Doctoral Dissertation Research: Biogeography of Island Flora in the Georgian Bay, Lake Huron, Ontario

种-岛关系的概念起源于海洋环境中的岛屿，并已被广泛应用于岛屿。 在考察岛屿物种丰富度时，地理学家和生态学家最常考察的因素之一是岛屿与殖民者来源地之间的相对和绝对距离，以及所考察的岛屿面积。 最近的研究强调了有效距离、岛屿形态、环境异质性、干扰、物种相互作用和植被动态等因素可能发挥的作用。 本博士论文研究项目将通过分析淡水环境中的岛屿，特别是影响格鲁吉亚湾东岸海岸马萨索加省立公园内岛屿植被时空变化的因素，扩大岛屿地理学概念的应用。 其中的研究问题要解决的是：物种面积和物种距离的关系适用于Massasauga群岛？ 除了面积和距离之外，还有哪些中介因素影响着岛屿上的物种丰富度？ 森林年龄级结构是否有助于确定物种丰富度是否存在长期平衡，或者目前的植被特征是否仅代表动态变化过程中的一个阶段？ 为了回答这些问题，草本和木本物种丰富度将确定沿沿着两个1米带样带的50个岛屿，通过分层随机抽样选择。 在沿横断面沿着随机居中的100平方米样方内，将按物种记录树木、树苗和幼苗的数量。 将记录样方内所有树木的直径，并从这些树木的子集中提取树芯。 从样方中心开始记录基质质地、pH值和基岩深度。 地形图和水文图将用于测量岛屿的大小和周长、岛屿距离和地形变化。 距离变量、主要大气模式、湖流和岛屿密度（即垫脚石）将用于确定有效距离。 岛状将计算为周长/面积比。 将计算整个数据集和森林、灌木和草本物种子集的因变量物种丰富度。 将使用多元回归测试比率水平自变量对物种丰富度的相对影响。 简单回归将用于建立直径和年龄之间的关系，以估计所有抽样树木的年龄。 将在每个岛屿上绘制一个二级林分图，以帮助确定优势物种是否在自我繁殖。 这将允许作出推论的可能性，改变物种的优势，从而改变生态时间尺度内的物种丰富度。 研究影响马萨索加公园物种丰富度的可测量因素将进一步理解淡水环境中的岛屿地理学概念。 通过将森林动态的时间维度作为当前物种丰富度的稳定性或非永久性的指标，拟议研究的结果将推广到更广泛的生态变化问题。 这项研究将为管理官员提供有关岛屿植被和生物多样性的基线数据和见解。 研究结果还将涉及格鲁吉亚湾海岸线，包括马萨索加群岛的生态完整性的当前问题。计划开展两项倡议（安大略遗产海岸项目和三万岛屿联合国生物圈保护区提案），在该区域开展生态旅游和发展活动，增加岛屿的使用。 日益增加的人类压力可能最终导致岛屿物种丰富度和组成的变化。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

Concepts of species-island relationships originated in and have been widely applied to islands in marine environments. Among the factors most often examined biogeographers and ecologists exploring variations as they examine species richness on islands have been the relative and absolute distances separating islands from sources of colonists and the area of the islands under examination. More recent studies have highlighted the possible role that factors like effective distance, island morphology, environmental heterogeneity, disturbance, species interactions, and vegetation dynamics may play. This doctoral dissertation research project will expand the application of island biogeography concepts through analysis of islands in freshwater environments, particularly the factors influencing spatial and temporal variation of island vegetation within the Massasauga Provincial Park on the eastern shore of the Georgian Bay. Among the research questions to be addressed are: Do species-area and species-distance relationships apply in the Massasauga islands? What mediating factors besides area and distance affect species richness on the islands? Do forest age-class structures help determine whether there is a long-term equilibrium of species richness, or do current characteristics of vegetation represent only one stage in a process of dynamic change? To answer these questions, herbaceous and woody species richness will be determined along two 1-m-belt transects on each of 50 islands selected through stratified random sampling. Within 100-m-squared quadrats centered randomly along the transects, the number of trees, saplings, and seedlings will be recorded by species. The diameter of all trees within the quadrats will be recorded, and tree cores will be taken from a subset of those trees. Substrate texture, pH, and depth to bedrock will be recorded from the center of the quadrats. Topographic maps and hydrographic charts will be used to measure island size and perimeter, island distances, and topographic variability. Distance variables, prevailing atmospheric patterns, lake currents, and island density (i.e. stepping stones) will be used to determine effective distance. Island shape will be calculated as a perimeter/area ratio. The dependent variable, species richness, will be calculated for the overall data set and for subsets consisting of forest, shrub, and herbaceous species. The ratio-level independent variables will be tested for their relative impact on species richness using multiple regression. Simple regression will be used to establish relationships between diameters and age in order to estimate ages for all of the sampled trees. Age-class plots of stands on each island will be drawn to help determine whether or not dominant species are reproducing themselves. This will allow inferences to be made about the possibility of changing species dominance and therefore of changing species richness within ecological time scales. Investigating measurable factors influencing species richness of Massasauga park will further understanding of island biogeographic concepts in freshwater settings. By incorporating a temporal dimension of forest dynamics as an indicator of the stability or impermanence of current species richness, the results of the proposed research will be generalizable to broader issues of ecological change. This research will provide management officials with baseline data and insight regarding island vegetation and biodiversity. Research results will also pertain to current issues concerning the ecological integrity of the Georgian Bay shoreline, including the Massasauga islands. Two initiatives (Ontario's Heritage Coast Project and the Thirty Thousand Islands United Nations Biosphere Reserve proposal) are planned to generate eco-tourism and development activities in the region, which would increase island use. Increasing human pressures may eventually lead to shifts in the species richness and composition of the islands. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.