Root traits predict decomposition across a landscape-scale grazing experiment

Acknowledgements We are grateful to the Woodland Trust for maintenance of and access to the Glen Finglas experiment. We thank Debbie Fielding, William Smith, Sarah McCormack, Allan Sim, Marcel Junker and Elaine Runge for help in the field and the laboratory. This research was part of the Glen Finglas project (formerly Grazing and Upland Birds (GRUB)) funded by the Scottish Government (RERAS). S.W.S. was funded by a BBSRC studentship.Peer reviewedPublisher PD

Aerosol physical properties in the stratosphere (APPS) radiometer design

The measurement concepts and radiometer design developed to obtain earth-limb spectral radiance measurements for the Aerosol Physical Properties in the Stratosphere (APPS) measurement program are presented. The measurements made by a radiometer of this design can be inverted to yield vertical profiles of Rayleigh scatterers, ozone, nitrogen dioxide, aerosol extinction, and aerosol physical properties, including a Junge size-distribution parameter, and a real and imaginary index of refraction. The radiometer design provides the capacity for remote sensing of stratospheric constituents from space on platforms such as the space shuttle and satellites, and therefore provides for global measurements on a daily basis

Combination of herbivore removal and nitrogen deposition increases upland carbon storage

© 2015 The Authors. Global Change Biology Published by John Wiley & Sons Ltd. Acknowledgements We thank Ruth Mitchell, Alison Hester, Bob Mardon, Eoghain Maclean, David Welch, National Trust for Scotland, Scottish Natural Heritage and the Woodland Trust for helping find appropriate exclosures and granting access permission. We thank Nick Littlewood and Antonio Lopez Nogueira for their assistance in the field and processing samples in the lab and Ron Smith and Tony Dore for providing N deposition data. SWS was funded by a BBSRC studentship.Non peer reviewedPublisher PD

Ion cyclotron resonance studies of radiative and dissociative electron attachment processes at low pressures

Ion cyclotron resonance spectroscopy is used to measure nondissociative electron attachment rate constants for C6F6 (perfluorobenzene), C7F8 (perfluorotoluene), c-C4F8 (perfluorocyclobutane), and C7F14 (perfluoromethylcyclohexane) at low pressure (<10−6 Torr). Infrared emission is assumed to stabilize excited species leading to long-lived molecular negative ions. Combining the present data with negative ion lifetimes measured at low pressures by time-of-flight methods and electron attachment rates measured at high pressures in swarm experiments allows estimates of radiative lifetimes to be made. These all fall in the range from 0.4 to 1.5 msec, which are typical of infrared radiative lifetimes. Data are also presented for dissociative electron attachment to CCl4, where the rate limiting step is shown to be thermalization of the electron energy distribution. A number of different buffer gases are examined and the ion cyclotron resonance results extrapolate to yield the attachment rate measured in high pressure swarm experiments

Recovery of ecosystem carbon fluxes and storage from herbivory

The carbon (C) sink strength of arctic tundra is under pressure from increasing populations of arctic breeding geese. In this study we examined how CO(2) and CH(4) fluxes, plant biomass and soil C responded to the removal of vertebrate herbivores in a high arctic wet moss meadow that has been intensively used by barnacle geese (Branta leucopsis) for ca. 20 years. We used 4 and 9 years old grazing exclosures to investigate the potential for recovery of ecosystem function during the growing season (July 2007). The results show greater above- and below-ground vascular plant biomass within the grazing exclosures with graminoid biomass being most responsive to the removal of herbivory whilst moss biomass remained unchanged. The changes in biomass switched the system from net emission to net uptake of CO(2) (0.47 and -0.77 mu mol m(-2) s(-1) in grazed and exclosure plots, respectively) during the growing season and doubled the C storage in live biomass. In contrast, the treatment had no impact on the CH(4) fluxes, the total litter C pool or the soil C concentration. The rapid recovery of the above ground biomass and CO(2) fluxes demonstrates the plasticity of this high arctic ecosystem in terms of response to changing herbivore pressure

Does interspecific competition affect offspring provisioning?

Offspring size is one of the most well-studied life-history traits, yet it is remarkable that few field studies have examined the manner in which the relationship between offspring size and performance (and thus, optimal offspring size) is affected by the local environment. Furthermore, while offspring size appears to be plastic in a range of organisms, few studies have linked changes in offspring size to changes in the relationship between offspring size and performance in the field. Interspecific competition is a major ecological force in both terrestrial and marine environments, but we have little understanding of its role in shaping selection on offspring size. Here we examine the effect of interspecific competition on the relationship between offspring size and performance in the field for the marine bryozoan Watersipora subtorquata along the south coast of Australia. Both interspecific competition and offspring size had strong effects on the post-metamorphic performance of offspring in the field, but importantly, they acted independently. While interspecific competition did not affect the offspring size-performance relationship, mothers experiencing competition still produced larger offspring than mothers that did not experience competition. Because larger offspring are more dispersive in this species, increasing offspring size may represent a maternal strategy whereby mothers produce more dispersive offspring when they experience high competition themselves. This study shows that, while offspring size is plastic in this species, post-metamorphic factors alone may not determine the size of offspring that mothers produce

The effects of H2SO4 and (NH4)2SO4 treatments on the chemistry of soil drainage water and pine seedlings in forest soil microcosms

International audienceAn experiment comparing effects of sulphuric acid and reduced N deposition on soil water quality and on chemical and physical growth indicators for forest ecosystems is described. Six H2SO4 and (NH4)2SO4 treatment loads, from 0 ? 44 and 0 ? 25 kmolc ha-1 yr-1, respectively, were applied to outdoor microcosms of Pinus sylvestris seedlings in 3 acid to intermediate upland soils (calc-silicate, quartzite and granite) for 2 years. Different soil types responded similarly to H2SO4 loads, resulting in decreased leachate pH, but differently to reduced N inputs. In microcosms of calc-silicate soil, nitrification of NH4 resulted in lower pH and higher cation leaching than in acid treatments. By contrast, in quartzite and granite soils, (NH4)2SO4 promoted direct cation leaching, although leachate pH increased. The results highlighted the importance of soil composition on the nature of the cations leached, the SO4 adsorption capacities and microbial N transformations. Greater seedling growth on calc-silicate soils under both treatment types was related to sustained nutrient availability. Reductions in foliar P and Mg with higher N treatments were observed for seedlings in the calc-silicate soil. There were few treatment effects on quartzite and granite microcosm tree seedlings since P limitation precluded seedling growth responses to treatments. Hence, any benefits of N deposition to seedlings on quartzite and granite soils appeared limited by availability of co-nutrients, exacerbated by rapid depletion of soil exchangeable base cations. Keywords: acidification, manipulation, nitrogen, ammonium, deposition, soil, drainage, pine, microcosms, fores

The assimilation and retention of carbon in upland heath plant communities typical of contrasting management regimes : a 13C tracer study

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Legacy effects of nitrogen and phosphorus additions on vegetation and carbon stocks of upland heaths

Open Access via the Wiley Jisc Agreement. Funding Information Scottish Natural Heritage Royal Society of Edinburgh Fellowship Scottish Government Rural and Environment Science and Analytical Services Division (RESAS) N8 AgriFoodPeer reviewedPublisher PD