The roles of habitat and interspecific interactions in the ecology of amphibians

野生物种数量下降的主要原因之一是栖息地的丧失和退化，两栖动物的消失也不例外。在加拿大，持续缺乏关于普通两栖动物的基本生物学和栖息地要求的信息，使保护成为一项挑战。在接下来的5年里，我的学生和我将在艾伯塔省开展三个项目，调查加拿大分布最广的两栖动物树蛙如何利用湿地和高地栖息地，以及栖息地的利用是如何通过与人类、海狸和鱼类的互动来塑造的。项目1的重点是埃德蒙顿的人工和自然湿地，以确定在城市环境中维持可存活的青蛙种群所需的结构和功能特征。我们将标记和跟踪个体，以检验林蛙使用两种策略在城市中生存的预测；一些青蛙是永久留在繁殖池周围狭窄河岸地带的居民，而另一些青蛙每年在城市池塘和天然林地之间迁徙。项目2将确定海狸是否作为生态系统工程师在易干旱的阿斯本公园为两栖动物创造和维护湿地栖息地。我们将比较有和没有活动海狸栖息地的林蛙数量，并记录成年和蝌蚪如何利用受海狸建造和洪水影响的池塘和河岸栖息地。在许多系统中，鱼类，特别是引进的物种，可以大幅减少两栖动物的数量。然而，在艾伯塔省北部丘陵的小湖泊中，我们发现放养的鲑鱼不会改变林蛙种群的大小或结构。为了找出原因，项目3将使用实验围栏来研究彩虹鲑鱼、本地小鱼和饲养湖泊、只有小鱼的湖泊和没有鱼的湖泊中的蝌蚪之间的相互作用。我们预测，来自有小鱼的湖泊的林蛙已经适应了鱼的存在，因此在引入鲑鱼时可以坚持下去。作为一个整体，我的项目将帮助我们了解两栖动物如何利用湿地和高地栖息地在城市化、气候变化和自然资源管理面前生存。

One of the chief causes of declines in populations of wild species is habitat loss and degradation, disappearing amphibians are no exception. In Canada, an ongoing lack of information on the basic biology and habitat requirements of even common amphibians makes conservation a challenge. Over the next 5 years, my students and I will conduct three projects in Alberta that investigate how the wood frog, the most widespread amphibian species in Canada, uses wetland and upland habitat and how habitat use is shaped by interactions with humans, beavers, and fishes. Project 1 focuses on constructed and natural wetlands in Edmonton to determine what structural and functional features are required to maintain viable frog populations in urban environments. We will mark and track individuals to test the prediction that wood frogs use two strategies to survive in the city; some frogs are residents that remain permanently in narrow riparian strips around breeding ponds, whereas others migrate annually between urban ponds and natural woodland. Project 2 will determine if beavers, acting as ecosystem engineers, create and maintain wetland habitat for amphibians in the drought-prone Aspen Parkland. We will compare wood frog populations between sites with and without active beaver colonies and document how adults and tadpoles use ponds and riparian habitats affected by beaver construction and flooding. In many systems, fish, especially introduced species, can drastically reduce amphibian numbers. However, in small lakes in Alberta's boreal foothills, we found that stocked trout do not alter the size or structure of wood frog populations. To find out why, Project 3 will use experimental enclosures to examine interactions between rainbow trout, native minnows, and tadpoles from stocked lakes, lakes with only minnows, and fishless lakes. We predict that wood frogs from lakes with minnows have adapted to the presence of fish, and thus can persist when trout are introduced. As a whole my program will help us understand how amphibians use wetland and upland habitats to survive in the face of urbanization, climate change, and natural resource management.