National Character Area 130 Hampshire Downs
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National Character Area 130 Hampshire Downs The National Character Area (NCA) following the Hampshire Downs (130) is particularly rich in arable plants: 79 out of 121 rare and threatened plants have been recorded since 1987, giving a total Important Arable Plant Area (IAPA) score of 372. This is one of the highest scores in the country, and thus the Hampshire Downs NCA should be prioritised for conservation measures. Seventeen of the 23 Section 41 (S41) arable plants listed under the NERC Act 2006 have been recorded in the Hampshire Downs. Of these, only nine species have recent post-2000 recorded populations, and all of the plants appear to have declined in coverage. This is most apparent for pheasant’s-eye, ground- pine (which is at the western limit of its range in the UK), red hemp-nettle, annual knawel, spreading hedge-parsley and broad-fruited cornsalad. A 2013 survey of an estate near Basingstoke located a large population of annual knawel, which is only the second population to be identified since 2000 in the Hampshire Downs. In addition, a new population of shepherd’s-needle was found on the same estate in 2014, indicating that there is still plenty of potential to discover new populations of arable plants. The naturally occurring populations from the soil seed bank of cornflower have declined, but the plant is being used in many annual seed mixtures along with Austrian chamomile, corncockle and corn marigold which is boosting the number of locations with this species. Corn buttercup historically had a widespread distribution across the NCA, but no populations have been found since 2000. Further surveys of arable land may find more populations of Section 41 species, and locations with historical records should be a target along with adjacent arable land. The coincidence of S41 species indicates that the richest location is adjacent to Longparish. Access to this site has been restricted since a solar array was constructed adjacent to the field. It is not known whether the threatened arable plants survive on this site, which ought to be a priority for conservation measures. An assessment of suitable agri-environment scheme options indicates that some measures are in place on the adjacent estate which also has S41 species, but they miss some of the other rare plants such as spreading hedge-parsley. Development pressure is also a concern, and the tetrad west of Basingstoke with three S41 species is under threat from expansion of the urban area. In addition, there are concerns about the application of suitable management practices at other locations with S41 species. Further feedback to farmers and landowners is needed to ensure that the disturbance requirements for these plants are in place, as this is contrary to management for other threatened habitats, such as species-rich grassland. Land managers may not realise the extent of the disturbance required by these annual plants to ensure their life-cycle requirements are met. The IAPA mapping indicates that in the Hampshire Downs there are 21 tetrads of European Importance, 91 of National Importance, and 81 of County Importance for arable plants. The distribution of these tetrads also follows the arable land that has been targeted for survey, and may not be the complete picture of the distribution of arable plants in the Hampshire Downs. Communities of arable plants and threatened species may be present in the southeast quarter of the NCA, which has not been as well-surveyed. In addition, there are suitable agri-environment measures present on these farms, and targeted surveys of these holdings would find out whether these measures are suitably located. In summary, the IAPA tetrad map does provide a good baseline for targeting agri-environment scheme measures and voluntary conservation measures, particularly cultivated margins. However, it is not a complete picture, and it is likely that there are undiscovered populations of rare and threatened arable plants in this particularly rich NCA. There is a need for additional surveys on holdings with historical and current populations of arable plants and feedback to land managers and Natural England Advisers, where appropriate, suggesting changes in management to help sustain populations of threatened plants and potentially resurrect populations from buried seed. Holdings that have agri-environment options suitable for arable plants should be surveyed to find out whether the management is suitably targeted, particularly if the farms are entered into higher-level options. Hampshire Downs Soils For the purpose of this mapping, soil has been categorised using the broad soil category dominant in the tetrad. The mapping does not show the finer changes in soils throughout the fields, and this can misrepresent particular hotspots of very chalky soil which tend to be very locally dominant where the bedrock is close to the soil surface. The most common soils in the Hampshire Downs NCA are within the slowly permeable and clay category and is the dominate substrate for 230 tetrads. The clay overlays chalk bedrock and are often very calcareous with outcrops of chalk at the surface where the soils are thin. Calcareous chalky soils are the second most common substrate present in the Hampshire Downs. This is the dominant substrate for 195 tetrads. Sandy and shale free-draining soils are only present in one tetrad to the east of the Hampshire Downs. One tetrad in the southwest of the area is dominated by soils other than the three types above; it is deep soils along a river corridor. With regard to the IAPA score, this tetrad is treated as if it falls under the slowly permeable and clay broad category, as the surrounding tetrads are dominated by these soils. Contains Ordnance Survey data © Crown copyright and database right 2015. ± Kilometers 5 Pheasant’s-eye Adonis annua There are a cluster of recent and mid- date pheasant’s-eye records from Wherwell (SU34W) to Basingstoke (SU55V). The chalk ridge in this area is known to be a hotspot for this plant. However, most of the records are historical, suggesting that there has been a recent decline. The most recent records are from Longparish (SU44G and SU44L) and Overton (SU44Y and SU54D). Data maintained by the Contains Ordnance Vice-County Recorder and Survey data © Crown provided by the Botanical copyright and database Society of the British Isles right 2015. and Ireland and accessed ± from the BSBI Distribution Kilometers 5 Database 2015. Contains Plantlife Important Arable Plant Area database data 2015. Ground-pine Ajuga chamaepitys There are three recently recorded populations of ground-pine in the Hampshire Downs. The western site is east of Wherwell (SU34W), and there are two sites close together near Freefolk Wood (SU44W and SU54B) and Roundham (SU54C). The populations in the Hampshire Downs are the most northerly locations for this plant in the UK. Contains Ordnance Data maintained by the Survey data © Crown Vice-County Recorder and copyright and database provided by the Botanical right 2015. Society of the British Isles and Ireland and accessed ± from the BSBI Distribution Kilometers 5 Database 2015. Contains Plantlife Important Arable Plant Area database data 2015. Thorow-wax Bupleurum rotundifolium Thorow-wax is critically endangered and possibly extinct in England. The recent (2009 and 2013) records from Hinton Ampner Gardens (SU52Y) in 2009 and 2013 were a deliberate introduction. The mid- date record at Four Marks (SU63S) in 1991 was also in a garden. All of the other records are historical. Contains Ordnance Data maintained by the Survey data © Crown Vice-County Recorder and copyright and database provided by the Botanical right 2015. Society of the British Isles and Ireland and accessed ± Kilometers from the BSBI Distribution 5 Database 2015. Cornflower Centaurea cyanus The Hampshire Downs are a known hotspot for cornflower. There are many populations that naturally occur from buried seed when the land is cultivated or disturbed. However, in more recent years cornflower has been included in amenity planting. This has made it difficult to distinguish which records are naturally occurring from the soil seed bank or introduced from sown mixtures. Much effort has been placed into determining the outcome of this distinction when the records have been collated by the vice-county recorder. There is the possibility that no known origin of the seed exists, particularly if it is a newly recorded population on farmland. Contains Ordnance Data maintained by the Survey data © Crown Vice-County Recorder and copyright and database provided by the Botanical right 2015. Society of the British Isles and Ireland and accessed ± Kilometers from the BSBI Distribution 5 Database 2015. Contains Plantlife Important Arable Plant Area database data 2015. Upright Goosefoot Chenopodium urbicum There is one record of upright goosefoot recorded near Thruxton (SU24S) in 2011. Several plants were recorded of this Critically Endangered species. Contains Ordnance Data maintained by the Survey data © Crown Vice-County Recorder and copyright and database provided by the Botanical right 2015. Society of the British Isles and Ireland and accessed ± Kilometers from the BSBI Distribution 5 Database 2015. Red-tipped Cudweed Filago lutescens There is one historical record of red- tipped cudweed from Grateley (SU24Q). This is just to the west of the Hampshire Downs National Character Area. Contains Ordnance Data maintained by the Survey data © Crown Vice-County Recorder and copyright and database provided by the Botanical right 2015. Society of the British Isles and Ireland and accessed ± from the BSBI Distribution Kilometers 5 Database 2015. Contains Plantlife Important Arable Plant Area database data 2015. Broadleaved Cudweed Filago pyramidata There are historical records from 1974 of a broadleaved cudweed population south of Chilbolton (SU33Z). Contains Ordnance Data maintained by the Survey data © Crown Vice-County Recorder and copyright and database provided by the Botanical right 2015.