Understanding how environmental heterogeneity and elevation drives the distribution of woody communities across vegetation types within the campo rupestre in South America

The campo rupestre sensu lato is a vegetation type that occurs in South American mountains,supports a distinctive flora characterized by high rates of endemism,high herbaceous species richness and often-neglected but also species-rich of the arboreal stratum.We aimed to investigate how environmental factors and elevation are associated with the distribution and diversity of woody species in different rupestrian vegetation types across South America.Using a database of 2,049 woody species from 185 sites across four vegetation types within the campo rupestre,we assessed how the vegetation types were grouped according to their floristic composition and number of shared indicator species,as well as by using different beta diversity indices.The most important variables from a set of 27 variables(e.g.altitude,geo-edaphic and climatic)explaining species distribution were identified using redundancy analysis(RDA)and variation partitioning methods.The distribution of vegetation types was related to both environmental and spatial fractions,with a set of 17 variables retained(e.g.rockiness,grass cover and temperature seasonality as the most important variables).There was an association between the floristic composition of each vegetation type and the elevation range.Although the identified vegetation types are floristically related,they are distinguished by exclusive and habitat-specialist woody species.This uniqueness of vegetation types should be considered in terms of complementarity for the conservation of campos rupestres.

Antioxidant activity profiling by spectrophotometric methods of aqueous methanolic extracts of Helichrysum stoechas subsp. rupestre and Phagnalon saxatile subsp. saxatile

AIM: The aqueous methanolic extracts of two plants from Algeria, Helichrysum stoechas subsp. rupestre and Phagnalon saxatile subsp. saxatile, were investigated for their antioxidant activity. METHOD: Total phenolics, flavonoids, and tannins were determined by spectrophotometric techniques..In vitro antioxidant and radical scavenging profiling was determined by spectrophotometric methods, through: Total antioxidant capacity, and radical scavenging effects by the DPPH and ABTS methods, reducing and chelating power, and blanching inhibition of the β-carotene. RESULTS: All of the extracts showed interesting antioxidant and radical scavenging activity. The highest contents in phenolics, tannins, and the highest total antioxidant capacity as gallic acid equivalents of 97.5 ± 0.33 mg GAE/g DW was obtained for the flowers of H. stoechas subsp. rupestre extract in the phosphomolybdenum assay. An extract of the leafy stems of P. saxatile subsp. saxatile revealed the highest content of flavonoids, and the highest antioxidant activity by the radical scavenging and β-carotene assays when compared with standards. The best activity was by the scavenging radical DPPH with an IC50 value of 5.65 ± 0.10 μg·mL-1. CONCLUSION: The studied medicinal plants could provide scientific evidence for some traditional uses in the treatment of diseases related to the production of reactive oxygen species(ROS) and oxidative stress.

Evaluating the role of fire over a decade in a tropical mountainous forestgrassland mosaic

Forest-grassland mosaics comprise a major component of tropical landscapes,hosting invaluable biodiversity and providing essential ecosystem services to hundreds of millions of people worldwide.While open biomes often benefit from disturbance,forests can particularly be susceptible to structural changes resulting from such disruptions.Here we evaluate the influence of fire on the structure and landscape properties within natural forest islands immersed in a matrix of megadiverse montane grasslands.We conducted this study in 15 forest islands located in southeastern Brazil,assessing its fire frequency,intensity,and post-fire time over an eleven-year period from January 2012 to December 2022.Our results show that fire frequency is linked to soil characteristics and the percentage of herbaceous cover within the forest islands.We also found that the post-fire time is related to the percentage cover of the forest islands’associated herbs and shrubs.However,neither fire frequency,intensity,nor post-fire time was connected to significant changes in plant species richness,abundance,or in the upper vegetation strata(tree species richness and abundance,and canopy cover)in the interior of the forest islands.Furthermore,these fire-related variables did not result in temporal changes in the forest island’s canopy variation or landscape metrics.Our results underscore a low fire frequency and intensity within our study area,potentially explaining the limited fire-associated impact,and primarily on the lower vegetation strata.Despite acknowledging the relative stability of these forest islands under current fire regimes,we suggest further studies that can experimentally manipulate not only fire but also other anthropic disturbances for understanding the temporal dynamics of the forest islands and,consequently,their preservation.This perspective is indispensable for comprehensively understanding the ecological consequences of anthropogenic disturbances in natural forest islands.

Vegetation Composition and Structure of Some NeotropicaMountain Grasslands in Brazil

The description and understanding of plant communities is fundamental for the implementation of conservation or restoration programs, especially when these communities are highly threatened and need to be restored.Campos rupestres, some Neotropical mountain grasslands located in central Brazil and part of the Cerrado biome(covering 2 million km2) host unique plant communities, currently threatened by quarrying and mining.The grassy matrix of campos rupestres, has long been considered a rich mosaic under the control of local topography and the nature of substrate, but this affirmation has not been well studied.We analyzed whether plant communities varied in relation to edaphic factors within the stony substrate and the sandy substrate of this grassy matrix.We selected 5 sites where occur both grasslands on stony substrate and on sandy substrate, and we carried out vegetation surveys and soil analyses.We counted 222 plant species within our communities, among which38.6% are exclusively found on campos rupestres.Our results show that both soil-types are strongly acidic, nutrient poor and exhibit a seasonal variation.Phosphorus increases and p H and organic carbon decrease during the dry season.Stony soils areslightly richer in nutrients than sandy soils and differences in soil granulometry and composition have led to the formation of distinct plant communities.Some species are confined to either one or the other grassland-type, which makes the plant composition of each community unique.Variations in edaphic factors generate heterogeneous grasslands favorable to a high plant diversity.Conservation programs and restoration actions have to maintain or recreate this heterogeneity.The presence of distinct plant communities implies that different strategies might be adopted to improve the restoration of these ecosystems.

Shared-role of vegetation types,elevation and soil affecting plant diversity in an old-tropical mountain hotspot

Despite the exceptional species richness and endemism,the environmental drivers of plant diversity along old tropical mountains remain underexplored.The respective importance of vegetation types,elevation,slope,and soil to drive diversity across life-forms is poorly addressed.Here,we tested whether environmental variables drove local and regional plant diversity along an old tropical mountain according to the three main life-forms:graminoids,herbaceous and woody species.We sampled all Angiosperm species on 180 plots across five elevations,at the tropical old-mountain region of Serra do Cipó,South-eastern Brazil.We assessed soil,slope,and vegetation types,and calculated richness and beta-diversity,applying generalized least square models,linear mixed-models and partial Mantel tests to test for relationships.Richness of graminoids and herbaceous species increased with greater elevation and more nutrient-impoverished soils,while woody richness showed the inverse pattern.Beta-diversity was primarily driven by species turnover,correlated with elevation and soil and higher in less dominant vegetation types,with unique species.Despite the limited elevational range in these old mountains,it still played an important role in filtering woody species,while fostering graminoid and herbaceous species.Conservation and restoration actions need to foster the high regional diversity supported by the old mountain heterogeneous landscape and the diversity of life-forms,especially the dominant and highly diverse grassy component.