啮齿动物对印度栲种子扩散的效率(英文)

Effectiveness of small rodents dispersing seeds of Castanopsis indica in Xishuangbanna tropical seasonal rain forest

从2007年11月到2009年11月,在西双版纳热带雨林中选取三棵母树,在每棵树下每年释放标记印度栲种子 200 粒 (三年共计1800 粒) ,并追踪其命运。通过调查啮齿动物搬运和分散贮藏印度栲种子的比例,以及调查贮藏种子的微生境、贮藏点大小和扩散距离,分析贮藏种子的存活情况,进而评估啮齿动物对印度栲种子扩散的效率。结果表明,啮齿动物搬运了 69. 3%的印度栲种子,被搬运的种子中 18% 被分散贮藏。所有被分散贮藏的种子均被埋于落叶下或埋于土壤表层,并且大部分贮藏点仅含一粒种子。种子的扩散距离从 0. 5 m 到43. 8 m,平均距离为 7. 1 m,扩散距离在年间没有显著差异。2007 年 ( 种子密度低,啮齿动物密度高) 没有种子能最终存活到实验结束,而 2008 和 2009 年 ( 种子密度高,啮齿动物密度低) 分别有 0. 3% 和 1. 5% 的种子存活。研究表明,啮齿动物是印度栲有效的种子扩散者,但其扩散效率很大程度上取决于森林中种子的密度和啮齿动物的丰富度。

The effectiveness of Castanopsis indica seed dispersal was studied in the tropical rain forest in the Xishuangbanna region,Yunnan Province,China.We experimentally tracked the fate of 600 tagged nuts of C.indica under three focal trees（200 nuts for each tree） each year from November 2007 to November 2009.We investigated the proportion of experimental nuts moved away from the seed stations,the proportion of cached nuts buried beneath leaf litter or in soil,the number of nuts per cache,the distance that nuts were transported,and finally the proportion of nut surviving after being removed by rodents.Our results show that 69.3% of the tagged C.indica nuts under focal trees were dispersed by rodents,18% of which were cached.All cached nuts were buried beneath leaf litter or in soil,and most caches contained only one nut,which may benefit nuts germination and seedling establishment.The dispersal distance of cached nuts averaged 7.1 m,ranging from 0.5 to 43.8 m,and there was no significant difference in distance variation among these three years.No nut survived to the end of the experiments in 2007（when seeds were less abundant and rodents were more abundant）,whereas 0.3% and 1.5% nuts survived to the end of the experiments in 2008 and 2009（years with high seed abundance and fewer rodents）.Overall,our results suggest that rodents are effective dispersers of C.indica,but the dispersal effectiveness is largely dependent on the relative abundances of rodents and available seeds.