Annual Variation in Seedfall, Postdispersal Predation, and Recruitment of a Neotropical Tree
Annual Variation in Seedfall, Postdispersal Predation, and Recruitment of a Neotropical Tree
复制标题
新热带树木的落籽量、扩散后捕食和补充的年度变化
作者：
E. Schupp
了解各个树种的种子生产和幼苗招募动态对于全面了解热带森林动态至关重要，但对热带树木种子和幼苗阶段的多年研究实际上不存在。在对巴拿马巴罗科罗拉多岛林下树 Faramea occidentalis 进行的为期 4 年的研究中，作者量化了可行的落籽、幼苗出苗和幼苗建立的自然水平，并通过实验估计了传播后的种子捕食。可行的种子脱落、种子捕食、幼苗出苗、早期幼苗存活和幼苗补充的水平在年份之间都存在显着差异。发芽前被捕食者破坏的落下种子的比例与 F. occidentalis 落籽量无关。然而，在一年之内，F. occidentalis 种子捕食似乎受到群落范围内种子掉落的影响，在种子丰度较低的时期，捕食率很高，而在旱季后期，群落种子掉落高峰期间，捕食率非常低。补充的大部分年度变化可以通过种子掉落和种子捕食的结合来解释。 4 年中的 3 年的幼苗出苗率可以通过了解可行的种子脱落情况和种子存活到发芽高峰的概率来预测。然而，第四年的情况表明，环境条件对招募产生了偶发性但重要的限制。与许多树种相比，早期幼苗的成活率相对较高，每粒落下的幼苗的补充率也较高。 F. occidentalis 的成功招募与研究区域内树苗和成虫的高种群密度有关。« less
Knowledge of the dynamics of seed production and seedling recruitment of individual tree species is crucial for a complete understanding of tropical forest dynamics, yet multiyear studies on the seed and young seedling stages of tropical trees are virtually nonexistent. In a 4-yr study of the understory tree Faramea occidentalis on Barro Colorado Island, Panama, the author quantified natural levels of viable seedfall, seedling emergence, and seedling establishment, and experimentally estimated postdispersal seed predation. The levels of viable seedfall, seed predation, seedling emergence, early seedling survival, and seedling recruitment all differed significantly among years. The proportion of fallen seeds destroyed by predators before germination was not related to the quantity of F. occidentalis seedfall. Within a year, however, F. occidentalis seed predation appeared to be influenced by community-wide seedfall, with high predation rates during times of low seed abundance and very low predation during the late dry season peak in seedfall by the community. Most of the annual variation in recruitment can be explained by the combination of seedfall and seed predation; in 3 of the 4 yr seedling emergence could be predicted from a knowledge of viable seedfall and the probability of a seed surviving until the peak ofmore » germination. The 4th yr, however, demonstrated that environmental conditions provide a sporadic, though important, limitation to recruitment. In comparison to many tree species, early seedling survival was relatively high, as was the ratio of seedlings recruited per seed falling. The highly successful recruitment of F. occidentalis is associated with a high population density of both saplings and adults in the study area.« less