Abstract:

On the basis of field observation and sample plot survey, the fruiting status and basic properties of cones and seeds at different elevations of the Abies georgeivar. smithiiforest on the eastern slope of Sejila Mountain in Tibet were described, and the differences were compared with other species of Abies. The results indicated that the fruiting of Abies georgeivar. smithiihad a obvious interval period, and recurrent period of an abundant year in the natural forest was usually three years. Among different elevations, the proportions and numbers of the fruiting seed trees had big variation. The proportion of the fruiting seed trees was between 25%-80% and its average was 45%. The number of the fruiting seed trees was between 128-483 tree·hm^-2 and the average was 230 tree·hm^-2. The number of individual fruiting cones was between 24-366 and its average was 157.The fruiting characteristics of Abies georgeivar. smithiistand and the canopy were as follows: Trees in canopy layer and upper canopy fruited; the south side of canopy layer set relatively more fruits. By the comparison with other species of Abies, the cone length of Abies georgei var. smithiiwas shorter and its width was in the medium. The seed length, width and thickness of Abies georgeivar. smithiiwere smaller and seed number of individual fruit was higher. The result of multiple comparisons at different elevations showed that the development degree of cones and seeds was relatively higher at middle and low elevations, and the cones and seeds were bigger and the 1 000-grain weight, seed output and seed plumpness were better than that of higher elevation.

Key words: Abies georgeivar. smithii, southeast of Tibet, Sejila Mountain, elevation gradient, cones, seeds characteristics