Hertfordshire has lost more than 70 per cent of its neutral, unimproved grasslands in the past half century, HNHS members were told in an online presentation on Saturday 28 November following the AGM.
Presenting on the Hertfordshire's State of Nature report, published earlier this year, Tom Day and Ian Carle of the Herts and Middlesex Wildlife Trust (HMWT) highlighted a decline in grass and healthland habitats. They cited Green Tiger Beetle, Eared Willow and Basil Thyme as examples of species that have become rare in the county as a consequence. Conversion to other land use and poor management – resulting in increasing encroachment by scrub – were among the chief causes.
Woodland, by contrast, had increased in area since the 1970s. It now accounted for over 60 per cent of 'semi natural' habitat and 10 per cent of total land cover in the county. Even so, woodland species such as Marsh Tit and Hazel Dormouse were in serious decline, while the Pearl-bordered Fritillary butterfly was no longer seen. More sympathetic management to support greater biodiversity was a priority for the future.
The HMWT's analysis was based on 2.8 million wildlife records, a majority of which had been obtained through the Society. They related to 10,863 different species, of which 1,524 were considered to be of conservation concern. In total, 76 former breeding species were identified that had become extinct – a rate of three species being lost to the county every two years. They included Nightingale, White-clawed Crayfish and Burnt Orchid.
More detailed records available for 563 species had made it possible to assess their populations over time, suggesting that 49 per cent were in decline, 39 per cent were stable and 12 per cent had increased.
The report identified chalk streams as a habitat that Hertfordshire has a special responsibility to protect in the UK context, as well as 25 species whose populations in the county are nationally significant. These include southern England's only breeding Black-necked Grebes, the emblematic Pasque Flower (pictured: © Huw Lewis) and the only colony of Down Shield-bug found in Eastern England.
Speaking to an online audience of 60, Tom Day referred to a theoretical 30 per cent habitat cover needed to achieve good species 'connectivity' and a functioning ecosystem. Achieving this in Herts would require a near doubling of the current area of semi-natural habitat. He argued that making councillors and other local leaders aware of the extend of the challenge would be an important part of the task ahead.