QUANTITATIVE REMOTE SENSING OF LAND SURFACES
CONTENTS URBAN FIRE SEVERITY AND VEGETATION DYNAMICS IN SOUTHERN CALIFORNIA EVALUATION OF THE MODIS LAI/FPAR ALGORITHM BASED ON 3D-RTM SIMULATIONS: A CASE STUDY OF GRASSLAND ASSESSMENT OF WORK?OW FEATURE SELECTION ON FOREST LAI PREDICTION WITH SENTINEL-2A MSI, LANDSAT 7 ETM+ AND LANDSAT 8 OLI ASSESSMENT OF UAV-ONBOARD MULTISPECTRAL SENSOR FOR NON-DESTRUCTIVE SITE-SPECI?C RAPESEED CROP PHENOTYPE VARIABLE AT DIFFERENT PHENOLOGICAL STAGES AND RESOLUTIONS RETRIEVAL OF THE FRACTION OF RADIATION ABSORBED BY PHOTOSYNTHETIC COMPONENTS (FAPARGREEN) FOR FOREST USING A TRIPLE-SOURCE LEAF-WOOD-SOIL LAYER APPROACH , CLIMATE DATA RECORDS OF VEGETATION VARIABLES FROM GEOSTATIONARY SEVIRI/MSG DATA: PRODUCTS, ALGORITHMS AND APPLICATIONS LEAD-INDUCED CHANGES IN FLUORESCENCE AND SPECTRAL CHARACTERISTICS OF PEA LEAVES ESTIMATING FOREST LEAF AREA INDEX AND CANOPY CHLOROPHYLL CONTENT WITH SENTINEL-2: AN EVALUATION OF TWO HYBRID RETRIEVAL ALGORITHMS A SIMPLI?ED AND ROBUST SURFACE RE?ECTANCE ESTIMATION METHOD (SREM) FOR USE OVER DIVERSE LAND SURFACES USING MULTI-SENSOR DATA PHYSICALLY-BASED RETRIEVAL OF CANOPY EQUIVALENT WATER THICKNESS USING HYPERSPECTRAL DATA ESTIMATION OF LAI WITH THE LIDAR TECHNOLOGY: A REVIEW URBAN FIRE SEVERITY AND VEGETATION DYNAMICS IN SOUTHERN CALIFORNIA ABSTRACT: A COMBINATION OF SATELLITE IMAGE INDICES AND IN-?ELD OBSERVATIONS WAS USED TO INVESTIGATE THE IMPACT OF FUEL CONDITIONS, ?RE BEHAVIOR, AND VEGETATION REGROWTH PATTERNS, ALTERED BY INVASIVE RIPARIAN VEGETATION SATELLITE IMAGE METRICS, DIFFERENCED NORMALIZED BURN SEVERITY (DNBR) AND DIFFERENCED NORMALIZED DIFFERENCE VEGETATION INDEX (DNDVI), WERE APPROXIMATED FOR NON-NATIVE, RIPARIAN, OR UPLAND VEGETATION FOR TRADITIONAL TIMEFRAMES (0-, 1-, AND 3-YEARS) AFTER ELEVEN URBAN ?RES ACROSS A SPECTRUM OF INVASIVE VEGETATION COVER LARGER BURN SEVERITY AND LOSS OF GREEN CANOPY (NDVI) WAS DETECTED FOR RIPARIAN AREAS COMPARED TO THE UPLANDS THE PRESENCE OF INVASIVE VEGETATION AFFECTED THE DISTRIBUTION OF BURN SEVERITY AND CANOPY LOSS DETECTED WITHIN EACH ?RE FIRES WITH NATIVE VEGETATION COVER HAD A HIGHER SEVERITY AND RESULTED IN LARGER IMMEDIATE LOSS OF CANOPY THAN ?RES WITH SUBSTANTIAL AMOUNTS OF NON-NATIVE VEGETATION THE LOWER BURN SEVERITY OBSERVED 1–3 YEARS AFTER THE ?RES WITH NON-NATIVE VEGETATION SUGGESTS A RAPID REGROWTH OF NON-NATIVE GRASSES, RESULTING IN A SMALLER MEASURED CANOPY LOSS RELATIVE TO NATIVE VEGETATION IMMEDIATELY AFTER ?RE THIS OBSERVED ?RE PATTERN FAVORS THE LIFE CYCLE AND PERPETUATION OF MANY OPPORTUNISTIC GRASSES WITHIN URBAN RIPARIAN AREAS THIS RESEARCH BUILDS UPON OUR CURRENT KNOWLEDGE OF WILD?RE RECOVERY PROCESSES AND HIGHLIGHTS THE UNIQUE CHALLENGES OF REMOTELY ASSESSING VEGETATION BIOPHYSICAL STATUS WITHIN URBAN MEDITERRANEAN RIVERINE SYSTEMS KEYWORDS: RIPARIAN; INVASIVE VEGETATION; BURN SEVERITY; CANOPY LOSS; WILD?RE 1 INTRODUCTION ACROSS THE WORLD, WILD?RES ARE INCREASING IN FREQUENCY AND MAGNITUDE UNDER A CHANG- ING CLIMATE AND INCREASED HUMAN INTERACTION, WHICH IN TURN IMPACTS NATURAL RESOURCES, INFRASTRUCTURE, AND MILLIONS OF PEOPLE [1] CONTINUOUS LANDSCAPE CONVERSION DUE TO THE EXPANSION OF THE HUMAN POPULATION IN SOUTHERN CALIFORNIA HAS FRAGMENTED CHAPARRAL ECOSYSTEMS AND ENCOURAGED URBANIZATION TO SPREAD INTO THE WILDLANDS THIS HAS INCREASED THE POTENTIAL FOR IGNITION AND DAMAGES TO HUMAN COMMUNITIES AND SURROUNDING ECOSYS- TEMS [2,3] RIPARIAN ENVIRONMENTS SERVE AS CORRIDORS THAT PROVIDE HABITAT CONNECTIVITY FOR ?ORA AND FAUNA THROUGHOUT WILDLAND AND URBAN RIVERINE SYSTEMS THESE CORRIDORS STARKLY DIFFER FROM THE UPLAND VEGETATION IN SPECIES COMPOSITION, FUNCTIONAL TYPE, CANOPY COVER, AND MOISTURE CONTENT [4,5] THE IMMEDIATE RIPARIAN ZONE SURROUNDING MEDITERRANEAN RIVERINE SYSTEMS (MED-SYS) IS ASSOCIATED WITH DIFFERENT VEGETATION TYPES WITH HIGH RELATIVE HUMIDITY AND COOL TEMPERATURES, WHICH CAN ACT AS A BARRIER TO ?RE SPREAD THESE RIPARIAN AREAS OFTEN EXHIBIT THE RAPID RECOVERY OF PRE-?RE VEGETATION BIOMASS IN COMPARISON TO UPLAND CHAPARRAL [4,6] HYDROLOGIC DISTURBANCES CAUSED BY URBANIZATION, ESPECIALLY THE INCREASE OF DRY WEATHER BASE-?OW DUE TO IMPERMEABLE LAND COVER (“URBAN DROOL”), SIGNI?CANTLY ALTER NATIVE RIPARIAN VEGETATION DENSITY AND COMMUNITY STRUCTURE [7] COMPOUNDED BY HIGHER NUTRIENT LOADS AND HEIGHTENED DISTURBANCE FROM MORE FREQUENT ?ASH ?OODS, URBAN RIPARIAN ENVIRONMENTS ENCOURAGE INVASIONS AND RAPID SETTLEMENTS OF OPPORTUNISTIC AND INVASIVE VEGETATION SPECIES [8–11] SINCE 2002, THE NUMBER OF ?RES UNDER 5 KM2 IN THE URBAN RIPARIAN ENVIRONMENT HAS INCREASED IN SOUTHERN CALIFORNIA [12] THIS CAN BE ATTRIBUTED TO HUMAN IGNITION SOURCES FROM TRANSPORTATION CORRIDORS, RECREATION, POWERLINES, AND PEOPLE EXPERIENCING HOMELESSNESS [2,13,14] FURTHER, INVASIVE PLANT INFESTATIONS INCREASE THE DENSITY OF VEGETA- TION BIOMASS, WHICH PROFOUNDLY ALTERS RIVERINE HYDROLOGY AND GEOMORPHOLOGY AND ALSO IMPACTS ?RE BEHAVIOR AND FREQUENCY WITHIN THESE SYSTEMS [13–15] THE UNIVERSAL INFESTATION OF NON-NATIVE VEGETATION THROUGHOUT THE STREAM AND RIVER SYSTEMS OF COASTAL CALIFORNIA IN CONJUNCTION WITH HUMAN IGNITION SOURCES HAS ARGUABLY INSTITUTED A NEW REGIME OF INVASIVE GRASS–?RE FEEDBACK CYCLES WITHIN THE URBAN ENVIRONMENT [14–16] THE IMPACT OF INVASIVE SPECIES INFESTATION ON ?RE BEHAVIOR, SPECI?CALLY IN THE URBAN ENVIRONMENT, HAS NOT BEEN PREVIOUSLY DOCUMENTED STUDIES INDICATE THAT AS CLIMATE AND OTHER ANTHROPOGENIC ALTERATIONS, SUCH AS DROUGHT, HUMAN IGNITION SOURCES, VEGETATION TYPE CONVERSION, AND FUEL ACCUMULATION, INTENSIFY, RIPARIAN ENVIRONMENTS IN SOUTHERN CALIFORNIA ARE CHANGING FROM ?OOD-DE?NED TO ?RE-DE?NED ECOSYSTEMS [10,15,17] HOWEVER, FURTHER RESEARCH IS NEEDED TO DESCRIBE THE IMPACT OF INVASIVE SPECIES ON ?RE PATTERNS AND ECOSYSTEM RECOVERY THROUGHOUT THE URBAN LANDSCAPE, AND TO PROVIDE INFORMATION FOR IDENTIFYING AND PRIORITIZING MANAGEMENT TECHNIQUES THERE IS AN INNATE AND IRREPLACEABLE VALUE IN IN-?ELD SURVEYS; HOWEVER, MODERN MONITORING APPROACHES WILL IMPROVE OUR ABILITY TO CAPTURE UNIVERSAL PATTERNS OF POST-?RE VEGETATION DYNAMICS ACROSS URBAN RIPARIAN ENVIRONMENTS, AS WELL AS PROVIDING RAPID AS- SESSMENTS AFTER ?RES ONE METRIC THAT PROVIDES CONTEXT FOR THE BIOPHYSICAL DISTURBANCE OF VEGETATION, AS WELL AS THE SOCIO-ECONOMIC IMPACT OF A ?RE, IS BURN SEVERITY [16] TWO WIDELY USED INDICES TO MEASURE THE EFFECT OF ?RE ON BIOMASS ARE THE DIFFERENCED NORMALIZED BURN RATIO (DNBR) AND THE DIFFERENCED NORMALIZED DIFFERENCE VEGETATION INDEX (DNDVI) GENER- ALLY, BOTH REMOTE SENSING INDICES ARE USED TO QUANTIFY THE LOSS OF BIOMASS OR ORGANIC MATTER WITH RESPECT TO THE PRE-?RE CONDITIONS OF AN ECOSYSTEM ALMOST ALL PREVIOUS STUDIES FOUND THAT DNBR HAD THE STRONGEST RELATIONSHIP WITH IN-?ELD OBSERVATIONS OF BURN SEVERITY [18] HOWEVER, THE DEVELOPMENT OF THESE METRICS FOCUSED ON THE MEASUREMENT AND DE?NITION OF BURN SEVERITY WITHIN BOREAL FORESTS AND UPLAND CHAPARRAL ENVIRONMENTS [18], WHILE THE EFFECT OF ?RE ON RIPARIAN ECOSYSTEMS IS GENERALLY UNDERREPRESENTED [4,19] THERE IS A NEED TO UNDERSTAND THE MEASUREMENT AND SENSITIVITY OF BURN SEVERITY METRICS IN MEDITERRANEAN RIPARIAN AREAS, MOST NOTABLY IN URBAN AND WILDLAND–URBAN INTERFACE (WUI) ENVIRONMENTS, WHICH ARE CAPABLE OF RAPID BIOPHYSICAL CHANGES UNDER CLIMATE AND ANTHROPOGENIC IN?UENCES DEVELOPING QUANTITATIVE ASSESSMENTS FOR TO EVALUATE THE EFFECT OF ?RE ON DIVERSE RIVERINE HABITATS WITHIN URBAN AREAS WILL IMPROVE THE MANAGEMENT AND MITIGATION OF ?RE’S IMPACTS ON HUMAN SAFETY AND ECOSYSTEMS WE HYPOTHESIZED THAT THE PRESENCE OF INVASIVE VEGETATION SPECIES WOULD ALTER THE RELATIONSHIP BETWEEN THE UPLAND, RIPARIAN, AND INVASIVE ZONES’ BURN SEVERITY AND CANOPY LOSS THE MAIN OBJECTIVES OF THIS STUDY ARE TO 1) MEASURE AND COMPARE DNBR (BURN SEVERITY) AND DNDVI (CANOPY LOSS) BETWEEN UPLAND AND RIPARIAN ZONES IN URBAN ENVIRONMENTS, 2) DETERMINE IF THE PRESENCE OF INVASIVE VEGETATION SPECIES ALTERS THE RELATIONSHIP BETWEEN THE UPLAND AND RIPARIAN ZONES, BURN SEVERITY, AND CANOPY LOSS OVER TIME, AND 3) DETERMINE IF THE CURRENT BURN SEVERITY AND CANOPY LOSS INDICES ARE VALID WITHIN THE URBAN MED-SYS 2 METHODS 2 1 STUDY AREA SOUTHERN CALIFORNIA HAS A SEMI-ARID, MEDITERRANEAN CLIMATE, WHERE A PROLONGED DRY SEASON FROM LATE SPRING TO LATE FALL IS INTERRUPTED BY A RELATIVELY SHORT WET PERIOD FROM DECEMBER TO MARCH [20] THE SOUTHERN CALIFORNIA MEDITERRANEAN TYPE ECOSYSTEM (MTE) IS CHARACTERIZED BY CHAPARRAL SHRUB- AND SCRUB-DOMINATED HILLSLOPES THAT FEED INTO DOWNSLOPE TEMPERATE WOODLAND RIPARIAN CORRIDORS THIS STUDY FOCUSES ON RIPARIAN AREAS OF SOUTHERN CALIFORNIA THAT EXIST IN OR ADJACENT TO THE URBAN ENVIRONMENT THAT ARE EXHIBITING ECOLOGICAL SHIFTS TOWARDS VEGETATION COVER DOMINATED BY NON-NATIVE SPECIES WE ALSO FOCUS ON ONE OF THE MOST PROLI?C SPECIES, ARUNDO DONAX, IN URBAN AND WUI SOUTHERN CALIFORNIA DRAINAGES, AND ITS ROLE IN THE GRASS–?RE CYCLE TO REPRESENT A RANGE OF URBAN AND MEDITERRANEAN VEGETATION AND ?RE CONDITIONS, DATA FROM ELEVEN ?RES WERE COLLECTED FROM THE SOUTHERN CALIFORNIA REGION TEN ?RES WERE SELECTED FROM THE CALIFORNIA DEPARTMENT OF FORESTRY AND FIRE PROTECTION (CALFIRE) FIRE AND RESOURCE ASSESSMENT PROGRAM (FRAP) 2018 DATABASE AND ONE ADDITIONAL ?RE, ESTIMATED FROM SATELLITE IMAGERY, USED AS A CASE STUDY (FIGURE 1) ALL ?RES SELECTED HAVE THE FOLLOWING CHARACTERISTICS: OCCURRED IN SOUTHERN CALIFORNIA FROM 2007 TO 2018, THE BURNED AREA WAS LESS THAN 40 KM2, INCLUDED A RIVER OR CREEK [21] AND THEREFORE A MEASURABLE RIPARIAN CORRIDOR, AND THE ?RE WAS NEAR OR ENCOMPASSED URBAN LAND-USE [22] SEVEN ?RES INCLUDED INVASIVE VEGETATION COVER [14], AND THREE CONTROL ?RES (COLINA AND WEST FIRES) HAD NO INVASIVE COVER (TABLE 1) THE 2018 DEL CERRO ?RE WAS A SMALL URBAN ?RE THAT WAS INCORPORATED AS THE EIGHTH INVASIVE ?RE, AND THE ELEVENTH ?RE IN TOTAL IN JUNE 2018, THE DEL CERRO ?RE BURNED A SUBSTANTIAL PORTION OF THE RIPARIAN ZONE ALONG ALVARADO CREEK, A PERENNIAL AND CHANNELIZED TRIBUTARY OF THE SAN DIEGO RIVER IN CALIFORNIA THIS HUMAN-IGNITED BRUSH ?RE WAS FUELED PRIMARILY BY THE PRESENCE OF NON-NATIVE AND HIGHLY INVASIVE ARUNDO DONAX AND WASHINGTONIA SPP FIGURE 1 ELEVEN URBAN ?RES IN SOUTHERN CALIFORNIA THE LAND CLASS IS SHOWN AT 30-M RESOLUTION WITHIN EACH COUNTY 1 89% 6 51% 78 44% CANYON 0 14% 11 86% 78 53% 2 2 VEGETATION CLASSI?CATION THE CALFIRE FRAP, IN COOPERATION WITH THE CALIFORNIA DEPARTMENT OF FISH AND WILDLIFE VEGCAMP PROGRAM AND USDA FOREST SERVICE REGION 5 REMOTE SENSING LABORATORY (RSL), COMPILED LAND COVER DATA AVAILABLE FOR CALIFORNIA INTO A SINGLE STATEWIDE DATA SET THESE DATA SPAN FROM APPROXIMATELY 1990 TO 2014 DURING THIS PERIOD, THE MOST CURRENT, DETAILED, AND CONSISTENT DATA WERE COLLECTED AND COMPILED INTO THE COMMON CLASSI?CATION SCHEME, THE CALIFORNIA WILDLIFE HABITAT RELATIONSHIPS (CWHR) SYSTEM THIS VEGETATION DATASET, FVEG [23], IN COORDINATION WITH THE NATIONAL HYDROLOGY DATASET (NHD) [21] WAS USED TO CLASSIFY LAND TYPES RELEVANT TO THIS STUDY, INCLUDING: (1) RIPARIAN, (2) UPLAND, (3) CROPLAND, (4) URBAN, AND (5) WATER NON-VEGETATED LAND COVERS “WATER” AND “URBAN” WERE CLASSIFIED BY FVEG, BUT VEGETATION- BASED LAND COVER, SUCH AS CROPLAND, RIPARIAN AND UPLAND AREA, WERE NOT PRE-DE?NED THUS, WE USED VEGETATED AREAS CATEGORIZED INTO THE FVEG DATABASE BY THE SPECI?C WILDLIFE HABITAT RELATIONSHIP NAME (WHRNAME), WHICH REPRESENTS MAJOR VEGETATIVE COMPLEXES AT A SCALE SUF?CIENT TO PREDICT WILDLIFE–HABITAT RELATIONSHIPS THE FOLLOWING WHRNAMES WERE COM- BINED AS “RIPARIAN” LAND COVER FROM THE FVEG DATASET: VALLEY FOOTHILL RIPARIAN, FRESH EMERGENT WETLAND, SALINE EMERGENT WETLAND, WET MEADOW, DESERT WASH, DESERT RIPARIAN, MARSH, ESTUARINE, AND RIVERINE THE RIPARIAN COVER CREATED FROM THE FVEG DATASET WAS OFTEN NOT CONTIGUOUS THROUGH URBAN CORRIDORS, SO THE NHD DATASET WAS USED TO IDENTIFY ADDITIONAL RIPARIAN ENVIRONMENTS FROM 2008 TO 2010, CAL-IPC MAPPED ARUNDO DONAX AND OTHER INVASIVE PLANT SPECIES AT HIGH RESOLUTION IN ALL COASTAL WATERSHEDS IN CALIFORNIA FROM MONTEREY TO SAN DIEGO [14] THESE HIGH-RESOLUTION DATA WERE GENERALIZED TO INCLUDE ALL INVASIVE SPECIES, RESAMPLED AT 30-M RESOLUTION TO MATCH THE LANDSAT RASTER GRID, AND APPENDED TO THE FVEG CLASSI?CA- TIONS IN ALL ELEVEN ?RE PERIMETERS, INVASIVE VEGETATION WAS LOCATED SOLELY IN THE RIPARIAN REGION AND CLASSI?ED INDEPENDENTLY FROM EITHER RIPARIAN OR UPLAND CLASSES WITHIN THE BURN PERIMETER (TABLE 1) THE ?NAL SIX LAND CLASSI?CATIONS IN THIS STUDY INCLUDED (1) RIPARIAN, (2) UPLAND, (3) CROPLAND (4) URBAN, (5) WATER, AND (6) INVASIVE PLANTS (FIGURE 1) CROPLAND, URBAN, AND WATER CLASSI?CATIONS WERE OMITTED FROM ALL CALCULATIONS TO REDUCE NOISE FROM NON-VEGETATION FEATURES AND LAND CLASSES THAT WERE NOT PRESENT 2 3 BURN SEVERITY AND VEGETATION METRICS DIFFERENCED NORMALIZED BURN RATIO (DNBR) IDENTI?ES AREAS THAT HAVE CHANGED IN THE AMOUNT OF CHARRED PLANT MATERIAL AND SOIL, WHILE DIFFERENCED NORMALIZED DIFFERENCE VEGETA- TION INDEX (DNDVI) IDENTI?ES THE CHANGE IN THE PRESENCE OR ABSENCE OF GREEN VEGETATION LANDSAT DATA IMAGES WERE ACQUIRED AND PROCESSED PRIOR TO CALCULATING DNBR AND DNDVI METRICS AT A 30-M RESOLUTION (TABLE 2) COLLECTION 1 LEVEL 1 DATA FROM THE LANDSAT 5 THEMATIC MAPPER™OR THE LANDSAT 8 OPERATIONAL LAND IMAGER (OLI) AND THERMAL INFRARED SENSOR (TIRS) IMAGE DATA WERE COLLECTED FOR EACH ?RE BASED ON THE DATE OF IGNITION THE LANDSAT DIGITAL NUMBER (DN) WAS CONVERTED INTO A TOP OF ATMOSPHERE (TOA) RE?ECTANCE OR THE AMOUNT OF LIGHT RE?ECTED TO THE SATELLITE THE CALCULATION OF TOA FROM DN CORRECTS FOR ATMOSPHERIC CONDITIONS AND THE POSITION OF THE SUN, WHICH MITIGATES THE EFFECTS OF LIGHT SCAT- TERING IN THE ATMOSPHERE AND RESULTS IN A REDUCED HAZE AND LESS WAVELENGTH DISTORTION [24] FURTHER ATMOSPHERIC CORRECTION WAS NOT REQUIRED AS THE IMAGES SELECTED FOR THIS STUDY CONTAINED MINIMAL CLOUD COVER (LESS THAN 5% COVER) OR OTHER OBSTRUCTIONS ACQUISITION DATES FOR EACH IMAGE ARE NOTED IN TABLE 2 TABLE 2 LANDSAT IMAGERY DATES FOR EACH TIME-POINT CONDITION FOR EACH ?RE FIRE NAME IMMEDIATELY PRE-FIRE (1) IMMEDIATELY POST-FIRE (2) ONE-YEAR POST-FIRE (3) THREE-YEARS POST-FIRE (4) DEL CERRO 16 MAY 21 JUNE 19 JUNE N/A COLINA 25 JULY 11 SEPTEMBER 27 JULY 17 JULY LINCOLN 7 AUGUST 10 OCTOBER 9 AUGUST 15 AUGUST LYON 10 AUGUST 27 SEPTEMBER 29 AUGUST 3 SEPTEMBER WEST 21 JUNE 13 JULY 8 JUNE N/A BERNARDO 19 MAY 29 MAY 12 MAY 1 MAY VUELTA 6 MAY 25 JUNE 20 MAY DELUZ 11 SEPTEMBER 14 NOVEMBER 30 SEPTEMBER 2 SEPTEMBER LILAC 25 NOVEMBER 27 DECEMBER 12 NOVEMBER N/A RYE 2 DECEMBER 4 FEBRUARY 26 NOVEMBER N/A CANYON 8 OCTOBER 24 OCTOBER 27 OCTOBER N/A 2 4 DIFFERENCED NORMALIZED BURN RATIO (DNBR) NORMALIZED BURN RATIO (NBR) IS AN EFFECTIVE MEASURE OF BURN SEVERITY IN A VARIETY OF LANDSCAPES RANGING FROM FOREST TO CHAPARRAL [25] THIS INDEX CAN BE RELATED TO THE SEVERITY OF A WILD?RE IN THE ECOSYSTEM BY QUANTIFYING THE TRANSITION FROM VEGETATED TERRAIN TO DRY, ASHY SOIL THAT IS INTERSPERSED WITH BLACKENED VEGETATION [26] THE NBR IS CALCULATED BY USING THE RELATIVE DIFFERENCE IN RE?ECTANCE BETWEEN THE NEAR INFRARED (NIR) AND SHORT-WAVE INFRARED (SWIR) (EQUATION (1)) FROM LANDSAT 5 TM OR LANDSAT 8 OLI/TIRS EQUATION (1) IS BASED ON THE PHYSICAL PROPERTIES OF VEGETATION, WHERE GREEN PLANT GROWTH RE?ECTS NIR WELL, WHILE DRY, BURNED SOIL RE?ECTS HIGHLY IN THE SWIR [24,26] NBR IS THE RATIO OF THE DIFFERENCE IN PERCENT RE?ECTANCE BETWEEN THE TWO SPECTRA AND RANGES BETWEEN ?1 AND 1 NBR WAS CALCULATED FOR THE PRE-?RE, IMMEDIATELY POST-?RE, AND ONE-YEAR POST-?RE CONDITIONS FOR EACH ?RE (TABLE 2) IMMEDIATE IMAGES MEASURE THE ?RE IMPACT ON THE LAND- SCAPE, WHILE NBR AFTER ONE YEAR SERVES AS A METRIC FOR LONGER-TERM AND INDIRECT ECOSYSTEM EFFECTS OF ?RE [25] DIFFERENCING THE PRE-?RE AND EITHER IMMEDIATE OR ONE-YEAR POST-?RE NBR (EQUATION (2)) CREATES A MEASURE OF BURN SEVERITY HIGH DNBR VALUES INDICATE HIGH SEVERITY BURN DAMAGE, AND NEGATIVE TO LOW VALUES INDICATE LOW BURN SEVERITY TO INCREASING VEGETATION PRODUCTIVITY DNBR FOR EACH ?RE WAS CALCULATED USING THE THREE LANDSAT DATES TO CAPTURE THE TWO TIME-POINT CONDITIONS (TABLE 2) SEE EQUATIONS (1) AND (2) BELOW: NBR = (NIR ?SWIR) * (NIR + SWIR)?1, (1) DNBR = NBRPRE-?RE ?NBRPOST-?RE (2) BURN SEVERITY APPROXIMATED BY DNBR, RELATES THE CHANGE IN RE?ECTANCE FROM PRE-?RE TO POST- ?RE CONDITIONS TO THE SURVEYED ECOLOGICAL AND SOCIO-ECONOMIC IMPACT OF THE ?RE [18,26,27] WE UTILIZED THE BURN SEVERITY LEVELS ESTABLISHED BY LUTES ET AL [18] AND KEY AND BENSON [26]: ENHANCED REGROWTH (?500 TO ?101), UNBURNED (?100 TO 99), LOW SEVERITY (100 TO 269), MODERATE SEVERITY (270 TO 659), AND HIGH SEVERITY (660 TO 1300) 2 5 DIFFERENCED NORMALIZED DIFFERENCE VEGETATION INDEX (DNDVI) PLANT HEALTH, NDVI, WAS ESTIMATED THROUGH THE RELATIONSHIP OF CHLOROPHYLL LIGHT ABSORPTION FOR PHOTOSYNTHESIS IN THE RED (RED) WAVELENGTH WITH HIGH RE?ECTANCE IN THE NIR [28] (EQUATION (3)) A LOWER NDVI REPRESENTS BARE SOIL TO SPARSE VEGETATION (0 025–0 09) AND A HIGHER NDVI REPRESENTS GREEN VEGETATION (?0 25) [24] THE VEGETATION INDEX WAS USED TO ESTIMATE THE VEGETATION OR BIOMASS CHANGE BEFORE AND AFTER ?RE THIS APPROACH ILLUMINATES THE SPATIAL AND ECOLOGICAL SHIFTS IN VEGETATION DISTRIBUTION WITHIN THE SAMPLE ?RES AND ESTIMATES VEGETATION HEALTH THROUGH “GREENNESS” [29,30] IN FORESTED ENVIRONMENTS, DNDVI HAS A WEAKER RELATIONSHIP WITH ?ELD-BASED MEASUREMENTS OF BURN SEVERITY THAN DNBR [26] HOWEVER, IN TRAN ET AL [31], IT WAS AN EFFECTIVE MEASURE OF ?RE SEVERITY IN RIPARIAN ENVIRONMENTS (EQUATION (4)) SEE EQUATIONS (3) AND (4) BELOW: NDVI = (NIR ?RED) * (NIR + RED)?1, (3) DNDVI = NDVIPRE-?RE ?NDVIPOST-?RE (4) KEELEY AND KEELEY [32] SHOWED THAT THE TOTAL CANOPY COVER FOR CHAPARRAL SYSTEMS STABILIZES THREE YEARS AFTER A ?RE THIS STUDY USED THE THREE YEARS AFTER A ?RE TO REPRESENT A “STABILIZED” STATE OF VEGETATION TO MONITOR BOTH THE IMMEDIATE AND LONGER-TERM POST-?RE VEGETATION TRENDS, THE DNDVI FOR EACH ?RE WAS CALCULATED USING PIXEL TO PIXEL ANALYSIS BETWEEN FOUR LANDSAT DATES (PRE-?RE, POST-?RE, ONE-YEAR, THREE-YEARS) TO DESCRIBE THREE TIME-POINT CONDITIONS (TABLE 2) SPARKS ET AL [33] RELATED ?RE RADIATIVE ENERGY DENSITY (FRED: MJ M?2) AND IN-?ELD MEASUREMENTS OF PERCENT CANOPY LOSS TO REMOTELY SENSED DNDVI OBSERVATIONS BASED ON SPARKS ET AL [33], WE CATEGORIZED LEVELS OF CANOPY LOSS (APPROXIMATED BY DNDVI) AS UNBURNED (<0 005), LOW (0 005 TO 0 049), MODERATE (0 05 TO 0 199) AND HIGH (>0 2) 2 6 STATISTICAL ANALYSIS TO COMPARE BETWEEN VEGETATION CLASSI?CATIONS AND BETWEEN ?RES WITH INVASIVE VEGETA- TION AND WITHOUT, CONTROL ?RES, ?RES THAT DID NOT CONTAIN INVASIVE COVER, WERE SEPARATED INTO “UPLAND CONTROL” AND “RIPARIAN CONTROL” VEGETATION AREAS OR “CLASSES ” NON-CONTROL ?RES, REFERRED TO AS “INVASIVE ?RES” THROUGH THE REST OF THIS STUDY, WERE SEPARATED INTO “INVASIVE,” “RIPARIAN,” AND “UPLAND” VEGETATION CLASSES SATELLITE IMAGE INDICES, DNBR AND DNDVI (BURN SEVERITY AND GREEN CANOPY LOSS), WERE COMPARED BETWEEN TIME-POINT CONDITIONS (TABLE 2) BY EACH LAND CLASS FOR EACH CONTROL OR INVASIVE ?RE USING AVERAGE VALUES DERIVED FROM 30-M RESOLUTION LANDSAT DATA THE AVERAGE VEGETATION CLASS VALUES OF BURN SEVERITY AND GREEN CANOPY LOSS BY EACH ?RE WERE ALSO AVERAGED ACROSS ALL CONTROL OR INVASIVE ?RES TO COMPARE THE BURN SEVERITY AND GREEN CANOPY LOSS BETWEEN UPLAND AND RIPARIAN ZONES IN URBAN ENVIRONMENTS (OBJECTIVE 1), WE TESTED THE HYPOTHESIS THAT RIPARIAN AND UPLAND VEGETATION WOULD BE DIFFERENT FOR BOTH BURN SEVERITY AND GREEN CANOPY LOSS ACROSS ALL ?RES (HYPOTHESIS 1) TO DETERMINE IF THE PRESENCE OF INVASIVE VEGETATION SPECIES ALTERS THE RELATIONSHIP BETWEEN THE UPLAND AND RIPARIAN BURN SEVERITY AND THE CANOPY LOSS IMMEDIATELY AND OVER TIME (OBJECTIVE 2), WE HYPOTHESIZED THAT RIPARIAN AND UPLAND BURN SEVERITY AND GREEN CANOPY LOSS WOULD REMAIN DIFFERENT BETWEEN EACH TIME-POINT, SHOWING A DISPARITY BETWEEN RECOVERY EF?CACIES (HYPOTHESIS 2; SEE TABLE 2) IT WAS ALSO HYPOTHESIZED THAT THE INVASIVE VEGETATION CLASS WOULD EXPERIENCE HIGHER IMMEDIATE BURN SEVERITY AND CANOPY LOSS THAN ALL OTHER VEGETATION CLASSES IN BOTH INVASIVE AND CONTROL ?RES (HYPOTHESIS 3) LASTLY, TO DETERMINE IF THE CURRENT BURN SEVERITY AND CANOPY LOSS INDICES ARE VALID WITHIN THE URBAN MED-SYS (OBJECTIVE 3), IT WAS HYPOTHESIZED THAT THE RELATIONSHIP BETWEEN DNBR