A week tracking lichen recovery on the Lido Trail, late September

Monday, September 22, 6:30 a.m. When I unzipped the tent, the first thing I noticed was the pale-green foliose lichen spreading over the sugar maple trunks, still wet from the previous night's rain. No frost had come yet, so the moisture on the bark hadn't dried, and the lichen thalli were visibly swollen. This is my third year walking the same stretch, so by now the patterns are familiar.

The goal for the week was simple: document the lichen recolonization status of 40 trees along the northern section of the Lido Trail, around the Lime Kiln loop, where bark had been stripped by ice-storm damage in 2022. No specimen collection, only non-destructive observation and photographic records. My equipment: a 10× loupe, digital calipers, a waterproof notebook, and two grid frames.

Monday, Tuesday: Re-establishing the Baseline

Monday morning was spent matching GPS waypoints one by one and locating the marked trees. Some of the orange flagging tape I had tied last summer had faded to near-white. I replaced it and re-wrote the tree numbers. Three of the 40 trees were dead; one had snapped halfway up the trunk and was lying on the ground. I recorded the lichen status of the dead trees as a separate entry.

Tuesday brought rain. Under the tarp, I organized the previous day's photo files on my laptop and entered each tree's lichen coverage relative to its bark-damage area into a spreadsheet. The steady sound of rain made it easy to concentrate. I finished off a bag of trail mix before it could go soggy.

Wednesday, Thursday: Time on the Grid

On Wednesday I began the grid surveys in earnest. I placed a 5 cm × 5 cm grid frame against the bark and recorded whether each cell contained lichen, whether it was crustose or foliose, and what its colour tone was. With the frame positioned at two damaged spots per tree, a single tree generates at least 50 cells of data, sometimes over 100. It's monotonous work, but there is a quiet satisfaction in watching the data grow row by row.

One finding stood out. Sugar maple No. 12, which had been almost bare right after the 2022 damage, now had a crustose lichen bearing yellow-green soredia covering roughly 35% of the damaged surface. At the same time last year the figure was around 15%, meaning coverage had more than doubled in a single year. Meanwhile, several paper birches in the same stretch remained below 5%. The difference in recolonization speed between tree species was unmistakable.

Thursday afternoon, on my way back from the survey, I heard a pileated woodpecker drumming on a dead trunk. I stopped and watched for about 30 seconds. After the bird flew off, I walked over and found lichen growing along the edges of the holes it had carved. The same story of disturbance followed by recolonization, repeating at a different scale.

Friday: Preparing for Remote Sensing

Friday I left the field and spent the day in Ottawa. I planned flight paths for a multispectral imaging drone flight scheduled for next month and aligned coordinate systems so I could overlay the NRC forest imagery data with my grid data. The drone will extract NDVI values over a broad area, and my grid data will serve as ground-truth validation within that coverage. It's screen-based work, but without field data behind it the step would be meaningless, which is why I spent the whole week crouching in front of a grid frame.

Saturday: Final Round

Saturday morning I headed back to the trail. I finished recording the three trees I had missed, then walked the entire stretch once more to take contextual photos. Fallen leaves were beginning to pile up on the forest floor in earnest, and the air had changed noticeably. At no point during the week had the temperature exceeded 20°C.

As I took down the tent, I felt a clear sense that this season's fieldwork was essentially over. From here on I'll be spending the winter between spreadsheets and satellite imagery. Inside my laptop sit roughly 4,200 grid-cell data points collected from 37 trees (excluding the dead ones). The numbers themselves aren't dramatic, but once three years of data from the same points accumulate, trend lines begin to emerge. That is the reason I repeat this work every year.

Sunday. At home, cleaning gear and wiping the loupe lens, I found myself picturing the yellow-green surface of tree No. 12 again. When I stand in front of that tree next September, how many more cells under the grid frame will be filled in? That one question is reason enough.