An arboriculturist’s reflections on the FSC Lichens: Ecology and Identification course – written by Daniel Burdus
Trees support more than structure and canopy; their bark hosts complex ecosystems that are often overlooked.
FPCR Aboriculturist, Dan Burdus, reflects on a recent Fields Studies Council course, exploring how lichens can reveal deeper insights into habitat quality and environmental change.
As arboriculturists, we’re trained to think at scale. We assess whole trees, structural form, decay pathways, and the risks posed by organisms we rarely see directly. When it comes to fungi, we often search for what isn’t there – hidden decay processes inferred from an occasional fruiting body, or from subtle external signs of dysfunction; the body language of trees.
Attending the Field Studies Council (FSC) Lichens: Ecology and Identification course was a shift in perspective. It was an opportunity to focus on fungi that are always present – living openly on bark, stone, soil, leaves, and wood.
The course ran over 2.5 intensive days and was superbly taught, with a strong emphasis on lichen biology, ecology, and morphology. Rather than treating lichens as superficial surface features, the tuition explored them as long-lived, structurally complex organisms that respond sensitively to environmental stability, substrate chemistry, and habitat continuity.
We spent time using hand lenses and microscopes to examine specimens in detail, learning to recognise growth forms and reproductive structures, and to use dichotomous keys and chemical spot tests to support identification. As we worked through the process, we built our own herbaria, reinforcing learning and creating a valuable reference resource that will continue to support future fieldwork.
Field trips played a central role throughout. Two contrasting site visits helped embed classroom learning in real-world contexts:
• A survey of mature public park trees, examining corticolous lichens associated with relatively stable, long-lived bark substrates.
• A visit to a churchyard, focusing on saxicolous species and the influence of stone type, age, moisture, and microclimate.
My own interest in lichens was sparked by concern over the fate of ash trees and the specialist lichen communities they support, some of which adapted to the loss of elm bark substrates following Dutch elm disease. Ash provides a relatively high-pH bark and light, dappled shade – conditions that are ideal for many lichens, including numerous nationally scarce and threatened species. As ash dieback continues to reshape the treescape, it raises important questions not just about the loss of trees, but about the quieter, less visible biodiversity that disappears with them. This course helped place those concerns into a much clearer ecological context; lichens add depth and continuity to the treescape.
Overall, the FSC lichen course was intellectually demanding, practical, and deeply engaging. It was a reminder that some of the most informative indicators of habitat quality are quite literally in front of us all the time – if we know how to see and interpret them.
About Dan
Dan Burdus is a Senior Arboricultural Consultant based in FPCR’s York office, where he has worked for the past three years. He contributes to a wide range of projects, including complex multi-phase and high-profile commercial developments.
Dan holds the Lantra Professional Tree Inspection certificate and is a VALID-certified tree risk-benefit validator. He is an active member of the York tree climbing team and has authored FPCR’s internal guidance on ash dieback tree climbing procedures.
Outside of work, Dan’s hobbies include woodturning, trail running, art, and military history, and – of course – trees!