Stricken sycamore reveals its secret

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The sycamore tree next to the Meeting House that came down in the latest round of storms was hiding a rare species of lichen in its canopy, an ecologist in BIOLS has discovered.

It was only when the tree's canopy came crashing to the ground during high winds that the rare lichen became visible.

In England, the lichen known as Physcia leptalea is usually restricted to the south-west. "Before this, it's only been seen in Sussex three times," said David Streeter.

Lichens are fungi that live in a symbiotic association with an alga, often on trees. The branches of the stricken tree - which David will now use for teaching - provided the habitat for at least a further seven species of lichen in addition to the Physcia.

The tree's demise will also enable David to estimate its age, by counting the number of rings on a section from the base of the trunk. The parts that he was not able to make use of have been removed and shredded by staff from Ecovert, the company that is now responsible for grounds maintenance on campus.

Certain information about the sycamore had recently been recorded as part of an evaluation of the condition of all 1,500 mature trees on the University campus, which involved tagging each one with a numbered metal disc.

Arboriculturists from a firm based in Southerham, near Lewes, estimated the height of tree number 332 at 17m. They recorded that its trunk was in a poor condition, with a heavy lean to the east, and recommended that the plant be reduced and reshaped.

The Estates and Facilities Management Division had commissioned the survey to assess the health and safety of the trees in and around campus. The arboriculturists made numerous site visits between May and August this year and identified 72 species, of which sycamore (Acer pseudoplatanus) was the most common.

The catalogue that has been compiled can also be used for educational and research purposes and to provide a framework for future management goals.

"The topographical layout and location of the campus and the varying soil types across it make it an ideal site for tree growth," the draft report concludes. "Relatively the number of trees in poor condition throughout the campus is very low." Specimen 332 was one of those few - and now only its stump remains.