The Ozette Prairies of Olympic National Park - Natural Resources ...

The Ozette Prairies of Olympic National Park - Natural Resources ... The Ozette Prairies of Olympic National Park - Natural Resources ...

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45 Figure 36. 1892-1897 Plat Map. Township 31 North, of Range 15 West of Willamette Meridian, Washington highlighting burned areas. Note the area burned (in yellow) is where Manny’s Prairie is today. The area burned (in orange) is where Sand Point Prairie is today.

Figure 37. Bracken fern (Pteridium aquilinum) on Roose’s Prairie .#480. Photograph by Fred Sharpe, 2007. Bracken fern grows throughout the Ozette Prairies, and its dead fronds burn readily enough to carry a fire and keep it burning over a large area (see Figure 37). Indeed, Lars Ahlstrom and Peter Roose were concerned enough about the fire danger posed by the previous year’s dead bracken fronds that they would burn them off each year. Myra Vanderhoof (1960) remarked that, “such a practice was necessary as a means of fire-prevention, for the dead bracken became dangerous tinder after the first warm, sunny days of spring.” According to scientific studies, bracken fern is not only well adapted to fire, it promotes fire by producing a highly inflammable layer of dried fronds every fall (Agee 1993; Frye 1956; USDA Forest Service 1937). In the Pacific Northwest western bracken fern fronds grow to 7 feet, resulting in several tons of flashy fuel per acre (McCulloch 1942). Fuel loading in areas dominated by bracken fern can be quite high (McCulloch 1942; Agee and Huff 1987). Brown and Marsen (1976) have developed a formula to estimate fuel loading using the relationship between fuel loading and the ground cover and height of bracken fern (Crane 1990). 46

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Figure 36. 1892-1897 Plat Map. Township 31 North, <strong>of</strong> Range 15 West <strong>of</strong> Willamette Meridian, Washington highlighting burned areas.<br />

Note the area burned (in yellow) is where Manny’s Prairie is today. <strong>The</strong> area burned (in orange) is where Sand Point Prairie is today.

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