Dr M is taking his University of Reading Plant Diversity MSc students on another field foray, this time not south not east but up north to West Yorkshire for a week in the peace, tranquility and botanical eXtacy that is Malham Tarn.
Malham Tarn is a glacial lake 377 metres (1,237 ft) above sea level, the highest altitude lake in England and one of just eight upland Marl (alkaline water with pH 8-8.6) lakes in Europe.
The whole area is designated for the conservation value of its geology, animals and of course plants.
The lake is located in the Malham and Arncliffe Site of Special Scientific Interest, the lake and its wetlands is designated as a National Nature Reserve and the lake listed as a Ramsar site, it is also in the Craven Limestone SAC, so all in all a pretty special area!
The lake’s basin was dammed by a moraine at the end of the last glacial period (ca 10,000 years ago). Previously about twice its current size, is has shrunk due to silting up of the western shore; this has formed a raised bog called Tarn Moss.
Following deforestation by Iron Age people, the land surrounding the lake has been used for grazing which has prevented further tree growth.
The average annual rainfall over the catchment area is 1,540 millimetres (60 inches, for comparison Reading in Berkshire receives only about half as much!).
The vegetation of Malham Tarn
The high rainfall at Malham is more than enough to maintain high water tables which result in formation of acid bog and alkaline fen vegetation of great botanical diversity.
It is these vegetation types that are the botanical magnet attracting Dr M and his students to the area and there is a high diversity of grasses, sedges, other flowering plants, bog mosses and lichens in prospect!
Here is a pdf of a paper by Elizabeth Cooper and Michael Proctor which describes the vegetation of Malham Tarn moss and fens.
The JNCC website now provides a lot of information on the UK National Vegetation Classification (NVC), this weblink is a good starting point for your investigations and you can retrieve a lot of information on different vegetation types.
A briefy history of human activity at Malham Tarn
People have been in and around Malham Tarn dating since the Mesolithic when the lake shores were used for camping during deer and cattle hunting trips by early man.
The bronze and Iron ages saw the surrounding area settled by farmers who used the land for grazing.
Following the Roman Conquest of Britain, upland areas were not thought attractive, the only Roman presence being a marching camp on Malham Moor.
The Medieval period found the lands under the ownership of the Monasteries and their use for grazing continued. Following the dissolution of the monasteries, the estates of Malham Moor changed hands several times, eventually acquired by Thomas Lister – later the first Lord Ribblesdale in the mid- to late-18th century.
Lister built a hunting lodge on the site of the old farm in the 1780s. This estate was then sold to businessman James Morrison in 1852 and following Morrison’s death the estates were inherited by his son, Walter, in 1857.
Walter Morrison died in 1921 and the estate changed hands a number times before being divided up. The house and the lake were eventually bought by Walter Morrison’s great-niece, Mrs Hutton-Croft, in 1928. In 1946 Mrs Hutton-Croft gifted the house to the National Trust who manage the property and lease the house to the Field Studies Council and it is now known as Malham Tarn Field Studies Centre.