Species interactions and ecological function under biodiversity loss and climate variability

森林对地球的健康至关重要，为人类提供清洁的空气、淡水和其他各种好处。它们也是大量植物和动物的家园，所有这些都在维持生态系统的平衡方面发挥着重要作用。然而，与所有生态系统一样，森林正日益受到生物多样性丧失和气候变化的威胁。虽然这些变化可以破坏物种之间复杂的相互作用，使森林正常运作，但我们对这些级联影响的理解仍然有限。这项研究利用一项独特的自然实验来调查一个关键物种——胡须猪——的消失是如何影响婆罗洲热带雨林的健康的。在这个生态系统中，胡须猪曾经是一种常见的动物，在种子捕食、食草和营养循环中起着至关重要的作用，但最近被一种引入的疾病消灭了。该项目将采用实地观察、实验和建模相结合的方法来了解胡须猪的消失是如何影响生态系统的。研究结果将分发给参与生物多样性评估和保护的非政府组织和决策者。该项目还将制作外联材料，向公众和K-12学生宣传生态功能以及它们如何受到全球变化的影响。具体来说，这项研究有三个主要目标。首先，它将评估胡须猪的损失如何影响树苗的生存和生长。猪通过吃许多植物的种子，在树木再生中发挥了关键作用。研究人员将重复在猪数量丰富时进行的一些封闭实验，以确定猪和其他破坏种子的消费者（如啮齿动物、昆虫和真菌）如何影响种子命运，以及这些其他群体是否会弥补猪的损失。这将有助于阐明一种重要哺乳动物物种的灭绝如何影响多种树种的再生。其次，这项研究将确定随着时间的推移，长胡子猪的减少和气候变化如何共同影响森林储存的碳量。通过比其他类型的树木更能影响高木材密度的大树的再生，胡须猪被认为以某种方式影响了森林的整体碳储量，而这种方式在该物种消失后正在发生变化。随着森林开始经历更频繁和更严重的干旱，这种生态系统的变化可能会变得更加严重。利用积分投影模型参数化大量的观测和实验数据，研究人员将研究许多树种的种群轨迹，这些树种在成虫大小、木材密度和其他对碳储存重要的特征上存在差异。最后，这项研究将确定胡须猪的消失对森林中其他动物的影响。猪是云豹等食肉动物的重要食物来源，它们与鹿等其他食草动物竞争食物，它们甚至可能通过与吃种子的昆虫竞争（并减少它们的丰度）来影响鸟类和蝙蝠。研究人员将利用过去十年的发生率和丰度数据，研究猪的减少是否会改变雨林中其他重要动物的丰度。该项目由人口与社区生态学、促进竞争研究的既定计划（EPSCoR）和生态系统科学共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Forests are vital to the health of our planet, providing clean air, fresh water, and a variety of other benefits to humans. They are also home to a vast array of plant and animal life, all of which play important roles in maintaining the balance of the ecosystem. Like all ecosystems, however, forests are increasingly threatened by biodiversity loss and climate change. Though these changes can disrupt the complex interactions among species that make forests function properly, we still have a limited understanding of these cascading impacts. This study takes advantage of a unique natural experiment to investigate how the loss of a key species – the bearded pig – affects the health of a tropical rain forest in Borneo. The bearded pig was once a common animal in this ecosystem, playing a vital role in seed predation, herbivory, and nutrient cycling, but was recently wiped out by an introduced disease. This project will use a combination of field observations, experiments, and modeling to understand how the loss of bearded pigs has affected the ecosystem. Research results will be disseminated to non-governmental organizations and policy-makers involved in biodiversity assessment and conservation. The project will also generate outreach materials to educate the public and K-12 students about ecological functions and how they are affected by global changes. Specifically, the research has three main objectives. First, it will assess how the loss of bearded pigs affects the survival and growth of tree seedlings. Pigs played a key role in tree regeneration by eating the seeds of many plant species. Researchers will repeat a number of exclosure experiments conducted when pigs were abundant to determine how pigs and other seed-destroying consumers like rodents, insects, and fungi affect seed fates, and whether these other groups compensate for the lost effects of pigs. This will help elucidate how extirpation of an important mammal species affects the regeneration of multiple tree species. Second, the research will determine how the loss of bearded pigs and climate change combine to affect the amount of carbon stored by the forest over time. By affecting regeneration of large trees with high wood density more than other types of trees, bearded pigs are thought to have influenced overall forest carbon storage in ways that are now changing after the species’ loss. Such ecosystem changes might become even more severe as the forest starts to experience more frequent and severe droughts. Using integral projection models parameterized with extensive observational and experimental data, researchers will examine the population trajectories of numerous tree species that vary in adult size, wood density, and other traits important for carbon storage. Finally, the research will ascertain how the loss of bearded pigs affects other animals in the forest. Pigs were an important food source for predators like clouded leopards, they competed with other herbivores like deer for food, and they potentially even affected birds and bats by competing with (and reducing the abundance of) seed-eating insects. Using occurrence and abundance data spanning the last decade, researchers will examine whether the loss of pigs is changing the abundance of these other important animals in the rain forest.This project is jointly funded by Population and Community Ecology, the Established Program to Stimulate Competitive Research (EPSCoR), and Ecosystem Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.