64 research outputs found

    Landscape-Scale Dynamics of Aspen in Rocky Mountain National Park, Colorado

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    Past studies of quaking aspen in Rocky Mountain National Park suggested that the aspen population is declining due to intensive browsing by elk (Cervus elaphus). These studies were conducted in the elk winter range, an area of intensive elk impact. The elk summer range experiences less intense grazing pressure. We tested the hypothesis that impacts of elk would be greater in the elk winter range than the summer range with landscape-scale data from the Park. The detrimental effects of elk on aspen are highly localized and, at larger spatial scales, elk browsing does not seem to be influencing the aspen population

    Initial carbon, nitrogen, and phosphorus fluxes following ponderosa pine restoration treatments

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    Southwestern ponderosa pine forests were dramatically altered by fire regime disruption that accompanied Euro-American settlement in the 1800s. Major changes include increased tree density, diminished herbaceous cover, and a shift from a frequent lowintensity fire regime to a stand-replacing fire regime. Ecological restoration via thinning and prescribed burning is being widely applied to return forests to the pre-settlement condition, but the effects of restoration on ecosystem function are unknown. We measured carbon (C), nitrogen (N), and phosphorus (P) fluxes during the first two years after the implementation of a replicated field experiment comparing thinning and composite (thinning, forest floor fuel reduction, and prescribed burning) restoration treatments to untreated controls in a ponderosa pine forest in northern Arizona, USA. Total net primary productivity (260 g Cm22yr21) was similar among treatments because a 3050(percent) decrease in pine foliage and fine-root production in restored ecosystems was balanced by greater wood, coarse root, and herbaceous production. Herbaceous plants accounted for ,20(percent) of total plant C, N, and P uptake in the controls but from 25(percent) to 70(percent) in restored plots. Total plant N uptake was ;3 g Nm22yr21 in all treatments, but net N mineralization was just one-half and twothirds of this value in the control and composite restoration, respectively. Element flux rates in controls generally declined more in a drought year than rates in restoration treatments. In this ponderosa pine forest, ecological restoration that emulated pre-settlement stand structure and fire characteristics had a small effect on plant C, N, and P fluxes at the whole ecosystem level because lower pine foliage and fine-root fluxes in treated plots (compared to controls) were approximately balanced by higher fluxes in wood and herbaceous plants

    Prescribed Fire Alters Structure and Composition of a Mid-Atlantic Oak Forest up to Eight Years After Burning

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    Background Prescribed fire in Eastern deciduous forests has been understudied relative to other regions in the United States. In Pennsylvania, USA, prescribed fire use has increased more than five-fold since 2009, yet forest response has not been extensively studied. Due to variations in forest composition and the feedback between vegetation and fire, Pennsylvania deciduous forests may burn and respond differently than forests across the eastern US. We measured changes in forest structure and composition up to eight years after prescribed fire in a hardwood forest of the Ridge and Valley region of the Appalachian Mountains in central Pennsylvania. Results Within five years post fire, tree seedling density increased more than 72% while sapling density decreased by 90%, midstory density decreased by 46%, and overstory response varied. Following one burn in the mixed-oak unit, overstory tree density decreased by 12%. In the aspen–oak unit, where pre-fire harvesting and two burns occurred, overstory tree density increased by 25%. Not all tree species responded similarly and post-fire shifts in species relative abundance occurred in sapling and seedling size classes. Abundance of red maple and cherry species decreased, whereas abundance of sassafras, quaking aspen, black oak, and hickory species increased. Conclusions Forest composition plays a key role in the vegetation–fire relationship and localized studies are necessary to measure forest response to prescribed fire. Compositional shifts in tree species were most pronounced in the aspen–oak unit where pre-fire overstory thinning and two prescribed fires were applied and significant structural changes occurred in all stands after just one burn. Increases in fire-tolerant tree species combined with reductions in fire-intolerant species highlight the role of prescribed fire in meeting management objectives such as altering forest structure and composition to improve game habitat in mid-Atlantic hardwood forests

    Designing a suite of measurements to understand the critical zone

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    Many scientists have begun to refer to the earth surface environment from the upper canopy to the depths of bedrock as the critical zone (CZ). Identification of the CZ as an integral object worthy of study implicitly posits that the study of the whole earth surface will provide benefits that do not arise when studying the individual parts. To study the CZ, however, requires prioritizing among the measurements that can be made – and we do not generally agree on the priorities. Currently, the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) is expanding from a small original focus area (0.08 km2 , Shale Hills catchment), to a larger watershed (164 km2 , Shavers Creek watershed) and is grappling with the prioritization. This effort is an expansion from a monolithologic first-order forested catchment to a watershed that encompasses several lithologies (shale, sandstone, limestone) and land use types (forest, agriculture). The goal of the project remains the same: to understand water, energy, gas, solute, and sediment (WEGSS) fluxes that are occurring today in the context of the record of those fluxes over geologic time as recorded in soil profiles, the sedimentary record, and landscape morphology. Given the small size of the Shale Hills catchment, the original design incorporated measurement of as many parameters as possible at high temporal and spatial density. In the larger Shavers Creek watershed, however, we must focus the measurements. We describe a strategy of data collection and modeling based on a geomorphological and land use framework that builds on the hillslope as the basic unit. Interpolation and extrapolation beyond specific sites relies on geophysical surveying, remote sensing, geomorphic analysis, the study of natural integrators such as streams, groundwaters or air, and application of a suite of CZ models. We hypothesize that measurements of a few important variables at strategic locations within a geomorphological framework will allow development of predictive models of CZ behavior. In turn, the measurements and models will reveal how the larger watershed will respond to perturbations both now and into the future

    Advancing dendrochronological studies of fire in the United States

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    © 2018 by the authors. Licensee MDPI, Basel, Switzerland. Dendroecology is the science that dates tree rings to their exact calendar year of formation to study processes that influence forest ecology (e.g., Speer 2010 [1], Amoroso et al., 2017 [2]). Reconstruction of past fire regimes is a core application of dendroecology, linking fire history to population dynamics and climate effects on tree growth and survivorship. Since the early 20th century when dendrochronologists recognized that tree rings retained fire scars (e.g., Figure 1), and hence a record of past fires, they have conducted studies worldwide to reconstruct [2] the historical range and variability of fire regimes (e.g., frequency, severity, seasonality, spatial extent), [3] the influence of fire regimes on forest structure and ecosystem dynamics, and [4] the top-down (e.g., climate) and bottom-up (e.g., fuels, topography) drivers of fire that operate at a range of temporal and spatial scales. As in other scientific fields, continued application of dendrochronological techniques to study fires has shaped new trajectories for the science. Here we highlight some important current directions in the United States (US) and call on our international colleagues to continue the conversation with perspectives from other countries

    The aesthetics and politics of ‘reading together’ Moroccan novels in Arabic and French

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    This paper attempts to break down the common practices of reading multilingual Moroccan novels, particularly Moroccan postcolonial novels in Arabic and French. I argue that dominant reading practices are based on binary oppositions marked by a reductionist understanding of language and cultural politics in Morocco. They place the Moroccan novel in Arabic and French in independent traditions with the presupposition that they have no impact on each other, thereby reifying each tradition. They also ignore the similar historical, social and cultural context from which these novels emerge, and tend to reinforce the marginalisation of the Moroccan novel within hegemonic single-language literary systems such as the Francophone or Arabic literary traditions. I advocate ‘reading together’ – or an entangled comparative reading of – postcolonial Moroccan novels in Arabic and French, a reading that privileges the specificity of the literary traditions in Morocco rather than language categorisation, and that considers their mutual historical, cultural, geographical, political, and aesthetic interweaving and implications

    integrated care for complex chronic patients

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    Background: In 2006, 35% - 40% of the population in the EU aged > 65 years reported a longstanding health problem and one in four currently receives medical long-term treatment. In Catalonia, data from the 2011-2015 health plan reported that about 30% of the general population has at least one chronic disorder. It is widely accepted that this increasingly important group of the population may suffer frequent unexpected hospital admissions or emergency room visits because of clinical or social circumstances triggering adverse outcomes. Accordingly, the Complex Chronic Patient (CCP) is defined as a patient with at least one+ chronic diseases, comorbidities, frail (due to social, economic and/or clinical factors), usually elderly, and who consumes a very high level of health resources. Although CCPs comprise about 5% of the general population, their health care needs consume an estimated 40% plus of all hospital admissions. Methods: CONNECARE (H2020-PHC-2015-689802) aims to develop and evaluate a new organizational model to enable integrated care of CCPs, supported by technological solutions following an adaptive case management approach. From the CCP's perspective, different healthcare professionals are central to patients' care: the general practitioners, specialist doctors, other hospital staff, and social workers. Moreover, the carers, unpaid relatives or friends, who typically deliver the majority of care that CCPs require, are indispensable. The CONNECARE integrated care organizational model will facilitate collaboration and communication among healthcare professionals, patients and their carers through integrated technological solutions in which the patients play a central role. CONNECARE will also support and empower patients for self-management, by providing them recommendations and suggestions according to continuous monitoring of their activities. CONNECARE will be deployed in three regions: Catalonia (Spain), Israel, and Groningen (the Netherlands). Results: The CONNECARE integrated care solution is built upon the experience of on-going large-scale deployment programs in each of the participating sites and the inclusion of the main stakeholders in the process (healthcare professionals, patients, carers, insurance companies, and policy makers). Therefore, a co-design methodology has been established to capture the feed-back of all actors in the integrated care process. Three clinical studies have been defined for field-testing the CONNECARE solution that will then be performed and evaluated (October 2016 to March 2019) in the three regions: community-based management of CCP, and integrated management of patients undergoing surgical procedures with a specific use case for pre-habilitation of high risk candidates for complex abdominal surgical procedures –which will only be performed and evaluated in Barcelona. The purposes of the clinical studies are: (i) assessing health value generation of the CONNECARE solution; (ii) enabling its refinement and fine tuning during the last six-month period; and (iii) generating guidelines for transferability of CONNECARE achievements to other sites. Conclusions: The ambition of CONNECARE is to co-design, develop, deploy, and evaluate a novel integrated care services model supported by a smart and adaptive case management system for better care coordination and self-management of CCPs. Pragmatic clinical trials will be held in the three sites to assess the health value generation of the CONNECARE solution. Guidelines for the transferability of CONNECARE achievements to other sites will be developed. This will save European healthcare organizations huge sums whilst improving patient outcomes

    Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

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    IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
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