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PREMISE: The herbaceous layer accounts for the majority of plant biodiversity in eastern North American forests, encompassing substantial variation in life history strategy and function. One group of early-season herbaceous understory species, colloquially referred to as spring ephemeral wildflowers, are ecologically and culturally important, but little is known about the prevalence and biogeographic patterns of the spring ephemeral strategy. METHODS: We used observations collected by the Global Biodiversity Information Facility (GBIF) to quantify the ephemerality of 559 understory forb species across eastern North America and classify them according to a continuous ephemerality index (ranging from 0 = never ephemeral to 1 = always ephemeral). We then used this information to model where ephemeral forbs were most common across the landscape with the goal of identifying geographic and environmental drivers important to their distributions and ranges. RESULTS: Only 3.4% of all understory wildflower species were spring ephemerals in all parts of their range, and 18.4% (103 species) were ephemeral in at least part of their range. Spring ephemerals peaked in absolute species richness and relative proportion at mid latitudes. CONCLUSIONS: Spring ephemeral phenology is an important shade-avoidance strategy for a large segment of the total understory species in temperate deciduous forests. In North America, the strategy is relatively most important for forest understories at mid latitudes. The definitions of spring ephemerality we provide here serve as an important ecological context for conservation priorities and to evaluate responses of this biodiverse group to future environmental change.

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Plant-plant positive interactions are key drivers of community structure. Yet, the underlying molecular mechanisms of facilitation processes remain unexplored. We investigated the 'nursing' effect of Maihueniopsis camachoi, a cactus that thrives in the Atacama Desert between c. 2800 and 3800 m above sea level. We hypothesised that an important protective factor is thermal amelioration of less cold-tolerant species with a corresponding impact on molecular phenotypes. To test this hypothesis, we compared plant cover and temperatures within the cactus foliage with open areas and modelled the effect of temperatures on plant distribution. We combined eco-metabolomics and machine learning to test the molecular consequences of this association. Multiple species benefited from the interaction with M. camachoi. A conspicuous example was the extended distribution of Atriplex imbricata to colder elevations in association with M. camachoi (400 m higher as compared to plants in open areas). Metabolomics identified 93 biochemical markers predicting the interaction status of A. imbricata with 79% accuracy, independently of year. These findings place M. camachoi as a key species in Atacama plant communities, driving local biodiversity with an impact on molecular phenotypes of nursed species. Our results support the stress-gradient hypothesis and provide pioneer insights into the metabolic consequences of facilitation.

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In the present study, a taxonomic review was conducted on representatives of the genus Tetmemorus (Desmidiaceae, Zygnematophyceae) documented within Brazilian territory. This review involved compiling data from the literature and analyzing samples collected throughout the Bahia State, updating our knowledge about this genus in Brazil. For each identified taxon, we provided information such as description, distribution across biomes and states, watersheds, ecological aspects (including habitat and community types), a list of examined (and excluded) materials, and taxonomic comments. Additionally, a taxonomic key for all species reported in Brazil was provided. Through this comprehensive review, we identified a total of eight Tetmemorus taxa occurring in Brazilian territory, comprising five species (T. brebissonii, T. furcatus, T. granulatus, T. laevis, T. planctonicus) and three non-typical varieties (T. brebissonii var. minor, T. laevis var. borgei, T. laevis var. minutus).

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In xeric environments, such as Caatinga Biome, habitat characteristics such as phytophysiognomy type and presence of water bodies can represent higher resource availability. In this context, the present study investigated the effect of phytophysiognomies and presence of water bodies in the abundance and community structure of medium and large mammal species (MLM) in the Serra de Santa Catarina, Paraíba, Brazil. To evaluate these variables we conduct an effort of 373 camera-trap days, between August 2012 and November 2014. We recorded 12 MLM species, distributed in six orders and 11 families. From those, Kerodon rupestris is the only one listed in the Brazilian List of Threatened Fauna. Regarding the habitat, the Mann-Whitney showed a significant higher frequency to the Shrubby habitat and the ANOSIM showed no shifts in the community structure between Arboreal and Shrubby. Concerning the presence of water bodies, both the Mann-Whitney and the ANOSIM showed significant higher frequency to the habitat with water presence. We observed that both phytophysiognomy and water bodies are important variables which affect mainly the abundance of mammalian species from semiarid environments. Nonetheless, whereas the forest remnants get smaller the existence of water bodies becomes a preponderant factor to the MLM species and its community structure.(AU)

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The Caatinga biome in Brazil comprises the largest and most continuous expanse of the seasonally dry tropical forest (SDTF) worldwide; nevertheless, it is among the most threatened and least studied, despite its ecological and biogeographical importance. The spatial distribution of volumetric wood stocks in the Caatinga and the relationship with environmental factors remain unknown. Therefore, this study intends to quantify and analyze the spatial distribution of wood volume as a function of environmental variables in Caatinga vegetation in Bahia State, Brazil. Volumetric estimates were obtained at the plot and fragment level. The multiple linear regression techniques were adopted, using environmental variables in the area as predictors. Spatial modeling was performed using the geostatistical kriging approach with the model residuals. The model developed presented a reasonable fit for the volume m3 ha with r2 of 0.54 and Root Mean Square Error (RMSE) of 10.9 m3 ha­1. The kriging of ordinary residuals suggested low error estimates in unsampled locations and balance in the under and overestimates of the model. The regression kriging approach provided greater detailing of the global wood volume stock map, yielding volume estimates that ranged from 0.01 to 109 m3 ha­1. Elevation, mean annual temperature, and precipitation of the driest month are strong environmental predictors for volume estimation. This information is necessary to development action plans for sustainable management and use of the Caatinga SDTF in Bahia State, Brazil.(AU)

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As human-caused extinctions and invasions accumulate across the planet, understanding the processes governing ecological functions mediated by species interactions, and anticipating the effect of species loss on such functions become increasingly urgent. In seed dispersal networks, the mechanisms that influence interaction frequencies may also influence the capacity of a species to switch to alternative partners (rewiring), influencing network robustness. Studying seed dispersal interactions in novel ecosystems on O'ahu island, Hawai'i, we test whether the same mechanisms defining interaction frequencies can regulate rewiring and increase network robustness to simulated species extinctions. We found that spatial and temporal overlaps were the primary mechanisms underlying interaction frequencies, and the loss of the more connected species affected networks to a greater extent. Further, rewiring increased network robustness, and morphological matching and spatial and temporal overlaps between partners were more influential on network robustness than species abundances. We argue that to achieve self-sustaining ecosystems, restoration initiatives can consider optimal morphological matching and spatial and temporal overlaps between consumers and resources to maximize chances of native plant dispersal. Specifically, restoration initiatives may benefit from replacing invasive species with native species possessing characteristics that promote frequent interactions and increase the probability of rewiring (such as long fruiting periods, small seeds and broad distributions).

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The influence of the Intertropical Convergence Zone (ITCZ) in the emerging South Atlantic region during the late Aptian (Early Cretaceous) is reflected in the spatio-temporal distribution of plant communities recorded in eight Brazilian sedimentary basins. The distribution of the bioclimatic groups of hygrophytes, hydrophytes, tropical lowland flora, upland flora, and xerophytes was quantified using pollen and spores. A predominance of xerophytes from the tropical xerophytic shrubland biome characterized the pre-evaporitic, evaporitic, and post-evaporitic paleoclimatic phases, in particular the evaporitic phase. The region experienced humidity events in the pre-evaporitic and post- evaporitic phases, especially near the paleoequator, where the tropical rainforest biome with two phytophysiognomies (lowland and montane rainforests) prevailed. Increasing humidity had a positive effect on plant diversity.

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The rocky outcrops in the municipality of Campo Mourão (Paraná State) are all surrounded by remaining Atlantic Forest, unlike the typical outcrops associated with river courses, fields, or hilltops. Because it is such specific vegetation, it is essential to record the floristic composition, verifying only species and the conservation status of local populations. This study cataloged the species of vascular plants occurring in four rocky outcrops areas of Campo Mourão: Nishida outcrop (1,808 ha); Bica do Rio do Campo outcrop (0.458 ha); Perdoncini outcrop (0.228 ha), and Lago Azul State Park outcrop (0.021 ha). A total of 203 collections were analyzed, representing 152 species (eight exotic to Brazil), distributed in 66 families and 135 genera. The more richness families were Poaceae, Asteraceae, Fabaceae, Rubiaceae, and Bromeliaceae. The predominant life form was herbs and shrubs, and most species are terrestrial and rupicolous. The rocky outcrops of Campo Mourão, despite the small total area (25,150 m2), have 10 % of the exclusive species in the municipality. Also, 14 species are endemic in Brazil, and two are endemic in Paraná, being Portulaca hatschbachii (Portulacaceae) officially threatened to extinction in Brazil. In these areas, several species found have been little collected in Paraná State and Brazil, in addition to the presence of life forms adapted to survival on the exposed rock. This demonstrates that despite being small, these sites are critical environments for preserving biodiversity in the region.(AU)

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Large mammal herbivores are important drivers of plant evolution and vegetation patterns, but the extent to which plant trait and ecosystem geography currently reflect the historical distribution of extinct megafauna is unknown. We address this question for South and Central America (Neotropical biogeographic realm) by compiling data on plant defence traits, climate, soil, and fire, as well as on the historical distribution of extinct megafauna and extant mammal herbivores. We show that historical mammal herbivory, especially by extinct megafauna, and soil fertility explain substantial variability in wood density, leaf size, spines and latex. We also identified three distinct regions (''antiherbiomes''), differing in plant defences, environmental conditions, and megafauna history. These patterns largely matched those observed in African ecosystems, where abundant megafauna still roams, and suggest that some ecoregions experienced savanna-to-forest shifts following megafauna extinctions. Here, we show that extinct megafauna left a significant imprint on current ecosystem biogeography.

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Frequent application of glyphosate for consecutive years has enhanced the selection pressure on sourgrass (Digitaria insularis) populations, which resulted in the development of glyphosate-resistant biotypes. Therefore, this work was developed with the objective of monitoring sourgrass resistance to glyphosate, develop a baseline of sourgrass susceptibility to this molecule and, consequently, identify the discriminatory dose between resistant and susceptible populations. This work was divided into three steps. The first step consisted of identifying and sorting sourgrass resistant and susceptible biotypes among 30 samples. In the second step, glyphosate baseline was elaborated considering exclusively the glyphosate-susceptible biotypes, which allowed the definition of a discriminatory dose. At the end, the third step, monitoring of glyphosate-resistant biotypes was achieved, considering five growing seasons (2016 ­2020) and 809 samples of sourgrass populations, collected throughout 12 states of Brazil. Glyphosate baseline was elaborated to sourgrass and ideal discriminatory rate was identified as 960 g ha-1.Glyphosate-resistant populations of sourgrass were found in all soybean growing regions sampled. Among 809 populations, 25.96% were considered resistant to glyphosate. The states with the highest frequency of glyphosate-resistant populations were Rio Grande do Sul, Mato Grosso do Sul, Bahia, Mato Grosso and Paraná.

Este trabalho foi desenvolvido com o objetivo de monitorar a resistência de capim-amargoso ao herbicida glyphosate desenvolver uma baseline de suscetibilidade da espécie e, por consequência, identificar a dose discriminatória de glifosato entre populações resistentes e suscetíveis de capim-amargoso. Todo o trabalho foi dividido em três fases. A primeira fase consistiu da análise de 30 amostras de capim-amargoso, identificando-as e classificando-as em resistentes ou suscetíveis. Na segunda fase, foi elaborada uma baseline para suscetibilidade do capim-amargoso ao herbicida glyphosate, o que permitiu a definição de uma dose discriminatória. Ao final, na terceira fase, obteve-se o monitoramento dos biótipos de capim-amargoso quanto à resistência, considerando-se cinco safras (2016 ­2020) e 809 amostras de capim-amargoso, oriundas de 12 estados brasileiros. Assim sendo, a baseline de suscetibilidade de capim-amargoso ao glyphosate foi estimada, cuja dose discriminatória ideal foi de 960 g ha-1. Populações de capim-amargoso resistentes ao glyphosate foram encontradas em todas as regiões produtoras de soja amostradas. Dentre 809populações, 25,96% foram consideradas resistentes ao glyphosate. Os estados com maior frequência de populações resistentes foram: Rio Grande do Sul, Mato Grosso do Sul, Bahia, Mato Grosso e Paraná.

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