Very few (if any) studies have successfully mapped ecosystem services at high resolution or over long temporal scales. However, to adequately gauge changes in services, or to map services linked to specific species (as opposed to general land cover classes), novel techniques must be developed and evaluated. Here we present an approach for historic reconstruction of species-based ecosystem services using examples from coastal British Columbia (BC) forests. We ask: 1) How has the amount of different ecosystem services changed through time?; 2) Which ecosystem services co-occur, and which appear to be mutually exclusive, across the landscape?; and 3) Which historical services can be reconstructed with the greatest accuracy? We used a set of historical aerial photographs representing original (pre-harvest) forested conditions to reconstruct ecosystem services in landscapes which have since been harvested.
Results/Conclusions
Services related to forest cover types as well as sizes and densities of individual trees were successfully reconstructed. For example, in coastal BC, a large cedar tree has enormous cultural value (for carving), as well as ecological value as large woody debris. Thus, the spatial location and abundance of services changed based on tree species composition and height, and their location and loss was linked to underlying productivity patterns. Errors in the amount and location of different ecosystem services resulted from several challenges which are likely exacerbated on historic aerial photographs. Estimates of the historic abundance of various ecosystem services can yield better estimates of the decline and recovery of services and aid in quantifying trade-offs among services in time and space.
