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Application. In standard (4-week) tests of root growth potential (RGP) of western conifers, root media temperature should be maintained at 20 "C for most species, and possibly higher (23-25 "C) for low-elevation sources of ponderosa pine. A high root media temperature (30 "C) should be avoided with Douglas-fir, Pacific silver fir, noble fir and possibly other true firs because root growth in these species is inhibited by high root temperature.Abstract. Root growth in seedling transplants of Douglas-fir (Pseudotsuga menziesii (Mirb.) France), Pacific silver fir (Abies amabilis@ougl.) Forbes), noble fir (Abies procera Rehd.), lodgepole pine (Pinus contorta Dougl. ex Loud.) and ponderosa pine (Pinus ponderosa Doug. ex Laws.) began when soil temperature exceeded 5 "C. Root growth increased rapidly after 10 "C and attained maximum values at 20 "C. At 30 T, no root growth occurred in the firs; in the pines, root growth was 30 to 39% of maximum. Maximum shoot growth also occurred at 20°C. In ponderosa pine, height growth of seedlings from a high-elevation source was unaffected by cold soil, but in low-elevation seedlings it was reduced. Budburst in Douglas-fir and the pines was delayed up to 11 days by cold soil, whereas in silver fir and noble fir, it was only slightly delayed. Prior to new root growth in ponderosa pine, xylem pressure potentials and stomatal conductances during the afternoon indicated reduced stomatal opening at all soil temperatures, whereas 23 days later, stomata were open to a greater degree when temperatures exceeded 10 "C.

is the Station statistician and DANIEL D. OSWALD was a program manager (now retired),

The seasonal and spatial patterns of dispersal of white spruce (Picea glauca (Moench) Voss) seed were studied from 1986 to 1989 in floodplain stands along the Tanana River near Fairbanks, Alaska. Analysis of the 1987 crop showed that production of filled seed was strongly related to estimated production of total seed and unrelated to selected stand structural characteristics. A mathematical expression, developed to estimate dispersal of filled seed into clearcut openings, predicted dispersal between 10 and 120 meters from the edge of an opening. The pattern of wind during the seed-dispersal season was predictable and consistent with winds measured at the Fairbanks Intemati0nal Airport. The results give forest managers ways to increase natural regeneration of white spruce in interior Alaska.

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