Changes in the floristic composition in flooded savannas in Arauca (Arauca, Colombia) were described and correlated with annual rain patterns. We surveyed the vegetation to determine species ...richness, relative abundances and the Importance Value Index (IVI) using eleven-point line transects and eleven 1 m² plots every two months for a year. 110 species were recorded, and there was a positive correlation between the monthly precipitation and the abundance of individuals in the vegetation community. The higher values of species richness (96) occurred during the wet season compared to the dry season species richness (57). Also, the wet season rank abundance curve had higher evenness compared to the dry season curve. Species that were dominant during the dry season included Hydrolea spinosa, Melochia spicata, Peltaea sessiliflora, Cyperus luzulae, Acroceras zizanioides, and Andropogon bicornis. 53 species were exclusive to the wet season and fourteen to the dry season. This study shows the high botanic biodiversity that can be found in the Orinoco savannas.
Mediante censos se documentó el recambio en la composición florística asociado al régimen de lluvias en comunidades de las sabanas de Arauca (Arauca, Colombia). Además, se cuantificó la abundancia relativa y el Índice de Valor de Importancia (IVI) de las especies en eventos de muestreo bimestrales a lo largo de un año. Se usaron transectos lineales con once puntos y once cuadrantes de 1 m². Se registraron 110 especies y se obtuvo una correlación positiva entre la precipitación mensual y la abundancia de individuos, acompañada de un aumento del 85,7 % en la riqueza de especies en los meses de lluvias. Debido al mayor número de especies (96) la equitatividad de la comunidad fue mayor en el periodo de lluvias en tanto que, de las 57 especies de la época de sequía hubo dominancia de especies como Hydrolea spinosa, Melochia spicata, Peltaea sessiliflora, Cyperus luzulae, Acroceras zizanioides y Andropogon bicornis. El periodo de lluvias tuvo 53 especies exclusivas mientras que catorce lo fueron durante el periodo seco. Este estudio resalta la alta diversidad botánica que existe en las sabanas de la Orinoquia.
Changes in the floristic composition in flooded savannas in Arauca (Arauca, Colombia) were described and correlated with annual rain patterns. We surveyed the vegetation to determine species ...richness, relative abundances and the Importance Value Index (IVI) using eleven-point line transects and eleven 1 m.sup.2 plots every two months for a year. 110 species were recorded, and there was a positive correlation between the monthly precipitation and the abundance of individuals in the vegetation community. The higher values of species richness (96) occurred during the wet season compared to the dry season species richness (57). Also, the wet season rank abundance curve had higher evenness compared to the dry season curve. Species that were dominant during the dry season included Hydrolea spinosa, Melochia spicata, Peltaea sessiliflora, Cyperus luzulae, Acroceras zizanioides, and Andropogon bicornis. 53 species were exclusive to the wet season and fourteen to the dry season. This study shows the high botanic biodiversity that can be found in the Orinoco savannas. Keywords. Botany, Llanos Orientales, Orinoquia, seasonality, vegetation Mediante censos se documentó el recambio en la composición florística asociado al régimen de lluvias en comunidades de las sabanas de Arauca (Arauca, Colombia). Además, se cuantificó la abundancia relativa y el Índice de Valor de Importancia (IVI) de las especies en eventos de muestreo bimestrales a lo largo de un año. Se usaron transectos lineales con once puntos y once cuadrantes de 1 m.sup.2. Se registraron 110 especies y se obtuvo una correlación positiva entre la precipitación mensual y la abundancia de individuos, acompañada de un aumento del 85,7 % en la riqueza de especies en los meses de lluvias. Debido al mayor número de especies (96) la equitatividad de la comunidad fue mayor en el periodo de lluvias en tanto que, de las 57 especies de la época de sequía hubo dominancia de especies como Hydrolea spinosa, Melochia spicata, Peltaea sessiliflora, Cyperus luzulae, Acroceras zizanioides y Andropogon bicornis. El periodo de lluvias tuvo 53 especies exclusivas mientras que catorce lo fueron durante el periodo seco. Este estudio resalta la alta diversidad botánica que existe en las sabanas de la Orinoquia. Palabras clave. Botánica, Llanos Orientales, Orinoquia, régimen climático, vegetación
•Higher surrounding forest cover increases species accumulation during succession.•Aboveground biomass accumulation during succession is reduced in highly transformed landscapes.•Landscape ...composition is more important than land-use intensity for forest regrowth.•Forest regrowth seems more useful as a forest restoration strategy in landscapes with high forest cover.
Regenerating forests after agricultural land abandonment are increasingly common in human-modified tropical landscapes. These secondary forests preserve biodiversity and provide multiple ecosystem services, but such important roles depend on their recovery rates, which can be difficult to predict. Recovery is expected to occur faster when landscape composition favors seed dispersal to the regenerating site, and when previous land-use does not significantly reduce propagule bank or future plant growth. Here, we test such expectations for the recovery of a Mexican tropical dry forest during secondary succession. For this purpose, we measured several indicators of landscape composition and site land-use intensity in 30 regenerating sites located along gradients of age of abandonment and amount of surrounding forest. Generalized linear models and redundancy analysis were fitted to test if values of four vegetation properties (aboveground biomass, total and dominant species diversity, and species composition) were indicative of such effects. We found evidence that, as expected, species richness recovers faster in sites surrounded by higher forest cover, while aboveground biomass recovers slower as surrounding pasture cover increases. Species composition was also significantly but poorly explained by the interaction between age of abandonment and the amount of forest cover. Contrary to our expectations, we found weak evidence on the impact of site land-use intensity on all vegetation properties, except on the number of dominant species, which showed higher values in sites with higher land-use intensity. Our findings show that landscape context plays a major role in structuring successional plant communities in this tropical dry region, even stronger than site land-use intensity. This seems to be related to the influence of landscape patterns on dispersal and recruitment limitation, but also on the likelihood of further human disturbances. Therefore, conserving landscape quality is paramount to enhance forest recovery and its contribution to the preservation of biodiversity and ecosystem services.
Context
Understanding the complex interdependencies between nature and people is a major challenge for the sustainable management of social-ecological systems. Spatially explicit identification of ...these interdependencies is particularly relevant for managing biodiversity hotspots, such as Tropical Dry Forests (TDF).
Objectives
We provided a methodology to spatially identify the components of social-ecological systems that have been shaped by both environmental conditions and management practices at three relevant decision-making scales: plots owned by individuals, plot owners, and governance units. To do so, we identified and characterized: (1) ecological clusters (EC), (2) social-management clusters (SC), and (3) social-ecological systems units (SESU) in a TDF in western Mexico.
Methods
We used multivariate analysis to identify and characterize the ECs, SCs, and SESU at the respective decision-making scales.
Results
We found four EC, SC, and SESU clusters. Differences between ECs were based on their elevation and land cover type. The SC differed according to the management intensity of cattle and forests. Differences between SESU were based on land management regime (individual vs collective), plot sizes, and time under private schemes.
Conclusions
Our findings suggested that decision-makers (
ejidatarios
) are bounded by the topographical characteristics and the public policies that determine communal (or private) governance, also by the number of resources available to them. The methodology can be applied to other contexts and nested decision-making scales. The spatial identification of these interdependencies is critical for landscape planning since it can contribute to reconciling productive activities and biodiversity conservation.
Soil resistance and recovery during neotropical forest succession van der Sande, Masha T; Powers, Jennifer S; Kuyper, Thom W ...
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
01/2023, Letnik:
378, Številka:
1867
Journal Article
Recenzirano
Odprti dostop
The recovery of soil conditions is crucial for successful ecosystem restoration and, hence, for achieving the goals of the UN Decade on Ecosystem Restoration. Here, we assess how soils resist forest ...conversion and agricultural land use, and how soils recover during subsequent tropical forest succession on abandoned agricultural fields. Our overarching question is how soil resistance and recovery depend on local conditions such as climate, soil type and land-use history. For 300 plots in 21 sites across the Neotropics, we used a chronosequence approach in which we sampled soils from two depths in old-growth forests, agricultural fields (i.e. crop fields and pastures), and secondary forests that differ in age (1-95 years) since abandonment. We measured six soil properties using a standardized sampling design and laboratory analyses. Soil resistance strongly depended on local conditions. Croplands and sites on high-activity clay (i.e. high fertility) show strong increases in bulk density and decreases in pH, carbon (C) and nitrogen (N) during deforestation and subsequent agricultural use. Resistance is lower in such sites probably because of a sharp decline in fine root biomass in croplands in the upper soil layers, and a decline in litter input from formerly productive old-growth forest (on high-activity clays). Soil recovery also strongly depended on local conditions. During forest succession, high-activity clays and croplands decreased most strongly in bulk density and increased in C and N, possibly because of strongly compacted soils with low C and N after cropland abandonment, and because of rapid vegetation recovery in high-activity clays leading to greater fine root growth and litter input. Furthermore, sites at low precipitation decreased in pH, whereas sites at high precipitation increased in N and decreased in C : N ratio. Extractable phosphorus (P) did not recover during succession, suggesting increased P limitation as forests age. These results indicate that no single solution exists for effective soil restoration and that local site conditions should determine the restoration strategies. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.
Forests that regrow naturally on abandoned fields are important for restoring biodiversity and ecosystem services, but can they also preserve the distinct regional tree floras? Using the floristic ...composition of 1215 early successional forests (≤20 years) in 75 human-modified landscapes across the Neotropic realm, we identified 14 distinct floristic groups, with a between-group dissimilarity of 0.97. Floristic groups were associated with location, bioregions, soil pH, temperature seasonality, and water availability. Hence, there is large continental-scale variation in the species composition of early successional forests, which is mainly associated with biogeographic and environmental factors but not with human disturbance indicators. This floristic distinctiveness is partially driven by regionally restricted species belonging to widespread genera. Early secondary forests contribute therefore to restoring and conserving the distinctiveness of bioregions across the Neotropical realm, and forest restoration initiatives should use local species to assure that these distinct floras are maintained.
Introducción: El recién nacido prematuro presenta una inmadurez del sistema cardiorespiratorio, lo que dificulta su adaptación al medio extrauterino y conlleva a múltiples complicaciones las cuales ...se requieren intervenciones que mejoren la ventilación y el intercambio gaseoso tales como la oxigenación a través de dispositivos de apoyo terapéutico como la presión positiva continua de la vía aérea o CPAP. Objetivo: determinar el efecto del tacto terapéutico en la adaptación del recién nacido pretérmino con CPAP. Materiales y métodos: Estudio cuasi-experimental, con una muestra de 13 RNPT a quienes se les aplicó el tacto terapéutico durante 15 minutos, con 2 sesiones diarias (6 am y 8pm), con evaluación antes y después del CRE: “Adaptación del prematuro”. A lo cual se le realizó el análisis descriptivo correspondiente. Resultados: El total de los participantes, fue asignado al grupo control y grupo intervenido de forma similar, evidenciando cambios antes y después de la intervención, pero en especial en el indicador postura de las manos, con una diferencia entre ambos grupos de p 0,74 con valor de 0.006. Conclusiones: La aplicación del tacto terapéutico al RNPT con CPAP nasal permite mejorar el confort del RNPT a través de indicadores fisiológicos y neurocomportamentales.
We assessed the circulation of severe acute respiratory syndrome coronavirus‐2 variants amongst vaccinated military personnel in Bogotá, Colombia to evaluate the mutations of certain variants and ...their potential for breakthrough infection in vaccinated subjects. We observed that in vaccinated individuals the most frequent infecting lineage was Mu (B.1.621 and B.1.621.1). The above is possibly associated with specific mutations that confer it with vaccine‐induced immune escape ability. Our findings highlight the importance of how genomic tracking coupled with epidemiological surveillance can assist in the study of novel emerging variants (e.g., Omicron) and their impact on vaccination efforts worldwide.
The continuing evolution of SARS-CoV-2 and the emergence of novel variants have raised concerns about possible reinfection events and potential changes in the coronavirus disease 2019 (COVID-19) ...transmission dynamics. Utilizing Oxford Nanopore technologies, we sequenced paired samples of three patients with positive RT-PCR results in a 1-2-month window period, and subsequent phylogenetics and genetic polymorphism analysis of these genomes was performed. Herein, we report, for the first time, genomic evidence of one case of reinfection in Colombia, exhibiting different SARS-CoV-2 lineage classifications between samples (B.1 and B.1.1.269). Furthermore, we report two cases of possible viral persistence, highlighting the importance of deepening our understanding on the evolutionary intra-host traits of this virus throughout different timeframes of disease progression. These results emphasize the relevance of genomic surveillance as a tool for understanding SARS-CoV-2 infection dynamics, and how this may translate effectively to future control and mitigations efforts, such as the national vaccination program.
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