The most in-depth survey of the British and Irish flora indicates how species’ distributions have changed since the 1950s, with the ranges of 53 per cent of all native plants and 62 per cent of ancient introductions estimated as having declined. The chief driver of these declines are the loss and conversion of semi-natural habitats caused by changes in land use.
The new Plant Atlas 2020, which is based on 30 million records collected by almost 9,000 botanists over the past 20 years, has been produced by the Botanical Society of Britain and Ireland, the UK Centre for Ecology & Hydrology (UKCEH) and the Joint Nature Conservation Committee (JNCC).
Of the 3,445 different plant species recorded, 1,692 are native to Britain and 1,753 non-native. Most of the non-native species, many of which have been deliberately or accidentally introduced into the wild by humans, are benign, though some such as New Zealand Pigmyweed and Sitka Spruce have become invasive, outcompeting native plants in some locations.
UKCEH plant ecologist Dr Oliver Pescott, who carried out analysis of trends based on the records, estimates that just over half our native plants such as heather and harebell may have declined in distribution since the 1950s, when records for the first Plant Atlas were made.
The Atlas authors say agricultural intensification has caused significant declines in native species, partly through loss and degradation of habitats and also increased grazing. In addition, nitrogen enrichment of soil through over-fertilisation and atmospheric pollution favours many non-native species which outcompete native plants.
Climate change has resulted in declines of some native plants but provided species originating from warmer countries more favourable conditions to survive and thrive.
Dr Pescott says: “We should be concerned about losses to British native plant diversity for the simple reason that it decreases the richness and variety of a countryside that has developed over thousands of years.
“Thanks to the dedication of thousands of volunteers who spend many hours every year collecting valuable data on plants, scientists are able to provide the essential evidence base to highlight that action is needed and to support conservation efforts.”
Key conclusions from the report include:
• Damp meadows have been drained, leading to substantial declines in plants such as Devil’s-bit Scabious
• Agricultural intensification has led to substantial declines in plants associated with arable crops, with an estimated 62 per cent of our ancient arable wildflowers such as Corn Marigold having declined in distribution.
• Many native mountain plants such as Alpine Lady-fern, Alpine Speedwell and Snow Pearlwort, which depend on areas where the snow lies late in the spring and summer, have declined in distribution due to climate change, but some southern species such as Bee Orchid have benefited and spread further north.
UKCEH has created a website, hosted by the Biological Records Centre (BRC), for the new atlas. BRC, based at UKCEH, supports biological recording for a wide range of species, and analyses distribution trends derived from these large-scale, long-term datasets.
This is the third plant distribution atlas. The Botanical Society of Britain and Ireland published the first in 1962, based on data collected from 1950 to 1960, and the second in 2002, based on data collected from 1987 to 1999. Production of the Plant Atlas 2020 was partly supported by the UK-SCAPE programme delivering National Capability, funded by the Natural Environment Research Council (award number NE/R016429/1).
There are digital and two-volume print versions of the atlas that show maps and graphics showing the range, phenology and time-series trends of species. The online edition has numerous interactive features.