Recovery Plan for the Northern Spotted Owl - DRAFT

e used to maintain a structure like that used by owls. However, if prescribedfire is used to reduce fuel accumulation and risk of an intense wildfire, then itlikely will be difficult to maintain a suitable structure in all parts of a stand forlong periods of time.* The stand was multistoried, but probably had many more small trees 1 to10 inches in diameter than would be present without fire prevention.* Two systems were used: 1) group selection to make small openings up toabout 1 acre, plus thinning among groups, and 2) small (1 to 2 acres)irregular shelterwood units to obtain regeneration and to keep large treesin the stand.* Regeneration and thinning were done every 20 years.* Prescribed underburning was used about every 40 years to reduce fuelloads and to make the stand less susceptible to a severe wildfire.Underburning was estimated to cause a reduction in numbers of trees inthe understory, but it would aid establishment of new seedlings.* The unmanaged stand lost its layered structure. Since there was nodisturbance to the overstory, large trees were projected to increase theirdensity (basal area) to well over 300 square feet per acre (Figures G. 15 andG. 16), and to form a dense canopy which would inhibit growth of trees intosize classes greater than 41 inches in diameter.This example shows that uneven-age management can be used to maintainmultilayered stands. Without disturbance to the overstory, the understorylayers would be reduced greatly over time. In these forests with a low intensityhigh frequency natural fire regime, prescribed burning is desirable to reducefuels and the chances of an intense fire which would kill all the trees. However,if fire is used, understory density is likely to be decreased for a number ofyears. These multistoried stands probably were not common prior to firesuppression and logging. Controlling stand density and obtaining regeneration,as well as fire control, will be needed to maintain these structures. If prescribedfire is used to reduce fuels and likelihood of an intense wildfire, it may not bepossible to maintain an ideal structure for owls in all parts of a stand overtime. Use of prescribed fire should be implemented on a landscape basis withburning varied over space and time.F. Multilayer and Mixed Species, East Side CascadesTypical east side Cascade multilayered, mixed species stands of ponderosapine, larch, lodgepole pine, Douglas-fir, and grand fir are projected: a) with notreatment of a stand originated by wildfire about 80 to 100 years ago, b) withheavy thinning applied to a stand which resulted from partial cutting duringthe past 80 to 90 years, and c) with light thinning applied to high densitystands which resulted following fire suppression but no partial cutting. Undernatural fire regimes, these stands would tend to be more open and probably tobe less suitable habitatfor owls (Oliver et al. 1991).* With no activity, a stand formed a very dense layer of grand fir and Douglas-firbeneath a sparse canopy of ponderosa pine (Figure G. 17, stand A).* Thinning (Figure G. 17, stands B and C) followed by natural regenerationchanged the understory to primarily grand fir and decreased ponderosapine in the overstory. This trend probably could be reversed with heavythinning and/or planting of pine. Trees with mistletoe brooms can be leftfor owl nest sites.* Risk of severe fire was high in all three systems due to slash followingtreatment or self-thinning due to crowding. Fuel management and firesuppression likely will be needed to maintain these structures (Appendix F).* Pathogens and insects killed trees of all species, added to fuel loading, anddecreased the density of the overstory. Thinning and salvage under a lowdensity scenario would help reduce effects of pathogens and insects.513