Ecological integrity in the Park Drive Ravine: 1977 to 2015
Anqi Dong, Master of Forest Conservation, 2015
Ecological integrity is an important concept in ecosystem management. It is a measure of ecosystem health, and the abundance and functionality of native species are the key components. The main objective of this study is to obtain estimates of the ecosystem health of the Park Drive Ravine, Toronto, Ontario, Canada through the lens of ecosystem health. A comprehensive survey was conducted in the Park Drive Ravine in 1977, and a canopy resurvey was conducted in 2015. Results indicated a degraded ecological integrity in this ravine – the relative contribution of native species has decreased with no or little evidence of regeneration, but the relative contribution of non-native species, especially Norway maple (Acer platanoides L.) has increased with lots of regeneration. Ash species (Fraxinus spp.) and American beech (Fagus grandifolia Ehrh.) used to be two of the dominant species in this ravine in 1977, but their populations have largely declined due to the massive infestation of emerald ash borer and beech bark disease. As the ravine canopy loses these major contributors and other native species, the population of Norway maple will further expand and severely degrade the ecological integrity. In order to restore the ravine ecosystem, long-term monitoring of various taxonomic groups in the ravines is recommended, and collaboration among various stakeholders is critical.
Awarded the Fred G. Jackson Prize for best Master’s Thesis 2015
A Protocol for Seed Forecasting Oaks in the Toronto Ravines
Jane Michener, Master of Forest Conservation, 2016
The City of Toronto has been described as, “a city within a park” because of its extensive ravine system; they make up 17% of the urban landscape encompassing over 11,000 thousand hectares. Recent studies have shown that there is limited to no native regeneration occurring in the ravines while non-native species are thriving, this makes it important to identify native seed trees within the ravine ecosystem in order to begin implementing artificial regeneration. The aim of this study is to set up seed forecasting protocols for native Quercus spp. within six ravines by identifying and mapping Quercus trees species on public property with a DBH of >50cm and setting up specific seed forecasting protocols that examine the acorn yield of the whole tree in the crown and on the ground. One hundred and twenty eight Quercus species were identified of the subspecies Erythrobalanu and Leptobalanus: 107 Quercus rubra, 20 Quercus alba and 1 Quercus marcrocarpa. Seed forecasting was preformed the last two weeks of August and from Sept 10th-21st and all three species, Quercus rubra, Quercus alba and Quercus marcrocarpa experienced crop failures with no acorns detected in the crown and on the ground. First year acorn measurements on the terminal branches of Erythrobalan were conducted in October and November within five of the ravines in order to assess the potential acorn yield for 2017. We found an average of 1.04 acorns per branch indicating that next year’s acorn crop will also be a failure. These finding highlight the importance of having a set database and seed forecasting protocols for Quercus spp. within the ravines to monitor acorn production and assist in artificial regeneration.
Ecological Integrity of Mammals and Birds in Toronto’s Ravines
Alex Stepniak, Master of Forest Conservation, 2017
With the increasing trend of urbanization throughout the world, the conservation of natural environments and their floral and faunal inhabitants becomes increasingly more important as well as challenging. Ecosystem services are provided by biodiversity and these services provide benefits that are highly desirable by humans. To secure the existence of healthy ecosystems and to facilitate restoration efforts, a monitoring system is necessary to determine the conservation or restoration needs of a given ecosystem. Monitoring systems such as the concept of „ecological integrity‟ has been successfully used by the US National Park Service and Parks Canada to assess and communicate the health of ecosystem to managers and the public. With global loss of bird and mammal species in cities, I found it important to determine the ecological integrity of these populations within the urban context in the City of Toronto‟s mature forests. I found that compared to historic populations, there has been a decline in a number of small mammal species since the late 1800‟s, but little species change since 1977. My study on birds had found that Toronto is missing many „area-sensitive‟ forest bird species and is also missing bird species that are typically found just north of Toronto in York region. I recommend that the City of Toronto must preserve its natural features and designate areas for naturalization to promote biodiversity in the city. Furthermore, increasing connectivity between naturalized areas and making citizens aware of potential human impacts on wildlife are other important factors that must be considered in urban planning.
Assessing Understory Vegetation Communities as Indicators of Ecological Integrity in the Toronto Ravine System
Jose M Kabigting, Master of Forest Conservation, 2017
Urbanization has resulted in the disturbance and loss of ecosystems around the globe. As this trend is unlikely to stop, it is essential for urban planning to adopt ecological concepts in order to increase the sustainability of urban centres. One of the first steps required for this to happen is the implementation of ecological monitoring within urban areas – this would allow a better understanding of the current ecological state of urban environments, from which future studies and management recommendations can be based on. The concept of ecological integrity, which aims to quantify the wholeness of an ecosystem’s structure, composition, and function, can be used as a guiding principle for such monitoring schemes. In this study, the ecological integrity of the urban ravine system in Toronto, Ontario is quantified using understory vegetation communities as an indicator group. Vegetation sampling sites were established in three ravines located in downtown Toronto, with plot selection based on a 1977 study of the same ravines. Each plot was then ranked as having low, medium, or high ecological integrity based on the proportion of native versus non-native ground cover in each plot. Additionally, two possible drivers of these patterns in ecological integrity were tested – the role of plot position along a slope, and the effect of non-native ground cover abundance. It was found that while invasive species dominated most plots, pockets of native vegetation were persisting within the ravines. Additionally, the majority of invasive ground cover appeared to be “leaking” down from residential areas at the tops of ravines, indicating the role of “garden escapes” as propagules for invasive establishment. Management recommendations include the implementation of citizen science programs to monitor the state of these vegetation communities, as well as using the information gathered to target their efforts.
An Analysis of Toronto’s Urban Ravine Policies and the Achievement of Ecological Integrity
John (Jack) Richard, Master of Forest Conservation, 2017
The city of Toronto contains a valuable urban forest that is composed of street trees, parks and ravines with a combined total of over 10.2 million trees. In order to protect the previous ravines and its native species, the City of Toronto requires strong, meaningful policies that will direct the ecological management of this ecosystem. While policymakers and the managers of urban forests have often relied upon canopy cover objectives as a measure by which to direct management, the use of ecological integrity measures as a standard for guiding management has gained popularity and usage in recent years, particularly following the declaration of Parks Canada, who announced that this principle would become the primary priority with federal parks management system (Parks Canada, 2016). Ecological integrity represents a sound principle for ecological management within urban forest areas, such as Toronto’s ravines. This project reviewed the critical policies of the current policy framework that guides the management of the Toronto’s ravines to evaluate how well compositional, structural, and functional measures of ecological integrity were protected within this framework. These policies included the City of Toronto Official Plan, the Ravine and Natural Feature Protection By-law of the Municipal Code, and the Conservation Authorities Act. These policies were found to contain provisions which promoted the achievement of certain components of ecological integrity but were inhibited by the scope of their policy
framework, lacking clear guidelines and specific management restrictions. Further, it was found that the body of policy governing Toronto’s ravines contained no outright restriction on the planting of invasive species, directly compromising the compositional integrity of the ecosystem. To increase the degree to which Toronto’s policy framework protects for components of ecological integrity within the ravines, both short and long-term policy recommendation were made. These recommendations included both minor provisions within the existing policy framework, as well as larger changes to the policies which guide ravine management itself.