Blackwater Valley – 23 August 2017

Mud and puddles greeted the 17 members who met for a walk, led by Ken and Sarah White, through the northernmost edge of the Bramshill Forest plantations and along the flood meadows of the Blackwater River. The recent rains had refreshed a lot of the vegetation such that many species were found bearing flowers.  The walk started on the south side of the river on the acid Quaternary sands & gravel, a site of former gravel extraction which ended about 25 years ago. Mature Scots Pine along the boundary have given way to new successions of pioneering plant communities which raced to fill the formerly bare ground and lake edges. Some conifer planting occurred, though much of the regrowth seems to have been from wind-blown seed. Ling, Bell Heather and Gorse dominate the ground, but in between these, patches of Dwarf Gorse Ulex minor in full flower contrasted beautifully with the mixed pinks of the heathers. The rides and pathways offered herbaceous interest in the way of Corn Mint Mentha arvensis, Brooklime Veronica beccabunga, three of the plantains including Plantago coronopus, Common Centaury Centaurium erythraea, Blue Fleabane Erigeron acris, Hare’s-foot Clover Trifolium arvense and Slender Rush Juncus tenuis. Large swathes of Common Fleabane Pulicaria dysenterica kept the yellow-flower theme going. Forestry plantings included not only 6 species of conifer but also some Black Locust Robinia pseudoacacia and Southern Beech Nothofagus sp. Various fungi were breaking through the ground but the best by far was a textbook Parasol Mushroom Macrolepiota procera. The final calcifuge was Alder Buckthorn Frangula alnus, now bearing some black fruits.

As we approached the footbridge back over the river, flowering Common Hemp-nettle Galeopsis tetrahit attracted a lot of attention, as did the Greater Celandine Chelidonium majus and a white flowering form of Selfheal Prunella vulgaris, but for the first members on the bridge a fast disappearing Kingfisher made a quiet approach worthwhile.  Orange Balsam Impatiens capensis studded the riverbank water’s edge, and surprising numbers of Banded Demoiselles Calopteryx splendens flitted up and down the gently flowing Blackwater River.  A superb Southern Hawker Aeshna cyanea was photographed not far from the river. We then passed through numerous horse-grazed meadows, and the damp London Clay soils here yielded a continuous margin of willows and Alder; other marginal plants included Gypsywort Lycopus europaeus and Himalayan Balsam Impatiens glandulifera. The clay fields to the north of the river are mixed with sands from the Tertiary capping on Farley Hill which has resulted in a rich sandy loam. The first field was a dense sward of flowering Italian Rye-grass Lolium multiflorum, previously cut for silage earlier in the season, but growing back strongly; a specimen of Dwarf Mallow Malva neglecta was growing on the footpath edge. The next three fields had very recently cut and harvested Lucerne [Alfalfa] Medicago sativa ssp. sativa which had attracted the attention of at least 11 Red Kites and an amazing flock of 60 Pied Wagtails, a mix of adults and juveniles.  The Lucerne field margin along the footpath had been missed by the cutters, and was a delight to investigate: Bugloss Anchusa arvensis in full flower alongside Field Pansy Viola arvensis and the odd Common Poppy Papaver rhoeas.  The ancient ford crossing the Blackwater – used by the Roman Road linking London to Silchester – was a daunting prospect to wade through at 2.5 feet deep, so the footbridge just a bit further on was much appreciated and provided the walk’s second Kingfisher. The group tail-enders had to make do with a fine stand of Common Club-rush Schoenoplectus lacustris, and the wailing of two young Buzzards overhead learning to fly with their parents in what had become a bright and breezy day. After the walk, most of the party stayed on for lunch at The Bull at Riseley.

Report by Ken White

Pictures by Rob Stallard

English Name Scientific Name Gridref
Plants
Marsh Cudweed Gnaphalium uliginosum
Selfheal (white form) *  Prunella vulgaris
Common Hemp-nettle Galeopsis tetrahit
Blue Fleabane  * Erigeron acer
Greater Celandine Chelidonium majus
Dwarf Mallow  * Malva neglecta SU 7528 6354
Common Stork’s-bill Erodium cicutarium
Italian Rye-grass Lolium multiflorum
Field Pansy Viola arvensis
Bugloss  * Anchusa arvensis SU 7486 6353
Lucerne [Alfalfa] Medicago sativa ssp. sativa
Common Poppy Papaver rhoeas
Orange Balsam  * Impatiens capensis
Branched Bur-reed Sparganium erectum
Himalayan Balsam Impatiens glandulifera
Gypsywort  * Lycopus europaeus
Common Centaury Centaurium erythraea
Hare’s-foot Clover Trifolium arvense
Scarlet Pimpernel Anagallis arvensis
Common Toadflax Linaria vulgaris
Alder Buckthorn   * Frangula alnus
Field Mint  * Mentha arvensis
Water Mint  * Mentha aquatica
Brooklime Veronica beccabunga
Upright Hedge-parsley Torilis japonica
Dwarf Gorse Ulex minor
Common Gorse Ulex europaeus
Southern Beech Nothofagus sp.
Scots Pine Pinus sylvestris
Black Pine Pinus nigra
Hemlock Tsuga heterophylla
Douglas Fir Pseudotsuga menziesii
Western Red Cedar Thuja plicata
Norway Spruce Picea abies
Fir sp. Abies sp.
Larch Larix decidua
Black Locust Robinia pseudoacacia
Wild Carrot Daucus carota
Bell Heather Erica cinerea
Cross-leaved Heath Erica tetralix
Ling [including a white form] Calluna vulgaris
Blackberry Rubus fruticosus
Greater Plantain Plantago major
Ribwort Plantain Plantago lanceolata
Buck’s-horn Plantain  Plantago coronopus
Common Spotted-orchid Dactylrhoriza
Club rush  * Schoenoplectus lacustris
Tufted Vetch Vicia cracca
Common Fleabane Pulicaria  dysenterica
Purple Moor-grass Molinia caerulea
Slender Rush Juncus tenuis
Fungi
Parasol Mushroom Macrolepiota procera
Invertebrates
Southern Hawker Aeshna cyanea
Brown Hawker Aeshna grandis
Banded Demoiselle Calopteryx splendens
Speckled Wood Pararge aegeria
Birds
Cormorant
Canada Goose
Mallard
Pheasant
Coot
Buzzard 4 with fledged young
Red Kite 11
Kestrel
Kingfisher 2
Great Spotted Woodpecker
Woodpigeon
Collared Dove
Stock Dove
Swallow
Starling
Bullfinch
Robin Autumn song
Pied Wagtail 60, adults and juveniles
Carrion Crow
Jay
Raven 2

List by Ken and Sarah White

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