Valuation and Evolution of Ecosystem Services in the Québec City Region

The importance of biodiversity and ecosystems for communities can be illustrated through the concept of ecosystem services (ES), i.e., the benefits to humans provided by nature.

In the face of climate change, natural environments and the ecosystem services they produce are under severe threat. The possibility of them disappearing is increasingly worrisome. To maintain or even increase ecosystems services that benefit the 83% of Canadians living in urban areas, development planning that integrates both natural and built infrastructures is necessary to make cities more resilient to a changing and uncertain future.

Economic valuation of these ecosystem services broadens economic horizons to represent their contribution to community well-being.

• Measure and analyse the economic benefits provided by the natural capital of Québec City and the Québec City metropolitan community (CMQ);

• Evaluate the future production of ecosystem services by the region’s ecosystems under various realistic land use scenarios.

• Assessment of the economic value of the ecosystem services provided by Québec City’s municipal tree canopy based on a municipal inventory (103,000 trees) and a field sampling campaign (data collected for 2,352 trees);

• Determination of the ecosystem services provided by the ecosystems and biodiversity in the CMQ and their economic value through a spatial analysis combined with an economic evaluation of the ecosystem services;

• Future evolution of the provision of ecosystem services in the CMQ under different future land use scenarios.

The functional value of municipal trees in Québec City is estimated at more than $625,000 per year in economic benefits arising from the ecosystem service flows evaluated in this report. The structural value of the city-managed trees, which includes cultural value and carbon storage, is estimated at $219 million.

Annualizing these results based on an average urban tree life span of 32 years, the annual value of cultural services is estimated at $6.9 million, namely $6.8 million in cultural value and $116,000 in carbon storage.

Study

This study evaluated the composition, function and economic value of the ecosystem services provided by municipal trees in Québec City. These trees represent a small fraction of the city’s total urban forest cover (about 6.7% of the total urban canopy of Québec City, which also includes private trees and public forests).

To better understand the benefits of the urban forest for the citizens of Québec City, we extrapolate the results of the municipal tree inventory analysis to all canopy areas within the urban perimeter, based on average estimates of ecosystem services per hectare. This exercise provides us with an estimate of the value of services provided by all the trees in the city (Table 1).

It should be noted, however, that this extrapolation does not take into account the species composition, size or density of private trees and public forests. In other words, it is assumed that these are similar in composition and structure to the municipal trees.

Table 1. A mean monetary value for pollution reduction services ($4,540$/T) was estimated based on the avoided health costs related to the different pollutants removed by the municipal forest cover.

The CMR and TCRQ study on natural capital value estimated the economic value of urban and peri-urban ecosystems in this area. Together, these ecosystems provide more than one billion dollars worth of annual benefits. Forest ecosystems, wetlands and waterways, agricultural land and uncultivated land are essential to the well-being of communities, providing a diversity of ES in the form of habitat for biodiversity, water supply, flood prevention, pollution reduction, and agricultural production.

These urban and peri-urban ecosystems are also an important carbon sink that stores as much as 124 million tonnes (Mt) of carbon accumulated over past centuries, corresponding to economic benefits of $18.8 billion. The stakeholders involved in the project considered water supply, recreation and tourism activities, water pollution regulation, and agricultural production as priority ES for development.

To better equip decision makers who wish to integrate the concept of ES into sustainable land management, stakeholders identified 25 policies and programs that are already in place and available to planners and decision makers.

Finally, the assessment of development scenarios explored the foreseeable impacts of urban sprawl and conservation actions on the provision of ES. The preservation of natural ecosystems in the interstitial spaces of cities plays an important role in the provision of several ES. These natural spaces will become even more important in a future marked by population growth and climate change. The conservation scenario, which focuses on the densification of residential areas and the reforestation of altered environments, demonstrates that it is possible to improve the provision of services while accommodating an increase in population without having to make significant compromises.

In conclusion, the following recommendations aim to increase the resilience of cities and rural communities to climate change:

• Increase or maintain the functional diversity of urban forests;

• Protect and develop natural environments in urban, peri-urban and rural areas;

• Raise awareness of the concept of ES among citizens and municipal stakeholders (professionals, technicians, managers, elected officials);

• Adopt an ES-based approach to land management and planning.

The participation of Ouranos in this project was in the form of expertise.

• Communauté métropolitaine de Québec

• Ville de Québec