Patterns of Fruit Presentation and Seed Dispersal in Bird-Disseminated Woody Plants in the Eastern Deciduous Forest
Patterns of Fruit Presentation and Seed Dispersal in Bird-Disseminated Woody Plants in the Eastern Deciduous Forest
复制标题
东部落叶林鸟类传播木本植物的果实呈现和种子传播模式
作者：
E. Stiles
我研究了东部落叶林中木本植物的鸟类传播的果实的呈现和传播。果实呈现的时间和果实丰度的纬度格局与果食性鸟类的秋季迁徙有关。根据营养成分、种子大小和在植株上的持久性的特点，我把鸟播散的果实分为四种类型。夏季小种子和大种子的水果在迁徙期之外利用鸟类和哺乳动物的混合传播群，通过非常小或非常大的种子来避免哺乳动物的种子捕食。秋季高品质的水果在秋季鸟类迁徙期间呈现。它们被鸟类大量食用，但容易受到微生物的迅速入侵。在秋季鸟类迁徙期间出现了秋季低质量的水果，但在与优质水果和昆虫的竞争中，它们在这个时候只实现了低水平的传播。这与植物上的长时间持久性和冬季的低扩散率相结合，这是微生物入侵率低所允许的。如果其他资源变得稀缺，这些物种的扩散可能会急剧增加。提出了高品质和低品质水果的破坏性选择的图形模型，并根据假设的选择压力讨论了中间水果类型。
I have examined presentation and dispersal of bird-disseminated fruits of woody plants in the eastern deciduous forest in terms of available dispersal agents. Timing of fruit presentation and latitudinal patterns in fruit abundance are correlated with fall migration of frugivorous birds. I have divided bird-disseminated fruits into four patterns based on characteristics of nutrient content, seed size, and persistence on the plant. Summer small-seeded and large-seeded fruits employ a mixed group of bird and mammal dispersers outside the migratory period, avoiding mammalian seed predation through either very small or very large seed size. Fall high-quality fruits are presented during fall bird migration. They are taken by birds in high numbers but are subject to rapid invasion by microorganisms. Fall low-quality fruits are presented during fall bird migration, but in competition with high-quality fruits and insects they achieve only low levels of dispersal at this time. This is coupled with long persistence on the plants and low rates of dispersal over winter which is allowed by low invasion rates by microorganisms. Dispersal of these species may increase sharply if other resources become scarce. A graphical model for disruptive selection in high- and low-quality fruits is presented and intermediate fruit types are discussed in terms of the postulated selective pressures.