Steve Tonkin, Dark Sky Advisor to the Cranborne Chase AONB, will be talking to us at our next meeting, at 7:30pm in the Victoria Hall, High Street, Tisbury on Thursday 12 Oct 2023 about Why dark skies matter: the importance to wildlife of responsible lighting. Steve has a life-long passion for astronomy which, of course, has made him aware of the effects of light pollution, and he has been raising the issue with anyone who will listen for the last 30 years. After a first career as a telecommunications engineer, he took a degree in Environmental Studies, did postgraduate work in technology policy, and went on to teach physics, maths and astronomy before retiring to concentrate on astronomy and outreach activities.
Steve supported the Cranborne Chase bid to become a designated International Dark Sky Reserve and his primary task now, as the AONB’s Dark Skies Advisor, is to continue and consolidate the good work that has already been done, and strengthen the AONB Reserve’s standing. The bar opens at 7pm. There's no need to book. Members and those under 21 have free entry. Guests £2 on the door or please contact us for our BACs information as we do prefer online payments. Dave Rumble, CEO of Wessex Rivers Trust (WRT) spoke to one of our largest audiences in recent memory when 56 people came along to the first meeting of the new season to hear about water quality in the River Nadder, why it matters, and what can be done about it.
He explained that the Wessex Rivers Trust works with landowners and others to conserve rivers in a wide area covering the catchments of the Dorset Stour, the Hampshire Avon, the Test and the Itchen, as well as rivers in the New Forest, East Hampshire and the Isle of Wight. These include most of the chalk streams that are one of the UK’s most distinctive ecological habitats and make up 85% of all the chalk streams on the planet. Of these, The Avon, with its tributary the Nadder, is arguably the most important of them all. What makes chalk streams distinctive are that their source, the underlying chalk aquifer, favours a range of plants, such as the distinctive ranunculus (water crowfoot), the range of invertebrate species such as river flies that feed on these plants and the fish that live there. Dave described the way different invertebrates fulfil different roles, complimenting one another in living off the plant life and help keep the river clean, and made the point that their presence, or absence, are good indicators of a river’s health. And he drew particular attention to the presence in the Avon catchment – in addition to the grayling and trout that chalk streams are commonly known for – of a genetically distinct salmon sub-species that returns from the ocean to spawn here. It is this unique salmon and its vulnerability that makes conserving the Avon, and the Nadder, so particularly important from an ecological perspective. Together these are the reasons why the Nadder and the Avon catchment are considered a Special Area of Conservation. He described the ‘Trinity of Health’, or ‘three-legged stool’, that a healthy chalk stream and its ecology depend on, as Sufficient Flow or volume of water, Sufficiently Clean, and a Natural Habitat, and he went on to discuss the threats to each of these. The first point he made is that legacy issues take a long time to become apparent; because it may take years or decades for rainwater to percolate through the chalk aquifer, problems may only become apparent long after they were caused. He characterised the principle sources and causes of issues as; pressure from increasing population, climate change, agricultural practices, highways, the underinvestment in sewage treatment infrastructure, and septic tanks. Before talking about each of these and what can be done about them, he described the quality of water in the Nadder along its length. The Environment Agency analysis (using methodology that dates back to the relevant EU regulation) shows the Headwaters of the Nadder - above Wardour Lake - are Poor in quality. The Upper Nadder, from Wardour down to Tisbury, together with the River Sem, is Moderate, as is the stretch from Tisbury to Wilton. From Lower Wilton to Salisbury the river’s quality improves to Good. Dave explained that the presence of Phosphates probably arising from septic tanks and agricultural practices, are the most likely largest contributors to the Poor rating in the Headwaters and the Moderate rating in the Upper and Middle stretches. But in addition to the these there are signs of mercury and PBDE (a family of man-made flame retardant compounds used in a wide range of applications) that may come from highways or industrial sources and that are persistent pollutants. Quality improves further down the river, partly at least, as a result of settlement further upstream, and as the river flow increases. He drew attention to the fact that even treated effluent can cause serious pollution harm, in particular due to the emerging problem that pharmaceutical residues that are toxic to wildlife are not removed during treatment. In this context he also drew attention to the harm that can be caused to invertebrates by traces of insecticides used to treat dogs for fleas, and appealed to dog-owners to be alert to this and not let their pets swim in the river for several days following treatment. Turning to the issue of effluent treatment, Dave homed in on the issue of storm water overflows of raw sewage into the Nadder at Tisbury, Fovant and Barford St Martin, drawing attention to recently reported data showing that between them the three largest water companies, Thames, Southern and Wessex had spilled raw sewage during dry weather for 3,572 hours in 2022, a problem that will take huge investment to rectify. He went on to discuss the issue of broken or poorly functioning septic tanks, a problem that is largely hidden and that the government has attempted to address with new regulations introduced in 2020 requiring an upgrade, with installation of what is effectively a mini-effluent treatment plant, if you want to sell a house with a septic tank. And he explained the significance of the overturning a day previously in the House of Lords of Government plans to remove a requirement to safeguard river health by ensuring the nutrient neutrality of new developments. Dave gave examples of Wessex River Trust’s work to address some of the other problems he had mentioned, including changes to drainage to reduce the build-up of silt incorporating tyre residues and other pollutants resulting from run-off from roads. And he showed pictures of work to revive the river Test by reintroducing meanders, and the major project currently underway at Amesbury to revive the Avon’s ecology by reintroducing meanders that had been removed when the river was canalised to permit building of the roundabout at the junction of the A303 with the A345. And, in comments on the need to reduce fresh water consumption so as to preserve the flow of these valuable natural river systems, Dave emphasised the Trust’s work in education and engagement, involving children in exploring the diverse natural world of chalk streams and explaining to them how important this is. In a closing summary he stressed that a healthy chalk stream is self-cleaning and suggested anyone interested in pursuing the topic further should read a ‘Guide To River Restoration Techniques’ (on the Wessex Rivers Trust website) and ‘Rivers’ a book describing the natural and man-made changes that have affected British rivers since the last ice written by two river ecologists, Nigel Holmes and Paul Raven. In response to a question from the audience, Dave remarked that usually the best way to manage a risk of flooding was not to carry out dredging, but to increase the river’s capacity by restoring natural meanders and the flood plain, so as to hold back the flow, and mentioned that DEFRA are about to launch a £35million scheme to support flood management schemes. In response to a question about the impact of watercress, Dave said that, as with other forms of horticulture and agriculture, watercress growers using excess fertilizer could lead to nitrogen and phosphate run-off that would pollute the river. And in response to a question regarding water meadows, like the ones at Harnham above Salisbury Cathedral, he said these are amongst the most abundant wildlife habitats, although entirely artificial, having been created by farmers in the Middle Ages to provide early grazing for sheep. Dick Budden We look forward to seeing you on Thursday 14 September at the Victoria Hall, Tisbury High Street. Doors open at 7:00pm for the bar and the talk starts at 7:30pm. Dave Rumble, CEO of Wessex Rivers Trust will give our first talk of the Autumn/Winter series on "Water quality and Biodiversity of the River Nadder and the Avon Basin". The Wessex Rivers Trust is dedicated to the conservation of chalk streams and rivers throughout the region, looking for ways to improve them and work with partners to make them healthy for both wildlife and people. Dave Rumble has had a love of rivers since his boyhood in Hampshire; before joining the Wessex Rivers Trust three years ago, he had sixteen years’ experience in leading roles with the Hampshire & Isle of Wight Wildlife Trust. In this talk he aims to cover the things that make the Nadder and the Avon catchment special, the threats they face from pollution, and what we should be doing about them.
No need to book. Members and those under 21 have free entry. Guests £2 on the door or please contact us for our BACs information as we do prefer online payments. We have made a few minor changes to the programme from September onwards, so please take note of the updated document on the Field Trips and Talks pages.
On 20th April we had our final evening talk given by Simon Martyn with photos provided by his wife Mandy.
Simon was the European Director of Earthwatch, an International NGO which started out in Boston, USA over 50 years ago but is now worldwide with offices in Australia, UK, India and Japan. Earthwatch sets up projects both for Wildlife and Archaeology with scientists running the projects, helped by a workforce of volunteers. They carry out research and provide essential statistics to establish conservation schemes for threatened species or habitats as they work alongside local people. The talk was ‘Glimpses of Wildlife Behaviour’ and was divided into sections. Firstly, we were shown various habitats and their wildlife such as the much depleted herds of bison in Yellowstone Park, the plains of Africa with the wildebeests and various antelopes, plus the harsh, freezing environment of the Arctic. Secondly, the emphasis was on territory and, especially during the breeding season. Male lions guarding their prides and fighting off the opposition were illustrated. We saw how Roe and Red deer will also become very aggressive fighting off other bucks and male tigers will kill another male tiger’s cubs in order to mate with the female and pass on his genes. We saw a grisly photo of this. (NB. Badgers also do this, as I can witness). The effects of climate change were visible in the photos of droughts in Africa, drying up the rivers and water holes, causing many animals to die and causing mayhem at the water points with competing animals. Thirdly, Simon showed us photos of how many species co-operate with others for the benefit of both. For instance, egrets and finches will hitch rides on buffaloes to eat the ticks and crocodiles will stir up the water and expose the fish for the storks on their backs. In India the Langhur monkeys work as lookouts for the Spotted deer when a tiger is about, shrieking in terror. Finally, we were treated to humorous photos of various animals and birds in compromising and amusing positions including a harassed mother Brown bear trying to control her three naughty cubs. One was up a tree, another near the river and the third heading up the mountain. It was an entertaining and illuminating evening with superb photography and a nice change from all things local. by Debbie Carter At the last of our indoor events this year, we shall hear from Simon Martyn, a former Europe Director of Earthwatch, that, for anyone unfamiliar with it, is the international NGO founded over 50 years ago to connect people with scientists worldwide, conduct environmental research and empower them with the knowledge they need to help conserve the planet. In this talk, Simon will share with us, along with pictures taken by his wife, Mandy, some “Glimpses of Wildlife Behaviour” in many different species, gathered from their own travels across many different countries, over many years of living, working and conservation-related travel. The Victoria Hall, High Street, Tisbury and its bar, will be open as usual from 7:00 p.m (cash & card payments). Members and those under 21 have free entry and we welcome any visitors to join us and pay a guest fee of £2. Please contact us if you'd like a visitor ticket. Juniper scrub prospers well on rocky screes, exposed to the light, away from heavy grazing activity. Matt Pitts, Meadows Adviser at the Salisbury-based environmental charity Plantlife, showed us striking photographs of sites in Cumbria and the Caledonian forest where juniper growth has persisted since the last Ice Age. Closer to home we heard about Plantlife’s project in the Wylye Valley and the Chilterns where they are regenerating juniper on chalkland downs. Not only will this conserve the habitats for the 50 species of insects and 40 of fungi which solely rely on juniper, but it will also contribute to the biodiversity of species on these sites.
Historical records of land usage show that juniper started to disappear when the downlands were fenced and the shift in grazing patterns caused an impact, with some land also being lost to arable, particularly after the Napoleonic War and World War II. Despite this, Juniper went through a mini regeneration during the myxomatosis period 1960-80 as it no longer had the threat of thousands of rabbits nibbling its young shoots. We learned a striking fact that the berries have a low fertility with only 1-5% viability, so gathering viable seed is difficult. The Juniper project team is aided by the Millenium Seedbank which stores seed and checks on viability. Plantlife mainly use two methods of cultivation: they grow from seed and store young plants in a nursery for several years until they are strong enough for planting out and they also scatter seed on prepared scrapes of chalkland. Locally they have extensive scrapes on the Fonthill Estate in the Wylye Valley where they are trialling juniper regeneration. Patience is definitely required because juniper takes a long time to establish. We saw photographs of a scraped chalk fenced area over a ten year period and only by year 3 were tiny shoots in evidence. By year 10 there were 688 clumps of juniper growing well, with a multitude of chalkland orchids, kidney vetch and other flowers naturally seeded. Matt advised against buying juniper from nurseries because firstly, it might not be a native plant and secondly it could be infected with phytophthora austrocedi, a pathogen which kills our native juniper trees. This fungus-like pathogen is difficult to detect without proper laboratory investigation and it is likely to be carried in the compost, so to preserve the strength and integrity of our native juniper we better leave the juniper regeneration to the specialists. More information about Plantlife’s juniper project is available on their website. You can now find the full listing of our Talks and Field Trips for March 2023 to April 2024 on the relevant pages of this website or as a pdf to print out. Members will receive email newsletters with more details closer to each event and Blog posts will follow as reminders. We look forward to your company!
Don't forget to sign up to the notifications for our website news by popping your email address into the subscribe box on the Blog page. This box is visible towards the bottom of your screen when viewing the Blog page on a mobile. Talk on Thurs 16th March at 7:30pm: Revitalising Wiltshire's populations of Lowland Juniper11/3/2023
Matt Pitts, Meadows Adviser at the Salisbury-based environmental charity Plantlife, is coming to give us a talk on his project to reinvigorate juniper’s growth after its significant decline and protect the wildlife that depend on its presence.
Over the past 60-70 years there has been an 80% loss in the area of chalk grassland in Southern Britain. Fragmentation of the habitat and a reduction in extensive grazing has resulted in a loss of plant species and of biodiversity more widely. Juniper is a specific example that faces extinction in southern Britain. Across our downlands, this iconic shrub has failed to regenerate for the past sixty years. As bushes reach the end of their lives, whole colonies are dying out; it has been lost from nearly 50% of its historic range. If this trend continues, over 100 specialist invertebrates and fungi that depend on the juniper to survive will disappear too. But although juniper is the focus for Matt’s project, the work is benefiting chalk grassland conservation overall. Since 2009, Plantlife has been trialling in-situ techniques to regenerate juniper from seed. 10 out of 14 trial sites now boast healthy populations both of young juniper bushes and populations of other wildflowers and plants. Focusing on the themes of nature conservation and connecting people with nature, Plantlife are now working to reinstate lost juniper landscapes on a larger scale, initially in the Wylye Valley and on the Berkshire Downs. The Victoria Hall, High Street, Tisbury and its bar, will be open as usual from 7:00 p.m (cash & card payments). Members and those under 21 have free entry and we welcome any visitors to join us and pay a guest fee of £2. Please bring cash for guest tickets! Sarah Barnsley, of the People’s Trust for Endangered Species, (PTES) presented a talk on 16th February entitled ‘Why Hedgerows matter’.
Sarah talked about some of the wildlife that lives in hedges, illustrated with beautiful slides, and how it is beneficial for them to cut hedges as late in the winter as soil conditions allow, to preserve the fruits as long as possible. She followed on to describe different hedgerow structures which result from different management practices, and how ideally the hedge will have a blended edge of scrub leading further out to long grass. Hedges can be assessed as to how healthy they are, in terms of how many woody species there are making it up, how well connected it is with others or woodland, its width, and how well it’s been managed. Sarah pointed us to the Great British Hedgerow Survey on the PTES website, which scores the overall health of an individual hedge, and provides management advice accordingly. She explained how under-managed hedges can eventually go through the process of succession to eventually turn into a row of trees, whereas an over-managed hedge, cut hard every year to the same height and width will become gappy and open, eventually disappearing. Sarah then described a hedgerow management cycle, which when done properly, rejuvenates the hedge so it keeps its structure and species diversity. This involves the hedge being cut every three years approx. 10 cm longer, along the top and sides, than the last cut. The hedge therefore continues to expand for some years (Sarah suggested between 10 and 40) before being laid or coppiced. Laying involves thinning out and cutting the individual trees near the base and bending them over. Sarah showed us several slides illustrating different styles of this ancient craft before revealing that the most favoured one in her view is ‘conservation’ hedge laying where very little of the hedge is thinned, so it is all laid to form a wide dense well-structured hedge. After the very well presented talk full of fascinating facts and advice Sarah took questions from the large audience (52 in the hall and 11 on-line). Hedges are well loved by the community and some of the questions reflected the concern about the over management of many of our hedges. Sarah fielded them well and the audience, which included at least 6 landowners who went away with plenty of food for thought. by Peter Shallcross |
Photo: Avocets (Izzy Fry)
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