Integration of landscape-scale and site-scale metrics for prioritising investments in natural capital

The maintenance of natural capital for ecosystem service provision is crucial to humankind. Natural capital is being exhausted at a rapid rate, manifest as loss of biodiversity, declining water quality and quantity, soil erosion and atmospheric changes leading to climate change. The investment required to ameliorate the rate and scale of degradation of natural capital exceeds available financial resources. A decision process comprised of evidence based planning and transparent decisions, coupled with prioritised investment, provides the greatest environmental benefits. Multi-criteria decision analysis (MCDA) and analytic hierarchy process (AHP) are two decision analysis tools to inform investment planning and decision-making. The strength of these decision-analysis tools lies with their ability to integrate complex and disparate data and model outputs into a simple framework for ranking and prioritisation among a series of alternatives. However there are few integrative case studies at either catchment or individual site scales. The metrics used to quantify the natural capital and ecosystem services benefits provided by investments at the scale of identified hotspots are typically those deployed for regional and landscape analysis. However, site-scale metrics are important to consider when estimating the efficacy, and therefore priority, of investment because landscape scale metrics may not sufficiently represent the fine-scale variation inherent in complex ecosystems. This study applies AHP to quantify a series of weights within a MCDA framework to integrate numerous landscape-scale and site-scale metrics for the region managed by the Adelaide and Mt Lofty Ranges Natural Resource Management Board, South Australia. The landscape-scale metrics describe management priorities for various elements of natural capital, namely biodiversity, soil, water and the atmosphere. The site-scale metrics value the relevant assets that enhance natural capital and the threats to those assets. The metrics describe the health, integrity and value of aquatic habitat and terrestrial remnant vegetation at a site. AHP was used to derive weights in a workshop setting with stakeholders and field experts. The AHP was used to assess the relative importance of each metric against every other metric within the branch of a decision tree. Weights were derived using a 3-stage process: first the relative values of the landscape-scale metrics were quantified. Second, the process was repeated with the site-scale metrics. Finally, the importance of the landscape-scale metrics was weighed against the site-scale metrics. The result was a series of global weights describing the relative management priority of each regional- and site-scale factor. The decision model was applied to a dataset of sites under consideration by the Adelaide and Mt Lofty Ranges Natural Resource Management Board for funding for on-ground works that enhance natural capital for improved provision of ecosystem services. In this case the on-ground activity being funded is the improved management and protection of remnant vegetation. The model was used to calculate investment prioritisation for: i) landscape-scale hotspots; ii) fine-scale on-ground works, and iii) integration of the two scales. The inclusion of site metric in the decision model had a large bearing on the ranking of sites for investment, demonstrating the influence of site scale metrics in the decision process.