Staff Research Highlight - Comparative Valuation of Three Ecosystem Services in a Canadian Watershed Using Global, Regional, and Local Unit Values
Aziz, T., Nimubona, A.-D. & Van Cappellen, P. (2023). Comparative Valuation of Three Ecosystem Services in a Canadian Watershed Using Global, Regional, and Local Unit Values. In Sustainability 2023, 15(14), 11024. https://doi.org/10.3390/su151411024
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Figure 1. Land cover in the Grand River watershed, Ontario, Canada (data taken from the Grand River Conservation Authority, or GRCA, website: https://data.grandriver.ca/downloads-geospatial.html. Accessed on 4 May 2020).
Economic valuations of ecosystem services have long relied on the transfer of global unit values to specific geographic locations, allowing for quick assessments. However, the reliability of this approach is contingent on the credibility of transferred unit values and their relevance to the local context. In this study, authors have undertaken the valuation of ecosystem services within Ontario's Grand River Watershed to shed light on the accuracy of such valuations.
The Grand River Watershed covers an area of nearly 7000 km2, houses a population of close to one million people, and possesses a humid continental climate. The watershed is primarily characterized by agricultural land cover. The research focuses on three key ecosystem services: water filtration, nutrient cycling, and carbon sequestration.
By estimating the values of these services, the study aimed to compare ecosystem services values derived from three different sources: locally derived unit values specific to the Grand River Watershed, unit values from a regional database, and unit values compiled in the global Ecosystem Services Valuation Database (ESVD).
As expected, the regional database produced monetary values for the ecosystem services that closely aligned with those obtained using the local unit values, albeit with larger uncertainties. However, employing the ESVD yielded significantly higher monetary values for these services. Notably, the value assigned to water filtration in the ESVD surpassed regional and local estimates by more than fivefold, highlighting potential discrepancies.
In addition, the impact of aggregating forested and agricultural land categories on the valuation of ecosystem services is examined. By subdividing the forest category into deciduous, coniferous, and mixed forests, it is found that the estimated value of carbon sequestration in forested areas within the Grand River watershed decreased by 7%. This change underscores the importance of considering land cover resolution when assessing ecosystem services.
Figure 2. Total value of three ecosystem services in the Grand River watershed based on three datasets (i.e., local, regional, and global) (see Section 2.3 for details on datasets). Error bars show standard deviations. All values are in CAD 2017.
The findings of the study emphasize the need to critically assess the origin of unit values and the resolution of land cover in ecosystem services valuation, particularly when such valuations serve as vital tools for guiding policy-making. As the debate surrounding the true value of ecosystem services intensifies, this research contributes essential insights that can shape informed decision-making and foster a more sustainable future.
If you are interested in utilizing a multidisciplinary approach of ecosystem services valuation in your jurisdiction, please feel free to contact Aquanty at info@aquanty.com for more information and support.
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Abstract:
Economic valuations of ecosystem services often transfer previously estimated global unit values to the geographical setting of interest. While this approach produces quick results, its reliability depends on how representative the large-scale average unit values are for the given local context. Here, we estimate the values of three ecosystem services (ES)—water filtration, nutrient cycling, and carbon sequestration—in the Grand River watershed (GRW) of southern Ontario, Canada. The watershed covers nearly 7000 km2, has a humid continental climate and a population of close to one million people. Land cover is dominated by agriculture. We compare ES valuations using locally derived (i.e., GRW-specific) unit values to valuations based on unit values from a regional database and those compiled in the global Ecosystem Services Valuation Database (ESVD). The regional database includes mean unit values from three case studies within southern Ontario and one boreal watershed in British Columbia. As expected, the regional database yields average monetary values for the three ES that are close to those obtained using the local unit values but with larger associated uncertainties. Using the ESVD, however, results in significantly higher monetary values for the ES. For water filtration, the ESVD value is more than five times higher than the regional and local estimates. We further illustrate the effect of the extent of aggregation of forested and agricultural land categories on the ES values. For example, by subdividing the forest category into three subcategories (deciduous, coniferous, and mixed forest), the estimated value of the carbon sequestration service from forested areas within the GRW decreases by 7%. Overall, our results emphasize the importance of critically assessing the origin of unit values and the land cover resolution in ES valuation, especially when ES valuation is used as a policy-guiding tool.