Elucidating the drivers of plant community dynamics on fragmented landscapes

我的研究计划的长期目标是测试有关人类景观上植物群落短期和长期变化的驱动因素的关键假设。在接下来的5年里，我将测试扩散能力、合适栖息地的可用性、景观环境以及这些因素之间的相互作用对预测当地社区是否存在受保护的重点植物物种的相对影响。这项工作建立在我过去5年的研究基础上，利用物种分布模型(SDMS)对安大略省南部零碎林地中稀有植物物种的适宜栖息地进行了量化。我的短期目标是：(1)测试在重点地点周围的景观上测量物种特定适宜栖息地的数量是否可以提高SDMS预测物种占有率的能力。利用地理空间分析，我的实验室将测试特定物种的栖息地划定是否提高了我们根据栖息地数量作为连通性衡量标准来预测是否存在受保护物种的能力。已有研究表明，栖息地连通性在预测鸟类物种存在或不存在方面的作用可以通过特定物种的栖息地描述来更准确地估计，但这种方法尚未在植物中进行测试。2)量化扩散限制和建立限制在植物定居适宜生境中的作用。我们将设计和实施第一个利用SDMS指导珍稀植物物种转移的项目。种植试验将在一系列栖息地适宜性水平上进行，包括目前每个物种已经占据的一些地点。我们还将通过向外播种种子、幼苗和成熟个体来测试传播能力和建立的相对重要性。这项研究将为SDM预测提供罕见的经验检验，并有助于填补加拿大目前在稀有植物易位研究方面的空白。3)估算破碎景观中稀有植物种群间花粉和种子的有效传播率。我们将使用遗传分析来测试珍稀植物种群之间的遗传差异是否对应于种群的地理隔离和/或合适栖息地的邻接性。我们将量化具有不同生活史的两个物种的种群内和种群之间的遗传多样性：木罂粟和弯茎紫荆。通过检查这些物种种群内和种群之间的遗传多样性，我们将确定安大略省南部森林的严重碎片化如何影响遗传模式。这项拟议的研究将提供对基本生态问题的洞察，例如在群落聚集中，生态位限制或扩散限制占主导地位。研究结果还将为未来安大略省南部和加拿大其他地区濒危植物物种的保护规划和政策提供参考。

The long-term goal of my research program is to test key hypotheses concerning the drivers of short- and long-term changes in plant communities on anthropogenic landscapes. Over the next 5 years I will test the relative influence of dispersal ability, availability of suitable habitat, landscape context, and interactions between these factors in predicting whether or not a focal plant species of conservation concern is present in a local community. This work builds on my research over the past 5 years quantifying suitable habitat for rare plant species in the fragmented woodlands of southern Ontario using species distribution models (SDMs). My short-term objectives are: (1) To test whether measuring the amount of species-specific suitable habitat on the landscape surrounding a focal site can improve the ability of SDMs to predict species occupancy. Using geospatial analyses, my lab will test whether species-specific delineation of habitat improves our ability to predict the presence or absence of plant species of conservation concern based on habitat amount as a measure of connectivity. It has been shown that the role of habitat connectivity in predicting the presence or absence of bird species is more accurately estimated using species-specific delineation of habitat, but this approach has yet to be tested for plants. 2) To quantify the role of dispersal limitation and establishment limitation in the colonization of suitable habitat by plants. We will design and implement the first project to use SDMs for directing translocation of rare plant species. Planting trials will occur over a range of habitat suitability levels, including some sites currently already occupied by each species. We will also test the relative importance of dispersal ability and establishment by out-planting seeds, seedlings, and mature individuals. This research will provide a rare empirical test of SDM predictions, and help to fill the current gap in rare plant translocation research in Canada. 3) To estimate effective dispersal rates of pollen and seeds between isolated populations of rare plants on a fragmented landscape. We will use genetic analyses to test whether genetic differentiation between rare plant populations corresponds to geographic isolation of populations and/or contiguity of suitable habitat. We will quantify genetic diversity within and between populations of two species with contrasting life histories: the wood poppy and the crooked-stem aster. By examining genetic diversity within and between populations of these species we will determine how the severe fragmentation of southern Ontario forests is influencing genetic patterns. The proposed research will provide insight into fundamental ecological questions, such as whether niche limitation or dispersal limitation predominates in community assembly. The results will also inform future conservation planning and policy for plant species at risk in southern Ontario and elsewhere in Canada.