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The Synergistic Effects of Environmental Change on the Population Dynamics of Localized Endemic Species, a Case Study in Hawai`i.

机译：环境变化对本地特有物种种群动态的协同效应-以夏威夷为例。

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摘要

The spatial distribution and abundance of organisms are shaped by interactions with the environment. Human-induced changes in the environment can have varying effects on plant vital rates across ontogeny, sometimes in opposite directions. It is commonly thought that plant endangerment is the result of the combined effects of multiple environmental stressors. The influences of environmental stressors on components of plant fitness have been well examined. Few studies, however, have explicitly evaluated the synergistic effects of environmental stressors on the geospatial distribution of endangered species. In this dissertation I examined the population dynamics of three Hawaii endangered plants, Schiedea obovata, Cyrtandra dentata, and Delissea waianaeensis . Furthermore, I used a combination of size and stage structured demographic models to quantify the individual and combined impacts of dominant non-native pests and changing abiotic conditions on plant dynamics. I also compared the economic costs of various restoration strategies, including the suppression of non-native frugivores and seedling herbivores. I found that for S. obovata and C. dentata, fine-scale changes in microhabitat heterogeneity and inter-annual precipitation patterns had a greater effect on plant dynamics than top-down stressors. Furthermore, I found that the endangered plant populations were not always at, or close to, their equilibrium state (i.e., stable stage distribution SSD). There are many factors that contributed to the populations moving away from equilibrium, including population augmentation and the suppression of non-native pests. For the D. waianaeensis and C. dentata populations, there was a greater proportion of individuals in later life stages than would be expected if the populations were at a stable equilibrium. High reproductive value of these populations caused them to grow faster in the near-term transient phase (i.e., 10 years) than over the long-term as the population reached equilibrium (i.e., transient amplification). Furthermore, I found that there were numerous combinations of restoration actions that would likely shift the growth rate of endangered species from declining to growing. However, the yearly economic costs of targeted restoration actions were highly variable. From a global perspective, this study illustrates that changing precipitation patterns and alterations in microhabitat can have a greater negative impact on plant dynamics than non-native frugivores and seedling herbivores and thus should be considered when developing rare plant restoration strategies. This research also emphasizes how important it is to evaluate both the near term transient and asymptotic dynamics of endangered species in order to fully capture the likely outcome of restoration effort.
机译：生物的空间分布和丰富度是通过与环境的相互作用而形成的。人为引起的环境变化可能会对整个个体发育过程中的植物生命率产生不同的影响，有时方向相反。通常认为，植物危害是多种环境胁迫因素共同作用的结果。已经充分研究了环境胁迫因素对植物适应性成分的影响。但是，很少有研究明确评估环境胁迫因素对濒危物种地理空间分布的协同作用。在这篇论文中，我研究了三种夏威夷濒危植物Schiedea obovata，Cyrtandra dentata和Delissea waianaeensis的种群动态。此外，我使用了规模和阶段结构的人口统计学模型的组合，以量化主要非本地害虫以及不断变化的非生物条件对植物动态的个体影响和综合影响。我还比较了各种恢复策略的经济成本，包括抑制非本地食肉动物和幼苗食草动物。我发现对于S. obovata和C. dentata，微生境异质性和年际降水模式的细微变化比自上而下的胁迫对植物动态的影响更大。此外，我发现濒临灭绝的植物种群并不总是处于或接近其平衡状态（即稳定的阶段分布SSD）。有许多因素导致种群脱离平衡，包括种群增加和非本地害虫的抑制。对于W.ianaiana和D. waianaeensis种群，处于后期生命阶段的个体比例要比如果种群处于稳定平衡时的预期比例要高。随着种群达到平衡（即瞬时扩增），这些种群的高繁殖力使它们在短期过渡阶段（即10年）比长期增长更快。此外，我发现有许多恢复行动的组合，它们很可能会将濒临灭绝物种的生长速度从下降转移到增长。但是，有针对性的修复行动每年的经济成本变化很大。从全球的角度来看，这项研究表明，与非本地食肉动物和幼苗食草动物相比，不断变化的降水模式和微生境变化对植物动态的负面影响更大，因此在制定罕见的植物恢复策略时应考虑到这一点。这项研究还强调了评估濒临灭绝物种的短期瞬态和渐近动力学的重要性，以便充分捕捉恢复工作的可能结果。

著录项

  • 作者

    Bialic-Murphy, Lala.;

  • 作者单位

    University of Hawai'i at Manoa.;

  • 授予单位 University of Hawai'i at Manoa.;
  • 学科 Botany.;Ecology.;Environmental economics.;Conservation biology.
  • 学位 Ph.D.
  • 年度 2017
  • 页码 166 p.
  • 总页数 166
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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