Collaborative Research: Ecological legacy effects of megacarcasses in African savanna ecosystems

大象和犀牛等大型动物因其极端的体型而被称为“巨型动物”，对它们所生活的生态系统产生了巨大的影响。他们通过砍伐树木和放牧来创造大片的草坪，帮助形成有利于其他动物的栖息地。但是，很少有研究涉及这些巨型动物或“巨型动物”的尸体在死亡后对生态系统的影响。它们的尸体是营养物质的巨大来源，对它们的尸体所在的生态系统地区具有长期的生态遗产。例如，非洲大象是最大的陆地动物，但几乎没有人知道它们巨大的尸体（高达6,000公斤）的营养物质如何影响热带草原生态系统。该奖项提出了一个主要问题：大象如何影响非洲热带草原的生态？这项工作将解决这些巨型生物如何影响微生物在土壤中的营养循环，植物初级生产和物种多样性，以及脊椎动物食草动物（如斑马和长颈鹿）和无脊椎动物食草动物（如蚱蜢）的食草性。这项研究将支持1名博士后学者，研究生和本科生在生态学以及科学传播和推广的指导。主要的更广泛影响将是制作一部科学纪录片《巨型食草动物的遗产》，该纪录片将“追踪”非洲大草原上大象的生与死，将这些大象的生命周期置于更广泛的生态环境中，了解它们如何影响生态系统以及当前对面临消失的生态系统的影响。为了解决这个首要问题，该奖项将使用南非克鲁格国家公园（KNP）不同年龄（15岁以上）的大象尸体。结合土壤（物理，化学和生物学特性），植物（生产力和多样性），和草食动物（脊椎动物和无脊椎动物）调查在50 megacarcass网站沿着温室实验，该奖项将评估如何营养脉冲从大象尸体驱动生态系统过程的综合反应。重要的是，大象巨型冰川分布在KNP的降雨量（375 - 700毫米）和土壤肥力（较不肥沃的桑迪、花岗岩土壤与较肥沃的粘土、玄武岩土壤）的梯度上。这些梯度的降雨和土壤养分提供了一个强大的实验框架，用于测试非生物环境如何影响陆地巨型冰川的生态系统级遗产效应。最后，通过将来自该领域的关于巨型动物对生态系统过程的影响的数据与KNP的大象种群数据库相结合，研究人员将使用生态建模来展示巨型动物的分布如何在整个稀树草原景观中产生生态系统过程的变化，因为大象会随着时间的推移自然死亡。这项研究将代表对陆地生态系统的生态遗产的首次审查。该奖项反映了NSF的法定使命，并且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。

Large animals such as elephants and rhinoceros, called ‘megafauna’ for their extreme size, have outsized impacts on the ecosystems they live in. They engineer their environments by knocking down trees and grazing grasses to create large lawns, helping to form habitats that facilitate other animals. But, there is little research that addresses the impact that the carcasses of these megafauna, or ‘megacarcasses’, have on ecosystems after they die. Their carcasses represent huge sources of nutrients that have a long-lasting ecological legacy on the areas of ecosystems where their carcasses occur. For example, African elephants are the largest land animals, but almost nothing is known about how the nutrients from their massive carcasses (up to 6,000 kg) affect savanna ecosystems. This award asks the main question: How do elephant megacarcasses affect the ecology of African savannas? The work will address how these megacarcasses affect nutrient cycling in the soil by microbes, plant primary production and species diversity, and herbivory by vertebrate herbivores, such as zebra and giraffe, and invertebrate herbivores, such as grasshoppers. This research will support the mentoring of 1 postdoctoral scholar, graduate and undergraduate students in ecology as well as science communication and outreach. The main broader impact will be the production of a scientific documentary, The Legacy of Megaherbivores, which will ‘follow’ the life and death of an elephant in the African savanna, that will put the life cycle of these elephants into broader ecological context, understanding how they impact ecosystems and the current implications for ecosystems facing their disappearance. To address the overarching question, the award will use elephant carcasses of different ages (up to 15+ years old) in Kruger National Park (KNP), South Africa. Combining soil (physical, chemical and biological properties), plant (productivity and diversity), and herbivore (vertebrate and invertebrate) surveys at 50 megacarcass sites along with greenhouse experiments, the award will assess how nutrient pulses from elephant carcasses drive integrated responses of ecosystem processes. Importantly, the elephant megacarcasses are distributed across gradients of rainfall (375-700 mm) and soil fertility (less-fertile sandy, granitic soils vs. more-fertile clayey, basaltic soils) in KNP. These gradients of rainfall and soil nutrients provide a robust experimental framework for testing how the abiotic environment impacts the ecosystem-level legacy effects of terrestrial megacarcasses. Finally, by combining the data from the field on the effects of megacarcasses on ecosystem processes with a database of elephant population across KNP, the researchers will use ecological modeling to show how the distribution of megacarcasses generates variability in ecosystem processes across the savanna landscape as elephants naturally die over time. This study will represent the first examination of the ecological legacies of megacarcasses on terrestrial ecosystems.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.