Journeys in ancient and old growth forests

Category Archives: Black Gum

Ontario’s Black Gums

Some of North America’s oldest hardwood trees persist in obscurity, and in peril. Nate Torenvliet describes finding a 580-year-old black gum tree in the Niagara region of Ontario.

A middle-aged black gum tree. Photo: Mike Henry

I first became acquainted with black gums on an outing to Grassie, Ontario with a local tree group, and it was a meeting I would not forget. Black gum, a member of the Tupelo family is one of those trees that doesn’t disappoint at any time of the year. Its Latin epithet, Nyssa sylvatica refers roughly to a Greek nymph of the watery woodland; a pretty name that black gum lives up to, as it is commonly found in wet woodlands, often on the very edge of standing water. The characteristic horizontal branching of young trees often becomes irregular and flat-topped in old trees, creating its unmistakable presence in the forest. Its thick glossy green leaves glisten and shimmer in the summer sunlight, and by autumn turn intense shades of red, scarlet, and purple. But the bark of this tree really sets it apart. Dark grey-brown and blocky in younger trees, becoming deeply fissured and ridged in middle-aged trees, and then balding into light-grey smooth plates in old age. Average sized trees top 15 meters in height and 40 cm in diameter.

My fascination with old trees stems from my innate love of trees, which began before I can remember, but also can be traced to the moment I first heard about the incredible ring counts from some of the ancient cedars on Ontario’s Niagara Escarpment. With those discoveries by Peter Kelly and Doug Larson it became clear to me that Ontario could grow superlative trees that far exceeded everyone’s expectations. More recently, when I learned of the ability for black gums to attain great ages, I revisited the Grassie black gum swamp and spent the time to carefully collect a few core samples to see if they might tell something of their age.

The rings of black gum at 40x magnification.

I knew Nyssa has what’s called ‘diffuse-porous’ wood, but that it has some of the faintest growth rings among North American tree species was new to me. Many trees, like oaks are ‘ring-porous’ which means that the larger vessels are grown first in the spring while the rest of the growth throughout the growing season is made of much smaller vessels and much higher wood content. This makes for easily distinguishable rings. In diffuse-porous woods, like black gum, the vessels are grown throughout the growing season instead of being collected in a clearly visible band. However, after mounting and sanding to a fine polish the rings begin to present themselves, but only under forty-or-so times magnification can a reliable ring count be made. To be certain, I treated the cores with a phloroglucinol dye treatment which in the presence of alcohol and HCl acid stains the lignin red to help further clarify the ring boundaries.

At nearly 50 cm in diameter, my best subject produced a core with over three hundred annual rings still intact. Densely stacked rings grown around 80 years ago revealed that this tree underwent serious stress that caused growth to all but stop for over a decade. With a germination date around 1690, I was excited to find that the oldest black gums in the Grassie swamp are over 325 years old.

Further exploration with the tree crew led me to an old black gum grove in Niagara that the late Bruce Kershner had written about in his old-growth survey of the Niagara peninsula. I had been eager to visit these trees to see if they might be older than those in Grassie. So, on a sunny and snowless holiday December morning, I went to find some old trees.

Black Gum, 510 years  Photo: Nate Torenvliet
Black Gum, 514 years. Photo: Nate Torenvliet 

Shortly after heading into the woods, the gums revealed themselves, each one uniquely oozing with character—character that had been forged by centuries of life in that quiet slough forest. After considering the many different bark patterns, one tree in particular caught my attention: a gnarly brute with a flaky baldness that extended well up into its broken crown. This tree almost beckoned me over to see it first, before any other that day. Of course, I obliged, and went over to stand before it as I do all special trees I visit. It loomed before me as I stood there; my knees a little bent, jaw a little low-slung as I gazed up at it. This one was special.

Sampling this tree was unforgettable; rarely are the oldest looking trees so accommodating, but this one was sound and delightfully cooperative. Once home, I mounted the core and prepared it in the special way these black gums demand. Then, under a microscope and with a pinprick beside each decade I read the rings. Again, serious stress was recorded in the rings. There were decades in the past where this tree all but gave up. Perhaps a bad storm smashed its top out, or maybe years of drought brought it near the edge. Growth ebbed and flowed, but this tree pressed on.

After I’d run through the length of the core, one decade at a time, I went back to its beginning and began pressing a second pinhole next to each century: one hundred, two hundred, three hundred,… four hundred,..four-sixty, four-seventy, four-eighty,.. And finally, the last ring at four hundred and ninety-eight years ago. This was incredible.

To the 498 annual rings we can conservatively add the approximate 15 years it took for the tree to grow to the height of the sample. This means that next spring, this tree will grow those glossy-green leaves for the 514th time. Indeed, decades before Europeans explored inland from the Newfoundland coast, this tree extended upward from its first set leaves in 1501.

With a peaked interest in Ontario’s ancient black gum potential I began a search for more locations that might be holding high quality black gum populations. After perusing aerial photography from the early 1900’s I outlined areas that warranted a ground-search. That winter, with the leaves off the trees I walked the best looking sites.  Many frozen winter days were spent searching untracked sections of woodland, and after many kilometers travelled through primeval snowy woods, more than a few old black gums were discovered. But one site in particular was remarkable.

Black gum slough. Photo: Nate Torenvliet

Over the next couple of months I visited and revisited that old gum slough, trying to take in what I could before the leaves came out. There were dozens and dozens of mature black gums, certainly hundreds of years old, and many more from young to old – certainly a black gum population of the highest quality. By all accounts this site was the best I’d seen, and yet this site was also different; it appeared to be much wetter which has allowed black gum to co-dominate the woods with red maple and to create an incredibly open and diverse understory complete with old growth highbush blueberry (Vaccinium corymbosum) and great masses of buttonbush (Cephalanthus occidentalis) occupying all but the wettest areas. South of the border in the U.S this forest type is referred to as a ‘Black Gum-Red Maple Basin Swamp’, it’s a rare, easily overlooked, and poorly understood wetland type – so uncommon in fact, that there is no precedent in Ontario of this forest type where black gum co-dominates the forest canopy.

oldest black gum2
A 580-year-old black gum in Ontario. Photo: Nate Torenvliet

It is known that black gum can attain great ages because of what some have called their ‘patient and persistent’ lifestyle. This in itself is due to their shade tolerance, resistance to wind throw, sloughing off of canopy mass, fire resistance, and certainly not least, their ability to reproduce vegetatively. There is perhaps no better place where black gum really settles in for the long-haul than in this soggy wetland type, for it is there that they’ve quietly managed to stay sheltered even further – from deer, from fire, and, most importantly, from people.

The gums seemed to grow differently on this new site, slower perhaps. There appeared to be less of the thick ancient gnarl I had noticed at the other sites, though all of their characteristic bark patterns were present. Depending on which century of life a black gum is in, unique bark patterns develop which offer valuable insight into its age; from alligator, to blocky, to deeply ridged, to bald, and then to an unmistakable flaky baldness in only the most ancient individuals. Throughout its life black gum can look like four or five completely different trees. I was eager to sample some of the trees to see just where they might fit in to Ontario’s ancient black gum puzzle.

On a sunny and warm spring day, under a chorus of spring peepers I returned and successfully collected core samples from some of the best looking individuals. A few kilometers away the tree that offered 498 rings a year earlier still reigned champion as the oldest flowering plant in Canada. Could these newly discovered ones be part of a once much larger population from the past? Or perhaps they persisted from a still older group that arrived earlier in the northern migration of black gum into Ontario.

Working with the cores from this site was a delight. The trees are unassuming with the secrets of their ancient beginnings hidden from the naked eye. Once again, the growth rates of these trees varied little and continued throughout their history almost unimaginably slow; never overextended, simply an entire existence of moderation and seeming caution. The final numbers were incredible, the sampled trees ranged from ages of 460, 470, and one a staggering 580 years old – that’s a germination (or sprout) date of 1435! This tree is perhaps the third oldest hardwood tree in North America. Only two other black gums in New Hampshire are older. And in Ontario, only the more energy-efficient evergreen cliff cedars are older. Others among the stand could very well be older still, but the recent centuries have rotted away all but the newest wood, and so perhaps keeping the gum’s best secrets.

Interestingly, black gum research from New Hampshire has found “one stem emerging from a wet hollow connected by a common root system to the main stem nearly three meters distant.” As black gum is clonal, total ages for genetic individuals may exceed 1,000 years of age! Could we be looking at this quality of history in this forgotten Niagara region slough?

The core exracted from Ontario’s oldest hardwood tree

Historically, people and trees have not gotten along very well, at least from a tree’s perspective. Whether for lumber, firewood, land clearing, or surely the worst; for potash production, the value of a tree was too often found in its destruction. How could any tree escape the approaching axe or saw? But, and in addition to its other secrets to longevity, black gum has managed to avoid people quite well; persisting through the centuries quietly residing in the shadows of obscurity. Too uncommon for the attention of lumber merchants, mature black gum are also often crooked and hollow which has left them ignored and forgotten even while their arboreal neighbours fell at their feet. More than a few black gum populations today grow among the blatant evidence of past timber harvesting. And black gum has managed to nestle even further into obscurity due to its tolerance and perhaps preference for wet feet. Relegated to some of the soggiest slough forests in Ontario, black gum often lies well out of reach of the farmer’s plough and grazing cow. Even deer and fire have forgotten about the lowly black gum that though firmly rooted still, safely hide amongst knee-deep muck and a slough pond or two out of reach.  Indeed, prosperity because of obscurity itself has been important in the history and success of black gum.

Black gum leaves

Unfortunately, long term survival invariably requires adaptability to change – yes, change for change’s sake. The very obscurity which has granted them inadvertent protection has meant that most black gum swamps have no formal recognition, or protection. Today, in a time when sloughs and wetlands are drained, and the dozer’s blade advances out in the ripples of development, Ontario’s black gum can no longer rest on its laurels in obscurity. For the first time in over 600 years Ontario’s black gum needs some attention; human attention, to rescue it from obscurity as a natural historical treasure, which once lost could never be known again.

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