关键词: 氮总矿化, 总硝化, 草地, ¹⁵N

Abstract: Based on field observation data,this paper studied the flowering phenology and the temporal and spatial dynamics of the reproductive modules of endangered plant Disanthus cercidifolius var.longipes natural populations.The results showed that there were certain differences of the flowering phenology among the populations in different communities,e.g.,in pure forest,the average flowering duration of individuals was the longest (75 d),while the flowering synchrony was the lowest (0.717 d),but in bamboo forest,the flowering duration of individuals was the shortest (47 d),while its flowering synchrony was the highest.The numbers of reproductive branches and inflorescences were increased with increasing individual age,and reached the highest at the age of 30～35yr.At the elevation of 810 m,the numbers of individual reproductive branches and inflorescences reached the peak,and there were significant differences among the crown levels.The reproductive branch number of individuals and the inflorescences per reproductive branch were the highest in pure forest,being 411.39 and 7.857,respectively,while the inflorescences per reproductive branch in bamboo forest were notably lower than those in other communities.The abortive ratio of reproductive modules of young individuals was higher than that of the older ones in the flower?bud,flowering,and fruit phases.The abortion of reproductive modules had no correlation with their distributed elevation,but some correlations existed with their development time,distributed crown levels and communities.The major factor affecting the abortive ratio of individual reproduction modules was probably the illumination condition in the distributed communities.

Key words: Gross mineralization, Gross nitrification, Grasslands, ¹⁵N isotope