Structure and natural regeneration in iberian pine forests: implications for management = Estructura y regeneración de los pinares ibéricos: implicaciones para la gestión

La gestión de los bosques ha pasado de estar centrada únicamente en la producción de madera a orientarse a la conservación y aprovechamiento de una gran variedad de recursos que incluyen entre otros aspectos la gestión de los hábitats de la fauna silvestre y de los productos no maderables ó la estabilidad del suelo. A su vez la regeneración natural en los ecosistemas Mediterráneos se encuentra expuesta a numerosos problemas que hacen el futuro de estos ecosistemas sea preocupante e incierto, y los escenarios climáticos predicen episodios de sequías más frecuentes y temperaturas más elevadas. Todo esto hace que sea necesario analizar las prácticas selvícolas que se llevan a cabo en la actualidad. En este contexto los propietarios y gestores forestales necesitan herramientas con base científica para gestionar de los bosques de manera que se consigan alcanzar múltiples objetivos a distintas escalas espaciales y temporales. Esta tesis pretende analizar el impacto que tiene la gestión forestal que se desarrolla en la actualidad en los patrones de regeneración y en la diversidad estructural de las masas de pino silvestre (Pinus sylvestris L.) y de pino piñonero (Pinus pinea L.), dos especies con una gran importancia ecológica y socio-económica, y que representan parte de la variabilidad de tipologías que se pueden encontrar en los pinares de la Península Ibérica. La regeneración del pino silvestre y del pino piñonero presentó una estructura de tipo agregado bajo todos los métodos selvícolas estudiados (Capítulos 2-4). Los resultados del análisis del patrón espacial indicaron que existe una relación de facilitación a pequeña escala del arbolado adulto sobre el regenerado (Capítulos 2-3). Sin embargo, a escalas mayores las propiedades del suelo fueron el factor más influyente en el patrón de regeneración (Capítulo 4), lo que sugiere que las estrategias para conseguir una regeneración natural adecuada deben centrarse tanto en escalas pequeñas, mediante la gestión de los árboles adultos, como en escalas mayores influyendo en las propiedades del suelo. Delimitando los principales factores subyacentes que determinan el patrón espacial del regenerado se alcanza un mejor conocimiento de los procesos que intervienen en el desarrollo de las masas forestales, lo cual representa un avance analítico y una referencia para futuros trabajos dedicados al análisis espacial de la regeneración. Los índices de diversidad fueron útiles para distinguir varios tipos de estructura (Capítulos 5 y 6). También se demostró su aplicación a los datos de inventarios forestales y a la toma de decisiones en la gestión forestal (Capítulos 5 y 6). Otra de las novedades metodológicas presentadas en esta tesis ha sido el desarrollo de un nuevo índice de diversidad basado en la raíz cuadrada de las diferencias de las alturas (SQRI), que se presenta como una alternativa a los índices existentes para el cálculo de la diversidad de estructura vertical (Capítulo 6). La diversidad resultó mayor en las masas irregulares tanto puras como mixtas que en las masas regulares (Capítulos 5 y 6) y su relación con la edad de la masa varió según la especie y el índice empleado para medir la diversidad. La diversidad vertical disminuyó a lo largo del turno en las masas regulares como consecuencia de las claras por lo bajo que se llevaron a cabo en estas masas (Capítulo 6), aunque esta disminución fue menos evidente en las masas de pino piñonero, más homogéneas que las de pino silvestre en los estados iniciales (Capítulo 5). Desde un punto de vista operativo, los resultados sugieren fomentar las masas irregulares o al menos emplear prácticas de gestión más flexibles, que utilicen cortas más frecuentes y más heterogéneas en el espacio (combinadas con perturbaciones del suelo a pequeña escala si es necesario) para generar estructuras con múltiples edades. De esta forma, se promoverían periodos de regeneración más largos, que conseguirían a su vez incrementar la diversidad estructural y el éxito en la regeneración de las masas de pino silvestre y pino piñonero. ABSTRACT Management of forests has changed towards the provision of a variety of resources, including wildlife habitat, soil stability or non-timber forest products, while still providing for timber products revenue. Moreover, since natural regeneration of Mediterranean ecosystems is very uncertain and fraught with problems, and since future climate scenarios predict more frequent droughts and warmer temperatures, the need to critically assess common silvicultural practices has arisen. In this context, forest owners and managers need adequate science-based decision support tools for management, in order to meet multiple objectives at different temporal and spatial scales. The present thesis aimed to analyze the impact of current management practices on the regeneration patterns and structural diversity of Scots pine (Pinus sylvestris L.) and Stone pine (Pinus pinea L.) stands, two species with a great ecological and socio-economical importance that represent some of the variability in forest typologies found in Iberian Peninsula pinewoods. Regeneration of both Scots pine and Stone pine showed a spatially autocorrelated structure under all of the silvicultural systems studied (Chapters 2-4). The results from spatial pattern analysis revealed a small-scale facilitative relationship between the upperstory and understory populations (Chapters 2-3). However, soil properties were the most important factor determining regeneration pattern at larger scales (Chapter 4), suggesting that strategies to enhance regeneration need to focus both on small scales and on larger scales by managing upperstory trees and soil condition. The delineation of the principal environmental determinates underlying spatial pattern formation as demonstrated in this study (Chapters 2-4) represents an analytical advancement and framework for further work in spatial analyses of forest regeneration. Diversity indices were successfully used to discriminate among various stand-type variants (Chapters 5-6). Their wider applicability in forest inventory (Chapter 5) and decision-making (Chapters 5-6) was also demonstrated. Another novelty of this thesis was devising a new diversity index, based on the square root of height differences (SQRI) as an alternative to the existing indices that quantify structural diversity (Chapter 6). Diversity was highest in the pure and mixed uneven-aged stands analyzed (Chapters 5-6) and changed in different ways with increasing age depending on the species and index used to measure diversity. Thinning from below accounted for the decrease in vertical diversity throughout the rotation in even-aged stands (Chapter 6), but this decrease was less evident in Stone pine stands, where the initial stand state was more homogeneous (Chapter 5). Operationally, the results suggest that implementing uneven-aged management strategies or management practices using more frequent but more spatially heterogeneous harvests (combined with small scale soil disturbances if necessary) that generate complex multi-aged structures and promote longer regeneration periods would increase both structural diversity and regeneration success within Scots pine and Stone pine stand types

Characterization of the spatial structure of the canopy in Pinus sylvestris L. stands from hemispherical photographs

The spatial pattern was characterized in five experimental plots of 0.5 ha established in Scots pine stands located in the Central Mountain Range of Spain with different ecological conditions and in which different silvicultural practises are employed. A new method is proposed to asses the spatial pattern from hemispherical photographs, based on the variance between the gap fractions in sky sectors, which was calculated as a function of the angular distance. The results were compared with the spatial pattern analysis based on the second moment measure, and with the analysis of the structure of the tree number semivariogram. The three methods give a very similar scale of the pattern for most of the plots. The mature plot with more intensive silviculture showed a regular pattern at scales below 6 m. The mature plot in which the silviculture was less intensive showed a cluster pattern at scales around 10 m, and clustering at similar scales was detected during regeneration. Cluster patterns at scales around 5 m were found at the upper limit of the altitudinal range of Scots pine as well as at the lower limit, where Pyrenean oak stands merge with the pinewood. The method proposed allows the scale of the pattern of the canopy to be determined from hemispherical photographs, and can be easily implemented in forest inventories

Evaluating height structure in Scots pine forests using marked point processes

In this study, the second-moment analysis of marked spatial point processes is applied to the characterization of the tree height distribution in two Scots pine (Pinus sylvestris L.) forests in the Central Mountain Range of Spain. The cumulative function Lm(d) weighted by the normalized mark variance is proposed to analyse the second-order properties of marked point patterns. The empirical Lm(d) was compared with two null models to assess the relationship between the spatial distribution of the trees and the tree height correlations: the first null model was used to characterize the spatial clustering of the trees and was derived from the complete spatial randomness model used with Ripley’s K(d) function. The second null model, which is derived from the random labelling model used with the intertype second-moment measure K12(d) (type 1 intensity conditioned to the type 2 intensity and vice versa), allows us to identify the mark correlations. The performance of the technique was assessed through simulated marked point patterns. The second-moment analysis showed that most of the analysed Scots pine stands have a uniform height distribution at small scale and greater heterogeneity at large scales, with the exception of an upper altitudinal stand, which exhibited heterogeneity at short distances. These results demonstrate the utility of second-moment analysis of marked point processes for characterizing height structure in forest stands and the interaction between the height and the spatial pattern of the trees

Sustainable livelihoods and livelihood diversification

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Efficacy and Safety of Inhaled Ethanol in Early-Stage SARS-CoV-2 Infection in Older Adults: A Phase II Randomized Clinical Trial

Background: Inhaled ethanol in the early stages of SARS-CoV-2 infection may reduce the viral load, decreasing progression and improving prognosis. The ALCOVID-19 trial was designed to study the efficacy and safety of inhaled ethanol in older adults at initial phases of infection. Methods: Randomized, triple-blind, placebo-controlled phase II clinical trial. Experimental group (n = 38) inhaled 65° ethanol through an oxygen flow, while in the control group (n = 37), water for injection was used. General endpoint was to evaluate disease progression according to the modified World Health Organization (WHO) Clinical Progression Scale. Specific effectiveness endpoints were body temperature, oxygen saturation, viral load assessed by cycle threshold (Ct) on real-time polymerase chain reaction (RT-PCR), analytical biomarkers and use of antibiotics or corticosteroids. Specific safety outcomes were the absence of ethanol in plasma, electrographic, analytical, or respiratory alterations. Results: In the intention-to-treat population, no differences were found regarding disease progression. Mean Ct values increased over time in both groups, being numerically higher in the ethanol group, reaching a value above 33 only in the ethanol group on day 14, a value above which patients are considered non-infective. No differences were found in the other specific effectiveness endpoints. Inhaled ethanol was proven to be safe as no plasma ethanol was detected, and there were no electrocardiographic, analytical, or respiratory alterations. Conclusions: The efficacy of inhaled ethanol in terms of the progression of SARS-CoV-2 infection was not demonstrated in the present trial. However, it is positioned as a safe treatment for elderly patients with early-stage COVID-19

Development and Characterization of Inhaled Ethanol as a Novel Pharmacological Strategy Currently Evaluated in a Phase II Clinical Trial for Early-Stage SARS-CoV-2 Infection

Inhaled administration of ethanol in the early stages of COVID-19 would favor its location on the initial replication sites, being able to reduce the progression of the disease and improving its prognosis. Before evaluating the efficacy and safety of this novel therapeutic strategy in humans, its characterization is required. The developed 65° ethanol formulation is stable at room temperature and protected from light for 15 days, maintaining its physicochemical and microbiological properties. Two oxygen flows have been tested for its administration (2 and 3 L/min) using an automated headspace gas chromatographic analysis technique (HS-GC-MS), with that of 2 L/min being the most appropriate one, ensuring the inhalation of an ethanol daily dose of 33.6 ± 3.6 mg/min and achieving more stable concentrations during the entire treatment (45 min). Under these conditions of administration, the formulation has proven to be safe, based on histological studies of the respiratory tracts and lungs of rats. On the other hand, these results are accompanied by the first preclinical molecular imaging study with radiolabeled ethanol administered by this route. The current ethanol formulation has received approval from the Spanish Agency of Medicines and Medical Devices for a phase II clinical trial for early-stage COVID-19 patients, which is currently in the recruitment phase (ALCOVID-19; EudraCT number: 2020-001760-29)