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The Toronto Ravines Study: 1977-2017 Long-term Changes in the Biodiversity and
Ecological Integrity of Toronto's Ravines
Eric Davies, Anqi Dong, Paul Scrivener, Dale Taylor, Catherine Berka, Lydia Wong, Sandy M SmithMap credit: Mary Grunstra
Map data: City of TorontoSource: ESRI, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS UserCommunity https://torontoravines.org/
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1907 - 2016
Over 100 Years of Forestry Leadership- Canada’s 1st Forestry School- helped start the MNR, OPFA
-etc, etc, etc
- Forest Restoration = Specialty-Forestry = Restoration
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Living Legends:Ken Armson
Forest Stewardship Ravine Health in 1960’s
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Long Tradition of focusing on“Forest Health”
The ‘Ravine Team’
Graduate students
Eric Davies, Anqi Dong, Alex Stepniak, Joey Kabging, Jane Michener, Jack Richards
Applying the concept of forest health to urban forests & ravines
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(Lydia W6oonfg3,12018)
v
(Lydia W7oonfg3,12018)
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(Bob Jefferies et al.)
Area (ha)Burke Brook 15.7Moore Park 14.4Park Drive 15Rosedale 6Total 51.1
The Rosedale Ravines Study 1977
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KEY QUESTIONS
• How to measure ecological integrity?
• What is the current status of ecological integrity in the ravines?
• What is the trend in ecological integrity over time?
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Forest Health: Ecological Integrity“A thing is right when it tends to preserve the
integrity, beauty & stabilityof the biotic community. It is wrong when it tendsotherwise”
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“maintenance of ecological integrity shall bethe first priority a
composition and abundance of nativespecies and biological communities
The new PPCRA (Provincial Parks and Conservation Reserves Act, 2006) states:
nd the restoration of ecological integrity shall be considered” for all provincial parks and conservation reserves.
The new Act defines ecological integrity as: “a condition in which biotic and abiotic components of ecosystems and the
are characteristic of their natural regions andrates of change and ecosystem processesare unimpeded.”
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Scientific resurvey under:Ecological Integrity Framework Ecological Integrity (EI)
= composition + abundance of native species= effective populations, functioning cycles, unimpeded ecosystem
processes…
1949 Aldo Leopold1972 US EPA1979 Parks Canada2000 Parks Canada2006 Ontario2017 Toronto?2020+ Toronto?
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TREES AS FOUNDATION SPECIESAaron Ellison
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Dan Janzen. 1974. The Deflowering of Central America. Nat. Hist.“What escapes the eye however, is a much more insidious type of extinction:
the extinction of ecological interactions”
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NATIVE SPECIES & REWILDINGDouglas Tallamy
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Native Trees Non-Native Trees
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2015-2017: Resurvey + 6 Masters’ papers
......Large decline in ravine health
1) Tree canopy resurvey Anqi Dong 2015
2) Acorn forecasting Jane Michener 2016
3) Seed collection Vincent Lepoivre 2016
4) Small mammal & bird resurvey Alex Stepniak 2017
5) Understory vegetation resurvey Jose M Kabigting 2017
6) Policy analysis John (Jack) Richard 2017
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30 43 72 53 20 9
Toronto Current Tree Species Pool (diversity up)
Tree Species in 10 Ravine Plots – 1977 (diversity down)
Non-native (introduced species)
(native diversity)nnn
(native diversity) Extirpated (locally extinct species) Extant (remaining native species)
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1977Location
Burke Brook
Park Drive
Rosedale
Total
Native Non-native
9 2
18 9
10 8
20 9
Ravine TreeSpecies Richness (presence)
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Native Non-native
9 2
18 9
10 8
20 9
Ravine TreeSpecies Richness (presence)
Native Non-native
15 3
16 11
9 11
19 16
1977 2016Location
Burke Brook
Park Drive
Rosedale
Total
(stable native diversity)
(increased invasive species)
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1977
BurkeBrook(1 plot)
Park Drive(5 plots)
Rosedale(4 plots)
Weighted Mean
Native Non-native
98% 3%115 3
91% 9%769 75
75% 25%520 173
85% 15%
No. Tree Stems (% abundance)
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1977 2016
Native Non-native Native Non-native
98% 3% 88% 13%115 3 182 26
91% 9% 58% 42%769 75 597 425
75% 25% 52% 48%520 173 392 363
85% 15% 59% 41%
No. Tree Stems (% abundance)
BurkeBrook(1 plot)
Park Drive(5 plots)
Rosedale(4 plots)
Weighted Mean
(decreased native diversity)(increased invasive species)
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■ Non-native
■ Native
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1977 2016
Burke Brook
1977 2016
Moore Park
1977 2016
Park Drive
1977 2016
Rosedale Valley
No. Tree Stems (% abundance)
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■ Non-native
■ Native
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1977 2016
Burke Brook
1977 2016
Moore Park
1977 2016
Park Drive
1977 2016
Rosedale Valley
No. Tree Stems (% abundance)
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400 m
Observed 197710% Non-Native
Tree Cover
Observed 201640% Non-Native
Tree Cover
400m
In a few decades… 60% Non-Native
Tree Cover 26
Maps by: Jonathan Schurman400m
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400 m
400 m
Observed 197710% Non-Native
Tree Cover
Observed 201640% Non-Native
Tree Cover
In a few decades…60% Non-Native
Tree Cover 27
Maps by: Jonathan Schurman400m
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400 m
400 m
400 m
Observed 197710% Non-Native
Tree Cover
Observed 201640% Non-Native
Tree Cover
In a few decades… 60% Non-Native
Tree Cover
Maps by: Jonathan Schurman
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Source: Google Maps
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Photo by Eric Davies
61 ground cover speciesl 31 native vegetationl 30 non-native vegetation
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Greg Lasley PhotoPhil Myers Photo
• 29 days, 432 trap-nights
• Only 3 species trapped
• Visual observation of other species
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Small Mammal Diversity in Toronto over Time(# specimens in ROM) 1866-2015
44-23 Meadow Vole 9-86 Masked Shrew
22-7 Deer Mouse
22-4 Red Squirrel
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One-hour bird survey in each ravine
Ravine #species #birdsBB 31 94MP 8 29PD 2 3RV 5 20Total 46 146
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Potential GTA Area-sensitive Forest Breeding Birds
Source: Environment Canada. (2007). Area-Sensitive Forest Birds in Urban Areas.
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l 7 out of 43 area-sensitive forest breeding bird species
l 31 out of 118 species native to Toronto
l 45 days
l 30-min recording at dawn
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2017-Now
Mapping invasive species
Mapping & seed forecasting old-growth native trees
Engage communities
Photo by Colin Stark
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Overall Conclusion• Toronto’s ravines are at a “tipping point”• Natural heritage could become a green
monoculture within decades• Even with immediate action, it will take
many decades to restore the EcologicalIntegrity of the ravines
The Toronto Ravines
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July 12, 2018 - Parks & Environ Committee Mtg 29
Current status of Toronto’s biodiversity:
“…holding steady…assigned a grade of D.”
− TRCA Watershed Report Cards, 2018
Photo by Jane Michener
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Executive Committee, Meeting 27,26 September 2017
Parks & Environment Committee,Meeting 23,17 November 2017
Credit: City of Toronto
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Photo by Jane Michener
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News stories about the Toronto Ravines
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One man’s quest to restore native Canadian trees to Toronto
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Journalist: Patrick White | Photo by Tijana Martin
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RecommendationsAdopt & Restore ‘Ecological Integrity’
• Increase ecological connectivity & buffers for biodiversity
• Regenerate & reintroduce: Seed forecasting & collection
• Plant ‘local’ native species
• Rank ‘invasiveness’ & remove invasive species
• Re-engineer law-making & enforcement
• Foster collaboration & partnership
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Ecological Integrity generates Forest Health
• Ecological Integrity derives from Biodiversity
• Biodiversity = Species Diversity+ Functional Diversity (native spp)+ Genetic Diversity (not clones)+ Habitat Diversity (age class mosaic)
• Biodiversity provides Ecological Resilience
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Forest Health: Species Diversity
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Forest Health: Species Diversity
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Current Native vs. Lost Dark DiversityToronto, ON
56% 44%
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Forest Health: Functional Diversity (native)
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Forest Health: Functional Diversity (native)
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Citizen Science: Biodiversity in the RavinesGenetic diversity
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500,000 10,000 400 150 10
40,000 1500 250 25
FOREST HEALTH: Retain Healthy Age Class Distribution
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How to Restore Ecological Integrity?
• Permanent plots• Prioritize restoration efforts: among &
within ravines• Erosion control• Control + remove invasive species• Collect local seeds + artificial regeneration• Community stewardship & citizen science
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Citizen Science: Seeds of the FutureFind and map heritage trees to start restocking and revitalizing native trees
üJoin a seed forecast workshopüCollect local seedsüGrow themüPlant them
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Recommendations – Cont’d
Create a new funding & operational model
• Consider New York City’s Natural Areas Conservancy
• Conservancy moving this way (e.g. co-ops in Germany, California coastlines, Nebraska, Oregon, Washington, Hawaii, Maine, Virginia & more)
• See The Atlantic, Issue December 2017
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NYC Model for Forest Management
• Framework provides key insights into the state of forests & recommends 25-year investment to improve their long-term health
• Joint project of the Natural Areas Conservancy & NYC Parks
• 7,300 acres (approx. 3000 ha), $385 million over 25 years
• Planted 500,000 trees, active local stewardship
Pregitzer, C.C., H.M. Forgione, K.L. King, S. Charlop-Powers & J. Greenfield. 2018. Forest Management Framework for New York City. Natural Areas Conservancy, New York, NY.
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Sustainable Sites Initiative (SSI – Leed Certification)
62 of 31David West photo
Keep & ReWild Toronto’s Ravines
