Wet meadow and fen mapping of Sequoia and Kings Canyon National Parks: A photo interpretation mapping project of wetland resources

Pyrooz, Natalie; Nesmith, Jonathan; Cann, Corie; Frenzel, Erik; Haultain, Sylvia; Hardwick, Paul

Meadows serve a variety of ecological functions including regulating water flow, recharging groundwater, and providing wildlife habitat; however, there has been relatively little historical monitoring of these important ecosystems. They are of particular interest within Sequoia and Kings Canyon National Parks (SEKI) due to current and historic anthropogenic use and influence, as well as the important ecological and hydrological functions they provide. The Wetland Mapping Project was a joint effort of the National Park Service Inventory & Monitoring Program, Sierra Nevada Network (SIEN) and the Plant Ecology Program of SEKI to identify and map all fens and wet meadows >0.5 ha within SEKI. The main goal of the project was to produce a comprehensive spatial dataset of all target wetlands (fens and wet meadows) within SEKI. Wetland mapping was conducted by two technicians based on aerial imagery photo interpretation during the spring of 2013. Multiple years of true color and color infrared National Agriculture Imagery Program (NAIP) imagery were used to map and classify target wetlands based on color signature, texture, vegetation density, slope, and expert knowledge of park wetlands. Other key data that were used to inform mapping decisions included meadow survey data, the SEKI vegetation map, wetland mapping data from the SIEN Wetland Ecological Integrity pilot study, and the National Wetlands Inventory data. All mapping was done using Environmental Systems Research Institute (ESRI) ArcGIS 10.1 software with versioning that allowed the two technicians to work simultaneously on the same feature class. The project leads were then able to merge the technicians’ edits into a master version. This allowed for each change made to the feature class to be reviewed by the project leads and reduced the quantity of conflicts and errors in the final version prior to posting the data in the parks’ spatial data warehouse. A total of 2,307 wetland polygons and 615 fen points of peat accumulating areas were created. Seventeen polygons represent fens, 260 represent fen-meadow complexes, and the remaining 2,030 represent wet meadows. Approximately 12% of the mapped wetlands in SEKI are thought to be peat accumulating. The total area of wet meadows, fen-meadow complexes, and fens mapped was 4,223 ha, which is 1.2% of the total acreage of the two parks. Overall classification accuracy was estimated to be 83% (90% CI = 78 – 89%) based on field assessments of 138 polygons that included both target wetlands mapped by this project as well as areas that were mapped as seasonal or perennial wetlands on the SEKI vegetation map, but were deemed to not meet the definition of a target wetland for this project . When these error rates are taken into account, the estimated area of fen and wet meadows in SEKI is 6,653 ha (1.9% of the total area of the parks). The products from this project will allow managers to better understand the distribution and current status of fens and wet meadows within SEKI. This information is already being used to aid several NPS planning and monitoring efforts including the SEKI Wilderness Stewardship Plan and the SIEN Wetland Ecological Monitoring Protocol.

Wet meadow and fen mapping of Sequoia and Kings Canyon National Parks: A photo interpretation mapping project of wetland resources

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