Record Details
Fire history of the ponderosa pine forests of the Warm Springs Indian Reservation, Oregon
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Fire history of the ponderosa pine forests of the Warm Springs Indian Reservation, Oregon |
| Names |
Soeriaatmadja, Roehajat Emon, 1936-
(creator) Chilcote, W. W. (advisor) |
| Date Issued | 1965-08-11 (iso8601) |
| Note | Graduation date: 1966 |
| Abstract | Fire has played a prominent role in the development and character of the ponderosa pine forests in western North American. Its records are written in the scars of trees that have survived the fire. Careful studies of these fire-scars may be used as a means of reconstructing the fire history of the forest. This study was conducted in the Warm Springs Indian Reservation of the east side of the Cascades in Oregon, and was aimed at describing the fire history of the area in terms of frequency of occurrence, extent, and chronology, as these relate to somewhat different climate, topography, and vegetation structure found within the ponderosa pine zone in this area. Since accurate interpretation of the fire history generally required the exposure of the fire-scarred stumps through felling, the study areas were selected where tree felling was recent or in progress. Four study areas were selected within the Warm Springs Indian Reservation. These areas were located within the cutting boundaries of the Tenino Bench, Seekseequa, Boulder Creek and Lionshead logging units. A total of 305 fire-scarred stumps were sampled during the course of the study. Information concerning the character of the stand in the vicinity of the fire-scarred stumps was obtained from 100 x 100 foot plots. The fire-scarred stumps provided data pertinent to the frequency of fires during the past as indicated by the presence of successive ring scars. The date of a given fire was determined by counting the number of annual growth rings formed since the occurrence of the ring scar. For the Tenino Bench area, numbers of successive ring scars observed on the stumps ranged from 5 to 23 with an average 9.4 per stump. Forty-seven percent of the total number of fire-scarred stumps sampled showed seven, eight, nine and ten successive ring scars with an average time interval of 16.5 years between the ring scars. Average minimum and maximum time intervals between the ring scars on the fire-scarred stumps observed on the Tenino Bench study area were 6.5 and 36.3 years respectively. The number of successive ring scars on individual fire-scarred stumps averaged 10.8 in the Seekseequa area. Seventy-eight percent of the trees observed here showed 7 to 12 successive ring scars. The least number of ring scars occurring on any given stump was six. The greatest number was 25. The average time interval between ring scars was 14.2 years with an average minimum interval of 6.2 years and the average maximum interval of 28.8 years. A sharp reduction in the number of successive ring scars per individual tree is noted in the Boulder Creek and Lionshead study areas located at higher elevations. Thirty-two percent of the total number of stumps examined in the Boulder Creek area showed two, three and four successive ring scars with an average of 7.2 per stump. The bulk of the trees sampled showed numbers of ring scars ranging from two to ten. On the Lionshead area 63 percent of the trees showed less than seven successive ring scars. The average number of successive ring scars per stump was 6.3. The maximum number of successive ring scars observed in this area was 14. Although the frequency of fires was higher in the two most xeric areas (Tenino Bench and Seekseequa) these fires did not appear to be as severe (as evidenced by the size of the fire-scars) as the two more mesic areas (Boulder Creek and Lionshead). The difference in frequency and severity of fires within the ponderosa pine zone appears in part related to the susceptability of the area to fire and the accumulation of the fuel materials. The greater frequency of less severe fire in the lower part of the pine zone may be due to the more open nature of the stand and the slower accumulation of fuel materials. The more moist conditions of the forest at higher elevation may explain the less frequent occurrence of fire. However, because of the more dense nature of the forest and especially the presence of young age classes of more shade tolerant tree species, once fires do become started the possibility of the fire escalating to the crown type fire is greater. Ring scar evidence during the past 400 years indicates a sharp reduction in the frequency of fire since 1900. This marked decline in the occurrence of fire reflects the effectiveness of fire control efforts instigated by Federal Agencies in recent years. Changes in the composition and structure of this forest as a result of fire exclusion are noted. |
| Genre | Thesis/Dissertation |
| Topic | Forest ecology -- Oregon -- Warm Springs Indian Reservation |
| Identifier | http://hdl.handle.net/1957/47833 |
