Modeling future forest conditions at San Juan Island National Historical Park: A planning tool for park managers and scientists

Amoroso, Mariano; Larson, Bruce

Coniferous forests cover almost half of San Juan Island National Historical Park’s (SAJH) landscape today as they did during the park’s historical period of 1853-1871. However, during the posthistoric period (1872 to 1966), large patches of forest were cleared for agriculture in both American and English Camps (Agee 1984). Following the park’s establishment in 1966, many of these fields were not managed and dense forest stands established after the fields were released from agriculture. By 1983, tree densities in some areas ranged from 2,000 to 8,900 stems/acre (Rolph and Agee 1993). These anthropogenic changes altered the historic landscape and increased fired danger in the wildland-urban interface between the park and adjacent development. In the early 1990s the park worked with Dr. James Agee at the UW CPSU to develop a Vegetation Management Plan for the Park (Rolph and Agee 1994). Following plan recommendations, the OLYM Fire crew initiated a program of forest thinning to reduce fire hazards and accelerate the development of healthy forest stands. Between 2005 and 2008, stands in field surveys were conducted at American and English Camp to describe the structure of forest stands and to project future development. Surveys were conducted to assist in the future development of silvicultural prescriptions and long-term monitoring programs. Stands were stratified into forest cover classes using aerial photos. Following field reconnaissance, initial stand delineations were refined to 33 forest stands; 15 at American Camp and 18 at English Camp. Field surveys were conducted to quantify species composition, tree size (diameter and height), and forest age. Data were entered into the Landscape Management System (LMS) database to project stand composition in 60 years. Stand ages ranged from 20 – 165 years indicating that most stands had been manipulated following the park’s period of historic significance (i.e., more than 133 years ago). The projections of what forest stands will likely look like in the future presented in this study will assist managers in developing silvicultural recommendations and tracking of the efficacy of forest management. In addition, this documentation of current conditions combined with the future projections will facilitate development of an effective long-term monitoring strategy.

Modeling future forest conditions at San Juan Island National Historical Park: A planning tool for park managers and scientists

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