Recovery Plan for the Northern Spotted Owl - DRAFT

allow redwood sprout clumps maximum development to form an upper canopyand to produce a mixed layered stand with the other species.* At 15 years, four to five sprout clumps per acre were selected and all largesaplings were removed within a 16- to 20-foot radius. Shorter seedlinggrand fir, western hemlock, and Sitka spruce were allowed to grow in theshade of the large sprout clumps. The rest of the stand was thinned at anirregular spacing, 9 to 18 feet (average about 13 feet.)* At 25 years, there was 100 percent cover within the sprout clumps, andabout 95 percent cover within the remainder of the stand with some gapsin the canopy. At this age, the stand may provide cover for dispersal,roosting, and foraging. Large redwood trees in sprout clumps could betopped to begin to produce potential nest sites.* At 40 years, the stand was multilayered within the redwood sprout clumps.It was thinned to 135 trees per acre. Two to four large trees per sproutclump were girdled for snags and logs on the forest floor.* At 40 to 50 years, this stand was multilayered, with a structure typical ofstands used by owls for nesting.Without management, this stand would not have a well-developed understory.This type of prescription could be started in older stands using the principles ofthinning around large trees to favor their development and keeping smallertrees of tolerant species in the understory to form a multilayered stand.D. Douglas-fir and Tanoak from Southwestern Oregon(Lewis 1 991)A 20-year-old Douglas-fir stand was modeled with treatments to produce amultilayered stand and without treatments. An old multilayered stand similarto stands used by owls for nesting was used as a goal, or the desired standstructure. Figure G. 14 compares the structure of the natural old growth standto the structure of the 2 modeled stands at age 135.* The managed stand was thinned to 200 trees per acre at age 20 years.* At age 50 years, the stand was thinned to about 80 trees per acre. Tanoakwere controlled to establish Douglas-fir in the openings created by thinning.These treatments minimized the establishment of openings createdby a moderately intense fire.* At age 80 years, the stand was thinned again, removing about 30 trees peracre. In practice, underburning might be considered to reduce fire hazardand duplicate the presettlement fire return interval.* By 135 years of age, a multilayered stand was achieved which resembledthe old stand used as a goal (Figure G. 14, stand C). Maximum treediameters were 40 inches compared to 52 inches in the old stand. Heightof trees in the lower layers were predicted to range from about 20 feet to 80feet. Projected crown closure was more than 70 percent. If burning weredone, there likely would be fewer conifers in the 10- to 16-inch diameterclasses in the managed stand at 135 years. The unmanaged stand was notprojected to have a multilayered structure, and maximum diameter waspredicted to be about 34 inches.E. Uneven-age Management in Mixed Conifer Forestsin Northern California (Weatherspoon and Ritchie 1991)In this case, the stand was multistoried, and it was simulated under unevenagemanagement and use of prescribed fire for 240 years (Figure G. 15). Thisexample illustrates that uneven-age management in mixed conifer forests can510