Seed Rain And Seedling Regeneration In The Mixed Broad-leaved Korean Pine Forest In Xiaoxing'an Mountains, China

Spatiotemporal dynamics of seed rain and seedling recruitment is important for understanding community regeneration mechanisms and vegetation patches distribution patterns.We established 287-319 seed traps in a 150m×150m sample plot of the 9-ha permanent plot to collect and identify fallen seeds from 2005 to 2008 in a broadleaved-Korean pine(Pinus koraiensis) mixed forest at Liangshui Natural Reserves.And we also established 319 small sample plot(1×1) nearby each seed trap to examine one-year-old seedling.The results showed that:(1) The intensity of seed rain for tree species had a great interannual variation, (864.2±1084.3),(300.9±349.4),(144.8±195.5),(3624.6±4086.4) inds·m^-2,in 2005,2006,2007 and2008,respectively.The intensity of seed rain of the 11 tree species included also showed a great interannual variation,and the density of Fraxinus mandshurica,Tilia mandshurica, Betula platyphylla,Picea koraiensis and Abies nephrolepis in certain years was little.However, the intensity of Pinus koraiensis was influenced by human disturbance.(2) Seasonal dynamics of the seed rain were significant.The seed rain started in May,reached a peak in October,and ended in the middle of November.But the temporal pattern of each tree species was different. From the peak of the seed rain phase,the seed rain was mainly made up by intact seeds,but at the beginning the seed rain was mainly by vacant seeds.(3) The seed rain components were stable among years.(4) The spatial heterogeneity of the seed rain varied among years,and it was positively correlated to the intensity of seed rain.(5) The composition of one-year-old seedling was stable among years,Fraxinus mandshurica,Acer ukurunduense,Acer tegmentosum and Acer mono have appeared in each year but the density of Pinus koraiensis, Abies nephrolepis,Ulmus pumila,Betula costata andTilia amurensis in certain years was little or even none.Fraxinus mandshurica was the dominant species in one-year-old seedling.(6) The most appearance of one-year-old seedling was between June and July.And the death of one-year-old seedling was most happened in winter to early spring.(7) Generally gap had no influence on seed rain but to different tree species there had different results.The density of seedling in non-gap significantly higher than gap,but the gap had no influence on seedlings' height grouth.