Dissertation Research: Invasion of Non-Indigenous Grasses into a Hawaiian Dry Woodland and the Ecosystem Consequences of Changes in Community Structure

9700737 D‘Antonio这项建议研究了生物入侵、群落组成的变化和生态系统过程的变化之间的联系，这些变化有助于全球氮(N)循环的变化。拟议研究的目的是确定夏威夷季节性亚山林地非土著牧草改变生态系统N循环的机制，以及这些变化如何影响植物生长的N有效性和生态系统N的积累。通过比较未焚烧的除草林地、未焚烧的牧草林地和以牧草为主的焚烧林地之间的氮素动态，将检验插草增加氮素循环速率和减少损失速率的假设。将使用15N示踪剂对矿物硝化作用、土壤微量气体排放、植物生产和生态系统N分配进行测量。这项研究通过探讨一种新的生长形式在生态系统氮动态中所起的作用，提供了群落和生态系统过程之间的独特联系。这项研究将区分牧草影响氮素动态的机制，并同时比较一种生长形式对养分动态的物理、化学和竞争效应。这项研究还讨论了入侵物种的生长形式和当地资源供应率之间的反馈，这可能会影响竞争互动，并最终影响入侵者的成功。

9700737 D'Antonio This proposal examines the links between biological invasions, changes in community composition, and alteration of ecosystem processes that contribute to changes in the global nitrogen (N) cycle. The objectives of the proposed research are to define mechanisms by which non-indigenous grasses in Hawaiian seasonal submontane woodlands have altered ecosystem N cycling and how these changes affect N availability to plant growth and ecosystem N accumulation. The hypothesis that insertion of grasses increases rates of N cycling and decreases rates of loss will be tested by comparing N dynamics among unburned woodland with grasses removed, unburned woodland with grasses, and burned sites that are grass dominated. Measurements of mineral nitrification, soil trace gas emissions, plant production, and ecosystem N partitioning using an 15N tracer will be made. This research provides a unique link between community and ecosystem processes by addressing the role that a new growth form plays in ecosystem N dynamics. This research will differentiate mechanisms through which grasses effect N dynamics, and it will simultaneously compare the physical, chemical, and competitive effects of a growth form on nutrient dynamics. This research also addresses feedbacks between growth form of invading species and local rates of resource supply that may influence competitive interactions and ultimately, the success of the invaders.