44 research outputs found
A counterfactual approach to measure the impact of wet grassland conservation on UK breeding bird populations
Wet grassland wader populations in the United Kingdom have experienced severe declines over the last three decades. To help mitigate these declines, the Royal Society for the Protection of Birds (RSPB) has restored and managed lowland wet grassland nature reserves to benefit these and other species. However, the impact that these reserves have on bird population trends has not been experimentally evaluated, as appropriate control populations do not readily exist. In this study, we compare population trends from 1994 ‐ 2018 for five bird species of conservation concern that breed on these nature reserves with counterfactual trends using matched breeding bird survey observations. Our results showed positive effects of conservation interventions for all four wader species that these reserves aim to benefit: Lapwing (Vanellus vanellus), Redshank (Tringa totanus), Curlew (Numenius arquata) and Snipe (Gallinago gallinago). There was no positive effect of conservation interventions on reserves for the passerine, Yellow Wagtail (Motacilla flava). We compared reserve trends with three different counterfactuals, based on different scenarios of how reserve populations could have developed in the absence of conservation, and found that reserve trends performed better regardless of the counterfactual used. Our approach using monitoring data to produce valid counterfactual controls is a broadly applicable method allowing large‐scale evaluation of conservation impact
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A national-scale assessment of climate change impacts on species: assessing the balance of risks and opportunities for multiple taxa
It is important for conservationists to be able to assess the risks that climate change poses to species, in order to inform decision making. Using standardised and repeatable methods, we present a national-scale assessment of the risks of range loss and opportunities for range expansion, that climate change could pose for over 3,000 plants and animals that occur in England. A basic risk assessment that compared projected future changes in potential range with recently observed changes classified 21% of species as being at high risk and 6% at medium risk of range loss under a B1 climate change scenario. A greater number of species were classified as having a medium (16%) or high (38%) opportunity to potentially expand their distribution. A more comprehensive assessment, incorporating additional ecological information, including potentially confounding and exacerbating factors, was applied to 402 species, of which 35 % were at risk of range loss and 42 % may expand their range extent. This study covers a temperate region with a significant proportion of species at their poleward range limit. The balance of risks and opportunities from climate change may be different elsewhere. The outcome of both risk assessments varied between taxonomic groups, with bryophytes and vascular plants containing the greatest proportion of species at risk from climate change. Upland habitats contained more species at risk than other habitats. Whilst the overall pattern was clear, confidence was generally low for individual assessments, with the exception of well-studied taxa such as birds. In response to climate change, nature conservation needs to plan for changing species distributions and increasing uncertainty of the future
Disentangling the Relative Importance of Changes in Climate and Land-Use Intensity in Driving Recent Bird Population Trends
Threats to biodiversity resulting from habitat destruction and deterioration have been documented for many species, whilst climate change is regarded as increasingly impacting upon species' distribution and abundance. However, few studies have disentangled the relative importance of these two drivers in causing recent population declines. We quantify the relative importance of both processes by modelling annual variation in population growth of 18 farmland bird species in the UK as a function of measures of land-use intensity and weather. Modelled together, both had similar explanatory power in accounting for annual fluctuations in population growth. When these models were used to retrodict population trends for each species as a function of annual variation in land-use intensity and weather combined, and separately, retrodictions incorporating land-use intensity were more closely linked to observed population trends than retrodictions based only on weather, and closely matched the UK farmland bird index from 1970 onwards. Despite more stable land-use intensity in recent years, climate change (inferred from weather trends) has not overtaken land-use intensity as the dominant driver of bird populations
Electron backscatter diffraction analysis and orientation mapping of monazite
Electron backscatter diffraction (EBSD) analysis of monazite requires a comparison of empirically collected electron backscatter patterns (EBSPs) with theoretical diffraction data, or 'match units', derived from known crystallographic parameters. Published crystallographic data derived from compositionally varying natural and synthetic monazite are used to calculate ten different match units for monazite. These match units are used to systematically index EBSPs obtained from four natural monazite samples with different compositions. Analyses of EBSD data, derived from the indexing of five and six diffraction bands using each of the ten match units for 10,000 EBSPs from each of the four samples, indicate a large variation in the ability of the different match units to correctly index the different natural samples. However, the use of match units derived from either synthetic Gd or Eu monazite crystallographic data yield good results for three of the four analysed monazites. Comparison of sample composition with published monazite compositions indicates that these match units are likely to yield good results for the EBSD analysis of metamorphic monazite. The results provide a clear strategy for optimizing the acquisition and analysis of EBSD data from monazite but also indicate the need for the collection of new crystallographic structure data and the subsequent generation of more appropriate match units for natural monazite
Pb, Nd, and Sr isotope mapping of Grenville‐age crustal provinces in Rodinia
New Pb, Nd, and Sr isotope data are presented for geochemically similar, ∼1.1–1.2 Ga, granitoids and tonalitic‐granitic orthogneisses from Antarctica, southern Africa, and the Falkland Islands and adjoining plateau, areas originally within the supercontinents of Rodinia and Gondwana. These data support contentions for the presence of a Mesoproterozoic (∼1.2 Ga) destructive plate margin running from Namaqua‐Natal (southern Africa), through the displaced microplates of the Falkland Plateau and Falkland Islands, the Haag Nunatak crustal block (West Antarctica) and into western Dronning Maud Land (East Antarctica). The bulk of these granitoids represent juvenile Mesoproterozoic additions to the crust, except for in parts of East Antarctica (i.e., the Sverdrupfjella) where older (Paleoproterozoic or Archean) crust was involved in granitoid generation. Our isotope data permit plate reconstructions in which southern Africa, East Antarctica, and the Falkland Islands and plateau were adjacent within Rodinia
Patterns and causes of covariation in bird and butterfly community structure
Context: Variation in biological communities is used to identify biodiversity responses to anthropogenic drivers, and to guide conservation responses. Often, such data are only available for a limited group of species, with uncertain applicability to unmonitored taxa.
Objective: Using equivalent data on the community structure of two contrasting taxa, we examine spatial co-variation in both communities, and test the extent to which any associations may result from large-scale latitudinal patterns, variation in habitat-type, or other factors.
Methods: Birds and butterflies were surveyed using standard methods across a stratified random sample of 1-km2 squares across the UK. Four measures of community structure were calculated and used to examine their association between the two taxa, before accounting for effects of latitude, habitat-type and observer.
Results: Species richness, diversity and community specialisation were significantly correlated between birds and butterflies, but evenness was not. There were strong latitudinal gradients in bird community specialisation, and butterfly richness and diversity. Habitat diversity significantly affected bird communities, whilst butterfly evenness and specialisation was reduced on farmland and human-related habitats. Covariation in richness and diversity between taxa remained after including effects of latitude and habitat-type.
Conclusions: Surrogacy approaches may be useful when considering fine-scale variation in species richness and diversity to inform site-based conservation and management decisions. However, limited covariance in evenness and specialisation metrics suggest that decisions based on the needs of rare or specialist species may be less relevant to other taxa
Molecular taphonomy of animal and plant cuticles: selective preservation and diagenesis
The nature of organic material and the environment in which it is deposited exert a major influence on the extent to which biomacromolecules are preserved in the fossil record. The role of these factors is explored with a particular focus on the cuticle of arthropods and leaves. Preservation of the original chemistry of arthropod cuticles is favoured by their thickness and degree of sclerotization, and the presence of biominerals. Decay and burial in terrestrial as opposed to marine, and anoxic rather than oxygenated conditions, likewise appear to enhance preservation. The most important factor in the long-term preservation of the chemistry of both animal and plant cuticles, however, is diagenetic alteration to an aliphatic composition. This occurs even in amber, which encapsulates the fossil, eliminating almost all external factors. Some plants contain an original decay-resistant macromolecular aliphatic component but this is not the case in arthropods. It appears that the aliphatic components of many plant as well as animal fossils may be the result of diagenetic polymerization. Selective preservation as a result of decay resistance may explain the initial survival of organic materials in sediments, but in many cases longer-term preservation relies on chemical changes. Selective preservation is only a partial explanation for the origin of kerogen