Elucidating the drivers of plant community dynamics on fragmented landscapes

我的研究计划的长期目标是测试关于人为景观中植物群落短期和长期变化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、适宜栖息地的可用性、景观环境以及这些因素之间的相互作用对预测当地社区中是否存在值得保护的焦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）量化了安大略省南部破碎林地中稀有植物物种的适宜栖息地。我的短期目标是：(1)测试测量焦点点周围景观中特定物种适宜栖息地的数量是否可以提高SDMs预测物种占用的能力。利用地理空间分析，我的实验室将测试物种特定的栖息地描述是否能提高我们预测保护植物物种存在与否的能力，基于栖息地数量作为连通性的衡量标准。已有研究表明，栖息地连通性在预测鸟类存在与否方面的作用，可以通过物种特异性的栖息地描述来更准确地估计，但这种方法尚未在植物中得到验证。2)量化植物在适宜生境定殖中的扩散限制和建立限制的作用。我们将设计并实施首个利用SDMs指导珍稀植物物种迁移的项目。种植试验将在一系列生境适宜程度的范围内进行，包括目前每种物种已经占据的一些地点。我们还将通过外植种子、幼苗和成熟个体来测试传播能力和建立的相对重要性。本研究将为SDM预测提供罕见的实证检验，并有助于填补目前加拿大珍稀植物易位研究的空白。3)估算破碎化景观中珍稀植物分离种群之间花粉和种子的有效传播速率。我们将使用遗传分析来测试稀有植物种群之间的遗传分化是否与种群的地理隔离和/或适宜栖息地的邻近相对应。我们将量化两种具有不同生活史的物种种群内部和种群之间的遗传多样性：木罂粟和弯茎紫菀。通过检查这些物种种群内部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破碎是如何影响遗传模式的。该研究将提供对基本生态学问题的见解，例如群落聚集中是生态位限制还是分散限制占主导地位。研究结果还将为安大略省南部和加拿大其他地方的濒危植物物种的未来保护规划和政策提供信息。

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.