The forest at Iroquois Heights has a unique composition and a strong diversity of plants, mammals, and birds. Forest fragmentation is a cause of this uniqueness but also makes the forest vulnerable.
Traffic passes by below us in an endless, noisy, polluting stream. Where the Bruce trail runs through Hamilton, it is squeezing through the most urbanized stretch of the Niagara Escarpment ecosystem. Inevitably, the trail here includes crossing massive city infrastructure, like the section of trail that is the 403 pedestrian overpass.
We’re on our way to explore Iroquoia Heights, a patch of forest and field on the edge of the escarpment in Ancaster. It’s been in the news a fair bit over the last year or so, because of its unhealthily large deer population. The forest there is no longer connected to any other suitable deer habitat, and the Meadowlands development encroaches from the south, so the deer can’t disperse. To animals, it is an endless, impassible barrier, keeping Iroquoia Heights to the East cut off from the much larger forests to the West.
Once across the bridge, we’ve entered Iroquoia Heights. We catch the Bruce Trail heading North-East into some scrubby lands, old fields that have re-wilded into tangled groves of Hawthorn and Dogwood. These shrub lands are ideal songbird habitat. As we walk the narrow path, we move through circles of the sharp ‘chip-chip’ alarm sound of cardinals. To encourage birds here further, folks have attached birdfeeders into many trees along the trail.
The trail descends slightly and the shrubs thin out, leaving us in a flat, low meadow. Now that the ground is clear, we can see that this land lacks the characteristic hills and bowls that form in an old forest as trees uproot and logs slowly decompose. The flatness of this land means that it was likely graded and ploughed after the original forest was cut. A hawk circles slowly above, and we get down into the grasses to excitedly watch a tiny black shrew squirm between Goldenrod roots.
To the east of the meadow is a dense deciduous forest. Approaching it along the trail, we observe that its border with the meadow is quite sharp. Typically, borders between forest and meadow are gradual, with distinct edge communities of shrubs forming a buffer between the two. But here, we see a large White Pine right next to open ground. One of the uses of that buffer area is to slow down the wind, and as we step into the forest, we’re immediately struck by the very large number of downed trees within the first fifty feet.
The most astonishing thing about this forest is the odd composition of tree species. Ironwood, or Hop-Hornbeam, is by far the most dominant tree species throughout. Normally, Ironwoods are scattered sparsely throughout Oak or Maple-Beech dominated forests, but here, there are more of them than all other tree species combined. So we wonder, why is that?
We remember what we know about Ironwood: their wood is very hard and dense, and they grow very slowly. It’s likely this forest was once used as a woodlot— a source of firewood, building material, and saleable timber that is selectively logged by many generations of farmers. On this site, we find some of the largest Ironwoods we have ever seen, but usually, their small size means they are of little economic importance. As well, their density means that they are difficult to cut down, to the point that someone doing so risks dulling or damaging their equipment.
In trying to follow the story of this land, we realize Ironwoods were the only trees that were not cut by humans during probably over a century of logging. It seems that Maples, Beech, and White Pine were selectively cut out of this forest as they reached maturity. Today, these species stand sparsely and mostly as young trees. We find several very large Red Oak, White Oak, White Ash, and the largest Black Cherry we’ve ever met, all scattered throughout, but these species likely experienced some logging as well, preventing them from dominating the forest.
So the humble Ironwood, with its flaky bark and hanging fruits, emerged to fill the canopy. The fruits are a favourite of White-tailed Deer, and are perhaps a key reason why this tiny forest has supported such a large population of them. Since it’s not connected to any other forests, there are no seeds arriving to help restore a more common balance of trees, and so this amazingly odd Hop-Hornbeam dominated forest has endured.
This forest is very unique and beautiful. Fragmentation is one of the causes of this uniqueness, but it also makes the forest vulnerable.
An herbalist friend gave us a definition of health that we use to guide our understanding of wild spaces: Health is the ability of a system to respond to stress and change. This forest seems healthy now, but it has almost no ability to respond to stress, whether that be a wind storm or a large population of hungry deer – it’s just too isolated. No amount of deer-culling, bird-feeding, or native-species-planting is going to fix that. It’s hard to say what would. To state, we can preventing further fragmentation of the wild spaces that exist today by resisting the types of mindless urban sprawl that persist on the west mountain. And by supporting projects to create wildlife corridors beneath or above highways to create space that is slightly less impossible to navigate. It’s hard to imagine solutions when this forest’s capacity for health has been damaged so.
With these thoughts in mind, we continue East through the forest, and within a few minutes it is reduced to a thin strip, at the place where the Chedoke Radial Trail and the Bruce Trail merge. We consider that this trail was once a rail line linking Hamilton to Brantford, built about one hundred years ago. Today, the rail lines are long removed, and the rich thicket we see lining the trail is what re-wilding traintrack lands can look like when left to heal for 50 years. The 403 was built about fifty years ago. What will this land look like in 50 more years?