B. Fire
Lodgepole pine is easily killed by fire, as it has thin bark even when old. Trees affected by fire but not killed directly succumbed in 10-12 months to bark beetles (Ips pini and Dendroctanus ponderosae) in the 1976 Panhandle control burn. Fire decreases the seed availability on the site, because cones are not serotinous. However, removal of overstory shade and litter enhances seedling survival. Major tree competitors, western white pine, the firs and mountain hemlock, are all very susceptible to fire when young, but develop thicker bark with age, and become more resistant than lodgepole. Many understory plants such as grasses and sedges may recover rapidly after fire and some may increase with repeated fires (see Appendix D). Others may be reduced in importance or eliminated at least temporarily. Thus, response of tree regeneration to fire may vary with the ground cover present, as a result of its interference with seedling establishment.
Although fire will reduce the litter on the forest floor, the dead lodgepole needles and twigs will rapidly replenish the fine litter and, as the snags fall, heavy fuels may become very dense. (In the Rocky Mountains, half the snags fall in about 15 years). The usual increase in fuels following fire in lodgepole is in sharp contrast to the fuel reduction which occurred after fire in the primeval ponderosa pine forests, where most of the overstory survived. Fire scar and age class data indicate that some areas which burned in the primeval forest were reburned within twenty to thirty years.
Evidence for the fire history of lodgepole forests comes from several sources: (1) Fire scars are rare. The few are mostly in one community. Those on other species in lodgepole forests are also rare, with the most common, on western white pine, having a record of only two fires. (2) Charcoal is present in variable amounts in the forests. Surface charcoal collected in many stands was identified as lodgepole pine, or white pine, or non-pine species. This can separate stands where fir and hemlock were previously present from those which were only lodgepole pine. (3) Presence of very common age classes may indicate an origin after fire; they may also indicate disturbance by bark beetles or wind effects, or simply the coincidence of heavy seed years with very favorable conditions for seedling establishment, in some communities. (4) Reports by the early qualified observers (e.g. Leiberg 1900), histories of Indian activity, and park records of lightning fires provide much pertinent information.
Lightning fires are common (7 per year recently) in the Crater Lake area and were almost certainly the major ignition source in primeval lodgepole pine forests. Although some low elevation stands were probably burned by Indian-caused fires moving up slope, there was little Indian activity at high elevations where most lodgepole forests are. This situation changed drastically with the arrival of white man in the area about 1855. Fires were used in road building and caused by visitors and hunters. Grazing on the west slope was accompanied by extensive burning. Considerable fir and hemlock forest was converted to lodgepole pine by this burning, which certainly also burned some of the lodge pole already present. Our age data confirm the historical reports, with many lodgepole stands originating between 1855 and 1900, and many older ones having large age classes established then. These are particularly evident in the areas of greatest activity by white man, the west slope, Pinnacles Valley, and the general route of the Union Creek – Fort Klamath road. With fire suppression, man-caused fires and the size of lightning fires were greatly reduced. These activities of white man have thus resulted in differences from the amounts of lodgepole forest one would have expected with primeval conditions; there is more area of 75 to 120 year old stands and less of younger stands than there would have been.
