Crucial Connections – Lichen on Wood Banks

Volunteers in the East Dartmoor National Nature Reserve have been taking the chance to do some real science; citizen science that is going to contribute to a better understanding of lichens across the ancient woodlands of the South West. The “Atlantic” woodlands around Dartmoor are under pressure and, in some areas, becoming isolated or disconnected from each other. But there are some remnants of ancient woodland, draped like threads across the landscape that provide a lifeline of natural habitat between these ancient woods, and these hedgerows and historic wood banks need some attention. The old boundaries, though time-worn and eroded, are an important broadleaved connection to both the past and the future of our precious woodlands, and it is here where they need a bit of help to build their resilience.

team white
Albert addresses the troops

Standing at the top of Houndtor Wood, Albert Knott of Natural England briefed the team of volunteers. “Running along the edge of this conifer plantation is an important connecting habitat of old wood banks, the hedges that were created many years ago to mark off ownership of different wood boundaries. Today, they are the last surviving links between areas of ancient woodland between Becky Falls and the woods along the River Bovey.” Introducing the lichen survey task, he said, “This Summer survey will be followed by some tree management work; targeted thinning and coppicing, then the next survey will begin in the winter.”

Additional expertise was on hand from Alison Smith of Plantlife. She added, “this project is about improving conditions for the lower plants in the valley, removing some trees will increase light that the lichen needs. Lichens will respond slowly, so the surveying will go on for at least ten years. This work should benefit the lichens for a long time – it’s something for the future.

Following their maps and locating the more mature trees, the volunteers began to collect their data. The survey started with checking their selected tree was of significant age and stature, then the examination began with a precise grid reference location. Using a hand lens, the general group of lichen species were identified before counting the number of different species with that growth form; either crustose, foliose or fruticose.

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The survey continued. Where there any mosses? How many? Any liverworts? A close inspection was required but specialist knowledge of species is not necessary for this task, just a count-up of different visual patterns or growth forms. The relative area of each species group was then recorded on a DAFOR scale, estimating whether the coverage of the plants on the trunk are Dominant, Abundant, Frequent, Occasional or Rare … or even none at all.

close inspection
Close up inspection using a hand lens

As the growth of lichen depends on the available sunlight, a canopy scope was used to record the area of space in the canopy. This is the simplest of gadgets – a transparent plastic sheet with a pattern of dots in a grid. The number of visible dots against the open spaces in the canopy gives a good estimate of the density, then, after the winter tree work has been done, there should be a greater proportion of open sky, additional light and increased lichen growth.

Lime on the old bank – a species not often seen in the woods of Dartmoor

bank vole
Lunch time visitor – a juvenile bank vole sniffing out the sandwiches [J Ritson]
This survey method covers a lot of ups and downs and clambering along the steep valley sides. Later in the day the volunteers followed the old wood bank over the hill fort on Houndtor ridge and down the valley towards Clam Bridge. An arduous descent through the oaks and ferns of an Atlantic oak wood can be challenging but knowing you are doing your bit to protect these special places leaves you with the feeling of a job well done. Today this valley is a reasonably good habitat for lichen, but it needs a helping hand to keep the shady holly in check. In a few years, the evidence should be clear, with the old wood banks providing the link between the ancient woods of the past and the wildlife havens of tomorrow.

For more info on the Building Resilience in South West Woodlands project see the Plantlife website

by Matt Parkins

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