55 research outputs found

    Prescribed Fire Impacts to Amphibians and Reptiles in Shelterwood-harvested Oak-dominated Forests

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    As part of a larger study examining the role of prescribed fire in regenerating upland oaks (Quercus spp.), seasonal prescribed burns (winter, spring, summer, and unburned control) were applied to first-stage shelterwood-harvested stands on Horsepen Wildlife Management Area in the Virginia Piedmont in 1995. Because fire impacts are poorly documented for herpetofaunal communities, we surveyed these stands in 1996 capturing 133 individuals of ten species during over 12,720 pitfall trapnights. We found no significant differences in relative abundance of Eastern Red-backed Salamanders (Plethodon cinereus) (P = 0.26), American Toads (Bufo americanus) (P = 0.93), or all amphibians combined (P = 0.25) among unburned shelterwood stands and those treated with winter, spring, or summer burns. Three species of reptiles (Northern Fence Lizard [Sceloporus undulatus], Ground Skink [Scincella lateralis], and Southeastern Five-lined Skink [Eumeces inexpectatus]) combined were captured more frequently in burned versus unburned stands (P = 0.02). Based on a stepwise multiple regression model, Eastern Red-backed Salamander captures were more strongly influenced by landscape variables (P = 0.0320), including distance to permanent water and mesic (i.e., eastern-northern) aspects, than by fire treatments (P = 0.26). Similar landscape models were not significant (P \u3c 0.05) for toads or reptiles. Based on these results, prescribed fire may not be detrimental to herpetofaunal communities in oak dominated forests in the Virginia Piedmont

    Una aproximación ecológica a la silvicultura del roble:síntesis de 50 años de investigación en ecosistemas de roble en Norteamérica

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    Oak (Quercus L.) is an abundant and widely distributed genus in eastern North America. A history of periodic ire, grazing, canopy disturbance and timber harvesting has favored oak's dominance. But, changes in this regime toward much less ire or complete ire suppression, and selective cutting are causing the successional replacement of oak. High populations of forest herbivores such as whitetailed deer (Odocoileus virginianus), invasive species such as gypsy moth (Lymantria dispar), or dominance of native lora such as mountain laurel (Kalmia latifolia) can also inhibit oak regeneration and add to its loss within a region. Successful oak regeneration is dependent on having an adequate number of large oak advance reproduction before stand regeneration. However, this prerequisite is often lacking in eastern oak forests. Many oak stands have either few or no oak advance reproduction, and when present, it is small and noncompetitive. These common situations can be addressed through silviculture. The lack of oak seedlings in older, mature stands is addressed with a three-stage shelterwood method that promotes acorn production and site preparatory burning that increases acorn germination success. In younger, i.e., sapling and pole stands, crop tree thinning to release co-dominant oaks promotes crown development and future acorn production. The lack of competitive-sized oak reproduction is addressed with a two ­ or three ­ stage shelterwood sequence because this method is very useful for providing adequate light to foster root development of the shade intolerant oak seedlings. Application of the shelterwood method often includes herbicides or prescribed ire to control competing vegetation either before or after the inal overstory removal. When adequate oak advance reproduction is present, then clearcutting is a viable option, but measures may be needed after harvesting to control competing vegetation. Prescribed ire applied several times after inal removal of the shelterwood, or clearcutting is proving a useful tool to favor oak. These silvicultural practices generally have either no or positive impacts on non-target communities of herbaceous plants, mammals, birds, and herpetofauna.Los encinos constituyen un género (Quercus L.) abundante y ampliamente distribuido en los bosques del este de Norte América. La dominancia de los encinos se debe, en gran parte, a una historia de frecuentes disturbios que incluyen fuegos, herbivoría por mamíferos y explotación forestal. Alteraciones a estos regímenes de disturbios históricos hacia disturbios con menos frecuencia e intensidad, y la supresión de fuego, han ocasionado un remplazo gradual de los encinos. El aumento de poblaciones de herbívoros mamíferos (por ejemplo, Odocoileus virginianus), de insectos invasivos (por ejemplo, Lymantria dispar), o la dominancia de arbustos nativos (por ejemplo, Kalmia latifolia) impiden la regeneración de los encinos y contribuyen a su deterioro dentro de una región. La regeneración exitosa de los encinos depende de obtener un nivel adecuado de regeneración avanzada antes de que se inicien los cortes inales. La producción de bellotas puede incrementarse en rodales jóvenes con la aplicación de raleos para estimular el desarrollo de los doseles, o en rodales maduros utilizando una serie de cortes de protección para estimular la producción de semillas. Los cortes de protección suelen estimular el desarrollo de especies helióilas como los encinos, porque aumentan la luminosidad en el sotobosque. Estos cortes usualmente se aplican en conjunto con procedimientos para controlar la vegetación en el sotobosque que compite con los encinos, como el uso de herbicidas o quemas prescritas. Si existe una cantidad adecuada de regeneración avanzada, el uso de la tala raza es apropiado, pero usualmente requiere el control de la competencia (por ejemplo, de malezas) que puede desarrollarse después de la cosecha. La quema prescrita, aplicada una o varias veces después de los cortes de protección o de la tala raza, es una práctica viable que favorece a los encinos. Todas estas intervenciones generalmente ocasionan una respuesta relativamente neutra o positiva a las comunidades de otros grupos de organismos como plantas herbáceas, aves, mamíferos, y la herpetofauna

    Towards an integrative understanding of soil biodiversity

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    Soil is one of the most biodiverse terrestrial habitats. Yet, we lack an integrative conceptual framework for understanding the patterns and mechanisms driving soil biodiversity. One of the underlying reasons for our poor understanding of soil biodiversity patterns relates to whether key biodiversity theories (historically developed for aboveground and aquatic organisms) are applicable to patterns of soil biodiversity. Here, we present a systematic literature review to investigate whether and how key biodiversity theories (species–energy relationship, theory of island biogeography, metacommunity theory, niche theory and neutral theory) can explain observed patterns of soil biodiversity. We then discuss two spatial compartments nested within soil at which biodiversity theories can be applied to acknowledge the scale‐dependent nature of soil biodiversity

    Towards an integrative understanding of soil biodiversity

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    Soil is one of the most biodiverse terrestrial habitats. Yet, we lack an integrative conceptual framework for understanding the patterns and mechanisms driving soil biodiversity. One of the underlying reasons for our poor understanding of soil biodiversity patterns relates to whether key biodiversity theories (historically developed for aboveground and aquatic organisms) are applicable to patterns of soil biodiversity. Here, we present a systematic literature review to investigate whether and how key biodiversity theories (species-energy relationship, theory of island biogeography, metacommunity theory, niche theory and neutral theory) can explain observed patterns of soil biodiversity. We then discuss two spatial compartments nested within soil at which biodiversity theories can be applied to acknowledge the scale-dependent nature of soil biodiversity.Peer reviewe

    EMU Detection of a Large and Low Surface Brightness Galactic SNR G288.8-6.3

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    We present the serendipitous detection of a new Galactic Supernova Remnant (SNR), G288.8-6.3 using data from the Australian Square Kilometre Array Pathfinder (ASKAP)-Evolutionary Map of the Universe (EMU) survey. Using multi-frequency analysis, we confirm this object as an evolved Galactic SNR at high Galactic latitude with low radio surface brightness and typical SNR spectral index of α=0.41±0.12\alpha = -0.41\pm0.12. To determine the magnetic field strength in SNR G288.8-6.3, we present the first derivation of the equipartition formulae for SNRs with spectral indices α>0.5\alpha>-0.5. The angular size is 1.\!^\circ 8\times 1.\!^\circ 6 (107.\!^\prime 6 \times 98.\!^\prime 4) and we estimate that its intrinsic size is 40\sim40pc which implies a distance of 1.3\sim1.3kpc and a position of 140\sim140pc above the Galactic plane. This is one of the largest angular size and closest Galactic SNRs. Given its low radio surface brightness, we suggest that it is about 13000 years old.Comment: Accepted for publication in The Astrophysical Journa

    Roflumilast in moderate-to-severe chronic obstructive pulmonary disease treated with longacting bronchodilators: two randomised clinical trials

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    Background Patients with chronic obstructive pulmonary disease (COPD) have few options for treatment. The efficacy and safety of the phosphodiesterase-4 inhibitor roflumilast have been investigated in studies of patients with moderate-to-severe COPD, but not in those concomitantly treated with longacting inhaled bronchodilators. The effect of roflumilast on lung function in patients with COPD that is moderate to severe who are already being treated with salmeterol or tiotropium was investigated. Methods In two double-blind, multicentre studies done in an outpatient setting, after a 4-week run-in, patients older than 40 years with moderate-to-severe COPD were randomly assigned to oral roflumilast 500 mu g or placebo once a day for 24 weeks, in addition to salmeterol (M2-127 study) or tiotropium (M2-128 study). The primary endpoint was change in prebronchodilator forced expiratory volume in 1s (FEV(1)). Analysis was by intention to treat. The studies are registered with ClinicalTrials.gov, number NCT00313209 for M2-127, and NCT00424268 for M2-128. Findings In the salmeterol plus roflumilast trial, 466 patients were assigned to and treated with roflumilast and 467 with placebo; in the tiotropium plus roflumilast trial, 371 patients were assigned to and treated with roflumilast and 372 with placebo. Compared with placebo, roflumilast consistently improved mean prebronchodilator FEV(1) by 49 mL (p<0.0001) in patients treated with salmeterol, and 80 mL (p<0.0001) in those treated with tiotropium. Similar improvement in postbronchodilator FEV(1) was noted in both groups. Furthermore, roflumilast had beneficial effects on other lung function measurements and on selected patient-reported outcomes in both groups. Nausea, diarrhoea, weight loss, and, to a lesser extent, headache were more frequent in patients in the roflumilast groups. These adverse events were associated with increased patient withdrawal. Interpretation Roflumilast improves lung function in patients with COPD treated with salmeterol or tiotropium, and could become an important treatment for these patients

    Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

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    Publisher Copyright: © 2021, The Author(s).Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.Peer reviewe

    Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV

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    We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with next-to-leading order (NLO) quantum chromodynamics (QCD)
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