GAP REGENERATION OF SHADE-INTOLERANT LARIX GMELINI IN OLD-GROWTH BOREAL FORESTS OF NORTHEASTERN CHINA

Stand mapping and vertical and oblique tree crown projections were use d to study gap characteristics and gap effects on the regeneration and stand development of Larix gmelini. The hypothesis is that waves of a dvance Larix regeneration are recruited into the canopy layer followin g the creation of canopy openings. In old-growth Larix forests of the northern Da Xingan Ling Mts., at 52 degrees N, obliquely projected gap s (OPG) begin at a distance of 60 - 80 % of the canopy tree height fro m the southernmost stems bordering the gap and thus the OPGs may exten d beyond the northern boundaries of the vertically projected gaps (VPG ). Changes in the environment and resource availability in the OPG res ult in increased Larix sapling survival. Due to a greater incidence of light, 10 - 30 yr old OPG saplings were more abundant than saplings i n either a near-oblique projected gap (NOPG) or in the shadow of obliq uely projected crowns (SOPC). The survival of saplings more than 30-yr old was highest when they were found in the OPG of one canopy opening and the VPG of another. This means that, following recruitment into a n OPG, saplings then require the space found in a VPG to permit growth into the canopy. Thus, various-sized gaps contribute to the survival of different aged saplings by increasing the complexity of stand struc ture. Although individuals may regenerate in an OPG, successful recrui tment into the canopy requires the available growing space of a VPG. T his research suggests that shade intolerant Larix gmelini can maintain its canopy dominance without fire via gap regeneration.