Study On Seed Rain Of Different Recovery Stages In Secondary Broad-Leaved Forest On The Tiantai Mountain Of Western Sichuan Basin Border In China

The seed rain is an essential link in the plant life history dynamic process, which can effect on species coexistence and maintain the species diversity in forest. To explore the characteristics of seed rain, and its relationship with the soil seed bank and aboveground vegetations of different recovery stages in secondary broad-leaved forest on the western margin of Sichuan basin-edged, and in-depth analysis of the secondary forest natural update the inherent law of western Sichuan basin border, With the prophase stage, the prometaphase stage and the metaphase stage as the research object, according to small sample supporting method, setting the secondary sample. Then setting 1 X 1 square meters seed rain collectors in the secondary sample. In 2013 and 2014 in August to November, in May 2015 to November, divided into 15 times to collect seed rain and in 2013 to 2015 in November,divided into 3 times to collect the soil seed bank, by statistical analysis from the following preliminary conclusions:(1) With increased the restoration time, the seed rain species showed a trend of gradually reduced. The species of seed rain in the three recovery stages consisted of 13 families and 25 species, Rosaceae was the family with the richest species,50.8% of the total seed rain. The prophase stage consisted of 11 families and 23 species, the prometaphase stage consisted of 12 families and 21 species, and the metaphase stage only consisted of 8 families and 14 species. Arbor species were more than shrub species in each stage. Each species had the wheel dynamic change characteristics.(2) With increased the restoration time, the seed density showed a trend of increase after the first reduce. The seed density of seed rain was 1549.02±9.57 ind·m-2. The prophase stage of the seed rain was the largest, but the gap among stages were small, which were within 34 to 40 ind·m-2. Arbor seed density were far more than shrub seed density in each stage, and the proportion was 94.52%,93.34%,92.38%.(3) The time of peak was different yearly in each stage. The trend of seed abundance with the time showed the simple peak curve, expect the prometaphase stage in 2015 and the metaphase stage in 2013. The peak of seed rain was in August or October. Due to the complex community structure, each species whereabouts peak, a greater difference between rainfall and interannual variability of itself phenomenon was the result of joint action.(4) With increased the restoration time, seed diversity showed a trend of gradually reduced. Pielou index, Shannon Wiener index and Simpson index on community gradient distribution trend was consistent, and the characteristics of the index arbor was slightly higher than the shrub general. Arbor species diversity taller than shrub species. Seed rain of shrub layer updates and succession of the contribution was very small, the difference was related to the solid volume difference more than the ground vegetation.(5) The seed rain showed obvious interannual variability. Seed rain density in 2015 was far more than the year of 2013 and 2014. In Augest the cumulant density of seed rain was highest. The seed rain density of dominant species,Swida macrophylla (Wall.) Sojak? Padus racemosa (Lam.) Gilib.and Bothrocaryum controversum (Hemsl.) Pojark were 81.23% of total seed rain density. They all had an alternate bearing in seed production of species, while defferent annual and cycle time.(6) Most of the seed rain pattern showed a clump distribution. The highest degree in the prometaphase stage of the gathered and the aggregation index as high as 86.98561. Most of seeds aggregated around the mother trees and only few seeds could disperse far. Such as the seeds of Aceraceae can be dispersed the whole plots with their wings can spread the whole forests.The seed rain pattern showed an uniform distribution.(7) The seed rain and soil seed banks similarity difference was obvious. Sorensen similarity index between 0?1, each time span larger similarity, from very not similar to the highly similar. The metaphase stage similarity was stable. The similarity of seed rain and the ground vegetation with restoration stage gradually reduced,while with time gradually increased. Whether the similarity of seed rain with soil seed banks, or seed rain with the ground vegetation, arbor layer were higher than shrub layer.(8) The recovery phase seed rain distribution model with the time meet the cubic function, the model imitation has a good result.