Guest blog by Dr Richard Gregory, RSPB Centre for Conservation Science and project manager of the State of Nature 2016 report.
The State of Nature 2016 report published today (14 September 3016) is jam-packed with new facts and figures describing the status of UK species; some of the statistics will be familiar to readers, some are entirely new. At first sight, there is an lot of information, but here is a pocket guide to help you through the statistics and what it means for our wildlife.
56% of UK species have declined over recent decades
We assessed change in species status, as we did in the first State of Nature report in 2013, based upon trends in abundance and occurrence for nearly 4000 species of animals and plants. In the 2016 report we categorise species trends into classes of increase, stability or decline, and we do that overall and by major habitat types. On this basis, we show that 56% of UK species have declined between 1970 and 2013.
Figure 1 from report (page 8) The percentage of species in each trend category over the long and the short term. The line in the “little change” category shows the division between declining species on the left and increasing species on the right. The values in brackets show the number of species assessed.
While this figure captures the big picture, it doesn’t show the degree to which different species populations are changing and that might be important. So we have developed an entirely new index - a ‘Living Planet Index’ for the UK and we present it overall and by habitat. The index shows species trends through time by combining time series data based on species’ counts or occurrence into a single index and because it demands higher quality data, species sample sizes are smaller. The new ‘Living Planet Index’ based on trend information for ~2500 UK species shows a steady decline of 16% in species populations in recent decades.
Figure 2 from report (page 8). An index of species’ status based on abundance or occupancy data for 2,501 terrestrial and freshwater species. The shaded area shows the 95% confidence intervals.
Population trends of species of special conservation concern have fallen by 67% since 1970
We also present trends for those species classified as priorities for conservation action by different UK authorities using similar index methods, and disappointingly, they show a downwards trend too of 67% since 1970 – although there are many individual success stories for species including the large blue butterfly, bitterns and lesser horseshoe bats featured in the report.
Figure 3 from report (page 9). The UK Priority Species Indicator 1 shows the Abundance Index (blue) for 213 priority species, and the Occupancy Index (red) for 111 priority species (measured as the proportion of occupied sites). The shaded areas show the 95% confidence intervals.
15% of species are thought to be extinct or threatened with extinction
We have also looked at the extinction risk of species at a national level and by habitat. Here we are able to pull together results from IUCN Red List assessments for a whole range of animals and plants. We are able to do this for nearly 8000 species and taken together this shows that 15% of species are thought to be extinct or threatened with extinction in Great Britain – a truly sobering statistic.
Figure 4 from report (page 9). The percentage of species in each risk category, based on the likelihood of extinction from Great Britain. Species considered to be threatened with extinction from Great Britain are those classified as Critically Endangered, Endangered or Vulnerable in the latest International Union for Conservation of Nature (IUCN) Red List assessments.
Biodiversity Intactness Index suggests that we are among the most nature-depleted countries in the world
Finally, we present graphically and by country the ‘Biodiversity Intactness Index’, that has been developed and published recently in the journal Nature by the PREDICTS project. The new index Reveals the UK index of 81%, is well below the global average of 85%, and is 29th lowest out of 218 countries assessed It is argued that such levels of biodiversity loss might exceed ‘planetary boundaries’ - a threshold below which ecosystems may no longer reliably meet society’s needs.
Figure 46 from report (page 70). Map of modelled estimates of “biodiversity intactness” across the United Kingdom. The Biodiversity Intactness Index (BII) estimates, as a percentage, the average abundance of originally-present species. Areas shown in yellow, orange, red or brown have BII values below 90%, which indicates that biodiversity has fallen below a threshold beyond which ecosystems may no longer reliably meet society’s needs.
Agricultural management and climate change are major drivers of UK biodiversity change
The recent paper published in the journal PLOSONE reveals that many factors have resulted in changes to the UK’s wildlife over recent decades, but policy-driven agricultural change was by far the most significant driver of declines. Climate change has had a significant impact too, although its impact has been mixed, with both beneficial and detrimental effects on species. Nevertheless, we know that climate change is one of the greatest long-term threats to nature globally.
The State of Nature report 2016 is the biggest and most comprehensive assessment of UK nature to date and the statistics are overwhelming and compelling– our nature is being lost at an alarming rate and is highly threatened.
Our report is as a wake-up call for action to help nature.
To find out more
Download The State of Nature report 2016 and follow @RSPBScience on twitter #StateOfNature