关键词: 东北红豆杉, 种群生殖力, 孢子叶球, 结实

Abstract:

In the Taxus cuspidata nature reserve of Muling County in southeastern Heilongjiang Province, we selected 29 males and 30 females from a population of 271 natural T. cuspidata trees found by a route-checking survey to investigate the population fecundity. The strobilus development and the fruiting status, and their relationships with various ecological factors were examined by using the method of standard branches. The results showed that the sex ratio of trees was 1 m︰2 f, and the natural T. cuspidata tree was able to sexually reproduce for many years. Male trees had fecundity when the diameter at breast height (DBH) ranged from 1.5 cm to 92 cm, while female trees had fecundity when the DBH from 9.5 cm to 68.1 cm. Male trees typically flowered at the age about 20 years earlier than female trees. The numbers of microstrobili were 3 times more than that of megastrobili, and only 1/10 megastrobili developed into seed. The numbers of strobili and seed were correlated with DBH, crown diameter and height of trees; however, no significant correlations were observed with other site factors. Numbers of strobili decreased from the upper to lower canopy layers, while the quantity of seed decreased from the middle, upper to lower canopy layers. Seed-setting rate increased from the upper to lower canopy layers. Numbers of strobili and seeds in different directions of the canopy were not uniform, but the differences weren’t significant. These reproductive characteristics of natural T. cuspidata reflected long-term adaptations to the environment, including the activities of wildlife and humankind.

Key words: Taxus cuspidata, population fecundity, strobilus, seed