Dominance of non-native species increases over time in a historically invaded strandline community

Aim: We lack a robust understanding of whether exotic species, in addition to causing changes immediately after establishing, might continue to increase in dominance long after invasion events occur. To address this, we resurveyed strandline plant communities, which are likely to have been invaded for over two centuries. Location: Northeastern USA. Methods: We resurveyed the richness and cover of native and exotic plants in 2008 and 2009 at 18 sites, which had originally been surveyed in 1998. We examined whether native and exotic dominance had changed, whether native-rich sites were less likely to be impacted by exotics over time, whether changes in dominance were driven by large changes in a small number of outlier species or by small, incremental changes among many species and whether disturbance mediated any of these relationships. Results: Exotic dominance increased across sites. Initial native diversity was unrelated to patterns of exotic dominance during resurveys. The identity of species that were outliers with respect to changes in distribution or cover varied between resurvey years. Significant changes in exotic-to-native richness ratios at sites were detectible with or without the inclusion of outlier species, but changes in abundance ratios were only significant when outlier species were included. Disturbance across sites was not correlated with species richness, cover, or changes in dominance. Main conclusions: In this historically invaded community, exotics have increased in dominance over the last decade. This change is not due solely to the success of a few hyper-dominant species, but also to the cumulative effect of small changes in distribution among many species. It remains unclear whether patterns observed are due to invasion processes that are playing out very slowly through time or to some other explanation. Our findings highlight the need for a more robust understanding of the long-term dynamics of species invasions

Determinants of species richness in the Park Grass experiment

The Park Grass Experiment at Rothamsted in southeast England was started in 1856, making it the longest-running experiment in plant ecology anywhere in the world. Experimental inputs include a range of fertilizers (nitrogen, phosphorus, potassium, and organic manures) applied annually, with lime applied occasionally, and these have led to an increase in biomass and, where nitrogen was applied in the form of ammonium sulfate, to substantial decreases in soil pH. The number of species per plot varies from three to 44 per 200 m2, affording a unique opportunity to study the determinants of plant species richness and to estimate the effect sizes attributable to different factors. The response of species richness to biomass depends on the amount and type of nitrogen applied; richness declined monotonically with increasing biomass on plots receiving no nitrogen or receiving nitrogen in the form of sodium nitrate, but there was no relationship between species richness and biomass on plots acidified by ammonium sulfate application. The response to lime also depended on the type of nitrogen applied; there was no relationship between lime treatment and species richness, except in plots receiving nitrogen in the form of ammonium sulfate, where species richness increased sharply with increasing soil pH. The addition of phosphorus reduced species richness, and application of potassium along with phosphorus reduced species richness further, but the biggest negative effects were when nitrogen and phosphorus were applied together. The analysis demonstrates how multiple factors contribute to the observed diversity patterns and how environmental regulation of species pools can operate at the same spatial and temporal scale as biomass effects

The influence of clouds on radical concentrations: Observations and modelling studies of HOx during the Hill Cap Cloud Thuringia (HCCT) campaign in 2010

The potential for chemistry occurring in cloud droplets to impact atmospheric composition has been known for some time. However, the lack of direct observations and uncertainty in the magnitude of these reactions led to this area being overlooked in most chemistry transport models. Here we present observations from Mt Schmücke, Germany, of the HO2 radical made alongside a suite of cloud measurements. HO2 concentrations were depleted in-cloud by up to 90% with the rate of heterogeneous loss of HO2 to clouds necessary to bring model and measurements into agreement, demonstrating a dependence on droplet surface area and pH. This provides the first observationally derived assessment for the uptake coefficient of HO2 to cloud droplets and was found to be in good agreement with theoretically derived parameterisations. Global model simulations, including this cloud uptake, showed impacts on the oxidising capacity of the troposphere that depended critically on whether the HO2 uptake leads to production of H2O2 or H2O

Повернення в Ніжин (корпус документів з епістолярію І.Г. Спаського)

Підготовка до друку та переднє слово Наталії ДМИТРЕНКО (Ніжин), коментарі Сергія ЗОЗУЛІ (Київ–Ніжин): Уперше вводиться до наукового обігу корпус джерел з епістолярію українського та російського радянського історика-нумізмата, музейника І.Г. Спаського. Корпус джерел який містить кореспонденцію, отриману відомим науковцем від кореспондентів-ніжинців, і де, здебільшого, відображена “ніжинська тематика” – проблеми збереження культурної спадщини Ніжина, післявоєнного розвитку міста тощо.Подготовка к печати и предисловие Наталии ДМИТРЕНКО (Нежин), комментарии Сергея ЗОЗУЛИ (Киев–Нежин): Впервые вводится в научный оборот корпус источников из эпистолярия украинского и российского советского историка-нумизмата, музейщика И.Г. Спасского. Корпус источников содержит корреспонденцию, полученную известным ученым от корреспондентов-нежинцев, и в котором преимущественно отображена “нежинская тематика” – проблемы сохранения культурного наследия Нежина, послевоенного развития города и т.п.Preparation to the print and preface of Nataliya DMYTRENKO (Nizhyn), comments of Serhiy ZOZULYA (Kyiv–Nizhyn): The corps of sources from the epistolary legacy of the Ukrainian and Russian soviet historiannumismatist and museum worker I.G. Spas’kiy is entered to the scientific appeal in the first time. This corps of sources contains correspondence got the known scientist from Nizhynians and contains mostly “Nizhyn themes” – problems of protect of Nizhyn’s cultural legacy, post-war development of this town etc

The use of yeast inoculation in fermentation for port production; effect on total potential ethyl carbamate

A commercial wine yeast Saccharomyces cerevisiae UCD 522 (pre-cultured in the presence of certain mass-labelled amino acids) was inoculated into a port must which was then allowed to ferment under controlled conditions of temperature and agitation. The influence of potential ethyl carbamate (EC) precursor formed due to yeast pre-culture, upon total potential EC levels was studied at various stages of fermentation. Pre-culture accumulation did not give rise to detectable levels of EC precursor during port fermentation

HOx observations over West Africa during AMMA: impact of isoprene and NOx

Aircraft OH and HO2 measurements made over West Africa during the AMMA field campaign in summer 2006 have been investigated using a box model constrained to observations of long-lived species and physical parameters. "Good" agreement was found for HO2 (modelled to observed gradient of 1.23 ± 0.11). However, the model significantly overpredicts OH concentrations. The reasons for this are not clear, but may reflect instrumental instabilities affecting the OH measurements. Within the model, HOx concentrations in West Africa are controlled by relatively simple photochemistry, with production dominated by ozone photolysis and reaction of O(1D) with water vapour, and loss processes dominated by HO2 + HO2 and HO2 + RO2. Isoprene chemistry was found to influence forested regions. In contrast to several recent field studies in very low NOx and high isoprene environments, we do not observe any dependence of model success for HO2 on isoprene and attribute this to efficient recycling of HOx through RO2 + NO reactions under the moderate NOx concentrations (5–300 ppt NO in the boundary layer, median 76 ppt) encountered during AMMA. This suggests that some of the problems with understanding the impact of isoprene on atmospheric composition may be limited to the extreme low range of NOx concentrations

Reactive Halogens in the Marine Boundary Layer (RHaMBLe): The tropical North Atlantic experiments

The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period. This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv (note the non-IUPAC adoption in this manuscript of pptv and ppbv, equivalent to pmol mol−1 and nmol mol−1 to reflect common practice). Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O3 and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens. Aircraft measurements of O3 and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O3 and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth