Maintenance of Tropical Tree Diversity by Herbivores and Pathogens: A Test of the Janzen-Connell Hypothesis

食草动物和病原体对热带树木多样性的维持：詹森-康奈尔假说的检验

• 批准号: 9420031
• 负责人: Phyllis Coley
• 金额: $ 8.5万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9420031&HistoricalAwards=false
• 关键词: Maintenance; Tropical; Tree; Diversity; Herbivores

9420031 Coley One of the most striking features of tropical forests is their great diversity. The most widely cited explanation for the maintenance of tropical forest tree diversity is the Janzen-Connell hypothesis, which suggests that seed predators, herbivores and pathogens maintain diversity by preferentially attacking seeds or young trees that are close to conspecific adults. This difference in the rate of attack results in higher juvenile mortality near adults and increases the distance between successful conspecific recruits. Thus, the natural enemies of trees are proposed to prevent competitive dominance, which allows a greater diversity of tree species to persist. Despite the theoretical importance of the Janzen-Connell hypothesis, few studies have looked for the predicted pattern of higher seed or seedling mortality near adults. Even less attention has been directed at understanding the predicted mechanism of natural enemies centered on the adults. This study will critically evaluate this hypothesis by asking: 1) whether damage depends on distance from adult conspecifics, 2) whether damage negatively impacts growth and survival, and 3) whether the herbivore and pathogens responsible for the majority of damage are host specialists centered on adults. Understanding the mechanisms which control diversity of tropical forests has applications to management of rain forests as well as cultivated plantations. In order not to lose diversity in managed forest reserves, policies should take into account the Janzen-Connell effects. For example, encouraging recruitment through plantings or selective cutting should consider distance to nearest conspecifics. Monocultures, such as are typically found in plantations, tend to have extremely high levels of damage from insect pests. Preliminary work suggests that one method for limiting damage would be to have mixed planting, with a minimum of 50m between any two individuals of the same species.

9420031 COLEY热带森林最引人注目的特征之一是它们的多样性。 维持热带森林树多样性的最广泛引用的解释是Janzen-Connell假设，它表明种子捕食者，食草动物和病原体通过优先攻击接近特定成年人的种子或幼树来维持多样性。 攻击率的这种差异导致成年人附近的少年死亡率较高，并增加了成功的同种新兵之间的距离。 因此，提出了树木的自然敌人，以防止竞争优势，这使得树种的多样性持续存在。 尽管Janzen-Connell假设具有理论上的重要性，但很少有研究寻找成人附近较高种子或幼苗死亡率的预测模式。 更少的关注是了解以成年人为中心的自然敌人的预测机制。 This study will critically evaluate this hypothesis by asking: 1) whether damage depends on distance from adult conspecifics, 2) whether damage negatively impacts growth and survival, and 3) whether the herbivore and pathogens responsible for the majority of damage are host specialists centered on adults. 了解控制热带森林多样性的机制在雨林和耕种种植园的管理中应用。 为了不要在托管森林储备中失去多样性，政策应考虑到Janzen-Connell效应。 例如，通过种植或选择性切割来鼓励招募应考虑到最近的特定物质的距离。 单一培养物（如种植园中通常发现）往往会受到害虫的损害极高的损害。 初步工作表明，一种限制损害的方法是混合种植，同一物种的任何两个个体之间的种植至少为50m。