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Net soil carbon balance in afforested peatlands and separating autotrophic and heterotrophic soil CO 2 effluxes

Peatlands are a significant global carbon (C) store, which can be compromised by drainage and afforestation. Quantifying the rate of C loss from peat soils under forestry is challenging, as soil CO2 efflux includes both CO2 produced from heterotrophic peat decomposition and CO2 produced by tree roots and associated fungal networks (autotrophic respiration). We experimentally terminated autotrophic below-ground respiration in replicated forest plots by cutting through all living tree roots (trenching) and measured soil surface CO2 flux, litter input, litter decay rate, and soil temperature and moisture over 2 years. Decomposition of cut roots was measured and CO2 fluxes were corrected for this, which resulted in a large change in the fraction heterotrophic : autotrophic flux, suggesting that even 2 years after trenching decaying root biomass makes significant contributions to the CO2 flux. Annual peat decomposition (heterotrophic CO2 flux) was 115 ± 16 g C m−2 yr−1, representing ca. 40 % of total soil respiration. Decomposition of needle litter is accelerated in the presence of an active rhizosphere, indicating a priming effect by labile C inputs from roots. This suggests that our estimates of peat mineralization in our trenched plots are conservative and underestimate overall rates of peat C loss. Considering also input of litter from trees, our results indicate that the soils in these 30-year-old drained and afforested peatlands are a net sink for C, since substantially more C enters the soil organic matter than is decomposed heterotrophically. This study does not account for fluvial C fluxes, which represent a small flux compared to the CO2 soil efflux; further, root litter and exudate deposition could be a significant C source that is only partially sampled by our approach, adding to these plantations being a potential carbon sink. However, the C balance for these soils should be taken over the lifespan of the trees, in order to determine if the soils under these drained and afforested peatlands are a sustained sink of C or become a net source over longer periods of forestry.

Date
19 January 2022
Authors
Hermans, Renée McKenzie, Rebecca Andersen, Roxane Teh, Yit Arn Cowie, Neil Subke, Jens-Arne
Published in
Biogeosciences
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Better utilisation and transparency of bird data collected by powerline companies

There is in an ongoing expansion of powerlines as a result of an increasing global demand for energy. Powerlines have the potential to negatively impact wild bird populations through collisions and/or electrocution, and reducing bird powerline collision and electrocution risk is a priority for companies running high-voltage powerlines (known as Transmission System Operators (TSOs)). Most TSOs are legally required to assess any potentially significant impacts via Enivronmental Impact Assessments, and so potentially collect a significant amount of data on the presence of species, species behaviour, and observed mortality rates. The value of such data, if available, for reducing and preventing bird casualties could be enhanced by increasing availability across TSOs and other decision-makers. We review the extent to which the sharing of data is happening across Europe, and how the quality, scope and availability of bird data collected by European TSOs could be improved, through use of a questionnaire and workshop with TSOs, conservationists and academics. Sixteen European TSOs responded to the questionnaire and 30 stakeholders attended the workshop. There was wide recognition of the value of different types of data on birds at powerlines, and a positive attitude to working together to share and enhance data across stakeholders to achieve the shared goal of reducing bird mortalities. Key barriers to the sharing of data included a lack of a centralised database, the lack of standardised methods to collect bird data and concerns over the confidentiality of data and reports. In order to overcome these barriers and develop a collaborative approach to data sharing, and ultimately inform best practice to reduce significant negative impacts on bird populations, we suggest a stepwise approach that (1) develops guidance around the field methods and data to be collected for mitigation effectiveness and (2) shares meta-data/bibliography of studies of powerline impacts/mitigation effectiveness for birds. In time, a more structured approach to the sharing of data and information could be developed, to make data findable, accessible, interoperable and reusable.

Date
15 January 2022
RSPB Authors
Dr Steffen Oppel
Authors
Kettel, Esther F Thaxter, Chris Oppel, Steffen Carryer, Andrew Innis, Liam Pearce-Higgins, James W
Published in
Journal of environmental management
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Cumulative impact assessments of multiple host species loss from plant diseases show disproportionate reductions in associated biodiversity

Non-native plant pests and pathogens are increasing exponentially, causing extirpation of foundation species. The impact of large-scale declines in a single host on associated biodiversity is widely documented. However, the impact of multiple host loss on biodiversity and whether these impacts are multiplicative has not been assessed. Ecological theory suggests that systems with greater functional redundancy (alternative hosts) will be more resilient to the loss of sympatric hosts. We test this theory and show its importance in relation to pest/pathogen impact assessments.
We assessed the potential impact on biodiversity of the loss of two widely occurring sympatric European tree species, Fraxinus excelsior and Quercus petraea/robur, both of which are currently threatened by a range of pests and pathogens.
At the UK scale, the total number of associated species at risk of extirpation from plant diseases affecting these two sympatric hosts is greater than the sum of the associated species at risk from declines in either host alone. F. excelsior hosts 45 obligate species (species only found on that host) and Q. petraea/robur hosts 326. However, a decline in both these trees would impact 512 associated species, across multiple taxon groups, a 38% increase. Assessments at a local scale, 24 mixed F. excelsior–Q. petraea/robur woodlands revealed that these impacts may be even greater due to a lack of functional redundancy. Only 21% of sites were able to provide functional redundancy for F. excelsior and Q. petraea/robur associated species which can use other tree species. In most woodlands, the tree species required to provide functional redundancy were not present, although the site conditions were often suitable for them to grow.
Synthesis. Understanding of functional redundancy should be applied to assessments of pests/pathogens impact on biodiversity. In risk assessments, higher impact scores should be given to pests/pathogens affecting hosts occurring with other host plant species already impacted by pests/pathogens. Current pest/pathogen risk assessment approaches that ignore the cumulative, cascading effects shown in this study may allow an insidious, mostly overlooked, driver of biodiversity loss to continue.

Date
01 January 2022
RSPB Authors
Paul Bellamy
Authors
Mitchell, Ruth J Bellamy, Paul E Broome, Alice Ellis, Chris J Hewison, Richard L Iason, Glenn R Littlewood, Nick A Newey, Scott Pozsgai, Gabor Ray, Duncan
Published in
Journal of Ecology
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The relative importance of COVID‐19 pandemic impacts on biodiversity conservation globally

The COVID-19 pandemic has had an enormous impact on almost all aspects of human society and endeavor; the natural world and its conservation have not been spared. Through a process of expert consultation, we identified and categorized, into 19 themes and 70 subthemes, the ways in which biodiversity and its conservation have been or could be affected by the pandemic globally. Nearly 60% of the effects have been broadly negative. Subsequently, we created a compendium of all themes and subthemes, each with explanatory text, and in August 2020 a diverse group of experienced conservationists with expertise from across sectors and geographies assessed each subtheme for its likely impact on biodiversity conservation globally. The 9 subthemes ranked highest all have a negative impact. These were, in rank order, governments sidelining the environment during their economic recovery, reduced wildlife-based tourism income, increased habitat destruction, reduced government funding, increased plastic and other solid waste pollution, weakening of nature-friendly regulations and their enforcement, increased illegal harvest of wild animals, reduced philanthropy, and threats to survival of conservation organizations. In combination, these impacts present a worrying future of increased threats to biodiversity conservation but reduced capacity to counter them. The highest ranking positive impact, at 10, was the beneficial impact of wildlife-trade restrictions. More optimistically, among impacts ranked 11-20, 6 were positive and 4 were negative. We hope our assessment will draw attention to the impacts of the pandemic and, thus, improve the conservation community's ability to respond to such threats in the future.

Date
01 January 2022
RSPB Authors
Dr Richard Bradbury
Authors
Gibbons, David W Sandbrook, Chris Sutherland, William J Akter, Rezvin Bradbury, Richard Broad, Steven Clements, Andy Crick, Humphrey QP Elliott, Joanna Gyeltshen, Ngawang Heath, Melanie Hughes, Jonathan Jenkins, Richard KB Jones, Alastair H Lopez de la Lama, Rocio Macfarlane, Nicholas BW Maunder, Mike Prasad, Ravikash Romero-Muñoz, Alfredo Steiner, Noa Tremlett, James Trevelyan, Rosie Vijaykumar, Savita Wedage, Irushinie Ockendon, Nancy
Published in
Conservation Biology
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The status of our bird populations: the fifth Birds of Conservation Concern in the United Kingdom, Channel Islands and Isle of Man and second IUCN Red List assessment of extinction risk for Great Britain

The fifth review of Birds of Conservation Concern (BoCC5) in the UK, Channel Islands and Isle of Man assessed and assigned 245 species to updated Red, Amber and Green lists of conservation concern and showed a continuing decline in the status of our bird populations.

In total, 70 species (29% of those assessed) are now on the Red list, up from 36 species in the first review in 1996. Since the last review, in 2015, Golden Oriole Oriolus oriolus has been lost as a breeding species. Eleven species have been moved to the Red list, while only six species moved from Red to Amber. Newly Red-listed species include Common Swift Apus apus, House Martin Delichon urbicum, Greenfinch Chloris chloris and the globally threatened Leach’s Storm-petrel Oceanodroma leucorhoa.

There has been no improvement in the overall status of species associated with farmland and upland, or Afro-Palearctic migrants; indeed, more such species have been Red-listed. Concerns over the status of our wintering wildfowl and wader populations have also increased. As a direct result of targeted conservation action, White-tailed Eagle Haliaeetus albicilla has been moved from Red to Amber.

We also present the separate, and distinct, second IUCN Regional Red List assessment of extinction risk for Great Britain, which shows that 46% of 235 regularly occurring species, and 43% of 285 separate breeding and non-breeding populations, are assessed as being threatened with extinction from Great Britain.

Date
01 December 2021
RSPB Authors
Andrew Stanbury, Dr Mark Eaton
Authors
Stanbury, Andrew Eaton, Mark Aebischer, Nicholas Balmer, Dawn Brown, Andy Douse, Andy Lindley, Patrick McCulloch, Neil Noble, David Win, Ilka
Published in
British Birds
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The status of our bird populations: the 5th Birds of Conservation Concern in the United Kingdom, Channel Islands and Isle of Man and 2nd IUCN Red List assessment of extinction risk for Great Britain

The fifth review of Birds of Conservation Concern (BoCC5) in the UK, Channel Islands and Isle of Man assessed and assigned 245 species to updated Red, Amber and Green lists of conservation concern and showed a continuing decline in the status of our bird populations.

In total, 70 species (29% of those assessed) are now on the Red list, up from 36 species in the first review in 1996. Since the last review, in 2015, Golden Oriole Oriolus oriolus has been lost as a breeding species.

Eleven species have been moved to the Red list, while only six species moved from Red to Amber. Newly Red-listed species include Common Swift Apus apus, House Martin Delichon urbicum, Greenfinch Chloris chloris and the globally threatened Leach’s Storm-petrel Oceanodroma leucorhoa.

There has been no improvement in the overall status of species associated with farmland and upland, or Afro-Palearctic migrants; indeed, more such species have been Red-listed. Concerns over the status of our wintering wildfowl and wader populations have also increased. As a direct result of targeted conservation action, White-tailed Eagle Haliaeetus albicilla has been moved from Red to Amber.

We also present the separate, and distinct, second IUCN Regional Red List assessment of extinction risk for Great Britain, which shows that 46% of 235 regularly occurring species, and 43% of 285 separate breeding and non-breeding populations, are assessed as being threatened with extinction from Great Britain.

Date
01 December 2021
RSPB Authors
Andrew Stanbury, Dr Mark Eaton
Authors
Stanbury, Andrew Eaton, Mark Aebischer, Nicholas Balmer, Dawn Brown, Andy Douse, Andy Lindley, Patrick McCulloch, Neil Noble, David Win, Ilka
Published in
British Birds
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The impact of tree loss on carbon management in West Africa

This study quantifies the amount of carbon stored and sequestered by vegetation in west Africa, carbon loss due to tree cover loss, and the potential natural sequestration relative to projected carbon emissions in 2030. GIS analysis of published data on vegetation biomass, tree cover, sequestration by vegetation and soil carbon indicate that vegetation and soil held 38,855 Mt of carbon in 2010, most of which was in above and below ground vegetation. The loss of 58,353 km2 (9%) of tree cover between 2010 and 2018 resulted in the loss of 672 Mt of 14,923 Mt carbon in vegetation. Key Biodiversity Areas, (sites of conservation importance), covered 7.4% of land but in 2010 contained 16% of carbon stored in vegetation. Trees sequestered between 23.6 and 53.6 Mt of carbon in 2018 (17% of which was in Key Biodiversity Areas). Restoration of the tree cover lost in west Africa between 2010 and 2018 could sequester an additional 27.5 Mt of carbon per annum during the first 30 years of growth. Our estimates indicate a combination of conservation and restoration of tree cover could sequester the equivalent of c.30% of projected 2030 regional emissions, contributing significantly towards mitigating climate change.

Date
23 November 2021
RSPB Authors
Dr Graeme Buchanan, Dr Rob Field, Dr Richard Bradbury
Authors
Buchanan, Graeme M Field, Rob H Bradbury, Richard B Luraschi, Beatriz Vickery, Juliet A
Published in
Carbon Management
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Wetlands support higher breeding wader densities than farmed habitats within a nature-rich farming system

Capsule

Wetlands with little or no agricultural activity support higher breeding wader densities than more intensively farmed habitats within a nature-rich farmed landscape.

Aims

To test whether breeding wader densities differ between habitats likely to receive varying agricultural management intensity, within a nature-rich farmed landscape.

Methods

Using the island of Sanday as a case study for the wader-rich Orkney archipelago, a whole-island breeding wader survey was used to generate population estimates and test whether breeding densities differed between habitats under varying management intensities.

Results

The island supported nationally high breeding wader densities, which approach those of high-density areas elsewhere in Europe. Densities of total waders and five out of six species tested varied significantly between habitats. Wetlands subject to no agricultural management or livestock grazing in some land units supported higher densities than more intensively farmed habitats for total waders, Northern Lapwing Vanellus vanellus, Common Snipe Gallinago gallinago and Common Redshank Tringa totanus and second-highest densities for Eurasian Curlew Numenius arquata. Agriculturally unimproved grassland supported the highest densities for many species after wetlands. Agriculturally improved grassland supported consistently low relative breeding densities, and other habitats managed using mechanized farming (lower intensity improved grassland and arable) supported generally low relative densities, apart from for Eurasian Oystercatcher Haematopus ostralegus.

Conclusions

Describing an entire mixed farming system as nature-rich may mask significant variation in the contribution of different habitats to the maintenance of high nature value. In this system, wetlands that were unmanaged or received low average grazing densities supported disproportionately high breeding wader densities and must be protected to maintain the high densities of most species. The further loss of wetlands, and the move towards intensively managed grassland, is a threat to the maintenance of high breeding wader densities on Orkney and in similar farmed landscapes.

Date
20 September 2021
RSPB Authors
Dr David Douglas
Authors
Douglas, David JT Lewis, Mark Thatey, Zuhail Teuten, Emma
Published in
Bird Study
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The time of singing by male Capercaillies Tetrao urogallus at leks

Counts at 16 Capercaillie leks revealed that singing started two hours before sunrise and reached a peak in the number that sang about one hour before sunrise. Most song had finished by sunrise, but some extended up to five hours after sunrise. The period of song was longer at leks where more males were seen and/or heard. Such field observations may be useful in interpreting data from unattended acoustic recorders.

Date
16 September 2021
RSPB Authors
Dr Ron Summers
Authors
Summers, Ron Doubleday, Molly Ames, Ellie
Published in
Bird Study
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Diet of the introduced Gough Moorhen Gallinula comeri on Tristan da Cunha

Gough Moorhens Gallinula comeri were introduced to Tristan da Cunha in the 1950s, and are now numerous in lowland habitat, filling the ecological niche of the extinct Tristan Moorhen G. nesiotis. On their native Gough Island, moorhens have a varied diet, ranging from vegetation and fruits to scavenging and even predatory behaviour. Here, we examined the stomach contents of four birds on Tristan da Cunha to provide insight into their diet. Moorhens mostly ate vegetation, but we also recorded spiders (Arthropoda: Aranea), earthworms (Oligochaeta: Lumbricidae), remains of introduced rodents (Mus musculus), and anthropogenic debris. As on Gough Island, moorhens on Tristan have a generalist diet, and the impact of ecosystem restoration (and of the moorhens themselves) should be considered.

Date
13 September 2021
Authors
Bond, Alexander L McClelland, Gregory
Published in
Ornis Svecica
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