Cork before cattle : quantifying ecosystem services in the Portuguese Montado and questioning ecosystem service mapping

Sammanfattning: People depend on the benefits derived from nature, so called ecosystem services (ES). ES are a promising framework to evaluate ecosystems and promote conservation, but they are also difficult to measure and visualize, and the accuracy of such efforts is questionable as a basis for land management. In this thesis, I both measured and problematized the measurement of ES. In the first part of this thesis, I used the InVEST toolkit to quantify and visualize ES for the Portuguese Montado (RQ1) and analyzed how ES provision is affected under three future scenarios: Urbanization, Cattle Intensification and Forest Improvement (RQ2). Results show that Montados have great potential to deliver both Provisioning (cork production) and Regulating & Maintaining (carbon storage and sequestration) services. Analyzing future LULC scenarios showed that Forest Improvement would result in 11.2 % more carbon storage (worth USD 2 million) and four times more cork production than Cattle Intensification. In the second part, to assess the accuracy of ES mapping, I conducted a literature review (RQ3) and tested the scientific validity of the InVEST toolkit by conducting a validity analysis of InVEST (RQ4). I found that the accuracy, transparency and reliability of ES mapping is limited by a frequent reliance on proxy methods, mismatches of scale, and subjectivity of map-makers. The validity analysis of InVEST revealed that accuracy and internal validity are case-specific and dependent on data availability. Out of 31 total input variables, five have been identified as low certainty and nine as medium certainty. Findings from the first part of this thesis suggest that decision-makers should account for ES as they contribute significantly to the landscape’s value. For the Montado a traditional, forest-centered land management is likely to increase ES provision. Results from the second part illustrate that maps and ES quantification should be treated with caution, especially if the underlying processes are not disclosed. ES maps should therefore be as transparent as possible to increase their validity and credibility. Nonetheless, mapping ES, particularly when comparing future LULC scenarios, still remains a useful tool because it provides helpful information for stakeholders and decision-makers. This thesis showed that forest-centered land management can provide higher amounts of ES while preserving the traditional character of the Montado. ES maps are a helpful tool for stakeholders to compare different land management options. However, decision-makers should be aware of the inherent drawbacks and cautious to solely base their decisions on ES maps.