Botany surveys can provide vast amounts of data about a site or landscape. In the most basic form, a Phase 1 survey can be undertaken which gives a broad overview of the habitat types. At the other end of the spectrum an NVC (National Vegetation Classification) survey can be carried out, which gives a highly detailed characterisation of a habitat type. Usually, however, a botanical survey that provides something between the two is most appropriate.
Botany surveys are often undertaken to determine the diversity and quality of habitats within a given area, whether for development (to assess the impacts), management reasons, or to evaluate the current ‘favourability’ of protected areas, such as Sites of Special Scientific Interest for monitoring purposes.
Botany surveys invoke images of higher plants; grasslands and woodlands brimming with wildflowers. However, bryophytes (mosses and liverworts), a hugely important aspect of our UK flora, are often overlooked. Being so diverse (there are approximately 1150 bryophyte species in the UK), they act as brilliant indicators of habitat type, habitat conservation value and any influential environmental factors.
Bryophytes are a mosses and liverworts, otherwise known as ‘lower plants’. However, they are not lower to any other plant in anything other than complexity. Bryophytes have been around for 450 million years and are the group from which all higher plants have evolved.
Image: Moss growth on the north side of a tree (Cumbria)
Lancashire and Greater Manchester contain habitats that support specialist communities of bryophytes including mossland (lowland raised bogs) and woodland. Lowland raised bogs, of which Sphagnum mosses are a key component, are present across Lancashire, Greater Manchester and Merseyside.
Given the historic loss of this habitat (much due to peat extraction) efforts are being made by the Lancashire Wildlife Trust to restore the habitats. Red Moss SSSI in Bolton is one of the best examples of this habitat in Greater Manchester and Merseyside with regard to the peat-forming vegetation and the hydrology, which has been little damaged. Astley Moss in Tyldesley, Manchester and Winmorleigh Moss in Garstang, Lancashire are also good examples.
Wet woodland (such as willow carr), low-land broad-leaved woodland (often a combination of ash and oak) and upland oakwood or ‘Atlantic woodland’ all support differing communities of bryophytes. Ethrow Country Park in Stockport is a good example of lowland broadleaved woodland, whilst Leavers Wood in Oldham, although small, is an example of upland oakwood close to home here in Rochdale.
The beautiful Healey Dell Nature Reserve in Whitworth, on the outskirts of Rochdale is designated as a Site of Special Scientific Interest (SSSI) for mosses and liverworts. There is a reason that Healey Dell supports so many bryophytes – it is an area of dense, diverse woodland that contains a deep, rocky ravine. It is the ravine that provides the microhabitat suitable for a range of species.
There are many factors that determine which bryophyte will grow where. These factors include, but are not restricted to, the substrate PH, substrate type (rock or soil), exposure, humidity and disturbance level, but generally, the more humid and sheltered it is, the more mosses and liverworts you will find – they like it wet. The species diversity of bryophytes therefore increases to the northwest of England.
Image: The Fairy Chapel, Healey Dell, Whitworth, Rochdale
Now… with this in mind, there is something special about Britain, which many people don’t know:
Britain supports 65% of Europe’s bryophyte flora, which amounts to about 5% of the world’s bryophyte flora. The bryophyte flora in our northwest Atlantic oakwoods is the richest in Europe. Indeed, Porley and Hodgetts (2005) suggest that the species richness associated with the rocky ravines and streams of our Atlantic oakwoods is comparable to that found within tropical-montane cloud forest.
How impressive is that? Are you proud to be British? I am!
Our Atlantic woodlands (or upland oakwoods), found in the west of England, cover an area of approximately 70,000ha. The most extensive and important areas are in Cumbria. These woodlands, undisturbed by anthropogenic influence and supporting rocky slopes, ravines and becks, provide ideal habitat for oceanic mosses and liverworts.
Many of the Atlantic woodlands, being so diverse, are of international importance and are designated as Special Areas of Conservation or Sites of Special Scientific Interest (SSSIs). Now, having highlighted how valuable our bryophyte communities are in Britain, I must also point out that there are many sites supporting these communities that are unprotected and are in need of conservation.
Given the specific habitat requirements of this diverse flora, all bryophyte communities may be heavily impacted by development works or by the indirect effects of wider climatic issues.
Hydroelectric power schemes are becoming more frequent in the northwest owing to the abundance of watercourses and greener energy objectives. Hydro-power systems are a sustainable source of energy, but do pose a risk to natural habitats within and adjacent to streams and also to the associated catchment area. Much like windfarms these systems provide a source of renewable energy that is somewhat controversial.
The bryophyte communities associated with the streams, given the dependence of the species on specific environmental factors such as humidity and flow disturbance, may well be at risk if spate flow is altered, or the drought conditions lengthened through installation of a weir and penstock.
Works in remote areas and even within protected areas are sometimes necessary, however, and can take place with minimal impact to the botanical communities as long as appropriate avoidance design and / or mitigation is in place.
We have recently been fortunate enough to assist with a project involving the reinstallation of a small hydro-power scheme in rocky beck situated in an area of Atlantic oakwood in Cumbria. The site was situated on the boundary of a Special Areas of Conservation (SACs) designated in part due to the quality of the bryophyte flora.
Due to the potential for bryophyte species and communities of importance, a detailed survey was necessary. This involved identification of the mosses and liverworts present along the length of the beck, with a particular focus on the depleted reach. The survey work informed the proposals to ensure there would be no significant negative impact on the bryophyte community present.
The importance of ecology surveys in relation to these schemes, or any other water-side development, cannot be under-rated. The species associated directly with the site must be considered. These include groups such as the flora, invertebrates (including white-clawed crayfish), fish and mammals, like water vole and otter.
However, as watercourses are, by nature, mobile, they influence a much wider area (including catchment sites), than the site in which the proposals are situated. This ‘zone of influence’ will differ in relation to each species group or community. It is important, therefore, that all potential impacts are taken into account and addressed early in a projects development and design process.
Don't forget, Verity Webster Ecology and Protected Species Consultancy regularly undertake botany surveys right across the northwest. So, if you would like a bryophyte survey, botanical survey, or simply more information about bryophytes, please do not hesitate to contact us on 07917 852401 or send us an email.
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