by David Wallace Barr
What could be more iconic of northern Ontario for Toronto residents than a hardy Eastern White Pine, clinging to a rocky shoreline, buffeted by the winds, survivor of many storms? From ‘group of seven’ painters to today’s smartphone photographers, this image of the survivor of the gale has captured our imagination for over 100 years. One of the best known examples is the painting entitled simply, ‘White Pine,’ featuring a weathered and defiant individual on a rugged Ontario shore by A. J. Casson, now in the collection of the McMichael Canadian Art Collection. The Eastern White Pine is in fact, Ontario’s official provincial tree.
Even more significant to indigenous cultures, Eastern White Pine has been described as a cultural keystone species. Interviews with the Kitcisakik Algonquin community, for instance, reveal the importance of this tree in legends, as a food and as a medicine. Ground into a paste, the seeds can be added to soups. The needles make a tea that has astringent qualities, and chewing pine gum was thought to be good for sore throats.
Walking in a grove of old growth White Pine is often compared[Ontario] Parks Blog
to walking through a cathedral.
This species, an integral component of the eastern temperate forest, is a survivor in more ways than one. With a contemporary range from New York State across to west of superior, and north-eastward through to the Maritimes, its conservation status is ‘S5’ for ‘Secure.’ But the security of this tree has not always been assured. In colonial times, Canadian and American forests were pillaged for the tallest and straightest white pines, logged for their strong, straight trunks, which made ideal masts for tall ships in the age of sail, the vessels of international commerce, naval warfare and exploration for over 300 years.
A Key Community Member
The original range of the species has been demonstrated by fossil evidence to have extended as far south as Florida. Today, many eastern forests no longer contain the structural diversity offered by this outstanding species. Literally outstanding, in that it is one of the tallest of eastern tree species. They frequently tower above the level of surrounding treetops. This makes the Eastern White Pine (EWP) a super canopy species, giving it a unique ecological role. Birds, small mammals, and insects find special opportunities for shelter and feeding in these sky-seeking, coniferous crowns. Because of the elevated viewpoint and protection from predators, large, strong-flying birds, like Bald Eagles and Ospreys, choose the top of the EWP for nesting.
Black bears have a unique relationship with this tree, not so much high in the air, but instead closer to earth where white pine roots meet forest soil. One study showed that in Spring, over 90% of mother black bears chose to bed down at the base of a white pine with her cubs. And this in a woodland where white pines were rare, less than 0.5 % of the canopy. The author notes that, “Old white pines have deeply-furrowed, strong bark that make them easier for cubs to climb for safe refuge.”
As a naturalist, I delight in the fact that the EWP is probably the easiest native coniferous species to identify in our region, with its long, slim needles in bundles of five. There are a couple of other closely related pine species, usually cultivated, that also have needles in bundles of five, but according to James Eckenwalder et al in A Field Guide to Trees of Ontario, these relatives are rare in natural settings in our area.
The few white pines in Toronto are some of our tallest and largest components of the urban forest. They have not been planted along streets in central Toronto by forest managers for many years in favor of introduced species like the Black Pine, thought to be more able to survive urban conditions. But they do occur in Eric Davies’ list of Toronto’s oldest and largest trees. iNaturalist sightings show individuals sparsely scattered across our region with concentrations in Tommy Thompson Park and the Don Valley between Evergreen Brickworks and Crothers Woods. /
“There is no finer tree.”Henry David Thoreau
The Role of White Pine Pollen
Only 40 km southwest of Toronto’s ravines, perched on top of the Niagara Escarpment, lies a small, deep lake that holds more clues to the fate of white pines in eastern North America than perhaps any other site. Surrounding the lake are woodland and agricultural areas dotted with the stumps of white pines logged for commercial purposes over the past few hundred years. And at the bottom of the lake itself, lies a cryptic, and yet more complete and detailed record of the history of this tree in the immediate vicinity.
This is Crawford Lake, first revealed as a valuable research site in the 1970s and recognized today as perhaps one of the most significant ecological sites on our planet. What Royal Ontario Museum geologist/biologist John McAndrews investigated in the 1970s is that Crawford Lake is what limnologists refer to as meromictic or non-mixing. Most lakes are holomictic with layers of water that mix completely with one another at least once during the year. All lakes are subject to annual cycles of warming in summer, cooling in winter, and periodic wind action across the surface. This regime of climatic activity is what normally drives mixing of the waters.
Crawford Lake is different and special. Formed by a collapse of limestone geologic structures, it is a sinkhole that is very deep for its surface area by comparison to most lakes. As a result, even vigorous wind action is insufficient to cause the waters of the lake to mix completely. Over centuries this has meant that waters at the bottom of the lake have become increasingly salt-rich and colder. Like all lakes, however, Crawford is subject to a continual dusting of fine particles carried by the wind. These particles include pollen grains and fungal spores.
Particulate matter from the atmosphere sinks to the bottom of all lakes. In normal ones however, the mud on the bottom is regularly churned up when the lake waters mix with the seasons. At the bottom of Crawford Lake, the particles just lie there, undisturbed. In time, materials sinking from above create layer after layer of whatever particulate matter was brought by the wind through one year after another. In summer pollen and spores predominate. During the winter, when the surface ices over, the rain of particles slows down to include only matter generated within the lake waters. Each annual layer becomes a lasting record, holding evidence of the ecology of the surrounding region. White pine produces copious, air borne pollen. Many of us are familiar with the sight of a visible layer of pine pollen floating on lakes and ponds in June and washed up in yellow windrows on the shore.
The Frigid Finger
What McAndrews discovered is if you sample those historic layers of sediment at the bottom of Crawford Lake you uncover a unique history of plant life in the vicinity. Building on his background as a geologist, he developed a method of coring lake sediment that was the inverse of geological coring. To extract cores of rock layers, a tubular drill with a diamond tipped cutting edge bores through the rock to bring up a cylindrical rock sample that is extracted from the center of the tube. But the rotational action of a typical geological drill would simply disturb the layers through which it passed, and result in a churned up and indecipherable core.
To collect their precious mud samples intact, McAndrews and his assistants rowed out to the center of the lake and poured a mixture of dry ice and ethanol into a long slim tube that was sealed and pointed at the bottom. When this ‘frigid finger’ was allowed to plunge down into the sediment, the rapid freezing action of the liquid nitrogen would turn a cylindrical layer of sediment around the outside of the tube into frozen mud that could not be churned when the tube was hauled up again. The result – frozen sediment samples with sequential layers or varves that could be investigated and subsampled to provide a chronological record, many hundreds of years long. Later modifications to the technique saw sampling through the ice in winter.
Among other things this research at Crawford Lake uncovered unique chapters in the history of Ontario‘s white pine. The earliest pollen layers, those closest to the bottom of the lake, recorded the gradual recovery of a barren landscape left by the retreat of the glaciers some 15,000 years ago. By 1000 AD, white pine played a significant role in the mixed hardwood forests that appeared. During the ‘Little Ice Age’ of the period 1600-1800AD, it came to dominate the forests.
Then, only a few hundred years ago, something new and unexpected appeared in the pollen record. Corn or maize and squash pollen appeared. This evidence led to the realization that indigenous peoples had arrived to settle the area, bringing their well-developed agriculture with them. Subsequent archaeological investigation in the vicinity of the lake uncovered the remains of complex indigenous villages. Later, during the period of European colonization, white pine decreased dramatically in the pollen record as trees were felled and carried off for construction and shipbuilding activities. A sawmill on the shores of the lake was a key player in ravaging local stands of EWP.
An Intense New Interest
Today, some 50 years after this dramatic record was discovered, it has become the center of an intense interest in the history of our planet for the last 200 years. During that time, something happened of staggering significance, not only for white pines, but for the entire environment and for we humans as well. Our civilization entered a period of explosive technological development that has changed the very climate of the planet, a change mirrored by the precipitous decline of Eastern White Pine at Crawford Lake.
So great have been the disturbances over the past 100 years, our time has come to be thought of as perhaps a new subdivision of geologic history, which many have been calling the Anthropocene. Those who seek formal recognition for the Anthropocene epoch have recently chosen Crawford Lake as the best global example demonstrating the dawn of this new era in earth’s eventful past. In addition to everything else, the sediments have also recorded the advent of radioactive byproducts of atomic testing in the 1950s. Proponents argue the lake should become the ‘golden spike’ that defines the transition from one geological age to the next.
All this international attention only adds to the significance of the Eastern White Pine for every naturalist. From iconic survivor and super canopy dominator to victim of commerce, can now be added another white pine distinction… herald of a new chapter in the eons old history of our planet.
Dig deeper into this topic with selected readings:
Anon. Retrieved July 2023. The amazing journey of Ontario’s provincial tree. Ontario Parks Blog. https://www.ontarioparks.com/parksblog/white-pine/
Chung, Emily. 2023. Sediments from Ontario’s Crawford Lake picked as ‘golden spike’ showing global human impact on Earth. CBC News · Posted: Jul 11, 2023 1:00 PM EDT | Last Updated: July 12. https://www.cbc.ca/news/science/crawford-lake-anthropocene-1.6902999
Eckenwalder, James. 2019. TREE OF THE MONTH: PINES (Pinus spp.), PARTs 1-3. TFN Newsletters for Feb, Mar & April, 2019.
McCarthy, Francine MG and 28 other authors. 2023. The varved succession of Crawford Lake, Milton, Ontario, Canada as a candidate Global boundary Stratotype Section and Point for the Anthropocene series. The Anthropocene Review, PMC PubMed Central: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10226010/