Collaborative research: The impact of an empty forest on tree recruitment and community structure

在亚洲、非洲和南美洲的许多热带森林中，食果脊椎动物的数量和多样性急剧下降。许多热带树木需要强光才能从种子生长到成年，这在很大程度上取决于这些脊椎动物将它们的种子带到森林中因树倒而形成的新开口或空隙。该项目将调查是否水果吃脊椎动物的消失正在减少这些树木的丰富度，并导致森林间隙持续存在和积累。 为了验证这一点，研究人员将比较关岛上的森林，由于引入了食肉蛇，关岛已经失去了几乎所有的水果食用脊椎动物，以及附近三个保留本地水果食用森林鸟类的岛屿，在一个案例中，还有一种本地水果食用蝙蝠。 研究将测量岛上森林空隙的动态，比较16种常见树种的光照需求，并测试在有鸟类的岛屿上通过实验防止种子传播的效果。这项研究将直接帮助州和联邦机构管理和恢复关岛的热带森林。研究结果对其他热带森林的管理者也有用处，因为热带地区的许多先驱物种是由脊椎动物传播的，并扩大了我们对将物种引入新地区的潜在环境后果的理解。该项目将为太平洋岛民提供科学培训，并为当地学院的学生举办为期三周的岛屿生态学特别课程。

Fruit-eating vertebrates have experienced steep declines in abundance and diversity in many of the tropical forests in Asia, Africa, and South America. Many of the tropical trees that need high light to grow from seeds to adults depend largely on these vertebrates to carry their seeds to new openings, or gaps, in the forest created by treefalls. This project will investigate whether the disappearance of fruit-eating vertebrates is reducing the abundance of these trees and causing forest gaps to persist and accumulate. To test this, researchers will compare forests on the island of Guam, which has lost nearly all its fruit-eating vertebrates due to the introduction of a predatory snake, and on three nearby islands that retain native, fruit-eating, forest birds and, in one case, a native, fruit-eating bat. Studies will measure the dynamics of forest gaps on the islands, compare the light requirements of 16 common tree species, and test the effects of experimentally preventing dispersal of seeds on islands that do have birds. This research will directly aid state and federal agencies to manage and restore tropical forests on Guam. Results should also be of use to managers of other tropical forests, since many pioneer species in the tropics are dispersed by vertebrates, and enlarge our understanding of the potential environmental consequences of introducing species to new areas. The project will provide scientific training for Pacific Islanders and run a special, three-week course in island ecology for students from local colleges.