Impacts of climate change on national biodiversity population trends

Climate change has had well-documented impacts on the distribution and phenology of species across many taxa, but impacts on species’ abundance, which relates closely to extinction risk and ecosystem function, have not been assessed across taxa. In the most comprehensive multi-taxa comparison to date, we modelled variation in national population indices of 501 mammal, bird, aphid, butterfly and moth species as a function of annual variation in weather variables, which through time allowed us to identify a component of species’ population growth that can be associated with post-1970s climate trends. We found evidence that these climate trends have significantly affected population trends of 15.8% of species, including eight with extreme (> 30% decline per decade) negative trends consistent with detrimental impacts of climate change. The modelled effect of climate change could explain 48% of the significant across-species population decline in moths and 63% of the population increase in winged aphids. The other taxa did not have significant across-species population trends or consistent climate change responses. Population declines in species of conservation concern were linked to both climatic and non-climatic factors respectively accounting for 42 and 58% of the decline. Evident differential impacts of climate change between trophic levels may signal the potential for future ecosystem disruption. Climate change has therefore already driven large-scale population changes of some species, had significant impacts on the overall abundance of some key invertebrate groups and may already have altered biological communities and ecosystems in Great Britain

Climate change refugia for the flora and fauna of England

A variety of evidence suggests that species have, in the past, been able to withstand the effects of climatic change in localised environments known as refugia, where specific environmental conditions acted as a buffer against broader-scale climatic changes. Therefore, an important question for conservation is whether refugia might exist under current and future anthropogenic climate change. If there are areas that are likely to remain relatively climatically stable and so enable species to persist despite climate change making surrounding areas unsuitable, identifying and protecting these places will be an important part of future conservation strategies. This report is part of a project that is investigating this question. The report was commissioned to identify the characteristics of potential refugia, to investigate evidence for the existence of contemporary refugia by analysing patterns of local persistence and disappearance of over 1000 species across a range of taxa, and to identify sites in England with the potential to function as refugia for different taxonomic groups at a range of spatial scales

BICCO-Net II. Final report to the Biological Impacts of Climate Change Observation Network (BICCO-Net) Steering Group

• BICCO-Net Phase II presents the most comprehensive single assessment of climate change impacts on UK biodiversity to date. • The results provide a valuable resource for the CCRA 2018, future LWEC report cards, the National Adaptation Programme and other policy-relevant initiatives linked to climate change impacts on biodiversity

A new approach to modelling the relationship between annual population abundance indices and weather data

Weather has often been associated with fluctuations in population sizes of species; however, it can be difficult to estimate the effects satisfactorily because population size is naturally measured by annual abundance indices whilst weather varies on much shorter timescales. We describe a novel method for estimating the effects of a temporal sequence of a weather variable (such as mean temperatures from successive months) on annual species abundance indices. The model we use has a separate regression coefficient for each covariate in the temporal sequence, and over-fitting is avoided by constraining the regression coefficients to lie on a curve defined by a small number of parameters. The constrained curve is the product of a periodic function, reflecting assumptions that associations with weather will vary smoothly throughout the year and tend to be repetitive across years, and an exponentially decaying term, reflecting an assumption that the weather from the most recent year will tend to have the greatest effect on the current population and that the effect of weather in previous years tends to diminish as the time lag increases. We have used this approach to model 501 species abundance indices from Great Britain and present detailed results for two contrasting species alongside an overall impression of the results across all species. We believe this approach provides an important advance to the challenge of robustly modelling relationships between weather and species population size

State of nature 2019

State of Nature 2019 presents an overview of how the country’s wildlife is faring, looking back over nearly 50 years of monitoring to see how nature has changed in the UK, its Crown Dependencies and Overseas Territories. As well as this long-term view, we focus on what has happened in the last decade, and so whether things are getting better or worse for nature. In addition, we have assessed the pressures that are acting on nature, and the responses being made, collectively, to counter these pressures

Assessing the cumulative impacts of wind farms on peatland birds: a case study of golden plover Pluvialis apricaria in Scotland

The distribution of golden plover across Scotland was modelled using land cover and management variables, and used to highlight the spatial association between golden plover abundance and current and proposed wind farm developments. Overlap was greatest in three biogeographical zones (the Western Isles, the Western Central Belt and the Borders Hills) and was estimated at ca. 5% of the biogeographical population in each case. New field data were used to predict the effects of wind farm development on golden plover populations, employing a conservative analytical approach to detect statistically significant wind farm related effects. The results provide evidence of significant avoidance of wind turbines by breeding golden plovers to a distance of at least 200 metres. Furthermore, wind farm sites appear to support lower densities of golden plover than predicted by the distribution model for sites without wind farms. Therefore, there is evidence for negative effects of wind farm developments on golden plover, and we suggest strategies to reduce any potential conflict between the need to promote wind energy and the need to maintain golden plover populations

The spatial scale of time-lagged population synchrony increases with species dispersal distance

Aim: Time-lagged population synchrony, where spatially separated populations show similar fluctuations in abundance lagged over time, is thought to be driven by dispersal among populations. When dispersal is proportional to population density or positively density dependent, and individuals move readily from population A to population B, then as population A increases, the increased number of dispersers from population A to B will cause a subsequent increase in population B. If true, then time-lagged synchrony should be strongest at a species’ typical dispersal distance, because the rate of exchange between populations will be greatest at that distance. Location: United Kingdom (U. K.). Time period: 1994 – 2013. Major taxa studied: Birds (class Aves). Methods: We estimated the spatial scale of 1-year-lagged population synchrony for 76 U.K. bird species, using 20 years of bird count data collected at 2,415 locations by the British Breeding Bird Survey. We then compared these spatial scales with published mean natal and breeding dispersal distance estimates (ranging from 0.1 to 25.8 km) for the same species based on an independent, large-scale, mark–recapture dataset of 492,272 bird recaptures in Britain and Ireland. Results: We found strong, positive cross-species relationships between the spatial scale of time-lagged synchrony and mean natal and breeding dispersal distance estimates from the mark–recapture study. However, average spatial scales of time-lagged synchrony were more than 60 km longer than those from mark–recapture data, with scales ranging from 5 to 185 km. Main conclusions: Ours is the first study to show that the spatial scale of time-lagged synchrony increases with species dispersal distance. The scale of synchrony was larger than expected, probably because mark–recapture data underestimated the real dispersal distances, or because dispersal synchronizes populations at a larger spatial scale than that of dispersal (e.g., through formation of travelling waves), or both. Nevertheless, the strong relative concordance is consistent with the explanation that time-lagged synchrony results from dispersal among populations

An indicator highlights seasonal variation in the response of Lepidoptera communities to warming

The impacts of climate change on species and ecosystems are increasingly evident. While these tend to be clearest with respect to changes in phenology and distribution ranges, there are also important consequences for population sizes and community structure. There is an urgent need to develop ecological indicators that can be used to detect climate-driven changes in ecological communities, and identify how those impacts may vary spatially. Here we describe the development of a new community-based seasonal climate change indicator that uses national population and weather indices. We test this indicator using Lepidopteran and co-located weather data collected across a range of UK Environmental Change Network (ECN) sites. We compare our butterfly indicator with estimates derived from an alternative, previously published metric, the Community Temperature Index (CTI). First, we quantified the effect of temperature on population growth rates of moths and butterflies (Species Temperature Response, STR) by modelling annual variation in national population indices as a function of nationally averaged seasonal variation in temperature, using species and weather data independent of the ECN data. Then, we calculated average STRs for annually summarised species data from each ECN site, weighted by species’ abundance, to produce the Community Temperature Response (CTR). Finally, we tested the extent to which CTR correlated with spatial variation in temperature between sites and the extent to which temporal variation in CTR tracked both annual and seasonal warming trends. Mean site CTR was positively correlated with mean site temperature for moths but not butterflies. However, spatial variation in moth communities was well explained by mean site summer temperature and butterfly communities by winter temperature, respectively accounting for 74% and 63% of variation. Temporal variation in moth and butterfly CTR within sites did not vary with the mean annual temperature but responded to variation in the mean temperature of specific seasons. There were positive correlations between moth seasonal CTRs and seasonal temperatures in winter, spring and summer; and butterfly seasonal CTRs and seasonal temperatures in winter and summer. Butterfly CTR and CTI both correlated spatially and temporally with winter temperature. Our results highlight the need for seasonality to be considered when examining the impact of climate change on communities. Seasonal CTRs may be used to track the impact of changing temperatures on biodiversity and help identify potential mechanisms by which climate change is affecting communities. In the case of Lepidoptera, our results suggest that future warming may reassemble Lepidoptera communities

Assessing trends in biodiversity over space and time using the example of British breeding birds

Partitioning biodiversity change spatially and temporally is required for effective management, both to determine whether action is required and whether it should be applied at a regional level or targeted more locally. As biodiversity is a multifaceted concept, comparative analyses of different indices, focussing on different components of biodiversity change (evenness vs. abundance), give better information than a single headline index. We model changes in the spatial and temporal distribution of British breeding birds using generalized additive models applied to count data collected between 1994 and 2011. Abundance estimates, accounting for differences in detectability, are then used in community-specific (farmland and woodland) biodiversity indices. Temporal trends in biodiversity, and change points in those trends, are assessed at different spatial scales. The geometric mean of relative abundance, a headline indicator of biodiversity change, is assessed together with a goodness-of-fit evenness measure focussing separately on the rare and common species in the communities. Our analysis reveals predominantly declining trends in biodiversity indices for farmland and woodland bird communities in southern and eastern England, perhaps signalling environmental deterioration in this part of the country. Conversely, our results also show generally more positive trends in the north of Britain, consistent with north-south gradient expectations from the effects of climate change. We also reveal predominantly positive changes in evenness for the common species and negative changes in evenness for the rarer species in the communities, consistent with previously documented homogenization in bird communities. Synthesis and applications. Bird populations are seen as good indicators of ecosystem health, and trends for different communities can be indicative of wider biodiversity changes within their respective habitats. However, temporal trends in biodiversity at the national level may miss opposing trends occurring at different locations within the nation. We develop methods that allow assessment of how temporal trends vary spatially and whether these trends differ for the rare and common species in the respective communities. Our methods may be used to test hypotheses about the processes that generate the trends. Bird populations are seen as good indicators of ecosystem health, and trends for different communities can be indicative of wider biodiversity changes within their respective habitats. However, temporal trends in biodiversity at the national level may miss opposing trends occurring at different locations within the nation. We develop methods that allow assessment of how temporal trends vary spatially and whether these trends differ for the rare and common species in the respective communities. Our methods may be used to test hypotheses about the processes that generate the trends