Urban woodlands plant surveys show decline in ecosystem health
Hamilton residents are encouraged to increase biodiversity across the city. Instead of digging up native plants in the wild, support native plant nurseries that grow plants from local genetic stock.
Paul O’Hara says, based on its unique flora, vegetation communities and geology, Crerar Woods West should be designated an Environmentally Sensitive Area (ESA) and an Area of Natural and Scientific Interest (ANSI) Photo credit: Paul O’Hara
Last Thursday was the first day of spring! Like many folks, I’ll be looking for those beautiful spring bulbs that have been hibernating all winter under a mountain of snow. I thought this would be a great time to explore how folks can improve the biodiversity of their gardens using native plants.
Paul O'Hara is a field botanist, landscape designer, native plant gardening expert and the owner/operator of Blue Oak Native Landscapes. He recently conducted a survey of Hamilton’s urban woodlands that revealed these natural areas are experiencing a marked decline in biodiversity and ecosystem function.
Plant surveys were conducted at 11 urban natural areas in the spring of 2024 in order to determine the ecosystem health of urban woodlands including three sites from the central Mountain, two along the Niagara Escarpment, one from Westdale, two from Ancaster and three from Dundas.
Across the 87.5 hectares /216 acres, a total of 409 vascular plants were documented of which 153 plants (37 per cent) were non-native species while 256 plants (63 per cent) were native species.
A closer look at the study reveals that of the 446 Provincially Rare Species found in the Carolinian Life Zone of southwestern Ontario, Hamilton is home to only 102 of those species. However, only two of these species were documented in the survey – butternut and Hill’s oak trees.
O’Hara concluded that with only two Provincially Rare Species and over a third of the flora composed of non-native species, these eleven urban natural areas are unable to provide habitat for these rare species and when they were observed, they were never abundant, were often represented by one small stand, or they were intentionally planted.
Not one of the eleven natural areas surveyed had forests with healthy ground layers, healthy shrub layers or vigorous canopy tree recruitment.
“These 11 urban natural areas are a microcosm of what is happening across the city. The results of the survey suggest the urban natural areas of the City of Hamilton have little to no ecosystem function and that urban biodiversity is in severe decline,” O’Hara said in a press release.
“The results of this survey should cause alarm for City of Hamilton officials and citizens alike. Current natural area protections are having little to no effect on preserving the natural heritage in the urban and near-urban fabric of the city,” O’Hara added.
Encroachment at Crear Woods West from the residents on Dolphin Court. In addition to the dumping, the residents here have cleared the vegetation along their backyard fences Photo credit: Paul O’Hara
Threats to ecosystem health include invasive species, dumping and encroachment by woodlot neighbours, tree pests and disease, deer browsing, non-native earthworms, damage from overuse, plant poaching and foraging, and climate change.
Signs of plant poaching at Dundas Driving Park Woods. April 29, 2024. Suspected stolen wildflowers include downy yellow violet, false Solomon's seal, and Virginia waterleaf Photo credit: Paul O’Hara
Plant poaching and foraging has resulted in dozens of holes where native wildflowers were removed at Dundas Driving Park, Westdale Woods, as well as Urban Dundas Spencer Valley.
O’Hara found that plant poaching and foraging have become increasingly common in recent years as apps like iNaturalist lead users directly to stands of native wildflowers, native foods like the wildly popular ramps or wild leeks and medicine plants. Not surprisingly, these native plants are becoming increasingly rare across the Carolinian Zone.
Early Saxifrage in flower at Dundas Driving Park is being impacted by climate change as it’s forced to compete with plants that flower earlier in response to more heat Photo credit: Paul O’Hara
Climate Change remains unpredictable resulting in extreme heat and cold, extreme rain and snow, extreme drought, increased erosion, disrupted seasonal rhythms for flora and fauna, and decreased snow cover to protect plant roots as well as overwintering insects, reptiles and amphibians.
The Hamilton Naturalists’ Club, in partnership with the City of Hamilton and Hamilton Conservation Authority, launched the 2024-2027 Natural Areas Inventory designed to survey the status of wildlife species and recommend ecological restoration priorities. Work has begun with 25 urban woodlots surveyed in 2024 with further surveys and volunteer opportunities in 2025.
City of Hamilton Council has endorsed the Montréal Biodiversity Pledge (COP15/2022) that invited cities across the world to make a commitment to protecting biodiversity. The challenge includes taking 15 tangible actions towards pursuing and accelerating the city’s efforts to preserve ecosystems.
Hamilton council also adopted the collaborative Hamilton Biodiversity Action Plan (HBAP) in June 2024. The plan is a multi-partner, 5-year plan of actions to protect, enhance, explore and restore biodiversity in Hamilton.
The urban woodland plant survey will provide guidance to ecological restoration activities planned within the HBAP.
Enchanter's nightshade seedlings in the Urban Dundas Spencer Valley North, is a native wildflower indicative of a dying woodlot Photo credit: Paul O’Hara
Hamilton residents are encouraged to help increase biodiversity across the city and to protect woodlands and natural areas by:
Planting native species at home like wild crab apple and tulip trees, wildflowers like phlox, tall bellflower, horsebalm, and yellow giant hyssop
Learning to identify and manage invasive plants like lily of the valley, English ivy, garlic mustard and European buckthorn the worst invasive plant species in Southern Ontario
Keeping dogs leashed in natural areas
Avoiding dumping in, and encroachment of, natural areas including not disposing of yard waste clippings in these areas
Not harvesting plants or mushrooms without the permission of the landowner
Supporting the implementation of the Biodiversity Action Plan and getting involved
In his report, O’Hara states, “Going forward, it is hoped that public funding is made available for the new Hamilton Natural Areas Inventory (2024-2026) to conduct full spring, summer and fall floral and fauna surveys in many more of the 139 urban natural areas identified by Paul Smith's map and Excel file. These surveys will give us an even better idea of the task ahead of us with regard to restoring ecosystem function across the region, so we can make Hamilton not only, the City of Waterfalls, but also the greenest, most biodiverse city in Southern Ontario.”
*Instead of digging up native plants in the wild, support native plant nurseries that grow plants from seed derived from local genetic stock. Here’s a list and find additional information from Paul O’Hara here.
Paul O’Hara’s complete Summary of Spring 2024 Botanical Fieldwork at Eleven Urban Natural Areas in the City of Hamilton.
Paul O’Hara’s book, A Trail Called Home: Tree Stories from the Golden Horseshoe, was published by Dundurn Press in 2019.
Thanks to everyone who read today’s article. With your continued support, a little Nicoll can make a lot of change.
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