EAPSI: Understanding the legacy of seabirds and fire regimes in tropical dryland ecosystems in Hawaii

地球上很大一部分陆地景观是由干旱的旱地组成的。火是干旱旱地的一个特征。火灾的频率和规模决定了这些生态系统的结构、组成和功能。然而，关于生态系统结构如何在很长一段时间内发展的大部分已知知识，都来自于在潮湿的生态系统中进行的研究，这些生态系统基本上不会受到火灾的影响。火灾会将植物组织转化为灰烬，从而显著降低生态系统的生产力，而暴露在火灾高发区的植物生长所需的营养物质可能会减少。最近的研究表明，史前火灾制度是夏威夷旱地的一个自然和持久的特征，可能导致磷的长期有效性和生态系统结构的明显下降。然而，在人类到达夏威夷之前，已知存在于夏威夷的大群海鸟储存的营养物质可能已经减少了与火灾有关的任何营养物质损失。这项研究与科廷大学世界级古代和环境DNA实验室的迈克尔·邦斯教授合作，将对夏威夷旱地蚂蚁挖掘出的半化石鸟类骨骼中保存的古代DNA(ADNA)进行测序。将对aDNA数据进行分析，以量化过去海鸟种群的多样性和丰富性，以及它们可能因人力资源使用而发生的变化。这项研究有助于从理论上理解干扰和动物营养补贴在旱地生态系统长期发展中的作用。这项工作将为夏威夷的管理者提供关于夏威夷过去旱地生态系统功能的新见解。对于管理者来说，这些洞察力对于为未来制定知情的保护目标至关重要。该NSF EAPSI奖是与澳大利亚科学院合作资助的。

A large percent of the earth's terrestrial landscape is composed of arid drylands. Fires are a characteristic of arid drylands. The frequency and magnitude of fires shapes the structure, composition and functions of these ecosystems. However, most of what is known about how ecosystems structure develops over long periods of time has been derived from studies conducted in humid ecosystems that are largely invulnerable to the effect of fires. Fires can significantly reduce the productivity of an ecosystem by turning plants tissues into ash and places exposed to a high frequency of fires may see a reduction in the availability of nutrients key to plant growth. Recent studies have shown that prehistoric fire regimes are a natural and persistent feature of Hawaiian drylands that can lead to apparent declines in the long-term availability of phosphorus and the structure of the ecosystem. However, nutrients deposited by large colonies of seabirds known to exist in Hawaii prior to human arrival could have potentially abated any nutrient losses associated with fires. Working in collaboration with Professor Michael Bunce at Curtin University's world-class ancient and environmental DNA labs, this study will sequence ancient DNA (aDNA) preserved in semi-fossil bird bones excavated from dryland middens in Hawaii. The aDNA data will be analyzed to quantify the diversity and abundance of seabird populations in the past and how they may have changed in response to human resource use. This research contributes to theoretical understandings about the role of disturbance, and animal nutrient subsidies in the long-term development of dryland ecosystems. This work will provide managers in Hawaii new insights about the function of Hawaiian dryland ecosystems in the past. For managers, these insights are critically needed to develop informed conservation targets for the future. This NSF EAPSI award is funded in collaboration with the Australian Academy of Science.