Browsing by Autor "Priscilla Muriel"

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Contribución al conocimiento de la vegetación altoandina: riqueza florística Y clave para la identificación de plantas vasculares en Cumbres de monitoreo de la red gloria-andes en Venezuela
(2021) Luis E. Gámez; Luis D. Llambí; Lirey Ramírez; Roxibell C. Pelayo; Jehison Torres; Nelson Márquez; Carmen Azócar; Priscilla Muriel; Francisco Javier Muñoz Cuesta
Los ecosistemas de los paramos enfrentan una creciente amenaza producto del cambio climatico. La red GLORIA-Andes constituye un esfuerzo a escala continental para documentar los cambios en la vegetacion en cumbres a lo largo de la Cordillera de los Andes. En Venezuela se establecieron siete cumbres de monitoreo entre los 3800 m y los 4600 m de elevacion en dos sitios de la Cordillera de Merida: “Gavidia-Sierra Nevada” y “Culata-Piedras Blancas”. En este trabajo presentamos una lista completa de la flora presente en las cumbres, describimos la riqueza taxonomomica, biogeografica y de formas de vida observada y presentamos una clave para la identificacion de todas las plantas vasculares. En los levantamientos durante la linea base (2012-2014) y el primer remuestreo (2017-2019), reportamos un total de 127 especies de plantas vasculares, incluyendo dos subespecies y dos hibridos, pertenecientes a 35 familias; siendo las mejores representadas Asteraceae con 36 (dos hibridos), Poaceae (20), Rosaceae (10) y Brassicaceae (6 y dos subespecies). Los generos con mayor cantidad de especies fueron Lachemilla (7), Espeletia (6), Draba (5 especies y dos subespecies) y Calamagrostis (5). Con referencia a su origen fitogeografico se observo una mayor riqueza de generos Neotropicales (31,65%), Ampliamente Templados (31,65%) y Holarticos (12,66%). Aun asi, observamos un alto nivel de endemismo a nivel especifico, con 80 especies endemicas de los paramos de Sur America y 30 restringidas a Venezuela. Para la elaboracion de la clave, se utilizo en lo posible rasgos vegetativos de facil observacion, minimizando el uso de caracteres reproductivos, de modo de facilitar la identificacion en campo. Aceptado: Diciembre 06 DE 2020
Latitudinal and altitudinal patterns of plant community diversity on mountain summits across the tropical Andes
(Wiley, 2016) Francisco Cuesta; Priscilla Muriel; Luis D. Llambí; Stephan Halloy; Nikolay Aguirre; Stephan Beck; Julieta Carilla; Rosa Isela Meneses; Soledad Cuello; Alfredo Grau
The high tropical Andes host one of the richest alpine floras of the world, with exceptionally high levels of endemism and turnover rates. Yet, little is known about the patterns and processes that structure altitudinal and latitudinal variation in plant community diversity. Herein we present the first continental‐scale comparative study of plant community diversity on summits of the tropical Andes. Data were obtained from 792 permanent vegetation plots (1 m 2 ) within 50 summits, distributed along a 4200 km transect; summit elevations ranged between 3220 and 5498 m a.s.l. We analyzed the plant community data to assess: 1) differences in species abundance patterns in summits across the region, 2) the role of geographic distance in explaining floristic similarity and 3) the importance of altitudinal and latitudinal environmental gradients in explaining plant community composition and richness. On the basis of species abundance patterns, our summit communities were separated into two major groups: Puna and Páramo. Floristic similarity declined with increasing geographic distance between study‐sites, the correlation being stronger in the more insular Páramo than in the Puna (corresponding to higher species turnover rates within the Páramo). Ordination analysis (CCA) showed that precipitation, maximum temperature and rock cover were the strongest predictors of community similarity across all summits. Generalized linear model (GLM) quasi‐Poisson regression indicated that across all summits species richness increased with maximum air temperature and above‐ground necromass and decreased on summits where scree was the dominant substrate. Our results point to different environmental variables as key factors for explaining vertical and latitudinal species turnover and species richness patterns on high Andean summits, offering a powerful tool to detect contrasting latitudinal and altitudinal effects of climate change across the tropical Andes.
Plant dispersal strategies of high tropical alpine communities across the Andes
(Wiley, 2020) Carolina Tovar; Inga M. Melcher; Buntarou Kusumoto; Francisco Cuesta; A.M. Cleef; Rosa Isela Meneses; Stephan Halloy; Luis D. Llambí; Stephan Beck; Priscilla Muriel
Abstract Dispersal is a key ecological process that influences plant community assembly. Therefore, understanding whether dispersal strategies are associated with climate is of utmost importance, particularly in areas greatly exposed to climate change. We examined alpine plant communities located in the mountain summits of the tropical Andes across a 4,000‐km latitudinal gradient. We investigated species dispersal strategies and tested their association with climatic conditions and their evolutionary history. We used dispersal‐related traits (dispersal mode and growth form) to characterize dispersal strategies for 486 species recorded on 49 mountain summits. Then we analysed the phylogenetic signal of traits and investigated the association between dispersal traits, phylogeny, climate and space using structural equation modelling and fourth‐corner analysis together with RLQ ordination. A median of 36% species in the communities was anemochorous (wind‐dispersed) and herbaceous. This dispersal strategy was followed by the barochory‐herb combination (herbaceous with unspecialized seeds, dispersed by gravity) with a median of 26.3% species in the communities. The latter strategy was common among species with distributions restricted to alpine environments. While trait states were phylogenetically conserved, they were significantly associated with a temperature gradient. Low minimum air temperatures, found at higher latitudes/elevations, were correlated with the prevalence of barochory and the herb growth form, traits that are common among Caryophyllales, Brassicaceae and Poaceae. Milder temperatures, found at lower latitudes/elevations, were associated with endozoochorous, shrub species mostly from the Ericaceae family. Anemochorous species were found all along the temperature gradient, possibly due to the success of anemochorous Compositae species in alpine regions. We also found that trait state dominance was more associated with the climatic conditions of the summit than with community phylogenetic structure. Although the evolutionary history of the tropical Andean flora has also shaped dispersal strategies, our results suggest that the environment had a more predominant role. Synthesis . We showed that dispersal‐related traits are strongly associated with a gradient of minimum air temperatures in the Andes. Global warming may weaken this key filter at tropical alpine summits, potentially altering community dispersal strategies in this region and thus, plant community structure and composition.
Strategies of diaspore dispersal investment in Compositae: the case of the Andean highlands
(Oxford University Press, 2023) Carolina Tovar; Lucia Hudson; Francisco Cuesta; Rosa Isela Meneses; Priscilla Muriel; Oriane Hidalgo; Luis Palazzesi; Carlos Suarez Ballesteros; Eleanor Hammond Hunt; Mauricio Diazgranados
Small achenes and high diaspore dispersal investment dominate among high-Andean Compositae, traits typical of mostly three tribes of African origin; but traits are also correlated with the environmental gradients within the high-Andean grasslands. Our results also suggest that diaspore dispersal investment is likely to shape species distribution patterns in naturally fragmented habitats.
Thermal niche traits of high alpine plant species and communities across the tropical Andes and their vulnerability to global warming
(Wiley, 2019) Francisco Cuesta; Carolina Tovar; Luis D. Llambí; William D. Gosling; Stephan Halloy; Julieta Carilla; Priscilla Muriel; Rosa Isela Meneses; Stephan Beck; Carmen Ulloa Ulloa
Abstract Aim The climate variability hypothesis (CVH) predicts that locations with reduced seasonal temperature variation select for species with narrower thermal ranges. Here we (a) test the CVH by assessing the effect of latitude and elevation on the thermal ranges of Andean vascular plant species and communities, and (b) assess tropical alpine plants vulnerability to warming based on their thermal traits. Location High tropical Andes. Taxon Vascular plants. Methods Temperature data for 505 vascular plant species from alpine communities on 49 summits, were extracted from 29,627 georeferenced occurrences. Species thermal niche traits (TNTs) were estimated using bootstrapping for: minimum temperature, optimum (mean) temperature and breadth (maximum‐minimum). Plant community‐weighted scores were estimated using the TNTs of their constituent species. CVH was tested for species, biogeographical species groups and communities. Vulnerability to global warming was assessed for species, biogeographical species groups and communities. Results Species restricted to the equator showed narrower thermal niche breadth than species whose ranges stretch far from the equator, however, no difference in niche breadth was found across summits’ elevation. Biogeographical species groups distributed close to the equator and restricted to alpine regions showed narrower niche breadth than those with broader ranges. Community‐weighted scores of thermal niche breadth were positively related to distance from equator but not to elevation. Based on their TNTs, species restricted to equatorial latitudes and plant communities dominated by these species were identified as the most vulnerable to the projected 1.5°C warming, due to a potentially higher risk of losing thermal niche space. Main conclusions Our study confirms that the CVH applies to high tropical Andean plant species and communities, where latitude has a strong effect on the thermal niche breadth. TNTs are identified as suitable indicators of species’ vulnerability to warming and are suggested to be included in long‐term biodiversity monitoring in the Andes.
Thermal tolerance of tropical and temperate alpine plants suggests that ‘mountain passes are not higher in the tropics’
(Wiley, 2023) Petr Sklenář; Ricardo Jaramillo; Susanne Sivila Wojtasiak; Rosa Isela Meneses; Priscilla Muriel; Adam Klimeš
Abstract Aim Tolerance of species to extreme temperatures largely determines their distribution and vulnerability to climate change. We examined thermal tolerance in tropical and temperate alpine plants, testing the hypotheses that: (a) temperate plants are resistant to more extreme temperatures and have an overall wider thermal tolerance breadth (TTB); (b) TTB in temperate plants is wider than TTB in tropical plants during the entire growing season; (c) resistance to frost and heat varies during the season in temperate plants but not in tropical plants; (d) TTB of a species predicts its latitudinal range. Location Tropical (Ecuador, Bolivia) and temperate (USA, Austria) mountains. Time period Four periods of the growing season (2014, 2016–2019). Major taxa Ninety‐six vascular plant species. Methods We employed the electrolyte leakage method to estimate the temperature resistance, that is, the temperature at which 50% tissue injury (Lt50) occurs in leaves. We used phylogenetic linear mixed‐effect models in a Bayesian framework to test for differences between the plant groups. Results Temperate and tropical plants do not differ in their temperature resistance. The four hypotheses are rejected since: (a) temperate plants do not have significantly wider overall TTB compared to tropical plants, (b) TTB of temperate plants is wider than TTB of tropical plants only at the end of the temperate summer, (c) seasonal acclimation is observed in both plant groups, (d) the latitudinal range of the plants is not related to TTB. Main conclusions The lack of TTB differences between temperate and tropical alpine plants is consistent with trends observed in ectothermic animals, which suggests a general latitudinal pattern in high‐elevation poikilotherm organisms. Limited acclimation capacity to cope with long freezing exposures restricts the occurrence of tropical alpine species to thermally aseasonal environments making them particularly vulnerable to climate change.