小果野芭蕉种子散布和不同时空尺度上种子被捕食格局

 以分布在云南西双版纳地区的大型先锋草本植物小果野芭蕉(Musa acuminata)为研究材料，研究其种子初次散布过程和不同时空尺度上种子被 捕食格局。小果野芭蕉的成熟果实有75%在夜间被取食和传播，在白天消失的果实则占25%。蝙蝠是其最主要的种子传播者，鸟类在其种子传播 过程中也起到一定的作用。人工摆放种子试验结果显示小果野芭蕉种子的主要转移者是小型啮齿类(鼠类)和蚁类：在开放处理下3 d后转移率为 86%，排除蚁类(鼠类可进入)处理下种子转移率为69%以及排除鼠类(蚂蚁可进入)处理下种子被转移率为56%。季节、地点和生境均显著影响人工 摆放种子被转移强度：雨季显著高于旱季(p<0.001)， 野芭蕉生境显著高于与其相连的自然森林和荒地(p<0.001)，在人为干扰较少的补蚌自然 保护区显著低于西双版纳热带植物园和新山，而后两者之间并无显著差异(p>0.05)。同时，地点和生境以及季节、地点和生境都有显著的交互 作用。与相邻的森林和荒地相比，野芭蕉群落中种子被鼠类捕食的强度最大且受蚁类二次转移的比例最少，森林和荒地中种子被鼠类捕食的强 度相对较小且蚁类对种子的二次转移比例较高，从而更好地帮助种子逃避鼠类捕食。因此，依赖于食果动物(主要是蝙蝠, 也包括鸟类)的初次 散布是小果野芭蕉种子逃避捕食的关键。

SEED DISPERSAL AND SPATIAL-TEMPORAL VARIATION OF SEED PREDATION OF MUSA ACUMINATA IN XISHUANGBANNA, SOUTHWEST CHINA

Aims Seed dispersal and seed predation are important on mechanisms of forest maintenance and degeneration.Understanding them can enable effective conservation measures,especially in Xishuangbanna tropical rainforest in China which is suffering severe pressures.Methods Musa acuminata is a large herbaceous plant in Xishuangbanna,Yunnan Province.We investigated seed dispersal and spatial-temporal variation of seed predation in three habitats(wild banana communities,virgin rainforest and open habitat) in three different sites of Xishuangbanna(XTBG,Xinshan and Bubeng).We used two treatments excluding ants and rodents and surveyed community structure of ants and rodents to explore the relationship between abundance of predators and intensity of seed predation.Important findings Bats were the most important,effective seed disperser,and birds also played an important role in seed dispersal,with approximately 75% of the mature fruits of M.acuminata dispersed at night and about 25% during daytime.After primary dispersal,seeds of M.acuminata were mainly removed by small rodents and ants.This seed predation was significantly influenced by season,site and habitat.Seed predation was significantly stronger in rainy than dry seasons(p<0.001).Seed predation in M.acuminata communities was the highest among the three habitats(p<0.001),and seed predation in Bubeng Nature Reserve,which had the least disturbance,was significantly lower than the other two sites(which were not significantly different at p>0.05).Seed removal was generally consistent with the abundance of rodents and ants in different seasons,habitats and sites.The interaction between sites and habitats and the interaction among seasons,sites and habitats had significant effects on seed predation.Compared to nearby forest and open habitats,Musa communities had the most abundant rodents and the highest seed predation and the lowest proportion of secondary seed dispersal by ants.In contrast,seed predation by rodents in forest and open habitat was relatively weak and a large proportion of post dispersal seed was removed by ants.Therefore,primary seed dispersal mostly by bats and birds is essential for M.acuminata seeds to escape seed predation.