Giant sequoia regeneration in group selection openings in the southern Sierra Nevada

Fire has been linked to the regeneration of giant sequoia (Sequoiadendron g iganteum) [Lindley] Buchholz but no studies have directly investigated the effects of opening size and fuel treatment on giant sequoia establishment. Giant sequoia seedling density was analyzed in 36 group selection openings harvested in 1993 at Mountain Home Demonstration State Forest, CA. The expe riment consisted of four replicates of a randomized 3 x 3 factorial design which investigated the effects of opening size and fuel treatment on giant sequoia regeneration. Small, medium, and large circular openings had averag e diameters of 15, 30, and 61 m, respectively. A total of 12 large, 12 medi um, and 12 small openings were created. Three fuel treatments were randomly applied to the openings: tractor pile and burn, broadcast burn, and lop an d scatter. Analysis of variance (ANOVA) detected no significant differences between treatments and seedling density (p < 0.05). All the treatments had low giant sequoia seedling density regardless of opening size or fuel trea tment. Regeneration was completely absent in all openings with the lop and scatter fuel treatment while small openings had low giant sequoia regenerat ion density regardless of fuel treatment. Giant sequoia seedling density wa s low because of below average annual and summer precipitation following th e creation of the openings and of low seed dispersal, The group selection s ilvicultural system attempts to simulate the structural complexity of the p rehistoric, patchy, high intensity fire regime that once existed in the mix ed-conifer forests of the southern Sierra Nevada but important ecosystem pr ocesses such as increased seed dispersal following patchy, high intensity f ire and large scale nutrient cycling are not duplicated. (C) 1999 Elsevier Science B.V. All rights reserved.