Valuation of Biodiversity Benefits (OECD)

Table 7.3 Service Risk Sub-index DevelopmentService Major threats to function* Major threats to services Potential components ofservice risk sub-indexOn-site Off-site On-site Off-siteRecreationalfishingopportunitiesBirding,hunting andgatheringopportunitiesWater qualitymaintenanceFlood damageavoidedBiological,physical andchemical threatsto wetlandBiological,physical andchemical threatsto wetlandChange in watertable depth; Alieninvasive plant /animal species;Erosion; Sea levelrise; Change insoil or plantcharacteristicsChange in watertable depth; Alieninvasive plant /animal species;Decrease infloodplain storageor roughnessBiological, physicaland chemicalthreats tolandscape featuresDelivery of excesssediments,nutrients orcontaminants(beyond wetlandfiltering capacity)Activities thatgenerate delivery ofexcess sediments,nutrients orcontaminants(beyond wetlandfiltering capacity)Excess sedimentdelivery; Increasedrunoff upslope;Change in floodfrequency; Changein floodplain slope;Change in channeln/aChange in access,property ownership,regulation and zoning;Change in land useChange in access / Change in access,property ownership; property ownership,Conversion to regulation and zoning;developed use Change in land use(agricultural/residential);excavation;drainingConversion todeveloped use:excavation,draining; Logging;FireConversion todeveloped use:excavation;drainingProjected land or wateruse that precludesservice; Waterdiversion; Logging;Fire; DredgingChange in land use•Projected population growthrates (by locale / zipcode /watershed); •Expecteddevelopment patterns in area(e.g. % impervious surface atbuildout); •Disturbance levelin adjacent area (mowing,boat traffic, agriculture,unsewered residential,channelization, invasivespecies); •Planned changesto nutrient loads, hydrologicregimes (e.g., waste waterdischarges, reservoirs, waterdiversions, groundwaterdrawdowns); •Invasivespecies spread rates.•Existing land use riskfactors: agriculture, feed lots,septic fields; •Projected landuse risk factors: waterwithdrawals; new feed lots,septic fields, logging , etc.;•Fire frequency; •Changes tohydrologic regime: floodcontrol structures, waterdiversions, groundwaterdrawdowns.•Homes in flood plainmodified, moved, destroyed;•Changes to hydrologicregime: flood controlstructures, water diversions,groundwater drawdowns.* Since services depend on function, the service risk sub-index includes risk factors related to threats tofunctions as well as threats to service flows.The explicit distribution of development in many regions can be examined through “scenarioanalysis” of growth under current zoning and regulatory conditions, or by using simplergeo-referenced indices of development. A regional planning tool called “build out” analysis is a typeof scenario analysis that considers multiple sources of risk. It combines forecasts of populationgrowth, landscape and land use data, and zoning and regulatory restrictions to evaluate effects ofdevelopment on economic and environmental conditions. In Maryland, a statistical scenario analysishas been used specifically to identify which parcels are most likely to be developed under variousregulatory and zoning conditions [Bockstael (1996) and Geoghegan et al. (1997)].Scenario analysis can involve complex models or simple correlations. A variety of variablescontribute to the level and location of development, but zoning and sewer extensions in particular havebeen shown to be strong predictors of future development. Many jurisdictions generate predictions ofpopulation growth by locale or zip code to facilitate this kind of analysis. Such projection tools can beused to show how changes in regulatory conditions will affect the size and location of wetlands at risk.The results of scenario analyses can also be used to show how the unavoidable degradation of certainwetlands will increase the expected value of the services provided by other wetlands that can be145