When: Sunday March 19th 2-4 pm Where: Meet at Riverdale Farm (Winchester St. / Sumach St.) at 2:00 pm How to get there: Take streetcar 505 to Dundas St. E at Sumach St., then walk north along Sumach St. to Winchester St. A walk led by Helen Mills from Lost Rivers Toronto along the Castle […]
via Lost Rivers Walk in the Rosedale Valley — Friends of Glen Stewart Ravine
These notes were taken by Bob Kortright, TFN member, and are also printed in the Toronto Field Naturalist newsletter for December. Thank you to the TFN for allowing them to be reprinted here.
The Toronto Botanical Garden (TBG) hosted an all-day ravine symposium on Friday, October 28, 2016:
Lorraine Johnson, noted environmental educator was Master of Ceremonies for the day.
Jason Ramsay-Brown deservedly received the greatest applause of the day for his sweeping and stirring presentation, Toronto’s Ravines: Past, Present, and Future, from the last glaciation to an imagined near future in which green infrastructure is treated as seriously as infrastructure for water, sewage and transportation. Jason also covered archeological evidence of first nation settlements over thousands of years, deforestation, dam-building for mills, sewage and industrial pollution, the advent of conservation following hurricane Hazel October 15, 1954, through recent and current projects like Corktown Common in the West Donlands, the proposed TBG expansion (from 4 to 30 acres) and the proposed G$ Raildeck park. He urged all to consider signing the petition to remediate yellow creek ravine, and to urge our councillors to support the investment necessary to remediation of all our ravines.
Gavin Miller, Toronto and Region Conservation, discussed the changes in plant species since Toronto Federation of Naturalists’ (TFN) surveys in the 1960s and 1970s, covering Glendon-Sunnybrook-Wilket Creek, Lambton Prairie, and High Park, as well as the Rouge. He also outlined threats (air pollution, deer, invasives, trails…) and solutions (fence trails, manage invasives…), and pointed to success in High Park in restoring oak savannah.
Wendy Strickland and Jane Welsh outlined the City of Toronto’s draft Ravine Strategy which, when approved (spring 2017 target approval), will be a framework to guide policy, investment and stewardship related to ravines. Next steps include identifying 8 priority investments, best practices for ravine management, and initiating development of management plans for the 86 ESAs (Environmentally Significant Areas).
Overview of Invasive Plants and Management Options
Kellie Sherman, Coordinator of Ontario Invasive Plant Council (OIPC), outlined the threat of the 441 invasive plants OIPC has identified in Ontario, management options, early detection and rapid response initiatives such as EDDMapS, biocontrol, and the role of homeowners in invasive plant management. Primary risks, which are also the ways most invasive plants have arrived are horticulture, the St. Lawrence Seaway, climate change, and degraded land that makes it easy for invasive species to take root. She outlined management of DSV(dog-strangling vine) and Norway maple in some detail. A new Invasive Species Act in Ontario should help.
Restoring Ecological Health to Toronto’s Ravines
Eric Davies and Anqi Dong of University of Toronto’s Faculty of Forestry were part of a team that resurveyed plots surveyed by the Toronto Field Naturalists (documented in Burke Brook Ravine (’74-76) and Park Drive Ravine (’76)), and in Moore Park and Rosedale Ravines. The study showed that although the number of native tree species remained stable (19 now as against 20 in 1996) non-native species had increased from 9 to 16. Most worrying was the total area covered by non-natives, particularly the steady encroachment of Norway Maples. The study predicted that, at this rate, by 2050 the area under study would be a “green desert” of Norway Maples. In response the Faculty of Forestry launched the Toronto Ravine Revitalization Study (www.TorontoRavines.org) in 2015. The main objectives are to quantitatively assess ecosystem health (native vs non-native species abundance, tree age structure, ground cover, mammal tracking, bird count, etc. These data will be analyzed to assist the regeneration and reintroduction of native species in the ravines. Eric urged the use of citizen science to help in collecting local seed of native trees to assist in restoration.
Patricia Huynh, University of Waterloo, presented on “Restoring the Urban Stream System”:
This project looked at water flow, sediment transport, and benthic macroinvertebrates in Wilket creek, Morningside creek, and a tributary of Duffin’s creek. They also did chemical analysis of the water (pH, O2, chlorides, sulphates, nitrates), turbidity, and suspended solids. They are finding that stormwater management and riffle pool restoration results in less flashiness of flow and consequent reduction in sediment transport, with consequent effects on water quality.
Paula Davies, Todmorden Mills Wildflower Preserve (TMWP), spoke on Lessons from a Decade of Stewardship at Todmorden Mills.
Paula showed images from the devastated landscape that was Todmorden in the 1950s compared to what it is now.
She stressed that:
She went on to describe the various techniques used at TMWP to suppress invasives:
Ten Years of Aquatic Monitoring by Citizen Scientists in the Rouge.
David Lawrie, Citizen Scientists, explained the role of citizen science in monitoring aquatic ecosystems, using volunteers to sample usually by electrofishing and netting, but also using high-speed photography, and monitoring of temperature and turbidity. Citizen Scientists have noted the disappearance of many species over time, especially as this is correlated to rising temperature and turbidity levels. Introduction of the rusty crayfish Orconectes rusticus has had a detrimental effect on aquatic ecosystems. Citizen Scientists have also been involved in road ecology research (I.e. effects of road-kill), and surveys of odonates (damselflies and dragonflies), salamanders, vernal pools, bats, meadow bird species, and moths.
David bemoaned the lack of research on native mussels, benthic invertebrates, and what he called the “urban stream syndrome”. He looks forward to the possibility of a world biosphere Reserve being established in east Toronto.
A useful directory of Ontario citizen Science projects can be found at www.ontarionature.org/directory-of-citizen-science/home.php.
Finally Harry Jongerden, Executive Director of the Toronto Botanical Garden, closed the proceedings with a brief synopsis of developments at TBG, its changing role (from artificial, horticultural to plant conservation and natural ecosystems) educational possibilities, research, displays, etc.
Speaker biographies and other information on the symposium can be found at: http://torontobotanicalgarden.ca/learn/adult/symposium/
Their talks can be accessed at this link:
Editor’s Note: The symposium was unique in bringing together a wide variety of people interested in ravines. Many participants commented that a group should be formed to maintain these relationships and the conversations that were beginning to build at the symposium. The organizers of the symposium will do their best to address this need.
by Doug Tallamy, Timber Press, 2007, 2009
The following is a review of this book, written by Bob Kortright for the October issue of the Toronto Field Naturalist newsletter, reprinted with their permission. Although this book is not recent, its message certainly is timely. Doug Tallamy can also be heard in person at the Toronto Botanical Garden, Tuesday, October 25, at 7:30 p.m. His topic is “Rebuilding Nature’s Relationships at Home”. TBG lectures
Tallamy’s book provided a long overdue treatment of a vital and underappreciated subject – the importance of replacing non-native plants with native ones. Given the evidence he marshals, it could have been titled How Traditional Horticulture is Wiping out our Wildlife, because traditional horticulture is largely based on non-native plants, which cover an ever-increasing fraction of the landscape around us. While the impact of invasive plants on native plants is acknowledged, at least by naturalists, I think most of us still don’t appreciate that non-native plants have contributed to the decline of our birds and other wildlife, whether they are invasive or not.
Non-native plants support fewer insects than native plants, because native insects did not evolve with them, so usually cannot eat them. Most of our birds depend almost entirely on insects to feed their young. There are some insects feeding on non-native plants (either generalist herbivores or non-native insects that were imported with the non-native plants.) And there are a few non-native plants that are similar enough to related natives that our insects do not appear to be able to tell the difference. But, why would we import Asian crabapples when our native crabapples are so similar that our insects cannot tell the difference? Especially when every plant we import carries the risk of bringing a plant disease or pest like the ones that have devastated our elms and the American Chestnut, and are devastating our butternuts, beech, and ash.
However, the fact that some insects eat some plants of alien origin does not change the argument –- non-native plants support fewer herbivores than native plants, and therefore fewer omnivores and carnivores in turn. So, we need native plants to sustain our wildlife.
While our society is unlikely to reject the use of non-native plants in agriculture, I see no excuse for using non-native plants in our gardens and parks, for which there are excellent native substitutes. Non-native tree, shrub and vine species which are invading natural areas (ailanthus, Siberian elm, Manitoba and Norway maples, black locust, European birch, Asian bittersweet and Asian honeysuckles, European buckthorn…) should be removed and replaced with native species as soon as possible, unless they are providing shade and where they are unlikely to spread to natural areas.
by Bob Kortright
Check out our story on U of T News: Saving Toronto’s ravines: forestry researchers track ecological changes
via We are on U of T News! — Toronto Ravines Revitalization Study
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