Advantage of early seedling emergence in Fagus crenata:: importance of cotyledon stage for predator escape and pathogen avoidance
Advantage of early seedling emergence in Fagus crenata:: importance of cotyledon stage for predator escape and pathogen avoidance
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DOI：
10.1007/s11284-007-0428-2
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发表时间：
2008-07-01
影响因子：
2
通讯作者：
Miguchi, Hideo
中科院分区：
文献类型：
--
作者：
Abe, Midori;Honda, Ayako;Miguchi, Hideo
为了研究早生幼苗如何利用落叶林的建立，我们探讨了毛毛豆幼苗的出现日期，生长阶段和主要死亡原因（真菌和啮齿动物的捕食）之间的关系。在一个生长季节中，以很短的间隔（早春3-7天）跟踪当年幼苗的出现及其存活和损害情况。生长期分为两个阶段，即只有子叶（CT期）和真叶（TL期）。成活率与出苗期呈负相关，说明出苗早的优势。这一优势在很大程度上是由于立枯病的发生率较低。与此相反，幼苗捕食发生独立的出现日期，但强烈依赖于发展阶段。啮齿动物消耗了相当数量的种子在出现后的早期，并强烈喜欢CT阶段TL阶段的幼苗在整个生长季节。因此，幼苗捕食被推断为集中在一个相对较短的时间内，而剩余的种子耗尽和CT阶段的幼苗丰富。苗期由CT期同步过渡到TL期。这种生长阶段的过渡是独立的出现日期，并出现对应于种子耗尽的时间。延迟的阶段过渡导致了不成比例的高风险，在本赛季晚些时候关闭。结果表明，出苗早有利于F。crenata的抗病原体和幼苗的生长阶段进展的时间出现重要的逃避捕食，因为不同的食物偏好的捕食者。
To examine how early-emerging seedlings take advantage of establishment in a deciduous forest, we explored the relationships among the emergence date, growth stage and major causes of mortality (damping-off by fungi and predation by rodents) in seedlings of Fagus crenata. The emergence of current-year seedlings and their survival and damage were followed at short (3-7 days in early spring) intervals for a growing season. The growth stage was divided into two stages, with only cotyledons (CT stage) and with true leaves (TL stage). The survival rate was negatively correlated with the emergence date, indicating the advantage of early seedling emergence. This advantage was largely explained by the lower occurrence of damping-off. In contrast, seedling predation occurred independently of the emergence date, but depended strongly on the developmental stage. Rodents consumed a considerable number of seeds during the early period after emergence, and strongly preferred CT-stage over TL-stage seedlings throughout the growing season. Therefore, seedling predation was inferred to be concentrated in a relatively short period while the remaining seeds were depleted and CT-stage seedlings were abundant. The seedling stage synchronously shifted from the CT to TL stage. This growth-stage transition was independent of the emergence date and appeared to correspond with the timing of seed depletion. Delayed stage transition resulted in a disproportionately high risk of damping-off later in the season. Our results indicate that early seedling emergence is advantageous for F. crenata for resistance to pathogens and that the timing of growth-stage progression of seedlings appears important to escape predation because of the distinct food preference of predators.