Methods

DATA GENERATION

This project aims to evaluate the urban factors that may influence biodiversity visitation rates in Edmonton by extracting data from the WildEdmonton program monitoring network. After filtering images using human interpreters and artificial intelligence algorithms, only wildlife images were saved and recorded in a spreadsheet. To avoid duplication, a modified version of the CamTrapR code was applied to the data, resulting in a comprehensive list of species and their corresponding frequencies recorded by each remote camera. Then, urban factors of interest were extracted using the geographic coordinates of the cameras and combined with the biodiversity data to create a final table used in this research project (Figure 5).

Figure 5. Methods Flow Diagram

This figure depicts the data frame generation process utilized for this research project. The initial raw data was collected in the form of pictures captured by 90 remote cameras strategically positioned throughout the City of Edmonton. By utilizing the geographic locations of these cameras, the urban factors (GIS variables) were extracted.

STUDY AREA

Figure 6. Edmonton Landscape

View of the North Saskatchewan River in Edmonton during the Fall Season. 

Source: Ⓒ Oscar Baron-Ruiz


Edmonton Landscape


The study is conducted in the landscape of Edmonton, Alberta, Canada (Figure 6), which encompasses an abundance of natural wonders. Among them are the biggest urban park in Canada, a vast river valley that comprises the North Saskatchewan river, and various ravine systems. In this metropolitan area, the natural protected zone is estimated to cover 44 km², which constitutes nearly 6% of the city's total area (~700 km²). Edmonton boasts a remarkable biodiversity, with 50 mammal species, 150 avian species, 30 fish species, and 500 varieties of vegetation identified within its limits (City of Edmonton, 2009).


Monitoring Sites


The WildEdmonton Program initially had a monitoring network consisting of 122 remote cameras, but not all of these cameras were used in the present analysis. Some cameras were excluded due to theft or vandalism shortly after deployment. Additionally, only sites that were at least 1 kilometre apart were selected to minimize spatial autocorrelation, which can exceed the home range size of many urban species (Stevenson, 2022). Another criterion was applied to select monitoring sites, with a minimum monitoring period of 30 days required for further calculations of visitation rates and standardization of diversity data. The final number of monitoring sites included in this research was 90, which are mapped in Figure 7. 

Figure 7. Study Area map a

Spatial distribution of 90 sites of wildlife monitoring in the City of Edmonton. 

URBAN FACTORS

The research objective includes four urban factors (Figure 8): the road network, trails surrounding the city, various types of water bodies, and land cover updated to 2021. These factors are described as follows:

Figure 8. Urban factors

Maps of urban factors included in this study: the road network (a), trails surrounding the city (b), various types of water bodies (c), and land cover updated to 2021 (d). The percentages enclosed in brackets indicate the proportional representation of each attribute concerning the overall area or length occupied by the respective urban factor. 

Source: Adapted from the City of Edmonton open data portal [https://data.edmonton.ca/].

STATISTICAL ANALYSIS

For the first research question, gradient analysis was applied to establish associations between two data sets, namely urban factors and wildlife visitation rates. In this case, the biological response was explained by the urban factors gradient. The direct approach gradient was utilized, which involves ordinating the predictor variable (urban factors) first and then examining how the response variables (wildlife visits per day) are associated with that ordination. This approach allows for the exploration of the relationship between urbanization and biodiversity and provides insights into how the environment is affected by urbanization. 


The second research question was addressed using the multivariate regression tree (MRT) approach to investigate the association between multiple predictor variables (urban features) and multiple response variables (visitation rates of different species). This method identifies groups of similar observations, but differentiates these groups by imposing the predictor variables as a constraint to create clusters. For instance, a threshold for the distance from the city centre and the nearest trail (as predictor variables) can be estimated, which is then utilized to distinguish the frequency of the most commonly identified mammal species (as response variables). The analysis is carried out to determine whether these species are more or less detected depending on their distance from the threshold. These predicted thresholds will serve as baseline values to support future strategies for biodiversity protection and urban planning. 

a The location of the monitoring sites in Figure 7 has been visually exaggerated, and the geographic coordinates and site names are not included in Table 1 (Data frame) due to data management policies implemented by the City of Edmonton to safeguard biodiversity.