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

Kinney Kealohanuiopunam, Hilo HI

Investigators

Abstract

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.