communities

et al. 2020

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Grazing exclusion may lead to biodiversity loss and homogenization of naturally heterogeneous and species-rich grassland ecosystems, and these effects may cascade to higher trophic levels and ecosystem properties. Although grazing exclusion has been studied elsewhere, the consequences of alleviating the disturbance regime in grassland ecosystems remain unclear. In this paper, we present results of the first five years of an experiment in native grasslands of southern Brazil. Using a randomized block experimental design, we examined the effects of three grazing treatments on plant and arthropod communities: (i) deferred grazing (i.e., intermittent grazing), (ii) grazing exclusion and (iii) a control under traditional continuous grazing, which were applied to 70 x 70 m experimental plots, in six regionally distributed blocks. We evaluated plant community responses regarding taxonomic and functional diversity (life-forms) in separate spatial components: alpha (1 x 1 m subplots), beta, and gamma (70 x 70 m plots), as well as the cascading effects on arthropod high-taxa. By estimating effect sizes (treatments vs. control) by bootstrap resampling, both deferred grazing and grazing exclusion mostly increased vegetation height, plant biomass and standing dead biomass. The effect of grazing exclusion on plant taxonomic diversity was negative. Conversely, deferred grazing increased plant taxonomic diversity, but both treatments reduced plant functional diversity. Reduced grazing pressure in both treatments promoted the break of dominance by prostrate species, followed by fast homogenization of vegetation structure towards dominance of ligneous and erect species. These changes in the plant community led to increases in high-taxa richness and abundance of vegetationdwelling arthropod groups under both treatments, but had no detectable effects on epigeic arthropods. Our results indicate that decision-making regarding the conservation of southern Brazil grasslands should include both intensive and alleviated levels of grazing

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Section: Plant Taxonomic Diversitymentioning

confidence: 99%

Long-term ecological research in southern Brazil grasslands: Effects of grazing exclusion and deferred grazing on plant and arthropod communities

et al. 2020

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“…This means that the regeneration of the grassland community after severe disturbances will depend heavily on the dispersal of exogenous propagules rather than on the germination of seeds stored in the SSB (D'Angela et al 1988). Consequently, active seed introduction may be necessary for the restoration of degraded grassland (Buisson et al 2018;Thomas et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Soil seed bank in a subtropical grassland under different grazing intensities

Silva

Overbeck

2020

Acta Bot. Bras.

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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.

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“…Although further studies are still needed to test efficient dormancy‐breaking treatments and to improve our knowledge of seed conservation, our findings show that dry storage methods can retain seed viability among many small‐seeded species for almost 3 years in a practical and cost‐efficient way. Ultimately, our results can contribute to the application of seed banking techniques designed to supply demand for locally adapted seeds for restoration projects in Brazilian montane grasslands (Buisson et al ., 2019; Thomas et al ., 2019), including the reintroduction of threatened species.…”

Section: Discussionmentioning

confidence: 99%

Germination, viability and dormancy of 47 species from threatened tropical montane grassland in southeast Brazil: Implications for ex situ conservation

2021

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To mitigate anthropogenic impacts on plant diversity in tropical montane grasslands, one of the most threatened ecosystems in Brazil, it will be essential to develop ex situ conservation strategies to preserve wild species. The lack of basic research on the seed storage behaviour of grassland species may, however, limit their use for reintroduction and restoration projects. We investigated seed storage behaviour at the community level by comparing the effects of cold–low RH (10 °C; 10% RH) and freezing–low RH (20 °C; 10% RH) conditions on seed viability, germination and dormancy of 47 species. Fresh seeds of 43% of the species showed primary dormancy. More than half of the species showed high seed survival responses (viability >60%) under both storage temperatures. Despite a variety of dormancy responses among the different species, the low RH storage conditions tested released dormancy for most species during 12‐ and 30‐month storage times. Multivariate analysis of the best (freezing–low RH, 30 months) storage condition evidenced the formation of five distinct groups, three with species having high conservation potential in seed banks. Although further studies are needed to test dormancy‐breaking treatments and improve seed conservation practices, this first approach to assessing seed banking techniques could contribute to demand for locally adapted seeds for ecological restoration projects in tropical montane grasslands.

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Restoration of abandoned subtropical highland grasslands in Brazil: mowing produces fast effects, but hay transfer does not

Cited by 15 publications

References 37 publications

Long-term ecological research in southern Brazil grasslands: Effects of grazing exclusion and deferred grazing on plant and arthropod communities

Long-term ecological research in southern Brazil grasslands: Effects of grazing exclusion and deferred grazing on plant and arthropod communities

Soil seed bank in a subtropical grassland under different grazing intensities

Germination, viability and dormancy of 47 species from threatened tropical montane grassland in southeast Brazil: Implications for ex situ conservation

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