SEV applicability to Waikato Regional Council Freshwater Ecosystem Services project
Ecosystem services describe the benefits that people obtain from ecosystems. They outline the direct and indirect contributions that ecosystems make to human well-being. Ecosystem services are directly linked to the underlying ecosystem functions, processes and structures that generate them.
Phase 3 of the Waikato Regional Council’s (WRC) Freshwater Ecosystem Services (FWES) project required numerically-based descriptors of ecosystem services which could be used to characterise freshwater ecosystem services in the Waikato Region, and which could be used in quantifying trends in the values of ecosystem services over time. The challenge was to be able to quantify the actual and potential value of ecosystem services, and the difference between these values. Such differences could then be used to guide policy and planning processes and would be especially useful for providing a method for comparing the ecosystem services such as “Regulation and Maintenance”. Ultimately this method would also provide ecosystem service measures that may be applicable across a range of spatial scales and thus could be mapped using GIS software.
To address this need, Streamlined Environmental Ltd (SEL) aquatic ecologists Dr Ngaire Phillips and Dr Rebecca Eivers (now Wai Kokopu Consulting) proposed investigating the applicability of the Stream Ecological Valuation (SEV) methodology (Storey et al. 2011) as a semi-quantitative framework from which to derive functional scores of FWES using WRC’s stream SOE monitoring data. This method provides numeric scores for the status/quality of 29 ecosystem function variables and thus may provide the measures required by WRC.
We reviewed the suitability of the Waikato Regional Council’s (WRC) existing State of the Environment (SOE) monitoring data as a basis for deriving proxy SEV function scores describing current state and potential state aligned to the FEWS. We found that approximately 85% of the 29 SEV variables could be populated using this existing data set, with 23 variables being fully covered, 2 partially covered and 4 not being directly covered by this data set. The significance of the data gaps was considered minor and could be addressed relatively easily. Based on this analysis proxy SEV scores were calculated for non-reference and reference stream sites.
We found that relatively few studies have developed methods to empirically quantify ecosystem services for freshwater ecosystems. The algorithms used in the SEV method provide a quantitative method for linking ecosystem functions to ecosystem services. Using a published methodology we matched SEV functions to ecosystem service classifications. Our analysis and resulting report has shown that the SEV method provides an effective means of deriving numeric measures for a range of ecosystem services, encompassing regulatory, provisioning, and cultural services.