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

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

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

Factors affecting severity of wildfires in Scottish heathlands and blanket bogs

Temperate heathlands and blanket bogs are globally rare and face growing wildfire threats. Ecosystem impacts differ between low and high severity fires, where severity reflects immediate fuel consumption. This study assessed factors influencing fire severity in Scottish heathlands and blanket bogs, including the efficacy of the Canadian Fire Weather Index System (CFWIS). Using remote sensing, we measured the differenced Normalised Burn Ratio at 92 wildfire sites from 2015 to 2021. We used Generalised Additive Mixed Models to investigate the impact of topography, habitat wetness, CFWIS components and 30-day weather on severity. Dry heath exhibited higher severity than wet heath and blanket bog, and slope, elevation and south facing aspect were positively correlated to severity. Weather effects were less clear due to data scale differences, yet still indicated weather's significant role in severity. Rainfall had an increasingly negative effect from approximately 15 days before the fire, whilst temperature had an increasingly positive effect. Vapour Pressure Deficit (VPD) was the weather variable with highest explanatory value, and predicted severity better than any CFWIS component. The best-explained fire severity model (R2 = 0.25) incorporated topography, habitat wetness wind and VPD on the day of the fire. The Drought Code (DC), predicting organic matter flammability at ≥10 cm soil depth, was the CFWIS component with the highest predictive effect across habitats. Our findings suggest that wildfires in wet heath and blanket bogs are typically characterised by low severity, but that warmer, drier weather may increase the risk of severe, smouldering fires which threaten peatland carbon stores.</p

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

Nitrogen transfer between herbivores and their forage species

Herbivores may increase the productivity of forage plants; however, this depends on the return of nutrients from faeces to the forage plants. The aim of this study was to test if nitrogen (N) from faeces is available to forage plants and whether the return of nutrients differs between plant species using (15)N natural abundance in faeces and plant tissue. To investigate the effect of grazing on N transfer, we carried out a grazing experiment in wet and mesic tundra on high Arctic Spitsbergen using barnacle geese (Branta leucopsis) as the model herbivore. N inputs (from faeces) increased with grazing pressure at both the wet and mesic sites, with the greatest N input from faeces at the wet site. The delta(15)N ratio in plant tissue from grazed plots was enriched in mosses and the dwarf shrub species, reflecting the delta(15)N signature of faeces-derived N, but no such pattern was observed in the dominant grasses. This study demonstrates that the delta(15)N signature of faeces and forage species is a useful tool to explore how grazing impacts on N acquisition. Our findings suggest that plant species which acquire their N close to the soil surface (e.g. mosses) access more of the N from faeces than species with deeper root systems (e.g. grasses) suggesting a transfer of N from the preferred forage species to the mosses and dwarf shrubs, which are less preferred by the geese. In conclusion, the moss layer appears to disrupt the nitrogen return from herbivores to their forage species

Milling plant and soil material in plastic tubes over-estimates carbon and under-estimates nitrogen concentrations

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Slow recovery of High Arctic heath communities from nitrogen enrichment

Acknowledgements We are indebted to Ian Alexander who initiated the fertilisation experiment with SJW; to successive researchers involved in the experiment, John Baddeley, Nanette Madan, Lars Hogbom, Bernard Moyersen, Carmen Gordon; and to field assistants, Alison Horsburgh, Andrew Coughlan, Jo Wynn, Lora Crabtree. We thank Hans Kruijer and Michael Stech for assistance with bryophyte species identification in 2011. Funding for the initial experiment was provided by the NERC Arctic Terrestrial Ecology Special Topic Programme (GR3/9424, GR9/3433) with additional support from the CEC TMR Programme, Ny-Ålesund LSF and the British Ecological Society. This recovery study was funded by NERC (NE/I016899/1). The research was made possible by use of NERC facilities at Harland Huset; special thanks to Nick Cox and colleagues for their unfailing hospitality and support.Peer reviewedPostprintPostprin

Transplanting the leafy liverwort Herbertus hutchinsiae : A suitable conservation tool to maintain oceanic-montane liverwort-rich heath?

Thanks to the relevant landowners and managers for permission to carry out the experiments, Chris Preston for helping to obtain the liverwort distribution records and the distribution map, Gordon Rothero and Dave Horsfield for advice on choosing experimental sites and Alex Douglas for statistical advice. Juliane Geyer’s help with fieldwork was greatly appreciated. This study was made possible by a NERC PhD studentship and financial support from the Royal Botanic Garden Edinburgh and Scottish Natural Heritage.Peer reviewedPostprin