Dr. Andrew Millward
Principal Investigator of the UFRED Group


Advisor in Ryerson’s Masters of Spatial Analysis (MSA) and Environmental Applied Science and Management (EnSciMan) graduate programs.

“I forget what I was taught. I only remember what I have learnt.” ~ Patrick White


 

Christopher Greene, EnSciMan Ph.D. candidate and MSA ‘09


Chris’ research published in Urban Forestry & Urban Greening:

Who is likely to plant a tree? The use of public socio-demographic data to characterize client participants in a private urban forestation program

City trees, and the ecosystems of which they are a part, provide important benefits to urban residents. In many cities across North America, suitable locations for the planting of trees – expansion of the urban forest – are mostly confined to privately owned land.


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Christopher Greene


Who is likely to plant a tree? The use of public socio-demographic data to characterize client participants in a private urban forestation program

City trees, and the ecosystems of which they are a part, provide important benefits to urban residents. In many cities across North America, suitable locations for the planting of trees – expansion of the urban forest – are mostly confined to privately owned land. Our primary motivation for conducting this study was to investigate whether aggregate socio-demographic characteristics, represented geographically by census tract, have explanatory value concerning participation in a large urban forestation program. Specifically, we used 2006 Statistics Canada census data and known geographic locations of participants in a privately administered urban forestation program to conduct a two-stage multiple regression analysis for East York, Etobicoke, Markham, North York, Scarborough, Toronto, and York (all densely populated centres within the Greater Toronto Area of southern Ontario, Canada). A priori assumptions about program participants were evaluated first based on a review of the literature and through solicitation of expert opinion. The second step employed an exploratory data analysis approach to identify variables that may have differed from a priori assumptions. Results indicate that there are marked regional differences in both the a priori assumptions, as well as in the variables identified through the exploratory regression analysis. The explanatory ability of the baseline regression model is strongest for East York and weakest for Markham, whereas the ability to explain program participation using the exploratory regression model is strongest for Markham and weakest for North York. While participation of Toronto and York residents is largely explained by a dwelling-specific variable (the number of homes constructed pre-1946), the participation of Markham residents is typified by a gender-specific income variable (the number of females reporting a gross income range of $50 to <$60k). Beyond provision of location-specific client information, our study presents a methodological framework that is of value to the refinement of current forestation efforts and to future target marketing of similar initiatives.

 

Michelle Sawka, MASc ‘11


Growing conservation through residential shade tree planting

Urban shade trees have the potential to modify their surrounding climate and conserve building energy use. Tree shade cast on residential buildings can lower inside temperatures, decreasing the electricity demand for cooling during hot times of the year.


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Michelle Sawka


Growing conservation through residential shade tree planting

Urban shade trees have the potential to modify their surrounding climate and conserve building energy use. Tree shade cast on residential buildings can lower inside temperatures, decreasing the electricity demand for cooling during hot times of the year. These benefits are most significant in the local utility’s peak power period and appreciate with tree growth. The effect of tree shade on cooling loads in residential buildings depends on factors that include climate and the quality and quantity of shading, which relates both to tree characteristics such as species, size, shape, foliation period, and canopy density, and to tree location, including its distance from and orientation with respect to surrounding buildings. This project uses energy conservation estimates derived from a model tailored for use in southern Ontario. These benefits are generated for a sample of trees planted by a non-profit in residential backyards across the City of Toronto. Specifically, this research seeks to quantify energy conservation benefits of urban shade trees that are growing (1) at different distances from buildings, (2) in varying orientations with respect to the sun, and (3) on properties with variable amounts of pre-existing shade cast by other trees. Quantifying the impact of strategically planted trees on electricity conservation can help spur the promotion of ecologically based policy, and will provide a basis for directing future urban forestation initiatives with the expressed purpose of energy conservation.

 

Greg Bowie, MSA ‘11


An interactive mapping tool for urban forest stewardship: fostering appreciation for the benefits of city trees using Google Maps API

Interactive web-based mapping is growing in popularity. With the advent of Google Maps, and similar online mapping tools, a powerful and yet simple medium for engaging the general public in the use of geospatial information has emerged.


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Greg Bowie


An interactive mapping tool for urban forest stewardship: fostering appreciation for the benefits of city trees using Google Maps API

Interactive web-based mapping is growing in popularity. With the advent of Google Maps, and similar online mapping tools, a powerful and yet simple medium for engaging the general public in the use of geospatial information has emerged. The purpose of this project is to build an interactive online interface to document the presence of city trees and to communicate their many benefits. The interface will be constructed using Google Maps API, Google Fusion Tables API and Adobe’s ColdFusion. Ryerson University’s urban forest will serve as the case study for the development of this tool, which will be designed in such a way that it can be easily transferred to other institutions, not-for-profits or community organizations seeking to protect and enhance trees within a city. Specifically, Ryerson’s complete urban forest inventory, with associated tree-specific ecological benefits, will be incorporated into a Google Maps interface allowing for wide-ranging user interactivity with extensive tree attribute data. Query capability will be at the centre of creating user interactivity and will be developed using MySQL and PHP. Overall, this project seeks to leverage contemporary mapping technologies to raise the profile of urban forest stewardship.

 

Suofei Li, MSA ‘11


Influence of organic mulch on soil temperature moderation in an afforesting urban park

This project investigates the effect of organic mulch on one of the important conditions necessary for tree growth in cities – moderation of soil temperature in the near-surface rooting zone.


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Suofei Li


Influence of organic mulch on soil temperature moderation in an afforesting urban park

This project investigates the effect of organic mulch on one of the important conditions necessary for tree growth in cities – moderation of soil temperature in the near-surface rooting zone. It is one component of a broader research collaboration between Ryerson University's Urban Forest Research & Ecological Disturbance (UFRED) Group and Bruce Tree Expert Company that is working on identifying management approaches that can protect and enhance the growing medium for city trees. The study area for this project is an urban park on the Exhibition Place grounds in Toronto, Canada. Intensive soil temperature sampling (collection of in-situ data using and offset grid sampling design) was performed from June through August 2011. Spatial variation in near-surface soil temperature was measured under mulch ring treatments with different radii (0.75, 1, and 1.5 m), and in adjacent soil covered with turf grass. Ordinary kriging was used for interpolation of point data (soil temperature measurements) to a surface. Cross-validation statistics and visual inspection of temperature prediction surfaces were used to select optimal parameters for inclusion in the ordinary kriging procedure. This study reports the findings of five temperature prediction surfaces produced for each of two contiguous sections of urban parkland. Overall, results show that the spatial pattern of near-surface soil temperature changed dramatically following the application of mulch. Soil was coolest nearest to the main stem of trees where mulch was applied. The extent of temperature moderation was positively associated with the size of the mulch ring, where this study found that a ring of radius 1.5 m was most effective at maintaining optimal temperatures in the rooting zone. Overall, this project demonstrates that larger diameter mulching treatments have the potential to reduce heat stress for city trees and are, therefore, recommended as an urban forest management strategy.

 

Michael Doren, MSA ’11


Spatio-temporal analysis of forest response to hurricane damage: Point Pleasant Park, Halifax, Nova Scotia

Remote sensing is both a practical and affordable technology for use in the assessment and monitoring of dynamic changes within forested landscapes.


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Michael Doren


Spatio-temporal analysis of forest response to hurricane damage: Point Pleasant Park, Halifax, Nova Scotia

Remote sensing is both a practical and affordable technology for use in the assessment and monitoring of dynamic changes within forested landscapes. In this project, we use high spatial resolution multispectral satellite imagery (QuickBird) to characterize the response of forest in Point Pleasant Park, Halifax, to damage caused by Hurricane Juan in 2003. Type and trajectory of forest response is evaluated for three time intervals (2005-2007, 2007-2009 and 2005-2009) using the normalized difference vegetation index (NDVI) as a biophysical indicator of vegetation change. A thresholding approach that combined field and other ancillary data with change vector analysis is used to separate change from no change, and to classify the magnitude of response as either moderate or large. Post-hurricane forest response followed a typical recovery path characteristic of other hurricane-disturbed forests. Moderate recovery of vegetation (mostly early successional species) was widespread and occurred in 52% of the originally damaged forest area between 2005 and 2007. The rate of response (vigour) slowed as well as retracted in spatial coverage between 2007 and 2009, only identified in 24% of the same forest area. NDVI values may have experienced saturation during the latter time interval, which could have resulted in an underestimation of the amount of actual vegetation change. Forest decline (dieback of pre-hurricane vegetation) was restricted to small areas representing less than 2% of the study area in either time interval. Physical landscape variables (slope, aspect, soil type and initial vegetation damage intensity) are investigated for correlation with forest response. Results show that slope, aspect, soil type and initial damage intensity were all influential variables governing the spatial variability of forest response between 2005 and 2007 but not between 2007 and 2009. Overall, results confirm that the type and rate of immediate forest response was highly influenced by spatial variability in initial hurricane damage intensity.

 

Daniele Magditsch, MASc ‘12


Restoration of the rooting medium: strategic mulching of trees in forested urban parkland

Ensuring good soil quality is essential to promoting plant growth in urban parks and building ecological resilience into a cityscape. While park managers and arborists have emphasized the importance of selecting vegetation adapted to urban conditions, surprisingly little attention has been given to the soil quality and volume necessary for trees to grow to maturity, thus maximizing their ecological and aesthetic values.


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Daniele Magditsch


Restoration of the rooting medium: strategic mulching of trees in forested urban parkland

Ensuring good soil quality is essential to promoting plant growth in urban parks and building ecological resilience into a cityscape. While park managers and arborists have emphasized the importance of selecting vegetation adapted to urban conditions, surprisingly little attention has been given to the soil quality and volume necessary for trees to grow to maturity, thus maximizing their ecological and aesthetic values. The goal of this project is to compare the effectiveness of several different organic mulching treatments designed to improve the physical and chemical characteristics of disturbed park soils, and thus promote conditions necessary to protect and enhance urban forests. Changes in soil characteristics that are known to influence tree health arising from variation in mulch type, application practice (depth and areal coverage), and duration of use will be monitored. Four mulching application practices will be evaluated using replicate treatment sites and corresponding non-treated rooting zones (control locations). Knowledge arising from this research will contribute to the discipline of urban forestry by providing a more in-depth understanding of the prescriptive use of organic mulches to improve the survival and long-term health of city trees.

 

Alison Jackson, Research Assistant (’09-’11)


Drivers of change in impervious surface cover: the role of socio-demographic and dwelling-specific characteristics

The principal objective of this study was to examine how changes in Toronto’s socio-demographic landscape may have influenced the quantity, quality and distribution of its urban forest and plantable green spaces.


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Alison Jackson


Drivers of change in impervious surface cover: the role of socio-demographic and dwelling-specific characteristics

The principal objective of this study was to examine how changes in Toronto’s socio-demographic landscape may have influenced the quantity, quality and distribution of its urban forest and plantable green spaces. Specifically, this project investigated whether aggregate changes in socio-demographic characteristics, represented geographically by census tract, could be used to predict change from non-impervious surface covers (i.e., open land, low density forest cover, high density forest cover and contiguous forest canopy) to impervious surface between 1985 and 2005. Global and stratified region approaches to data analysis were used in a series of step-wise regressions. Classified Landsat Thematic Mapper satellite imagery of Toronto acquired in 1985 and 2005 was used to map the land use transitions to impervious surface. Overall, results show that land cover change toward impervious surface cover was correlated with the predictor variables of education level, primary language spoken and dwelling age. Model predictive ability was significant for both global and regionally stratified approaches and accounted for 30% and between 26 to 76%, respectively.

 

Adriano Nicolucci, Research Assistant ('10 - '12)


An unwelcome neighbour: the shady side of Acer platanoides

Norway Maple (Acer platanoides) is ubiquitous in most North American cities. Native to continental Europe, its planting was encouraged to replace dead and dying elm (Ulmus spp.) in the mid-1960s. It was selected for its urban-hearty traits including tolerance of air pollution and soil compaction, rapid growth, and high shading potential; its invasive traits went unreported until the early 1990s.


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Adriano Nicolucci


An unwelcome neighbour: the shady side of Acer platanoides

Norway Maple (Acer platanoides) is ubiquitous in most North American cities. Native to continental Europe, its planting was encouraged to replace dead and dying elm (Ulmus spp.) in the mid-1960s. It was selected for its urban-hearty traits including tolerance of air pollution and soil compaction, rapid growth, and high shading potential; its invasive traits went unreported until the early 1990s. Norway Maple easily outcompetes (and replaces) native plants in urban ravines and natural spaces, largely resulting from its shade tolerance. This project investigates the spatio-temporal colonization of Norway Maple into a small forested urban ravine (10 ha) in Toronto, Canada. Completely surrounded by a residential neighbourhood, this ravine is believed to have remained free of Norway Maple until the 1970s. Using a transect-based study design we investigate the abundance and age of Norway Maples along nine randomly placed 5m swaths bisecting the ravine. Hemispheric photography is used to measure light penetration at the canopy floor. Results show a clear spatio-temporal trend in the movement of Norway Maple from the periphery of the ravine to its interior. Trees within 50 m of the ravine's boundary are significantly larger (p<0.05) and more numerous than those found in the interior (100m from ravine edge). Canopy light penetration in the forest understory is significantly darker where Norway Maple are abundant. Due to the invasiveness of this unwelcome neighbour, aggressive strategies that promote native species and highlight the importance of programs to control invasive plants are needed to maintain (and restore) indigenous flora.

 

Suzanne E. Kershaw (Briggs), MSA ‘10


A day of extreme heat and humidity: a spatio-temporal index for heat vulnerability assessment

The public health consequences of extreme heat events are felt most intensely in metropolitan areas where population density is high and the presence of the urban heat island (UHI) phenomenon exacerbates the potential for heat exposure. The purpose of this research was to develop a metric for mapping exposure to heat using meteorological data that would assist public health decision makers in assessing locations of potential vulnerability within their communities.


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Suzanne E. Kershaw (Briggs)


A day of extreme heat and humidity: a spatio-temporal index for heat vulnerability assessment

The public health consequences of extreme heat events are felt most intensely in metropolitan areas where population density is high and the presence of the urban heat island (UHI) phenomenon exacerbates the potential for heat exposure. The purpose of this research was to develop a metric for mapping exposure to heat using meteorological data that would assist public health decision makers in assessing locations of potential vulnerability within their communities. Furthermore, this study will stimulate conversation about the value of establishing urban networks of meteorological stations for long-term heat vulnerability monitoring. In this study we use geostatistics (ordinary kriging) to interpolate apparent hourly prediction surfaces describing apparent temperature (humidex index) across the Greater Toronto Area (GTA), Canada. Meteorological data were obtained from 65 locations for six days in 2008 when extreme heat alerts were issued for the City of Toronto. We develop a humidex degree hours (HDH) index that integrates apparent temperature intensity and duration into one metric. Results show a significant difference in humidex values between urban and rural locations; this discrepancy is greatest at 3 AM (3.8°C), t(42) = 6.362, p<0.000. A cumulative heat exposure map, showing humidex degree hours (HDH) ≥30°C, identifies the downtown core of the City of Toronto and much of Mississauga (west of Toronto) as likely to experience dangerous levels of prolonged heat and humidity (HDH ≥ 65) during a heat alert. We recommend that public health officials use apparent temperature and exposure duration when developing spatially explicit heat vulnerability assessment tools; HDH is one approach that unites these risk factors into a single metric.

 

Aaron Pothier, MSA ‘10


Institutional valuation of tree cover in a city centre: an urban forest management opportunity

A well-managed urban forest delivers essential environmental services to the city in which it grows. Few entities are better positioned to provide consistent broad-scale maintenance and protection of urban trees than are large downtown institutions. In this study, we investigate the structure and function of an urban forest growing on a large institutional property in the city centre of Toronto, Canada.


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Aaron Pothier


Institutional valuation of tree cover in a city centre: an urban forest management opportunity

A well-managed urban forest delivers essential environmental services to the city in which it grows. Few entities are better positioned to provide consistent broad-scale maintenance and protection of urban trees than are large downtown institutions. In this study, we investigate the structure and function of an urban forest growing on a large institutional property in the city centre of Toronto, Canada. In total, 584 trees comprising 41 species were inventoried and their characteristics modeled using i-Tree ECO and STREETS. Five tree species were determined to dominate this forest (66%), with Green Ash (highly vulnerable to the Emerald Ash Borer) accounting for 16% of all trees and delivering the highest value of ecological services. The annual worth of environmental services provided by the entire urban forest was estimated at US$15,453 in 2009, and its compensatory value assessed at US$543,367. An economic benefit-to-cost analysis of investment in tree maintenance produced a ratio of 1.32:1; monetization of the aesthetic value of trees would increase this ratio in favour of benefits. Our approach to the design of this study provides a roadmap easily followed by other institutions to assess the ecological benefits flowing from their current and future tree population.

 

Melissa Torchia, MASc ‘09


Vegetation placement for temperature moderation in an urban microclimate

Inhabitants of densely settled urban centres are especially vulnerable to the impacts of elevated summertime temperatures. Strategic selection and placement of vegetation is one approach to mitigating microclimatic heating in the urban core. To evaluate the temperature-moderating influence of trees and vines, a total of 13 pairs of temperature loggers were installed on eight buildings in downtown Toronto, Canada.

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Melissa Torchia


Vegetation placement for temperature moderation in an urban microclimate

Inhabitants of densely settled urban centres are especially vulnerable to the impacts of elevated summertime temperatures. Strategic selection and placement of vegetation is one approach to mitigating microclimatic heating in the urban core. To evaluate the temperature-moderating influence of trees and vines, a total of 13 pairs of temperature loggers were installed on eight buildings in downtown Toronto, Canada. The loggers were positioned 5 m above the ground, such that one logger in each pair was shaded by vegetation while the other received unobstructed solar radiation; all other substantive physical characteristics (building aspect, construction material) were held constant. The temperature-moderating benefits of perennial vines (Parthenocissus tricuspidata), solitary mature trees, and clusters of trees were compared and the effect of species, size, proximity to building, and location relative to solar path were also assessed. A linear mixed model approach was employed to evaluate the longitudinal study data, which were collected every 10 minutes over a six-month period. Significant temperatures differences between paired loggers were observed; in one instance, a difference of 11.7 °C was recorded. Overall, vegetation on the west-facing aspect of built structures provided the greatest temperature moderation. Large mature trees growing within 0 to 5 m of buildings showed the greatest ability to moderate microclimatic temperature, with those growing in clusters providing limited additional benefit compared with isolated trees. Perennial vines proved as effective as trees at moderating temperatures on the south and west sides of buildings (p>0.05), providing an attractive option where lack of soil or space precludes the use of trees. These results provide valuable insights for urban planners seeking to limit climate change by reducing demand for energy-intensive air conditioning.

 

Anna Banaszewska, MSA ‘09


Spatial investigation of photosynthetically active radiation (PAR) and its role in natural regeneration of Quercus rubra: a case study of Kew Gardens Park, Toronto

This research addresses recent concern that natural regeneration of red oak (Quercus rubra) may be declining in eastern North America. It examines the role of understory canopy light, measured as photosynthetically active radiation (PAR), in supporting natural regeneration of red oak within a naturalized area of urban park, located in Kew Gardens, Toronto.

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Anna Banaszewska


Spatial investigation of photosynthetically active radiation (PAR) and its role in natural regeneration of Quercus rubra: a case study of Kew Gardens Park, Toronto

This research addresses recent concern that natural regeneration of red oak (Quercus rubra) may be declining in eastern North America. It examines the role of understory canopy light, measured as photosynthetically active radiation (PAR), in supporting natural regeneration of red oak within a naturalized area of urban park, located in Kew Gardens, Toronto. PAR was recorded at three instances during spring and early summer by taking measurements in the forest understory (2 m above ground) and near ground level (20 cm above ground). Ordinary kriging was used to generate prediction surface maps for PAR light levels; these were complemented with spatial delineations of optimal light level probability thresholds. Overall, light availability was demonstrated to be a major limiting resource for natural regeneration of this tree species. Specifically, results show that at the beginning of the growing season, PAR levels were favourable for regeneration but dropped significantly in most areas as the season progressed. In contrast, in those areas where optimal light levels were recorded throughout the data collection period (April to June), an abundance of seedlings were found. Thus low PAR levels, found especially in May and June, may be seriously curtailing germination and seedling establishment in most of Kew Gardens’ naturalized areas. These findings have the potential to directly impact ground-level forest management strategy; PAR prediction surfaces could be used to select areas for understory thinning and removal of aggressive shade-tolerant colonizing vegetation.

 

Carolina Molina, MSA ‘09


Spatial variability in hurricane damage intensity across a forested urban park: Juan’s impact on Point Pleasant Park, Halifax, Nova Scotia, Canada

Remote sensing techniques have been used effectively in both near real-time and post-event analyses of broad-extent disturbances within forested landscapes. In this project, high spatial resolution imagery (0.6 m pansharpened Quickbird data) was used to map forest disturbance in Point Pleasant Park, Halifax, Nova Scotia, Canada caused by Hurricane Juan in fall 2003.

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Carolina Molina


Spatial variability in hurricane damage intensity across a forested urban park: Juan’s impact on Point Pleasant Park, Halifax, Nova Scotia, Canada

Remote sensing techniques have been used effectively in both near real-time and post-event analyses of broad-extent disturbances within forested landscapes. In this project, high spatial resolution imagery (0.6 m pansharpened Quickbird data) was used to map forest disturbance in Point Pleasant Park, Halifax, Nova Scotia, Canada caused by Hurricane Juan in fall 2003. To identify location and intensity of damage, image differencing of atmospherically corrected 2002 and 2004 Normalized Difference Vegetation Indices (NDVI) was used. A thresholding approach, based on known forest damage intensity, was applied to classify the difference image according to non-damaged forest, moderate to severely damaged, and complete canopy loss. Moderate to severe forest damage intensity was found to have occurred in 16% of the park; whereas 28% of park trees experienced complete canopy loss. Remaining forest showed little to no appreciable damage. A Getis Gi* analysis of damage patterns revealed the presence of significant spatial clustering of damage intensity. Physical landscape characteristics (slope and aspect) as well as soil and vegetation type were variably correlated with damage intensity, suggesting their role in predisposing forest to damage. Uninvestigated variables, including stand age and tree condition, as well as random downbursts of wind during the hurricane, are believed to be additional explanatory factors that contributed to observed damage patterns.

 

Senna Sabir, MASc ‘09


Structure of a forested urban park: implications for strategic management

Informed management of urban parks can provide optimal conditions for tree establishment and growth and thus maximize the ecological and aesthetic benefits that trees provide. This study assesses the structure, and its implications for function, of the urban forest in Allan Gardens, a 6.1 ha downtown park in the City of Toronto, Canada, using the Street Tree Resource Analysis Tool for Urban Forest Managers (STRATUM).

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Senna Sabir


Structure of a forested urban park: implications for strategic management

Informed management of urban parks can provide optimal conditions for tree establishment and growth and thus maximize the ecological and aesthetic benefits that trees provide. This study assesses the structure, and its implications for function, of the urban forest in Allan Gardens, a 6.1 ha downtown park in the City of Toronto, Canada, using the Street Tree Resource Analysis Tool for Urban Forest Managers (STRATUM). Our goal is to present a framework for collection and analysis of baseline data that can inform a management strategy that would serve to protect and enhance this significant natural asset. We found that Allan Garden’s tree population, while species rich (43), is dominated by maple (Acer spp.) (48% of all park trees), making it reliant on very few species for the majority of its ecological and aesthetic benefits and raising disease and pest-related concerns. Age profiles (using size as a proxy) showed a dominance of older trees with an inadequate number of individuals in the young to early middle age cohort necessary for short- to medium-term replacement. Because leaf area represents the single-most important contributor to urban tree benefits modelling, we calculated it separately for every park tree, using hemispheric photography, to document current canopy condition. These empirical measurements were lower than estimates produced by STRATUM, especially when trees were in decline and lacked full canopies, highlighting the importance of individual tree condition in determining leaf area and hence overall forest benefits. Stewardship of natural spaces within cities demands access to accurate and timely resource-specific data. Our work provides an uncomplicated approach to the acquisition and interpretation of these data in the context of a forested urban park.

 

Brahma Toleti, MSA ‘08


Drought in the city: soil moisture implications for a forested urban park in downtown Toronto, Canada

For trees in densely built urban settings, already under stress as a result of their surroundings, the increased risk of droughts predicted as a consequence of global climate change adds to the pressure they face. This study examined soil characteristics in a downtown Toronto park in summer 2007, the driest in 50 years. Bulk density, compaction and soil moisture levels were measured at 117 sample locations in Allan Gardens in early May to capture baseline readings at 76 mm and 200 mm (the soil zone where most fibrous roots absorb water).

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Brahma Toleti


Drought in the city: soil moisture implications for a forested urban park in downtown Toronto, Canada

For trees in densely built urban settings, already under stress as a result of their surroundings, the increased risk of droughts predicted as a consequence of global climate change adds to the pressure they face. This study examined soil characteristics in a downtown Toronto park in summer 2007, the driest in 50 years. Bulk density, compaction and soil moisture levels were measured at 117 sample locations in Allan Gardens in early May to capture baseline readings at 76 mm and 200 mm (the soil zone where most fibrous roots absorb water). Soil moisture measurements were then taken prior to, and following, a precipitation event that terminated a prolonged dry period spanning July and August. Using ordinary kriging, the data were converted into two-dimensional prediction surfaces mapping soil characteristics. Spatial variability was noted in all characteristics, with compaction levels in some areas exceeding the threshold that restricts root growth. During the prolonged period without rainfall, soil moisture levels in many areas dropped below the permanent wilting point for plants, potentially affecting tree health and longevity. The first of its kind to monitor and map soil moisture conditions across a forested urban park, this study points to the importance of minimizing compaction and building soil organic matter to enhance tree health and help regulate soil moisture levels when summer precipitation is sporadic or absent. Such management practices will assist in building the resilience of urban forests in the face of climate change.

 

Kamal Paudel, MSA ‘08


Naturalization as a strategy for improving soil physical characteristics in a forested urban park

Ensuring good soil quality is essential to promoting plant growth in urban parks and building ecological resilience into a cityscape. Periodically used to restore a degraded urban ecosystem, parkland naturalization is a management approach designed to facilitate the return of an area to a natural state by largely discontinuing maintenance activities and restricting public access.

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Kamal Paudel


Naturalization as a strategy for improving soil physical characteristics in a forested urban park

Ensuring good soil quality is essential to promoting plant growth in urban parks and building ecological resilience into a cityscape. Periodically used to restore a degraded urban ecosystem, parkland naturalization is a management approach designed to facilitate the return of an area to a natural state by largely discontinuing maintenance activities and restricting public access. This study investigates the potential for parkland naturalization to improve soil quality in a forested portion of Kew Gardens Park, Toronto, Canada by comparing soil physical properties in three six-year-old naturalization enclosures with those found in adjacent managed parkland. Soil texture, compaction, bulk density, and surface water infiltration rate were measured at 104 sample sites, while ordinary kriging was used to interpolate two-dimensional prediction surfaces representative of soil properties. Sand and loamy sand were the dominant soil texture classes found across the study site. Highly compacted soil (>2,000 kPa) and soil with a bulk density >1.8 Mg/m3 (values sufficiently elevated to restrict tree root growth and respiration and impair soil water infiltration) were spatially correlated with high pedestrian traffic areas and corridors used by festival and park maintenance vehicles. In contrast, compaction and bulk density measurements in the naturalized areas were at or below thresholds known to impair root function (X at 10 and 30 cm depth: 849 and 1,311 kPa, 1.15 and 1.51 Mg/m3, respectively). Similarly, water infiltration rates were rapid (470 mm=hr) within the naturalization enclosures but retarded to the point of surface pooling in parkland subjected to regular public use. In the absence of quantitative baseline data, our use of spatial analysis demonstrates that parkland naturalization is a good management practice for restoration of soil physical characteristics. While our results show improvements to soil properties in a relatively short period of time, variability in the soil response rate to parkland naturalization will be dependent upon disturbance history as well as on soil and climate type.

 

Harry Morrison, MSA ‘08


Estimating land cover distribution and change in Toronto from 1985-2005

The purpose of this study was to estimate the change in abundance and distribution of the predominant land cover surfaces within the City of Toronto between 1985 and 2005. Two Landsat Thematic Mapper satellite images (1985 and 2005) were classified into seven land cover classes. Citywide percentages and associated area of land cover changes were calculated in order to investigate the dynamic composition of Toronto’s landscape with respect to pervious/impervious surfaces, and the density of tree canopy coverage.

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Harry Morrison


Estimating land cover distribution and change in Toronto from 1985-2005

The purpose of this study was to estimate the change in abundance and distribution of the predominant land cover surfaces within the City of Toronto between 1985 and 2005. Two Landsat Thematic Mapper satellite images (1985 and 2005) were classified into seven land cover classes. Citywide percentages and associated area of land cover changes were calculated in order to investigate the dynamic composition of Toronto’s landscape with respect to pervious/impervious surfaces, and the density of tree canopy coverage. On a more local scale, municipal ward land cover change statistics were calculated in order to provide information of a finer spatial resolution with the desire to stimulate political discussion. The impetus for this study was to provide the City of Toronto with an inventory of contemporary land cover, and a trajectory of land cover change for the past two decades, so that elected officials and city planners may have enhanced knowledge with which to model the future of Toronto’s urban-ecological landscape. The most significant land cover change trends were an increase in impervious surface, and a decrease in both open land and contiguous treed areas. The most predominant land cover type in the City of Toronto, in both classification years, was impervious surface.

 

Colin Squirrell, MSA ‘07


Landscape extent response of Adirondack forest to the 1998 Ice Storm

In 1998, an unprecedented ice storm produced a wide swath of forest damage across Eastern Ontario, Southern Quebec, Northern New York State, and much of New England. This study builds upon previously collected data that mapped damage intensity immediately following the storm. It uses a time-series of six Landsat satellite images to investigate vegetation response within the heavily damaged Adirondack Forest, New York State.

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Colin Squirrell


Landscape extent response of Adirondack forest to the 1998 Ice Storm

In 1998, an unprecedented ice storm produced a wide swath of forest damage across Eastern Ontario, Southern Quebec, Northern New York State, and much of New England. This study builds upon previously collected data that mapped damage intensity immediately following the storm. It uses a time-series of six Landsat satellite images to investigate vegetation response within the heavily damaged Adirondack Forest, New York State. Forest biophysical properties were modeled using two vegetation indices: the Normalized Difference Vegetation Index (NDVI) and the Disturbance Index (DI). Using these indices, some variability in pre-storm baseline conditions was found; however, a statistically significant difference in vegetation response was observed in the first post-storm image acquired in the summer of 1998. NDVI and DI showed a rapid response in both moderately and heavily damaged forest, returning to pre-storm values within two to four years. Fieldwork conducted in July 2007 confirmed that the majority of this vegetation response was attributable to vigorous understory growth, and not a return of the upper forest canopy to pre-storm conditions.

 

Vadim Sabetski, Research Assistant ('11 - '12)


Ultra high-resolution imagery for evaluation of urban tree canopy condition

Effective assessment of canopy condition is essential to the management of trees in an urban environment. Most appraisals of tree health are reliant on an evaluation of branching structure and foliar condition, which are usually conducted by an individual standing on the ground looking up into the tree canopy. However, decline, or more localized dieback, frequently begins at the top of the tree crown and may not be readily visible in an assessment that is conducted from below. Such a circumstance is common with large stature mature trees growing in residential neighbourhoods or city parks.

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Vadim Sabetski


Landscape extent response of Adirondack forest to the 1998 Ice Storm

In 1998, an unprecedented ice storm produced a wide swath of forest damage across Eastern Ontario, Southern Quebec, Northern New York State, and much of New England. This study builds upon previously collected data that mapped damage intensity immediately following the storm. It uses a time-series of six Landsat satellite images to investigate vegetation response within the heavily damaged Adirondack Forest, New York State. Forest biophysical properties were modeled using two vegetation indices: the Normalized Difference Vegetation Index (NDVI) and the Disturbance Index (DI). Using these indices, some variability in pre-storm baseline conditions was found; however, a statistically significant difference in vegetation response was observed in the first post-storm image acquired in the summer of 1998. NDVI and DI showed a rapid response in both moderately and heavily damaged forest, returning to pre-storm values within two to four years. Fieldwork conducted in July 2007 confirmed that the majority of this vegetation response was attributable to vigorous understory growth, and not a return of the upper forest canopy to pre-storm conditions.

 

Geet (Gary) Grewal, MASc '13


Present and future delivery of ecological services by City of Toronto urban parks trees

Abstract Forthcoming

 

Michelle Blake, MASc '13


An evaluation of the potential for perennial vines to mitigate warming of the urban microclimate

Abstract Forthcoming

 

Shawn Mayhew-Hammond, MASc '13


Spatial analysis of the effect of Tillage Radish®, a soil remediating cover crop, on soil compaction and soil nutrient content in a Toronto urban park

Abstract Forthcoming

 

Ruthanne Henry, MSA '13


Spatial analysis methods for trails planning within environmentally significant areas: a case study in Toronto, Canada


In this study, spatial analysis was used to evaluate the changes in core area habitat, or those areas outside the disturbance zone of trails, within four of Toronto's priority ESAs. Results indicate that between 19 and 49% of high quality habitat (core areas) of these ESAs may be lost in the near future, (within the next 10-20 years) under a "no management" scenario where ad-hoc trails and existing uses progress unrestricted.

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Ruthanne Henry


Spatial analysis methods for trails planning within environmentally significant areas: a case study in Toronto, Canada

Natural green spaces provide many benefits to urban dwellers, but are vulnerable to the pressures of increasing use. More specifically, natural parklands are prone to ecological degradation where operational and capital management are not able to minimize impacts associated with the increasing use. Approximately 7.2% of Toronto is natural parkland distributed throughout the city area. Since 1981 many of Toronto's highest quality natural areas have been identified as Environmentally Significant Areas (ESAs) based on field inventories of flora, fauna and ecological functions. Unofficial trails have been established within these ESAs and more trails continue to be established by users of these areas and on other natural parkland. Dog walkers, hikers, off-road cyclists, as well as schools, camps and other recreational programs are the primary trail users. In this study, spatial analysis was used to evaluate the changes in core area habitat, or those areas outside the disturbance zone of trails, within four of Toronto's priority ESAs. Additionally, Vector based Landscape Analysis Tools (V-LATE) and ArcGIS software was used to both visualize and quantify changes to ESAs based upon future management scenarios. Results indicate that between 19 and 49% of high quality habitat (core areas) of these ESAs may be lost in the near future, (within the next 10-20 years) when comparing a "no management" scenario where ad-hoc trails and existing uses progress unrestricted with an "increased management" scenario. The discussion considers the results within a municipal decision-making framework including economic valuation of benefits at risk. This research provides a parks planning precedent for other cities seeking to maintain ecological resilience within urban natural areas under increasing recreational pressures.