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

地球陆地景观的很大一部分是干旱的旱地。火灾是干旱旱地的一个特点。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长期发展的大部分知识都来自对基本上不受火灾影响的潮湿生态系统进行的研究。火灾可以通过将植物组织变成灰烬来显着降低生态系统的生产力，并且暴露于高频率火灾的地方可能会减少对植物生长至关重要的营养物质的可用性。最近的研究表明，史前火灾状况是夏威夷旱地的一个自然和持久的特征，可导致磷的长期供应和生态系统结构明显下降。然而，在人类到达之前，已知存在于夏威夷的大型海鸟群沉积的营养物质可能会减少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的古代和环境DNA实验室的迈克尔·邦斯教授合作，将对从夏威夷旱地的粪坑中挖掘出来的半化石鸟类骨骼中保存的古代DNA（aDNA）进行测序。将分析aDNA数据，以量化过去海鸟种群的多样性和丰度，以及它们如何因人类资源的使用而发生变化。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。这项工作将使夏威夷的管理人员对过去夏威夷旱地生态系统的功能有新的认识。对于管理人员来说，这些见解是非常需要的，以制定明智的保护目标的未来。这个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.