Biodiversity

Biodiversity in Three Rivers

Biodiversity encompasses all life on earth from fungi and bacteria to plants and animals, it forms a complex web of interactions between species providing everything needed for life on earth to exist.  Although complex it is also delicate, a fine balance of species.  However, human activity and, in particular climate change are taking the natural world off –balance.

Three Rivers District is approximately 89 km2 (34 square miles), underlain by several types of geology which influence the habitats that can thrive in this area. The District is a complex mix of landscapes and habitats from rural to urban areas that include woodland, grassland, wetland and farmland, among others.  Approximately 6 km2 (2 square miles) of the District is within The Chilterns Area of Outstanding Natural Beauty (AONB), comprising of a mosaic of grassland, woodland, arable land and its distinctive chalk streams.

The Council owns and manages over 240 hectares of woodland on sites from large local nature reserves to small pockets of woodland adjacent to residential areas. More information on how Trees are managed within the District (PDF).

Please read the Three Rivers Nature Recovery Strategy 2023-2028 (PDF).

Alternative Grassland Management Initiative

The Council manages its grasslands using the Alternative Grassland Management Initiative- which manages the councils grasslands for the benefit of both biodiversity and recreation.

Grasslands cover much of the British countryside and include a wide range of uses, for example: recreation, grazing livestock, producing hay or providing a refuge for wildlife. Meadows are a type of grassland with a rich variety of wild flower species where the grasses are left to grow taller. Species such as Cow Parsley, Cowslip, Oxeye Daisy and Knapweed not only fill the meadow with colour but provide plenty of opportunity for pollination creating a vital food source to the insects and birds that visit.

In the UK, biodiverse grasslands, including wildflower meadows, are under threat and have been for a while. Wildflower meadows saw a dramatic decline in the second half of the 20th century due to intensified agriculture and urban development. Following the Climate Emergency, declared by Three Rivers in 2019, the Climate Change and Sustainability Strategy was created to assist the district in achieving its targets to become net zero and grasslands may be able to help. In addition to their value to wildlife these wildflower meadows hold the ability to store 500% more carbon than fields of grass alone.

How do we manage our grasslands?

The following grassland management techniques are used throughout the district:

• Meadow Cut: this takes place twice per year, and the cut grass is collected from the first cut. This gives the opportunity for a wide array of wildflowers to bloom.
• Woodland Edge Management: is the cutting of grass, bramble and small scrub along woodland paths and edges. This habitat management takes place outside of the bird breeding season to prevent disturbance to any nesting birds, in late Autumn or Winter. It prevents scrub from expanding into open grassland, keeps woodland paths clear but does not remove the scrub habitat entirely.
• Amenity Cutting: this does keep the grass short but the grass cutting is less often than in the past and the height of the mower is raised. This enables low growing wildflowers to flourish where they would not previously have had the opportunity.
• Pasture: also known as Conservation Grazing uses livestock, normally cattle, to manage the grass without the need to use machinery. The small herd of cattle graze the grassland in Summer and Autumn and is only used on sites which are appropriate.

Council officers will monitor progress across the district  to see what naturally evolves as a result of the Grassland Management techniques outlined above and let nature guide the way forward.

Biodiversity opportunities audit

Each year the council plants trees for a variety of reasons for example: as part of the biodiversity opportunities audit; as memorial trees; to replace trees that were lost due to storms or disease and more. The majority of these will be standard trees; however, this does sometimes include woodland trees.

The council approved and published the Three Rivers Nature Recovery in Spring 2023. The Strategy specifically addresses the council’s approach to protection of the natural world within the District recognising the rich diversity of wildlife already present within the district; both within protected nature reserves as well as public open space, residential gardens, grass verges, and more.

The biodiversity opportunities audit can be downloaded here (PDF).

How to get involved with nature

Many of the Council’s greenspaces are support by the excellent work of Friends groups who help to maintain the site for both biodiversity and recreation. These groups are always welcoming new volunteers who would like to contribute to the natural world on their doorstep.

• Friends of Leavesden Country Park - friendsofleavesden@gmail.com
• Friends of Chorleywood House Estate - www.chorleywoodhouse.org.uk
• Friends of the Withy Beds - leisure@threerivers.gov.uk
• Friends of Carpenters Wood - www.carpenterswood.com
• Friends of Croxley Common Moor - www.croxleycommonmoor.org.uk
• Oxhey Wood Conservation Volunteers - www.e-voice.org.uk/oxheywoodsconservationvolunteers
• Friends of Chorleywood Community  Orchard - www.chorleywoodorchard.org.uk

Hertfordshire County Council's Countryside Management Service
Hertfordshire County Council’s Countryside Management Service runs a weekly Practical Conservation Volunteer group that operate throughout the County.  For more information visit their website.

River Rangers
Sign up to become a River Ranger and get involved with a range of volunteer work including contributing to surveys to help understand the condition of the river, water quality and creatures who call the river home. For more information and to sign up, please visit: https://www.colnevalleypark.org.uk/job/colne-valley-river-rangers/ or email: Rivers.Team@groundwork.org.uk.

Chalk streams

Chalk streams are a rare and attractive characteristic of our local environment. There are three chalk streams in the area that give rise to the name of the district – Three Rivers:

• The River Gade rises from a spring in the Chiltern Hills in Buckinghamshire and flows into Three Rivers after passing through Cassiobury Park in Watford
• The River Chess rises near Chesham and flows for 11 miles to its confluence with the Colne in Rickmansworth
• The River Colne which has its source near North Mymms is fed by numerous chalk rivers, including the Gade, Chess, Ver and Misbourne, finally discharging at its confluence with the Thames at Staines

These chalk streams are important habitats for plants and wildlife, including aquatic plants, mayflies, otters, kingfishers and water voles.

Sadly, the rare and precious habitats created by chalk streams are under threat from water pollution, over-abstraction – where too much water is taken from aquifers – and global warming. Household water use has increased by 75% since 1985, and abstraction rates have soared across the country. This is especially true in Three Rivers, where we consume 10 litres more water per person each day than the national average.

Global warming is triggering more heatwaves, which dry out the streams. At present, less than a fifth of all of England’s rivers are in healthy condition, including our precious chalk streams. In the 2019 drought, 67% of the chalk streams in the Chilterns dried out. This harms the vulnerable wildlife that depends on these habitats for their survival.

Affinity Water manage clean water in Three Rivers District and work to protect the three chalk streams in the district. Affinity Water voluntarily stopped abstracting water from two boreholes on the River Chess with support from the Chiltern Chalk Stream Project and have committed to ending environmentally unstainable abstraction from these precious water catchments.

Thames Water will stop abstraction from another borehole in the upper reaches of the Chess in 2024. This will increase flow and improve the health of the river.

Save our Streams campaign

More needs to be done to protect the chalk streams in Three Rivers District, and all of us can help. The Affinity Water Save our Streams campaign provides information on how to save 10 litres of water a day. Join the water-saving community to receive free water-saving devices for your home and save money on your water bills while helping preserve the habitats of wildlife living in our chalk streams.

Japanese knotweed

Japanese knotweed is an invasive plant species that can cause ecological harm and damage to housing.

We will take action to control the spread and safely dispose of Japanese knotweed growing on council-owned land.

If you are concerned about Japanese knotweed, you can report it online. We will identify the landowner and advise them of their responsibilities.

If you have Japanese knotweed growing on land you own, it is your responsibility to stop it from spreading outside your land. If you do not control its spread beyond your property, you may face enforcement action.

You can find out further information on Japanese knotweed from the Environment Agency.

Three Rivers Biodiversity Policy

The Environment Act, 2021, introduced a strengthened biodiversity duty for Local Authorities; an amendment to the original section 40 duty of the Natural Environment and Rural Communities (NERC) Act, 2006. The aim of this duty is to not only conserve biodiversity, but to improve, enhance and expand it.

By 1 January 2024, public bodies, including local authorities, must make their first consideration of what could be done for the benefit of biodiversity. At Three Rivers District Council, this first consideration has included a review of existing strategies and policies which aim to benefit biodiversity and identifying further opportunities for investigation.

Three Rivers District Council’s First Consideration for Biodiversity Duty:

In line with the strengthened biodiversity duty introduced by the Environment Act 2021, the council has completed a review of the actions it has and can take to conserve and enhance biodiversity. A list of policies and objectives arising from this review will be published in due course, following formal agreement. The council will periodically publish a report detailing progress on the actions identified. The first report is scheduled for publication in 2026.

In July 2024, at Full Council, the Three Rivers Biodiversity Policy was unanimously adopted. The policy seeks to bring together and align all council and local documents that protect, enhance, and improve biodiversity in the district.

Welcoming wildlife to your garden or window box

With thanks to Kate Watkins.

Native planting

Planting native wildflowers in your garden or window box is a simple way to attract pollinators like butterflies and bees. Attractive plants for pollinators include English bluebell, lavender, common mallow, lesser knapweed, common vetch, and many more.  As wildflowers also attract other insects in turn this provides a food source for bats and birds. Avoid using pesticides in your garden as they attack the bee’s nervous system, causing them to struggle to find their way back to their hive, or not make it at all.

Helping hedgehogs

Hedgehog numbers in the UK are declining, and they need our help. The main reasons for their decline include habitat destruction, increased road traffic, and pesticide/slug pellet use which can poison the hedgehogs. Instead of this, use crushed eggshells or coffee grounds as a natural slug repellent. One way to support hedgehogs is to create hedgehog highways, which allow them to easily travel through your garden. You can make one by cutting a 13x13cm hole in the bottom of your fence, or by digging a small channel to let them pass underneath.

Bee hotels

A fun and effective way to support bees and other insects in your garden is to make a bee hotel. Bee hotels provide soliitary bees with a convenient and safe place to live, and can be very simple to build. You can also purchase pre-built bee hotels in a variety of shapes and sizes. Bees can also benefit from a shallow dish of water in the garden, with a safe place to land without risk of drowning, such as stones placed above the waterline.

Rickmansworth Aquadrome Student Data Hub

This student data hub provides access to a collection of ecological survey data collected at Rickmansworth Aquadrome throughout 2024.

Surveys included:

• Invertebrates
• eDNA vertebrates
• eDNA mammal
• Otter
• Water Vole
• Bats
• Habitat Condition

Three Rivers District Council is inviting students, researchers or educators who are working on a school project, dissertation or ecological research to use this data. It provides an invaluable resource for understanding local biodiversity, habitat trends and conservation management.

From detailed species inventories to habitat condition assessments, there is a range of data to use to understand Three River’s biodiversity. Explore the data, analyse the trends and contribute to the growing knowledge of the Aquadrome.

Please remember to reference ‘Three Rivers District Council, Leisure Services’ and send any work completed to leisure@threerivers.gov.uk

Please follow the link below to view a comprehensive summary of the surveys, as well as PDFs of the surveys themselves.