A Winterbourne – a Tale of Two Rivers
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ISSUE 94 WINTER UPSTREAM 2021 Inside this issue © Tim © Tim Johns » p5 Lambourn Drying at Maidencourt in Spring » p7 » p8 5 Autumn Railway Walk A Winterbourne 7 Discovering Moths 8 Antisocial Behaviour in Lockdown 1 – a tale of two rivers Plus lots more... West Berkshire is home to months when groundwater is highest. phenomenon was not lost on our The stark contrast between flowing ancient ancestors, with many springs some of the country’s best waters and a dry river channel, and winterbournes thought to have known and well-studied typically through the summer and a spiritual significance in pre-history. chalk streams. Rivers, such autumn months, has resulted in these In the summer, groundwater levels intermittent reaches developing their naturally recede as drier conditions as the Kennet, Lambourn own peculiar ecology that responds prevail. Consequently, springs near the and Pang, together with to the different conditions throughout head of the river, at higher elevations, the year. stop flowing, the stream becomes the Dun, Shalbourne and ponded and then dries, initiating One of the defining characteristics of Winterbourne make up ecological transformations. the lower reaches of chalk streams is the county’s contribution their steady flow of clear, cool water that The wet and dry states of the ephemeral to this globally rare is derived from the constant supply of reaches of chalk streams create a mosaic groundwater from the underlying chalk of flowing, ponded and dry habitats as habitat, supporting a rich aquifer. The aquifer acts like a sponge water either recedes or starts to flow. In array of wildlife of high soaking up rainfall that percolates turn these conditions support different biological communities, including both conservation value. into the rock. There it is held in pores and fissures as groundwater. In winter terrestrial and aquatic species that The headwaters of these streams to early spring, when groundwater “time-share” the habitats, adding to the are naturally ephemeral (flowing levels are at their maximum, water overall biodiversity of the chalk stream environment. intermittently) and are often named gushes from springs along the length ‘winterbournes’, flowing in the winter of the river supplying ‘base-flow’. This Continued on page 4 > West Berkshire Countryside Society Caring for our Countryside – Join Us and Help Make a Difference. West Berkshire Countryside Society The aim of the West Berkshire Countryside Society is to promote the understanding, appreciation and conservation of the West Berkshire countryside… furthering these objectives through practical conservation work and guided walks and talks from local experts. It was formed in 2012 by amalgamating the Friends of the Pang, Kennet & Lambourn Valleys; the Bucklebury Heathland Conservation Group; the Pang Valley Conservation Volunteers & the Barn Owl Group. Upstream is our quarterly publication designed to highlight conservation matters in West Berkshire and beyond and to publicise the activities of the Society. Chair, Webmaster & Enquiries: Tony McDonald Membership Secretary: Jathan Rayner ([email protected]) Upstream Editor: John Salmon ([email protected]) Hon President: Dick Greenaway MBE RD Initial contact for all above and for the Barn Owl Group, Bucklebury Heathland Conservation Group and West Berks Conservation Volunteers should, unless otherwise stated, be made via [email protected] Future Events As a consequence of Covid 19 restrictions, this issue of Upstream does not include any diary dates for walks, talks or tasks. If some restrictions are lifted which then enable us to arrange such events before the next issue of Upstream is distributed during March then the events will be publicised on the diary page of our website. So please check the website if there is some easing in the guidance. Society Publications The Society has a number of excellent publications available for sale. Most notably, Dick Greenaway’s latest book, ‘What’s in a Berkshire Wood? And how did it get there?’ Full details can be found on WBCS website. All publications can be obtained from [email protected] 2 © Tony McDonald © Tony Conservation Volunteers Round Up Paths & rides cleared at Grove Pit, Leckhampstead Leckhampstead Pit, at Grove & rides cleared Paths With renewed enthusiasm and pent-up allotments aims to maintain a strong ground level to produce new shoots energy, we resumed our environmental relationship between the wildlife areas or layering them to produce new trees. tasks in mid-August, when the rules and allotment holders, recognising the (Layering is when a long stem is laid on concerning voluntary and charitable differing, but aligned, needs of each. We the ground and pegged down until it services allowed us to do so – but not thinned over-hanging vegetation from roots.) We also cut down self-seeded before much time and effort had been the allotments to aid their productivity birch trees to allow in more light to the devoted to ensuring safe working. and their holders will use residue from woodland floor and protected hazel the fires to fertilise their plots. stools from deer with wire fencing. On Thorough Covid Risk assessments the second visit the larger of two teams revised many of our working practices We had two wet visits to Bucklebury continued the coppicing, the other to ensure the safety of volunteers and Common, the first one weekend to cut resuming laying a tall hedge along a any members of the public whom we down silver birch, gathering the risings field boundary nearby. might encounter. Measures included: to await later disposal. The second only undertaking tasks at sites that coincided with more rain, despite which At Redhill Wood we removed plastic were suited to social distancing, no we started a small fire and nurtured it guards placed around trees planted car sharing from different households, using standing deadwood, consuming several years ago to prevent damage by sanitising tools, no sharing of tools or practically all the birch and scots pine deer, stacking them along the path for protective equipment, no provision we had cut from a long bund. later removal. We also cut down invasive birch trees that had grown tall and were of refreshments & temporarily not At Grove Pit Common we cut back shading the planted trees and then accepting new members into activities. growth along the main right-of-way and placed them alongside the path to act its side spurs and removing a tree that A welcome new site was the Wildlife as a hedge. Allotment Gardens in Cold Ash had fallen onto the path. This will enable Our clearing rhododendron at that is a haven for wildlife and rich in the public, including horse-riders, to Grimsbury Castle enhanced a large wildlife biodiversity. We cleared and enjoy easy access. We also cleaned the fallen Scots Pine as a feature and burnt wood debris from previous bench and information boards and exposed fungus identified as either tree-felling, forming the larger logs repaired and re-erected a footpath Death Cap or Destroying Angel – both into eco-piles, and cleared brambles to signpost that had rotted at the base. as dangerous to eat as their names produce two sites in which some 100 Two visits saw us continuing hazel suggest. trees will be planted. Work around the coppicing along the eastern edge of Winterbourne Wood, work that started We resumed clearing rides at Rushall some 10 years ago. Impressive regrowth Farm to let in sunshine, thus reducing on stools coppiced in the past showed the tracks’ muddiness and encouraging that our hard work does pay off. Other wildflowers and plants to grow along stools, untouched for decades, had the verges. grown to an impressive size, proving Unfortunately, towards the end of challenging to those working on them. October, the arrival of Lockdown II On two visits to Malt House Farm brought about a new suspension of our our main task was to renovate a hazel Conservation work. Coppicing at The Malt House © Tony McDonald coppice, cutting tall stems to near Terry Crawford 3 Continued from page 1. As drier conditions prevail, terrestrial exploit this habitat. The hyporheic zone plants and invertebrates encroach upon is also home to a host of permanent the stream bed as water-loving species residents, most are worm like in shape, are lost. The plant community tends pale in colour and blind. The well shrimp to move to one dominated by more is a good example and is common in the marginal herbs and grasses, brooklime subsurface sediments of chalk stream being characteristic of this community. winterbournes. Specialist species such Similarly, terrestrial beetles, other insects as the mayfly, use an alternative strategy and spiders start to occupy the stream by laying desiccation-tolerant eggs bed, although some aquatic species which lie dormant in the dry conditions, persist, especially when the river gravels only hatching when flow returns. remain wet. Similarly, personal observation has witnessed the sudden proliferation in The number of truly aquatic invertebrate the abundance of the stonefly, following species declines with stream bed drying. Lambourn Flowing at Maidencourt in February the recommencement of flowing waters. Species that cannot tolerate the loss of © Tim Johns flow are simply lost, move downstream The ephemeral winterbourne stretches conditions as well as periods of heavy or fly away until the flow returns. Some of many chalk streams as well as other more intense rainfall. The protection and are adapted to persist in patches of intermittent rivers globally are under careful management of chalk streams pooled water where they must endure considerable pressure from human and their winterbourne stretches is higher water temperatures and reduced activities. Threats include: alterations to critical to their continued existence. oxygen levels. These pools may also be the natural flow regime through water We need to improve our knowledge colonised by other species who prefer abstractions, habitat damage, nutrient of the patterns of flow intermittence these conditions and can exploit the enrichment and the spread of invasive to understand the ecological response concentration of prey.