贮藏种子的啮齿动物对油茶种子沉积形式的影响

种子沉积的质量常常涉及种子扩散作用者(如鸟类和小型啮齿动物)对生境和微生境的选择以及种子沉积的形式(如种子埋藏)。然而,很少的研究涉及到种子在离开母树后被这些动物沉积在何处。在四川省都江堰一个实验林场的2个林分(次生林和原生林)内,通过追踪用带编号的金属薄片标记的油茶(CamelliaoleiferaAbel.)种子的命运,研究了贮藏种子的啮齿动物对种子沉积的影响。研究发现在2个林分内,80%以上的种子被很好地埋藏在0~60mm深的土壤中,而小部分种子则被放置在地表(但有少量落叶遮盖)。小型啮齿动物喜好在灌丛下或灌丛边缘贮藏和取食种子,可能是在这样的微生境下它们在觅食时将遭遇较小的捕食风险。研究还发现,贮藏点的微生境分布随贮藏点等级而逐渐变化在两个林分内较高等级的贮藏点(如次贮藏点和三级贮藏点)比初级贮藏点有更多的种子被贮藏在灌丛下或灌丛边缘。这表明,啮齿动物对油茶种子的埋藏可能更有益于种子的存活、萌发以及幼苗的建成。啮齿动物将散落在母树下或其附近的油茶种子扩散到不同的微生境,这可能有利于他们遭遇到更多的适宜环境而萌发,实现幼苗补充。

Seed Deposition Patterns of Oil Tea Camellia oleifera Influenced by Seed-caching Rodents

The quality of seed deposition often involves habitat and microenvironment selection byseed-dispersing agents (e.g. birds and small rodents) and deposition patterns (e.g. burial of seeds). However,little is known where seeds and nuts are deposited by these animals after their shedding from parent trees.In this study, seed deposition patterns of oil tea (Camellia oleifera Abel., Theaceae) influenced by seed-caching rodents were studied by tracking individual oil tea seeds (labeled with small coded tin-tags) at twostands (secondary stand and primary stand) in an experimental forest of Dujiangyan City, Sichuan Province,China. We found that over 80% of the tagged seeds were well buried 0-60 mm deep in the soil and a smallpart of them were deposited on the soil surface with some leaf litter covering at both stands. Small rodentssignificantly preferred to select some specific microenvironments (e.g. shrub edge and under shrubs) tocache and eat seeds at each stand. In these microenvironments, they may experience less predation riskduring the foraging process. We also found that the microenvironment distributions of caches changedslightly with cache order: a higher proportion of the cached seeds was deposited under shrubs or at shrubedge at higher order cache sites (i.e. secondary and tertiary caches) than at primary cache sites at bothstands. Our results indicate that burial of oil tea seeds by small rodents might be a greater benefit for seedsurvival, seed germination and seedling establishment. Small rodents dispersed seeds from seed sources orparent trees to different microenvironments, which may be beneficial to seed germination and seedlingestablishment due to more seeds deposited in a favorable environment.