DISSERTATION RESEARCH: The Consequences of the Interaction Between Flooding and Drought for Tree Physiology and Diversity in Seasonally Flooded Forests

热带雨林经历了干旱时期，我们的研究表明，热带雨林树木，包括普里奥里亚，是干旱敏感的。热带森林也是地球上最多样化的生态系统之一，相对没有干旱可能会带来更大的多样性。这些观察结果导致PIS提出，许多热带森林的多样性减少可能是周期性干旱的结果。PIS的研究重点是光叶松树，这是一种出现在巴拿马近乎纯林中的物种，尽管周围没有被洪水淹没的森林非常多样化。在平均一年的时间里，轮虫会经历洪涝和干旱。PI假设这对植物来说是一个严重的压力环境，并解释了P.Copaifera的优势是通过允许它在水分供应存在极端变化的地方生存和生长的适应来解释的。这一假设与最近提出的观点是一致的，即对洪水的耐受性虽然是必要的，但可能不足以解释被洪水淹没的生境中植物的分布。相反，假设一个物种对洪水结束后的干旱条件做出反应的能力也可能非常重要。马尾松也是巴拿马收获的主要树种，更好地了解其建立的要求将有助于制定这一物种的管理计划。

Tropical rainforests experience periods of drought and our studies indicate that rainforest trees, including Prioria copaifera, are drought-sensitive. Tropical forests also are among the most diverse ecosystems on earth and the relative absence of drought may permit greater diversity. These observations led the PIs to propose that the reduced diversity of many tropical forests may be the consequence of periodic drought. The PIs research focuses on P. copaifera, a species that occurs in nearly pure stands in Panama even though the surrounding, nonflooded forest is highly diverse. In an average year, P. copaifera experiences flooding followed by drought. The PIs hypothesize that this is a severely stressful environment for plants and that the dominance by P. copaifera is explained by adaptations permitting it to survive and grow where there is extreme variation in water availability. This hypothesis is consistent with recent proposals that tolerance of flooding, while necessary, may not be sufficient to explain the distributions of plants in flooded habitats. Instead, it is hypothesized that the capacity of a species to respond to drought conditions that follow the end of flooding may also be very important. P. copaifera also is the main tree harvested in Panama and a better understanding of its requirements for establishment will assist in developing a management plan for this species.