Vegetation Inventory Project: American Memorial Park [and associated files]

Cogan, Dan; Kittel, Gwen; Selvig, Meagan; Ainsworth, Alison; Benitez, David

American Memorial Park (AMME) and adjacent ocean areas cover approximately 54 ha (133 ac) on the island of Saipan in the Northern Mariana Islands. The park was established in 1978 to commemorate those who lost their lives on the Mariana Islands in military campaigns during World War II. Designated as a “living memorial,” AMME protects several historical and cultural sites and provides recreational areas for the public. AMME supports over 128 species of vascular plants (Raulerson & Rinehart 1989) including examples from coastal strand, mangrove/swamp, and woodland/forest communities. Much of the landscape has been severely altered and many non-native species dominate the park’s vegetation. However, remnant native mangrove (mangle lahi; Bruguiera gymnorrhiza) forests persist and efforts are made to mitigate previous degradation. Woodlands are generally dominated by gagu (Casuarina equisetifolia), an indigenous tree that often grows with non-native trees or shrubs such as kamachile (Pithecellobium dulce), royal poinciana (Delonix regia) or tangan-tangan (Leucaena leucocephala). Introduced grasses, such as Australian beardgrass (Bothriochloa bladhii), Napier grass (Cenchrus purpureus) and Hilo grass (Paspalum conjugatum), are common in semi-natural communities and manicured lawns. 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 AMME in 2009. A three-year, four phase program was initiated to complete the task of mapping and classifying the vegetation at AMME. PACN staff collected 11 field plots and 9 observation points in 2009 during Phase 1. In phase two, NatureServe’s Western Regional Office used this field data to classify 10 new plant associations for AMME based on the National Vegetation Classification (NVC). Phase three, directed by Cogan Technology Inc. (CTI), produced a digital vegetation map and supporting accuracy assessment (AA) materials. In the final phase, PACN staff collected 48 accuracy assessment points between 2010 and 2011 to check and finalize the map. To produce the spatial database and map layer, 0.6-meter, 4-band Quickbird satellite imagery from 2006 was provided by PACN. By comparing the signatures on the imagery to field and ground data 27 map classes (16 vegetated, three barren, and eight land-use / land-cover) were developed and directly crosswalked or matched to their corresponding NVC 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 48 independent accuracy assessment points. The final overall accuracy of the map layer was determined to be 92% with a Kappa value of 88%.

Vegetation Inventory Project: American Memorial Park [and associated files]

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