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Because of the falls on the Willamette River at Oregon City, the Willamette was not a major <br />salmon stream, and the Kalapuya did not utilize salmon to the extent that tribes along the <br />Columbia River did. Instead, the Kalapuya hunted game such as deer and elk, and gathered food <br />plants from the native flora. The prairies provided the majority of their food plants, including <br />camas (Camassia spp.) bulbs, yampah (Perideridia spp.) roots, and tarweed (Madia spp.) seeds. <br />Though they were not farmers in the conventional sense, they used fire to maintain habitats for <br />valued food plants just as a farmer tills and plants a field to produce a crop. In addition, they may <br />have found fire useful in hunting game, by attracting animals to browse on the fresh green <br />growth that emerges soon after a fire. During the millennia that the Kalapuya people <br />(presumably) subjected the Willamette Valley to fires, a diverse flora and fauna evolved that had <br />appropriate adaptations to avoid, withstand, or even become dependent on fire to maintain <br />suitable habitats. In some cases, these were animal and plant species occurring nowhere else in <br />the world except the Willamette Valley. <br /> <br />Thus it was a "natural" landscape shaped (most likely) by human-set fires that the first explorers <br />and settlers encountered in the early 1800's (Habeck 1961, Johannessen et al. 1970, Towle 1974). <br />Morris (1934), Johannessen (1971) and Boyd (1986) document this practice through reviews of <br />the early explorers and missionaries journals (David Douglas-1826, John Work-1834, C. Wilkes- <br />1845, B. Hines-1881, etc.). These records report that fires were set annually in late summer and <br />early fall, and covered extensive portions of the Willamette Valley. The main difficulty with the <br />historic record is that it does not clearly describe how often presettlement fires returned to any <br />given location, and that is a pertinent question that cannot necessarily be determined from the <br />historical record (Whitlock and Knox, 2002). <br /> <br />Drastic population declines resulting from introduced diseases, and ultimately, the removal of the <br />Kalapuya Indians to the Grand Ronde Reservation halted wide scale burning in the Willamette <br />Valley in the 1830's and 1840's. Without fire, wet prairies that have been left undisturbed have in <br />many cases gradually changed into ash forests, while the drier prairies and savannas have <br />succeed to oak woodlands and maple and Douglas-fir forests. <br /> <br />2. Fire Effects <br /> <br />Having established that fires likely were a significant feature of the presettlement landscape, <br />scientists began developing hypotheses regarding the specific roles that fire plays in maintaining <br />prairie habitats. Historical analyses of vegetation change at individual sites led to the <br />development of a number of hypotheses, including: <br /> <br />1) Fires occurring at frequent intervals maintained open prairie habitats and prevented <br />colonization of trees and shrubs on sites where they would be able to occur if fire was excluded; <br /> <br />2) Many herbaceous prairie species possess tolerance or even adaptation to fire as a frequent <br />influence; and <br /> <br />3) Some non-native plant species, particularly those coming from regions where fires do not <br />occur, are negatively affected by fire. <br />d <br />d 2 <br />