Near the field centre where we worked in the 1990’s there was a sandpit at the top of a ravine in the middle of many kilometres of red pine plantation. It was littered with shotgun shells and criss-crossed with ATV tracks; several old cars had been pushed over the brink and rested at the bottom of the escarpment next to the creek, half-filled with stones that had been thrown from above. A hand-painted sign labelled the spot “Devil’s Canyon.”
We had spent previous summers studying pristine ancient forest landscapes, but because this area was adjacent to Algonquin Park and formed a linkage to protected areas further north, we put in some study plots to characterize the plantation forest. One afternoon at the end of the work day, my co-worker James emerged from the brush along the old fire-road where we were picking him up. “There’s a white pine stump down there that’s over 6 feet across,” he told us excitedly. The stump had been cut many decades ago and was clearly a remnant of the forest that predated the red pine plantation. This discovery changed my perception of the area. In my mind the forest here was characterized by the fast growing aspen and stunted black spruce in bogs scattered through the plantation. The realization that ‘Devil’s Canyon’ had relatively recently been part of a magnificent old-growth white pine forest could hardly have surprised me more on an intuitive level, even though it was not at all surprising intellectually.
Later that summer we surveyed historically logged landscapes in Temagami Ontario, where logging had occurred between the 1940’s and 1990’s. Stumps of white and red pine persist for many years following logging, and we were able to get some sense of Temagami’s once extensive old-growth forests from the stumps that we found in our plots. Some were dramatic; the largest red pines we’d ever seen, alive or dead, were piled in a log dump left over from 1970’s logging at Rabbit Point. In another generation the evidence of many of Temagami’s former old-growth forests will largely be gone, but because of Temagami’s unusual history as a forest reserve, which left large areas unlogged until the 1940’s, some fragments remain in White Bear Forest, Obabika, Temagami Island,etc..
These fragments were left by chances of history or geography, and were once average, or sometimes below average, in terms of size and density of old trees. Many of the most exceptional old-growth forests were probably logged, like the huge red pines we saw at Rabbit Point. Sloan Watters, a retired veteran of the logging industry recalled that “I never thought of the White Bear Forest as being better than the other stuff at one time.” It was left by accident, because the mill owner liked the view across the bay, but now that it is protected trees up to 400 years old have been found there. Our modern perception of forests in Temagami is obviously different from that of Sloan Watters, who was present for much of the heyday of logging there.
The term “shifting baseline syndrome” was coined by marine biologist Daniel Pauly in 1995, when he wrote “essentially, this syndrome has arisen because each generation of fisheries scientists accepts as a baseline the stock size and species composition that occurred at the beginning of their careers, and uses this to evaluate changes. When the next generation starts its career, the stocks have further declined, but it is the stocks at that time that serve as a new baseline.” Studies have shown that not only resource managers, but also resource users and the general population misperceive historical conditions, thinking that whatever conditions they experience in their lifetime are ‘natural’. Interviews with Mexican fishers in 2005 found that an older generation of fishers reported declines in many fish species and fishing sites, but “despite times of plentiful large fish still being within living memory, few young fishers appreciated that large species had ever been common or nearshore sites productive. Such rapid shifts in perception of what is natural help explain why society is tolerant of the creeping loss of biodiversity.”
Scientific studies of shifting baselines are still overwhelmingly applied to fisheries, but the concept applies to all habitats. Wildlife biologist Ian Thompson contributed an essay to Ontario’s old-growth forests, in which he wrote about changing perceptions of wildlife habitat during his own career. At the start of his career the best black duck habitat in Quebec was Nun’s Island, just south of Montreal. The island, which had been farmed for years by nuns of the Congregation of Notre Dame, was sold and rapidly developed from the 1960’s onward. “Nun’s Island is now home to high-rise apartments and high-priced condominiums but not ducks,” Thompson wrote, but importantly “waterfowl managers in that province only see where the birds live and breed today and have no concept of the superior habitats that once existed, even from just as little as four decades ago.” With continuous change over time our perceptions become increasingly divorced from historical realities – for wildlife species, this allows us to continuously chip away at habitat and be largely unaware of it. “When we think of grizzly bears, we think of uninhabited mountain ranges with meadows and river valleys where humans rarely travel,” wrote Thompson. “But if we read history, we know that grizzly bears once inhabited the great plains and foothills of Canada and the United States, where the amount of prey alone (huge herds of bison along with deer and antelope) would indicate that the this habitat was far superior than the mountains to which the bears are now relegated. Humans eliminated the bears from these prime areas and so history has altered our perception of what high quality grizzly bear habitat really is.”
When we apply this to forests, we can see shifting baseline syndrome occurring on a very short time-scale in Temagami, but it’s important to realize that Temagami itself was simply the last stop in centuries of logging of old-growth pine forests, and it was probably spared for so long because of relatively thin soils and poor climate. Tallies of logs that were rafted down the Ottawa River in the early-to mid-1800’s show that the average log came from a tree that was almost 100 cm in diameter, and it was not rare to find logs that were 20 metres (65 feet) long and close to 100 cm in diameter at the small end (Lower 1938, Legett 1975). Old-growth forest was once abundant in the Ottawa valley, but the best growing conditions would have been in southern Ontario. While I was researching Ontario’s old-growth forests I found a description in the Canadian archives of a white pine that was cut from southern Ontario, a portion of which was displayed at the international exhibit of London in 1862. It was over 200 cm (7 feet) in diameter, 67 metres (20 stories) tall, and the first branch was more than 10 stories above the ground – higher than the tops of most pine trees today. The tallest white pine in Ontario today is only 47 metres tall, a little over two thirds the height of this historic tree. The 1862 pine contained enough wood to build six modern three-bedroom bungalows. Near the shores of Lake Erie the larger pines were reported to often reach 60 metres in height and over 150 cm (5 feet) in diameter (Hurlbert, 1862).
The forest sites with the best soils and climate were long ago plowed under for farming, and generally remain as farmland to this day unless they have been paved over or built on. Average sizes for many of Ontario’s hardwoods would have been 37 to 40 metres in height and 80 to 90 cm in diameter – but they commonly grew larger. We have some anecdotal evidence of how large trees could grow given the best soils and climate – for example in his 1853 autobiography, Samuel Strickland describes a tree known as the Beverly Oak, in Cambridge Ontario. “I measured it as accurately as I could about six feet from the ground, and found the diameter to be as near eleven feet as possible, the trunk rising like a majestic column, towering upwards for sixty or seventy feet before branching off its mighty head.” Strickland measured other trees, such as an oak tree on his land that was 1.6 metres in diameter at a point 7.3 metres up the trunk, or a black cherry that was over one metre diameter and 15 meters to the first branch. Southern Ontario had old-growth forests that were much closer to west coast old-growth forest than we could imagine today, and there were consequences to clearing them.
One of the most significant species to go extinct due to the alteration of the eastern forests was the passenger pigeon. Numbering an estimate three to five billion individuals, passenger pigeons were once North America’s most numerous bird, moving in flocks that literally blocked the sun and took hours to pass overhead. The common narrative is that we hunted the passenger pigeon to extinction – but while hunting certainly tipped the species over the edge, it was primarily the destruction of eastern North America’s old-growth forests that caused the extinction of the passenger pigeon, by eliminating the large mast crops of nuts that were essential for successful breeding. As their habitat dwindled, passenger pigeons populations declined and were increasingly concentrated in small areas where hunting was easier.
The passenger pigeon story is dramatic, but it is comfortably in the past. Today, however, we’ve seen severe and ongoing range declines in woodland caribou, and declines in American marten, and forest songbird populations, to name a few examples. These trouble us, but perhaps not as much as they should, because shifting baselines lull us into quiescence – for example we think of woodland caribou as being a far northern species, but caribou once ranged as far south as Algonquin Park. As the range continues to shrink, we think of caribou as something far away, not as a once-ubiquitous species being pushed ever closer to the brink. We know, thanks to the North American breeding bird survey, that songbird populations have been declining since at least the 1960’s when the survey began. Our knowledge of bird populations before the 1960’s is more limited, but the decline in songbirds is another example of an incremental decline that is hard for most people to perceive.
As habitats degrade, both perceptibly and imperceptibly, it begs the question: are we in a biodiversity crisis, and why haven’t even more species gone extinct? When we push species into increasingly marginal habitats, we may be creating a situation known as an “extinction debt” in which stressed species are very susceptible to environmental changes, introduced species, or further habitat degradation, and may go extinct at some point in the future. There is growing scientific evidence for the concept of extinction debt, and a 2013 paper examined species-area relationships and concluded that as habitat is degraded and fragmented the majority of extinctions are delayed extinctions, which may exceed imminent extinctions by orders of magnitude, and can occur with time lags of as much as thousands of years, in some cases. This impending loss of biodiversity is troubling given that already we see global extinction rates that are orders of magnitude higher than historic background levels. While we are not yet in a sixth mass extinction event, with current trends it appears that we are likely heading there.
This loss of biodiversity has costs in terms of declining ecosystem resiliency, lost ecosystem services (a direct economic cost), and impoverishment of human experience. However, one might go further and propose that species extinction is a moral wrong, or as Aldo Leopold famously posits, simply unethical. “All ethics so far evolved rest upon a single premise: that the individual is a member of a community of interdependent parts,” writes Leopold. “The land ethic simply enlarges the boundaries of the community to include soils, waters, plants, and animals, or collectively: the land.” As we wrestle with these questions and move forward, we should also keep a strong historical perspective, an awareness of our own limited perception, and a sense of humility.