9101,6700HBWageninengen,herlandskGraduateSchoolofPublicandInternationalAffairs,UniversityofPittsburgh,Pittsburgh,Pennsylvania15260,USA¶GeographyDepartmentandNCSA,UniversityofIllinois,Urbana,Illinois61801,USA#InstituteofEcosystemStudies,Millbrook,NewYork,USA**DepartmentofEcology,EvolutionandBehavior,UniversityofMinnesota,StPaul,Minnesota55108,USA††EnvironmentalSciencesDivision,OakRidgeNationalLaboratory,OakRidge,Tennessee37831,USA‡‡DepartmentofEcology,FacultyofAgronomy,UniversityofBuenosAires,Av.SanMartin4453,1417BuenosAires,Argentina§§JetPropulsionLaboratory,Pasadena,California91109,eographicInformationandAnalysis,DepartmentofGeography,UniversityofCaliforniaatSantaBarbara,SantaBarbara,California93106,USA¶¶EcologicalEconomicsResearchandApplicationsInc.,POBox1589,Solomons,Maryland20688,USA10