在没有掠食者的森林碎片中生态融化
1Center for Tropical Conservation, Duke University, Box 90381, Durham, NC 27708, USA. manu@duke.edu
概括
捕食者控制食草动物种群,防止过度放牧. 在没有捕食者的岛屿上,食草动物密度增加导致树苗存活率降低,表明了上下生态系统调节.
科学领域:
- 生态生态学 生态生态学
- 生态系统法规 生态系统法规
- 热量级布 (Trophic Cascades) 是一种热量级布.
背景情况:
- 关于陆地生态系统监管存在争议:自上而下 (捕食者控制) 和自下而上 (植物防御).
- 委内瑞拉的水力发电封存所创造的没有捕食者的岛屿提供了一个独特的自然实验.
研究的目的:
- 测试生态系统调节的竞争理论 (自上而下与自下而上).
- 调查捕食者缺席对食草动物种群和植被的影响.
主要方法:
- 研究了小岛 (0.25-0.9公) 动物数量有限,缺乏脊椎动物捕食者.
- 岛上和大陆上的动物,子, iguana 和剪叶的密度比较.
- 在受草食动物影响的岛屿上评估了树冠树苗和树苗的密度.
主要成果:
- 草食动物密度 (动物,子,,,) 在岛上是大陆的10-100倍.
- 在岛屿上,树冠树的种植和树苗密度大大减少.
- 脊椎动物捕食者的缺席导致了草食动物种群的增加和随后的植被减少.
结论:
- 这些发现支持陆地生态系统上下调节理论.
- 捕食者缺席可能会释放食物源级流,严重影响植物群落.
- 生态系统结构受到捕食者的存在和活动的重大影响.
相关概念视频
Threats to Biodiversity
There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...
What is Conservation Biology?
Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the human population. Humans require properly functioning ecosystems to maintain our supply of natural resources, including food, medicines, and building materials.
Conservation of Small Populations
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...
Ecological Disturbance
An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced change in an ecosystem. The impact of an ecological disturbance, which can depend on its intensity, frequency, and spatial distribution, plays a significant role in shaping the species diversity within the ecosystem.Ecological disturbances can be caused by an event as small as the trampling of underbrush to an incident as wide-ranging as a forest...
Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
Habitat Fragmentation
Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land conversion, as well as slower geological processes leading to changes in the physical environment, are the two leading causes of habitat fragmentation. The fragmentation process typically follows the same steps: perforation, dissection, fragmentation, shrinkage, and attrition.


