Using range-edge ecology to inform conservation of Canada's rare plants

在加拿大，大多数被认为濒危的物种只出现在其地理范围的北部边缘。因此，加拿大的物种保护与山脉边缘种群的生态密不可分。然而，关于边缘种群的广泛生态学理论或研究它们的田间技术很少被应用于加拿大的濒危物种，以指导它们的保护。例如，理论预测物种的北部活动范围经常受到寒冷的限制。如果是这样的话，最近的气候变暖应该会为许多山脉边缘物种创造新的栖息地，但濒危物种政策的重点是防止现有种群的损失，而不是帮助物种跟上气候变化的步伐。我们建议结合我们在生物地理学(AH)、牧场边缘种群(AH、MV)和加拿大濒危植物(JM)的野外实验方面的专业知识，帮助将珍稀植物的保护从简单的防止损失转变为促进恢复。问题：使用加拿大范围仅限于安大略省南部和/或魁北克的濒危植物，我们将提出两个关于边缘种群的基本问题，这两个问题直接关系到它们的长期保护。1)它们的北缘是由生态因素决定的，还是由扩散决定的？扩散限制将意味着它们的范围可以通过建立新的种群来扩大；生态因素(例如雪深)的限制将建议缓解战略，以支持现有种群的规模(例如雪夹)。2)气候变暖是否在物种当前范围以北创造了新的适宜栖息地？尽管经历了50年的变暖，我们的候选物种的活动范围都没有扩大；如果存在新的栖息地，它们将需要帮助才能到达那里。方法：首先，我们将使用物种分布模型来预测ON/QU中90多个稀有物种的范围。JM已经成功地使用分布模型来确定物种范围内的合适栖息地；我们将增加模型的地理范围，以确定它们以外的潜在栖息地。我们预测，温度最能预测其分布的物种，由于气候变暖，最有可能在其范围之外拥有合适的栖息地。其次，我们将使用3种省级珍稀草本植物的移植实验来检验模型预测。我们将把种子和插条移植到我们的模型预测在当前气候下高度适合(处理1)和中等适合(处理2)的超出范围的地点，监测以比较在范围内控制移植的性能(处理3)。如果植物的表现远远超出它们的范围，这表明它们的分布是有限的；如果移植表现不佳，监测将揭示哪些生态因素限制了适应性。处理1比处理2的性能更好将验证模型预测栖息地的能力；例外情况将揭示哪些模型需要改进。第三，我们将重新运行分布模型，使用未来的气候预测来预测物种的适宜气候将移动到哪里。我们将把植物移植到这些“未来的地点”，用试验性的加温室环绕一半，以测试植物在变暖的情况下是否能在那里存活，或者非温度因素是否会阻止变暖驱动的扩张。影响：加拿大未来的生物多样性将受到物种范围边缘动态的强烈影响。该项目将有助于建立预测这种变化的科学基础，并为加拿大稀有植物确定有效的恢复战略。

Most species considered imperilled in Canada only occur here at the northern edge of their geographic range. Species conservation in Canada is therefore inextricably tied to the ecology of range-edge populations. Yet little of the extensive ecological theory about edge populations or field techniques for studying them have been applied to Canada's species-at-risk to guide their conservation. For example, theory predicts that species' northern ranges are often limited by cold. If so, recent climate warming should be creating new habitat for many range-edge species, yet species-at-risk policy is focused on preventing loss of existing populations rather than helping species keep pace with climate change. We propose to combine our expertise on biogeography (AH), field experiments with range-edge populations (AH, MV), and Canadian plants at risk (JM) to help shift conservation of rare plants from simply preventing loss to promoting recovery. Questions: Using at-risk plants whose Canadian range is limited to southern Ontario and/or Quebec, we will ask two fundamental questions about edge populations that bear directly on their long-term conservation. 1) Is their northern range edge determined by ecological factors or dispersal? Dispersal limitation would mean their range could be bolstered by founding new populations; limitation by ecological factors (e.g. snow depth) would suggest mitigation strategies to bolster the size of existing populations (e.g. snow traps). 2) Is climate warming creating newly-suitable habitat north of species' current ranges? None of our candidate species' ranges have expanded despite five decades of warming; if new habitat exists they will need help getting there. Approach: First, we will use species distribution models to generate predictions about the ranges of 90+ rare species' in ON/QU. JM has successfully used distribution models to identify suitable habitat within species' ranges; we will increase models' geographic extent to identify potential habitat beyond them. We predict that species whose distributions are best predicted by temperature will be most likely to have suitable habitat beyond their range due to warming. Second, we will test model predictions using transplant experiments for 3 provincially-rare herbs. We will transplant seeds and cuttings to beyond-range sites that our models predict to be highly-suitable (treatment1) and moderately-suitable (treatment2) under current climates, monitoring to compare performance to control transplants within the range (treatment3). If plants perform well beyond their range, it suggests their distribution is dispersal limited; if transplants perform poorly, monitoring will reveal which ecological factors limit fitness. Better performance in treatment1 than treatment2 will validate models' ability to predict habitat; exceptions will reveal which models need refining. Third, we will re-run distribution models using future climate projections to predict where species' suitable climate will move. We will transplant plants to these 'future sites', surrounding half with experimental warming chambers to test whether plants could survive there given warming, or whether non-temperature factors will prevent warming-driven expansions.Impact: Canada's future biodiversity will be strongly shaped by dynamics of species range-edges. This project would help establish a scientific foundation for predicting such changes and identify effective recovery strategies for Canada's rare plants.