Seed dispersal is a key process within community dynamics.The spatial and temporal variations of seed dispersal andthe interspecific differences are crucial for understanding species coexistence and community dynamics.This might alsohold for the mixed evergreen broadleaved and deciduous forests in the mountains of subtropical China,but until now littleexisting knowledge is available for this question.In 2001,we chose to monitor the seed rain process of our mixed evergreenbroad-leaved and deciduous forest communities in Mount Dalaoling National Forest Park,Yichang,Hubei Province,China.The preliminary analyses show obvious variations in seed rain density,species compositions and timing of seed rain amongfour communities.The average seed rain densities of the four communities are 2.43±5.15,54.13±182.75,10.05±19.30and 24.91±58.86 inds./m^2,respectively;about one tenth the values in other studies in subtropical forests of China.In eachcommunity,the seed production is dominated by a limited number of species,and the contributions from the others aregenerally minor.Fecundity of evergreen broadleaved tree species is weaker than deciduous species.The seed rain of fourcommunities begins earlier than September,and stops before December,peaking from early September to late October.The beginning date,ending date and peak times of seed rain are extensively varied among the species,indicating differenttypes of dispersal strategies.According to the existing data,the timing of seed rain is not determined by the climateconditions in the same period,while the density of seed rain may be affected by the disturbances of weather variations ata finer temporal resolution.
Ze-Hao ShenYuan-Yuan TangNan LüJun ZhaoDao-Xing LiGong-Fang Wang
描述了湖北省神农架地区发现的石竹科一新种——神农架无心菜Arenaria shennongjiaensis Z. E.Zhao & Z. H. Shen,并绘出了线图。该种与秦岭无心菜A. giraldii (Diels) Mattf.相近,为柔弱草本,具纺锤形块根,花瓣顶端齿裂;不同之处在于其茎有1列腺毛,花瓣顶端具4齿裂,裂片又2浅裂。
