Regularly hitting moderate levels for pollution, as monitored and recorded by the 91 Air Quality Monitoring Stations that are situated across Edinburgh and the central belt of Scotland, I knew that Salamander Road in the north-east of the city was not going to be a biodiversity hotspot for lichens.

Now my remit is to survey lichens on trees (known as epiphytes) in the vaccinity of the monitoring stations. What I hadn’t envisaged was the difficultly in actually finding any trees, or finding trees that I can get access too.

Air quality monitoring station on Salamander Road

Arriving at some of my survey sites I find only trees behind walls, fences (which may buffer the effects of pollution), or in private gardens or as at Salamader Road –  there just aren’t any trees on the same road as the monitoring station to survey!  The closest trees I can find are just around the corner – Encased but breaking out through their protective metal guards, stand four common lime (Tilia) trees.

Lime (Tilia) trees just off Salamander Road

The guards make close up inspection of the trunks awkward, but it is very quickly evident that there are no lichens to find.  What I do find however is an investation of Scale insects (limpet-like insects that feed on sap).  I also find three out of the four trees I look at on St John’s Road also have investations of these same insects.

Scale insects – live on plant sap. Heavy infestations can result in poor growth

Scale insects and eggs deposited under a covering of white waxy fibres

And interestingly at another site (Edinburgh Queensferry Road  – link to follow shortly) where liches are replaced by lots of green algae or blackened bark, I noticed lots of slug trails on all the tree trunks.

I begin to wonder if there is anything in this.  A connection between potenitally high levels of pollution and certain ‘pest’ insect species??

Part of the Edinburgh Living Landscape initiative & the TCV Natural Talent scheme