A dendrochronologist counts her millionth tree ring, and nothing happens…or does it?
The clock ticks as I click my mouse and stare at the computer screen. A warm breeze blows through the University of Victoria Tree Ring Lab, and it’s incredibly quiet save for the constant beep of the Velmex machine and the whirring sounds of a flatbed scanner readying tree cores for analysis. It’s a hot Friday afternoon in August, and the campus is empty.
There have been many days and months like this since I set out to measure 4200 tree cores for my PhD on fire ecology. But today is a day like no other—it’s the day I will measure my millionth tree ring. And little by little, 1200 years of chronicled events recorded on western redcedar trees from British Columbia’s coastal temperate rainforest will become clearer.
Dendrochronology is the science of tree rings and tree ring sequences. With each ring showing a specific year’s growth, it’s not just the rings themselves that are special, but also the monumental life span of rainforest species and their ability to record major climate and disturbance events. In this part of the world, large rings indicate good growing years with moderate conditions; tight rings chronicle insect outbreaks, years with extreme weather or droughts associated with El Nino cycles. Fire scars, also present within the rings, show low-intensity ground fires that injured, but did not kill, the trees. The trees are sampled with an increment borer, which removes five millimetre cylindrical cores from the trees and resembles a large corkscrew.
Tree coring builds character and muscles.
The trees whose rings I’m counting grow on British Columbia’s Central Coast, an area that contains one of the largest remaining intact temperate rainforests in the world. Despite looking like untouched woodland, forests here have been managed by Indigenous Peoples since time immemorial. Western redcedar, also known as the tree of life, provided people with shelter, clothing, tools and transportation. People managed their forests like gardens through selective harvesting, fertilizing and controlled burning, and that long-term relationship is recorded like an annual calendar on trees that still live today. The ability to go back in time, and the potential of these trees to provide an understanding of the past, is constantly on my mind as I measure and record each ring.
I suspect other researchers have shared my feelings of wonder, doubt and frustration as they’ve tried to fit, match and decipher the puzzle that is dendrochronology. The scientific quest can be lonely at times, but I take comfort in the relationships I’ve established with fellow ecologists and dendrochronologists around the world who are asking similar questions and striving to understand the past. I am using tree cores to reconstruct what the coastal forests would have looked like hundreds of years ago and to understand how, why and when people used fire as a resource management tool.
The Velmex, a microscope designed to count and measure trees, beeps for the millionth time. I stop and lean back in my all-too-familiar swivel chair—after four years of studies, I’ve measured one million rings and one million years of growth. The lucky ring dates from the year 1656, embedded in the middle of a tree standing five feet tall in a bog woodland on Hecate Island. I take a moment to think of all the things I’ve learned from these trees—like the fact that big trees are often the youngest, while small trees gnarled by storms and perched on sphagnum hummocks are often the oldest, or that a tree can give you a pretty good clue as to what the weather was like in the year 1376.
An 800-year old fire-scarred western redcedar sampled on the Central Coast of BC, Canada.
I click ahead: One million and one. And then I laugh, because no one comes into the room with a bottle of champagne. Over the years, I’d heard whispers of a secret society of million ringers at dendrochronology conferences, and I’d seen blog posts questioning who really the Lord/Lady/Lordx of the Tree Rings is. I click ahead again: One million and two. Maybe the Velmex beeps do sound a little different—or maybe it’s the knowledge that in the world of dendrochronology, I’ve officially become a member of the fellowship of the rings.
Kira wrote this during her PhD at the University of Victoria in the now retired Tree Ring Lab (UVTRL). She is currently a Postdoctoral researcher at the University of British Columbia’s Tree Ring Lab and continues to sample and measure long-lived and hard to cross-date tree species. She still loves trees and all the stories they tell about the past.
Comentarios