Alaska LANDFIRE Application Project: Map and Classification Review in Seven Locations across Alaska Tina Boucher, Keith Boggs Lindsey Flagstad, Mike Duffy Alaska Natural Heritage Program CAS, University of Alaska Anchorage 707 A Street, Anchorage, AK 99515 907-257-2784 [email protected] 1 4°¢¨• ض #ØÆ¥•Æ¥≥ aa!wò hC CLb5LbD{ LbÇwh5Ü/ÇLhb a9ÇIh5{!//Üw!/ò !{{9{a9bÇ {ÇÜ5ò !w9! a9ÇIh5{ a9ÇIh5{v Ü![LÇ!ÇLë9 w9ëL9í {ÇÜ5ò !w9! a9ÇIh5{ w9{Ü[Ç{!//Üw!/ò !{{9{{a9bÇ{ 59b![L 9ëÇ a!t 59b![L t[hÇ !{{LDba9bÇ Çh 9/h[hDL/![ {ò{Ç9a 59b![L /[!{{LCL/!ÇLhb !bL!Y/I!Y 9ëÇ a!t !bL!Y/I!Y t[hÇ !{{LDba9bÇ Çh 9/h[hDL/![ {ò{Ç9a !bL!Y/I!Y /[!{{LCL/!ÇLhb w9{Ü[Ç{v Ü![LÇ!ÇLë9 w9ëL9í òÜYhb!/I!w[9ò b!ÇLhb![ t!wY Y9b!L CWhw5{ b!ÇLhb![ t!wY D[!/L9w .!ò b!ÇLhb![ t!wY D!Ç9{ hC ÇI9 !w/ÇL/ b!ÇLhb![ t!wY íw!bD9[[!{!LbÇ 9[L!{ b!ÇLhb![ t!wY w9/haa9b5!ÇLhb{ !/Ybhí[95D9a9bÇ{ $ w9C9w9b/9{ $ !tt9b5Ló 9wwhw a!ÇwL/9{ !bL!Y/I!Y 9wwhw a!ÇwLó 59b![L 9wwhw a!ÇwLó !tt9b5Ló íw!bD9[[!{Ç 9[L!{ 59Ç!L[95 {/w99b {IhÇ{ !b5 Ç9óÇ 2 aa!wò hC CLb5LbD{ We conducted accuracy assessments for two national park units (the north side of Denali National Park and Aniakchak National Monument) and qualitative assessments in five additional areas representing the major ecological zones across the state including boreal, boreal transition, maritime, arctic, and Aleutian. In each assessment we reviewed the Existing Vegetation Type (EVT) Map and the ecological system classification. In three assessments we also reviewed the results of the sequence table assignment of plots to EVT class. The major findings and recommendations are summarized below. Mapping: in all areas that were reviewed, we found significant errors in all the widely distributed EVT classes. The types of error included: • Low and tall shrub confused with dwarf shrub • Freshwater marsh and other wetlands mapped extensively on upper mountain sideslopes • Floodplain wetlands mapped extensively outside of the floodplain and on mesic terrain. • Rock mapped as water • Sparse vegetation mapped as barren • Coniferous forest mapped as shrub • EVT classes mapped outside of their range (maritime classes in boreal, e.g.) To fix these accuracy problems we recommend refining all of the map zones. Some of the improvements will be simple whereas others more complicated. For example, some errors appeared to be related to spectral confusion (like rock vs. water), while other problems can be improved by slope and elevation modeling. The major errors were not between closely related classes. We identified certain classes to collapse, but the major errors should be addressed before collapsing classes. Also, the floodplain and polygonal ground EVT errors can be fixed by first mapping the dominant existing vegetation, and then deriving the appropriate Ecological Systems using masks and models. Plot assignment to Ecological System: a large percentage of the plots were not keyed to a specific EVT because species data alone was not enough information to accurately classify each plot. We do not know how these plots were used in the map or if ancillary data layers were used in classification. In the plots that were classified, we found that plots were generally classified correctly, but that confusion occurred between closely related types such as low shrub and tussock tundra, or marsh and wet meadow. The errors in plot classification, however, did not occur between the same classes as the mapping errors. Collapsing classes did little to improve map accuracy. The spatial accuracy of the plots appeared to be good; however, we did not review polygon data. We recommend manually reviewing those plots that were not designed for use in landcover mapping. We found that plots collected for purposes other than landcover mapping were often not suitable for training or accuracy plots because they occurred either in transitions between landcover classes or in small inclusions within a larger class. These plots may be classified correctly, but can lead to confusion when applied as training data. 3 Ecological System Classification: Typically we interact with the image analyst to identify classes that are difficult to map and either collapse classes or modify the classification. This step was not completed but is something that can still be done to improve the map accuracy. We identified classes that may be difficult to distinguish accurately, and we made recommendations for potential combinations. We reviewed the classification and keys used to produce the sequence tables and identified areas that need clarification or review. For example, we recommend collapsing some of the dwarf shrub classes and revisiting the classification of tussock tundra. Early seral vegetation presented a problem in both classification and mapping because the vegetation indicators and spectral classes do not match those of the later seral stages. We recommend reviewing the treatment of these classes. LbÇwh5Ü/ÇLhb The Nature Conservancy and the Alaska Natural Heritage Program initiated a project to review LANDFIRE map products associated with the Statewide Alaska map produced by the LANDFIRE mapping team. The original goal was to assess LANDFIRE products, including BPS and FRCC, in Denali National Park, but because the products were not available for review, and because initial reviews from Denali and the north slope (Dan Fehringer, Ducks Unlimited) revealed a high error level in the Existing Vegetation Type (EVT) layer, the focus of the project shifted to a statewide assessment of the EVT layer, the ecological system classification, and the associated plot data. For our review, we used national park units because they generally had high quality imagery, recent land cover maps, and abundant plot data. Reviewers had on-the-ground experience in the parks reviewed. We conducted two accuracy assessments and qualitatively reviewed five additional park units. The selected parks represent the major ecological zones across the state including boreal, boreal transition, maritime, arctic, and Aleutian. Our goal was to evaluate the quality of the map and the quality of the information used to produce the map, including the ecological system classification and plot data in the LANDFIRE reference database. The results of this assessment are intended to be used to provide insight into the source of error and provide information that can be used to improve the Alaska map and classification. a9ÇIh5{!//Üw!/ò !{{9{a9bÇ {ÇÜ5ò !w9! We selected two areas in which to conduct accuracy assessments: 1) north side of Denali National Park and 2) Aniakchak National Monument (Figure 1). We chose Denali because of its location in the boreal portion of the state (map zone 73), and because we had a large existing dataset to use that had not been used in the LANDFIRE mapping process. Aniakchak National Monument is located on the Alaska Peninsula in map zone 76. We chose Aniakchak because we were able to collect accuracy assessment plots in 2009 as part of a project for the National Park 4 Service. Both areas had 1-meter IKONOS imagery (all of Aniakchak and portions of Denali) and prior landcover maps. &©ßµ≤• !¨°≥´° °∞∞¨©£°¥©ØÆ ∞≤Ø™•£¥ ≥¥µ§π °≤•° !££µ≤°£π °≥≥•≥≥≠•Æ¥≥ ∑•≤• £ØƧµ£¥•§ ©Æ ∞°≤´≥ ≥®Ø∑Æ ©Æ ≤•§ ±µ°¨©¥°¥©∂• ≤•∂©•∑≥ ∑•≤• ∞•≤¶Ø≤≠•§ ©Æ ∞°≤´≥ ≥®Ø∑Æ ©Æ 𕨨Ø∑ $%.! ÆØ≤¥® ≥©§• ض $•Æ°¨© .°¥©ØÆ°¨ 0°≤´ !.)! !Æ©°´£®°´ .°¥©ØÆ°¨ - ØƵ≠•Æ¥ '!!2 '°¥•≥ ض ¥®• !≤£¥©£ .°¥©ØÆ°¨ 0°≤´ 95#( 9µ´ØÆ(#®°≤¨•π .°¥©ØÆ°¨ 0≤•≥•≤∂• 7 234 7 ≤°Æß•¨¨(3¥ %¨©°≥ .°¥©ØÆ°¨ 0°≤´ +%&* +•Æ°© &™Ø≤§≥ .°¥©ØÆ°¨ 0°≤´ °Æ§ ',"! '¨°£©•≤ "°π .°¥©ØÆ°¨ 0°≤´ a9ÇIh5{ To quantitatively assess the accuracy of the LANDFIRE EVT classes and the reliability of the map we compared known reference plots with the mapped classification. We used an error matrix to provide a category-by-category description of error distribution (Campbell 1987, Congalton 1991, Jensen, 1996). The columns and rows of an error matrix show the number of sample units assigned to a particular map class (classification data) relative to the actual number of sample units that belong to the map class (reference data). From an error matrix the overall accuracy of the classification of a map can be quantified along with both the producer’s accuracy (or errors of omission or exclusion) and user’s accuracy (or errors of commission or inclusion). The overall accuracy is computed as the sum of all the main diagonal cells in the error matrix divided by the total number of sample units used in the error matrix. The overall accuracy shows the proportion of the classification that is correct but it does not indicate how the accuracy is distributed across the individual map classes (Story and Congalton 1986). 5 The producer’s accuracy is the sum of all correctly classified sample units in a map class divided by the total number of reference data in that map class. It indicates how well members of a particular map are classified, or shows the ease or difficulty with which members of a particular map class are correctly identified, classified or mapped by the mapping methodology. On the other hand, the user’s accuracy indicates the probability that a particular map class (classification data) would represent that map class in the reference or ground truth data. The user’s accuracy, computed as the sum of all correctly classified sample units in a map class divided by the total number of classification data in that map class, is termed a measure of reliability in specific map categories. The error of commission is computed as 100% minus the producer’s accuracy and error of omission is 100% minus user’s accuracy. We made an effort to account for variation in vegetation cover interpretation. We classified each plot using species composition data, height, structure, detailed soils maps (where available), field photos, and field notes.