Abstract:

In order to explore the succession mechanism of Chinese fir forests,three 40 m×40 m mixed fir and broad-leaved forests were set up in blocks with similar habitats,such as altitude,slope and aspect,in the mixed forest of fir and broadleaf that have been in natural succession for about 30 years in Wuchao Mountain,Hangzhou.In the sample plot,a seed rain collector was arranged in the sample plot for two years of collection,and the litter layer,0~5 cm humus layer and 5~10 cm soil layer were collected in a sampling area of 0.20 m×0.20 m,and then bagged and marked.75 samples were taken from each plot,in a total of 450 samples,and the seed germination experiment was carried out.Our results showed that there were nine species in the seed rain,of which Cunninghania lanceolata (seed rain density 12.91 seeds/m²)and Elaeocarpus(seed rain density 7.60 seeds/m²)were the main components,accounting for 94.16% of the total.The duration of C.lanceolata seed dispersal was 70 months,with two peaks in July and October,respectively.The duration of seed dispersal of Elaeocarpus was 4 months,with a peak in November to December.Seed of C.lanceolata and Elaeocarpus were also the main species in the soil seed bank.C.lanceolata seeds were mainly stored in the litter layer.In contrast,Elaeocarpus seeds were mainly stored in the 0~5cm soil layer.The seed density and germination rate of Elaeocarpus were 2~5 times higher than those of C.lanceolata.Moreover,the composition of non-dominant species in soil seed bank varied greatly from year to year.The retention of seeds in the litter layer resulted in low seed density in the C.lanceolata forest soil,which was the main reason for the difficulty of the natural regeneration of C.lanceolata.The results indicated that,broad-leaved species could regenerate via seeds in natural succession.

Key words: Cunninghania lanceolata, Elaeocarpus glabripetalus, seed rain, seed bank