Collaborative Research: Reverberating Responses to Trophic Cascades across Ecosystems: from Land to Streams and Back Again

在食物网中，捕食者和猎物之间的许多相互关联的关系可以将看似遥远的生物和过程联系起来。本研究探讨了陆地环境中顶级捕食者的影响如何跨越生态系统边界，影响水生环境中的初级生产和食物网。本研究还探讨了水生生态系统对捕食者的反应如何反射回溪流，从而影响依赖于从溪流中输出新兴成虫的陆地捕食者。跨生态系统食物网的联系将在三个不同的国家公园（锡安国家公园、落基山国家公园和黄石国家公园）进行研究，从而提供大空间尺度的复制，并利用国家公园提供的机会，教育公众关于食物网生态学和顶级捕食者在构建生态系统中的作用。这项研究将是同类研究中首次调查营养级联的回响效应，即间接效应可能跨越生态系统边界（陆地到水生），然后随后回响到原始生态系统中的动植物（水生到陆地）。这项工作将提供一个更完整的画面，说明世界范围内顶级掠食性物种的消失是如何间接影响许多远亲物种的。先前的调查已经证明了顶级捕食者（例如，黄石公园的狼和锡安国家公园的山狮）在控制河流沿岸植被方面的间接作用。此外，溪流和河岸区通过物质和生物交换的良好过程连接在一起，使它们成为识别和量化营养混响的理想系统。该研究将在河流和邻近的河岸区进行，并将包括(1)河边有蹄动物和河岸植物群落，(2)群落组成和河中生物群的丰度，陆地通量（有机物和无脊椎动物）流向溪流的量化，以及溪流生物群的饮食，以及(3)河岸区出现的成年水生昆虫和蜘蛛和蝙蝠的反应。这些河岸食虫动物是河流昆虫出现和河流-河岸联系变化的风向标。在每个公园里，复制研究地点将沿着河流建立，有或没有控制有蹄类动物对河岸木本植被的浏览。通过对三个国家公园内和公园间的比较，本研究将更好地了解社区和景观环境如何调节有蹄类动物在陆地上自上而下的浏览控制下的回响反应的强度，甚至是信号。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The many interconnected relationships between predators and prey in a food web can link seemingly distant organisms and processes. This study explores how the influence of top predators in a terrestrial environment is linked across ecosystem boundaries to impact primary production and food webs in aquatic environments. This study also explores how aquatic ecosystem responses to predators can reverberate back out of the stream to impact terrestrial predators that rely on the export of emerging adult insects from the stream. Cross-ecosystem food web connections will be studied at three different National Parks (Zion, Rocky Mountain, and Yellowstone National Parks), thereby providing replication at large spatial scales and leveraging the opportunities that National Parks provide to educate the public about food web ecology and the role of top predators in structuring our ecosystems. This research will be the first of its kind to investigate reverberating effects of trophic cascades whereby indirect effects may cross ecosystem boundaries (terrestrial to aquatic) and then subsequently reverberate back to animals and plants in the original ecosystem (aquatic back to terrestrial). This work will provide a more complete picture of how the loss of top predatory species worldwide may be indirectly influencing many distantly connected species.Previous investigations have demonstrated the indirect role of top predators (e.g., wolves in Yellowstone Park and mountain lions in Zion National Park) in control of riparian vegetation along streams. In addition, streams and riparian zones are connected by well-understood processes of material and organism exchange, making them ideal systems to identify and quantify trophic reverberations. The study will be conducted in streams and adjacent riparian zones and will encompass (1) streamside ungulate browsing and riparian plant communities, (2) community composition and abundance of in-stream biota, quantification of terrestrial fluxes (organic matter and invertebrate) fluxes to streams, and diets of stream biota, and (3) emergent adult aquatic insects in the riparian zone and the response of spiders and bats. These riparian insectivores serve as a bellwether for changes in stream insect emergence and stream-riparian linkages. In each park, replicate study sites will be established along streams with and without controls on ungulate browsing of riparian woody vegetation. By comparing within and across three national parks, this study will yield a greater understanding of how community and landscape context may mediate the strength, or even sign, of reverberating responses to terrestrial top-down control of ungulate browsing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.