Vegetation inventory project: Pu‘uhonua o Hōnaunau National Historical Park

Cogan, Dan; Schulz, Keith; Benitez, David; Kudray, Greg; Ainsworh, Alison

Pu‘uhonua o Hōnaunau National Historical Park (PUHO) covers approximately 177 ha (437 ac) on the southwestern coast of the island of Hawai‘i. The park was established to preserve, protect, and interpret ancient Hawaiian temples, ki‘i (wooden statues), burial sites, stone house platforms, royal canoe landing areas, royal fish ponds, sledding tracks, anchialine pools, and coastal village sites. PUHO supports over 180 vascular plant species including examples of coastal strand and wetland native plants. Most of the remaining vegetation has been extremely altered over the years and consists primarily of non-native koa hoale (Leucaena leucocephala) shrubs and kiawe (Prosopis pallida) trees with guinea (Panicum maximum) and natal redtop (Melinis repens) grasses common in the canopy openings. To better understand the distribution of the plant assemblages located on this site, the National Park Service (NPS) Pacific Island Network (PACN) Inventory and Monitoring Program (I&M) started a vegetation inventory effort at PUHO in 2007. A three-year, four phase program was initiated to complete the task of mapping and classifying the vegetation at PUHO. Phase one conducted by PACN staff in 2008, collected 42 field plots and 13 observation points. In phase two, NatureServe’s Western Regional Office used this field data in conjunction with data collected at two other West Hawai‘i parks to classify 20 new plant associations for PUHO based on the revised US National Vegetation Classification (rUSNVC). Phase three, directed by Cogan Technology, Inc produced a digital vegetation map and supporting accuracy assessment (AA) materials. In the final phase, PACN staff collected 80 accuracy assessment points in 2009/10 used to check and finalize the map. To produce the spatial database and map layer, year 2006 0.6-meter, 4-band Quickbird satellite imagery was provided by PACN. By comparing the signatures on the imagery to field and ground data 40 map units (23 vegetated, five barren or geologic, and 12 land-use / land-cover) were developed and directly crosswalked or matched to their corresponding rUSNVC plant associations. The interpreted and remotely sensed data were converted to Geographic Information System (GIS) databases and maps were printed, field tested, reviewed, and revised. The final map layer was accessed for thematic accuracy by overlaying 77 independent accuracy assessment points. The final overall accuracy of the map layer was determined to be 86% with a Kappa value of 88%. Products developed for PUHO are described and presented in this report. These include: A Final Report that includes keys to the vegetation and imagery signatures, AA information, and all of the project methods and results; A Spatial GIS Database containing spatial data for the vegetation, plots, and AA points; Digital Photos from the field sampling efforts; Metadata for all spatial data (Federal Geographic Data Committee -compliant); Vegetation Descriptions and Photo Signature Key to the map classes and associations/alliances.

Vegetation inventory project: Pu‘uhonua o Hōnaunau National Historical Park

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