食果鸟类对樟树种子的空间散布作用

摘要

Fruit-eating birds are potential seed dispersers due to their capability of fruit eating and pulp consumption.Cinnamomum camphora is a kind of evergreen broad-leaved tree species widely distributed in the subtropical region,however,the research about its seed dispersal pattern is rarely reported.We investigated seed crop of 1 139 C camphora and seeds dispersed by fruit-eating birds under the tree crown and into the non-tree spaces in the Yaohu lake campus of Jiangxi Normal University,to the effects of fruit-eating birds on seed distribution of C camphora trees.More than 6 000 quadrats scattered in an area of more than 40 thousand square meters were searched for seeds of C camphora.The results show that the average seed crop was 110.00±3.84 N/m2,while fruit-eating birds are mainly Sturnus sericeus,Turdus merula,Streptopelia chinensis,Pycnonotus sinensis,and Hypsipetes mcclellandii.These fruit-eating birds directly swallowed fruits of C camphora,and vomited or excreted out after a period of time of digestion.Seed density under the crown of C camphora was 148.71±7.41 N/m2,in which 37.93±7.60/m2 of seeds were found under the non-fruiting individual trees.Moreover,the amount of seeds distributed in the space free of C camphora trees was as high as 15.93±2.80 N/m2.Our study shows that fruit-eating birds play a potential role in seed distribution and seedling recruitment of C camphora.%食果鸟类通过取食果实,消化果肉后散布种子,从而存在潜在的种子传播作用.樟树(Cinnamomum camphora)是亚热带地区广泛分布的一种常绿阔叶树种,有关其肉质果实传播模式的研究还鲜见报道.本研究调查了江西师范大学瑶湖校区1 100余株樟树的结实量、树冠下以及空地中食果鸟类散布的种子量,研究了食果鸟类对樟树果实的空间散布模式.共调查6 000余个小样方,面积达40 000 m2,共收集樟树果实和种子20万多粒,40余kg.结果表明:樟树平均结实量为110.00±3.84粒/m2.取食樟树果实的食果鸟类主要有丝光椋鸟(Sturnus sericeus),乌鸫(Turdus merula),珠颈斑鸠(Streptopelia chinensis),白头鹎(Pycnonotus sinensis),绿翅短脚鹎(Hypsipetes mcclellandii)等.这些食果鸟类均以直接吞食樟树成熟果实,并经一段时间消化后通过呕吐或排泄的方式在空间上散布樟树的种子.经食果鸟类消化后被散布至樟树树冠下的种子量为148.71±7.41粒/m2,但非结实的樟树下也发现较多被消化排出的种子(37.93±7.60粒/m2).另外,在无樟树分布的空地中发现的种子量高达15.93±2.80粒/m2左右.食果鸟类通过散布樟树种子,对樟树种子传播和幼苗建成有潜在促进作用.