Abstract: Population structure and quantitative characteristics are useful information that reflect mechanism of the population formation and its relevant influencing factors. Rhodiola fastigiata is national level 2 protective plant species that presently under approximately dangerous state and has been listed in CHINA SPECIES RED LIST. We investigated its population structure and quantitative characteristics in order to provide theoretical basis for the survival mechanism and conservation of the population.A total of 304 sample plots in 76 sample area was established on the south slope, north slope, viewing platform and top of the highway near National Station for Field Observation and Research of Alpine Forest Ecosystem, located in Sejila mountain, Linzhi, Tibet.R. fastigiata mainly distributes in six communities in the Sejila mountains: Abies georgei var. smithii forest (P1), Sabina saltuaria forest (P2), Rhododendron aganniphum shrub (P3), Salix pilosomicrophylla shrub (P4), R. lepidotum shrub (P5) and S. sclerophylla shrub (P6). The average density of R. fastigiata in the communities was ranked in the order of P3>P1>P2>P4>P6>P5 while the average basal diameter followed by the order of P6>P2>P5>P4>P1>P3. The order of P6>P2>P5>P1>P3>P4 was found for the average height, P6>P2>P1>P3>P5>P4 for the average scape number, P6>P5>P2>P1>P3>P4 for the average number of scape rings, P6>P1>P3>P2>P4>P5 for the average number of branches, and P5>P4>P3>P2>P1>P6 for the important values. The basal diameter, the height and the scape rings of R. fastigiata population have shown different deformity in different communities. With less numbers of larvae and larger number of the adult and the old, but there were obvious periodic phenomena in its seed propagation and vegetative propagation under natural condition, so it was also an increase type population. The R. fastigiata’s large breeding population cycle was 8-10 years through the scape ring analysis. The percentage of plant number with branches range within 5 to 8 was over 50% in R. fastigiata and the largest numbers of branches was up to 45, but these branches were relatively slender because of limited nutrition absorption from the roots. The number of scape distributed on lateral branches was 1~2, and accounting for 32.21%, the scape above 7 accounted for 25.82%, mainly on the main axis. On the whole, more scape was found in the main axis than in the lateral branches. The growth parameters of R. fastigiata increased with the increase of the basal diameter.

Key words: Rhodiola fastigiata, structure characteristics, quantitative characteristics, growth parameter