Litter effects on seedling establishment interact with seed position and earthworm activity
Litter effects on seedling establishment interact with seed position and earthworm activity
复制标题
DOI：
10.1111/j.1438-8677.2011.00490.x
复制
发表时间：
2012-01-01
期刊：
影响因子：
3.9
通讯作者：
Eckstein, R. L.
中科院分区：
文献类型：
--
作者：
Donath, T. W.;Eckstein, R. L.
枯枝落叶层覆盖和种子捕食者对幼苗的形成有影响，但对这两个因素之间的交互作用知之甚少。我们在微观世界实验中测试了它们对五种典型草原物种出苗的影响。我们通过控制草地凋落物的数量、种子播种位置和蚯蚓活动来确定：(I)凋落物对种子捕食的保护作用取决于盖度和种子播种位置，即枯枝落叶的顶部或下面；(Ii)蚯蚓的种子运输改变了种子播种位置对出苗的影响；以及(Iii)蚯蚓运输到更深土层的种子仍然可以萌发。枯枝落叶和蚯蚓的存在降低了出苗率。种子位置的影响随着种子大小的增大而增大。地表播种减少了大粒种的出苗率。此外，我们还发现了一个重要的种子位置x蚯蚓互作与种子大小有关。在有蚯蚓存在的情况下，在枯枝落叶顶部播种的大种子物种的出苗量是没有蚯蚓的情况下的三倍。蚯蚓还显著改变了种子在土壤和各处理中的深度分布：平均有6%的种子在埋藏后萌发。与种子位置效应相比，种子埋于土壤后的迁移率和发芽力没有受到大小的影响。然而，不同大小的种子的命运可能会有所不同。虽然埋葬会将大种子从再生池中移除，但它可能会加强小种子物种的种子库建立。因此，凋落物盖度和无脊椎动物群落的变化对植物群落组成有重要影响。
Seedling establishment is influenced by litter cover and by seed predators, but little is known about interactions between these two factors. We tested their effects on emergence of five typical grassland species in a microcosm experiment. We manipulated the amounts of grass litter, seed sowing position and earthworm activity to determine whether: (i) the protective effect of litter against seed predation depends on cover amount and seed sowing position, i.e., on top or beneath litter; (ii) seed transport by earthworms changes the effect of seed sowing position on seedling emergence; and (iii) seeds transported into deeper soil layers by earthworms are still germinable. Litter cover and presence of earthworms lowered seedling emergence. The impact of seed position increased with seed size. Emergence of large-seeded species was reduced when sown on the surface. Additionally, we found an important seed position x earthworm interaction related to seed size. Emergence of large-seeded species sown on top of the litter was up to three times higher when earthworms were present than without earthworms. Earthworms also significantly altered the depth distribution of seeds in the soil and across treatments: on average 6% of seeds germinated after burial. In contrast to the seed position effect, we found no size effect on mobility and germinability of seeds after burial in the soil. Nevertheless, the fate of different-sized seeds may differ. While burial will remove large seeds from the regeneration pool, it may enhance seed bank build up in small-seeded species. Consequently, changes in the amount of litter cover and the invertebrate community play a significant role in plant community composition.