Browsing by Autor "Carolina Tovar"

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Glacial melt content of water use in the tropical Andes
(IOP Publishing, 2017) Wouter Buytaert; Simon Moulds; L. Acosta; Bert De Bièvre; Carlos Francisco García Olmos; Marcos Villacís; Carolina Tovar; Koen Verbist
Accelerated melting of glaciers is expected to have a negative effect on the water resources of mountain regions and their adjacent lowlands, with tropical mountain regions being among the most vulnerable. In order to quantify those impacts, it is necessary to understand the changing dynamics of glacial melting, but also to map how glacial meltwater contributes to current and future water use, which often occurs at considerable distance downstream of the terminus of the glacier. While the dynamics of tropical glacial melt are increasingly well understood and documented, major uncertainty remains on how the contribution of tropical glacial meltwater propagates through the hydrological system, and hence how it contributes to various types of human water use in downstream regions. Therefore, in this paper we present a detailed regional mapping of current water demand in regions downstream of the major tropical glaciers. We combine these maps with a regional water balance model to determine the dominant spatiotemporal patterns of the contribution of glacial meltwater to human water use at an unprecedented scale and resolution. We find that the number of users relying continuously on water resources with a high (>25%) long-term average contribution from glacial melt is low (391 000 domestic users, 398 km 2 of irrigated land, and 11 MW of hydropower production), but this reliance increases sharply during drought conditions (up to 3.92 million domestic users, 2096 km 2 of irrigated land, and 732 MW of hydropower production in the driest month of a drought year). A large proportion of domestic and agricultural users are located in rural regions where climate adaptation capacity tends to be low. Therefore, we suggest that adaptation strategies should focus on increasing the natural and artificial water storage and regulation capacity to bridge dry periods.
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.
Predicting species distributions in poorly-studied landscapes
(Springer Science+Business Media, 2008) Pilar Adriana Rey Hernández; Irma Franke; Sebastián K. Herzog; Víctor Pacheco; Lily Paniagua; Heidi Quintana; Aldo Soto; Jennifer J. Swenson; Carolina Tovar; Thomas Valqui
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.
WHAT TO LOOK FOR IN CHEST X-RAYS OF PEDIATRIC PATIENTS WITH COVID-19: INSIGHTS FROM A COLOMBIAN COHORT.
(2023) Melisa Naranjo Vanegas; Claudia Burgos; Laura Melissa Mendez; María Margarita Rodriguez; Arianna Martinez; Paola Andrea Sánchez; Carolina Tovar; Pablo Vásquez‐Hoyos; María Lucia Mesa-Rubio; Gustavo Triana
Background: Despite advancements in vaccination and the transition from pandemic to endemic, SARS-CoV-2 continues to pose a medical challenge, particularly among children. In this context, imaging diagnostics, such as chest x-rays, are crucial to the initial treatment of patients. This study aims to characterize the radiological findings in pediatric patients with confirmed SARS-CoV-2 infection in Colombia between April 2020 and November 2021, as well as their potential association with intensive care admission. Methods: In Colombia, a multicenter cohort comprised patients aged 29 days to 17 years with confirmed SARS-CoV-2 infection and chest X-ray administered within 72 hours of hospitalization. In two separate groups, four radiologists evaluated the images. A fifth radiologist reviewed all the X-rays; and subsequently, these readings were used to calculate the kappa coefficient and to resolve discrepancies among the other radiologists. The results were compared to admission to intensive care. Results: Analysis was conducted on 392 patients with a mean age of 2 years, the majority of whom (42%) were infants. Sixty-eight percent of the radiographs had normal results. Peribronchial thickening and interstitial opacity were the most common aberrant findings (59%), followed by alveolar opacity (12%). 88 percent of findings were bilateral. The most common association between peribronchial thickening and intensive care admission was ventilatory failure. Interobserver agreement was low for peribronchial thickening (kappa = 0.1), but higher for consolidations and alveolar opacities (kappa = 0.4 and 0.5, respectively). Conclusion: In pediatric patients with SARS-CoV-2, radiological findings are nonspecific and interobserver agreement is minimal. Although consolidation and alveolar opacities demonstrated greater concordance, they were not associated with clinical differences; therefore, chest radiography is not considered useful for determining the severity of COVID-19 in children.