Seed dynamics during forest succession in Costa Rica
Seed dynamics during forest succession in Costa Rica
复制标题
哥斯达黎加森林演替过程中的种子动态
DOI：
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
Becky Brown
中科院分区：
文献类型：
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作者：
Kenneth R. Young;J. Ewel;Becky Brown
土壤种子库和当前的种子投入在热带演替中都发挥着作用。我们通过使土壤中的种子发芽、测量 3 年的种子输入并监测森林空地中最早的殖民者，比较了哥斯达黎加地点这两个来源的种子的丰度和植物组成。 3.3 年生植被土壤中估计有 6800 个可存活种子/平方米，11 年生植被土壤中估计有 9500 个种子/平方米，75 年生森林中每平方米有 7000 个种子。据估计，3 年期间，年轻演替植被的土壤表面有 10100 颗种子/平方米掉落，同期森林中的种子数量为 3700 颗/平方米。当地生产的种子约占早期连续输入土壤表面的种子的 75%。从年轻的演替植被中散布的种子增加了邻近森林中种子输入和储存的数量和物种丰富度。幼年演替植被的物种丰富度很大程度上来自于动物从其他群落传播的种子。森林砍伐刺激了老森林表层土壤中大多数种子的发芽，包括主要树冠树的种子。从土壤种子库补充的幼苗在数量上超过了干扰后种子雨和芽苗的补充。我们评估了演替过程中土壤种子储存的模式，并预测了不同年龄的植被对干扰的反应能力。干扰发生后，土壤中的种子数量由于死亡率、低投入和发芽率而急剧下降。随着植被的重新生长，土壤种子库在4至7年后达到顶峰，然后逐渐减少到干扰前的大小。高频脉冲干扰会导致物种丰富度降低、长寿命种子物种占主导地位，以及从土壤种子库中招募幼苗来快速恢复。
Soil seed banks and current seed inputs each play a role in tropical succession. We compared the abundance and floristic composition of seeds from these two sources at a Costa Rican site by germinating seeds from the soil, measuring seed inputs for 3 yr, and monitoring the earliest colonists in a forest clearing. There were an estimated 6800 viable seeds/m2 in the soil of 3.3-yr-old vegetation, 9500 seeds/m2 in 11-yr-old vegetation, and 7000 seeds/m2 in a 75-yr-old forest. An estimated 10100 seeds/m2 fell on the soil surface of the young successional vegetation during 3 yr and 3700 seeds/m2 fell during that same time in the forest. Locally produced seeds accounted for about 75% of the seed input to the soil surface early in succession. Seeds dispersed out of young successional vegetation increased the quantity and species richness of the seed input and storage in an adjacent forest. Much of the species richness of the young successional vegetation resulted from seeds dispersed there from other communities by animals. Deforestation stimulated germination of most seeds in the surface soil of the old forest, including seeds of the dominant canopy tree. The recruitment of seedlings from the soil seed bank numerically overwhelmed that from post-disturbance seed rain and sprouts. We evaluated patterns of soil seed storage during succession and predicted the ability of vegetation of differing ages to respond to disturbance. Immediately after disturbance the number of seeds in the soil plummeted due to mortality, low inputs, and germination. As the vegetation regrew, the soil seed bank increased to a peak after 4 to 7 yr, then gradually decreased to its pre-disturbance size. High-frequency pulses of disturbance should result in reduced species richness, dominance by species with long-lived seeds, and fast recovery by seedling recruitment from the soil seed bank.