Elkhorn Slough National Estuarine Research Reserve, Royal Oaks, California, United States of America.
Ecology and Evolutionary Biology, University of California, Santa Cruz, California, United States of America.
PLoS One. 2021 Feb 22;16(2):e0247374. doi: 10.1371/journal.pone.0247374. eCollection 2021.
Wetland restoration provides remarkable opportunities to understand vegetation dynamics and to inform success of future projects through rigorous restoration experiments. Salt marsh restoration typically focuses on physical factors such as sediment dynamics and elevation. Despite many demonstrations of strong top-down effects on salt marshes, the potential for consumers to affect salt marsh restoration projects has rarely been quantified. Recently, major restoration projects at the Elkhorn Slough National Estuarine Research Reserve in central California, USA provided an opportunity to examine how herbivory influences restoration success. We quantified the strength of consumer effects by comparing caged to uncaged plantings, and compared effects among plant species and sites. We used camera traps to detect which herbivores were most common and how their abundance varied spatially. Beyond characterizing consumer effects, we also tested management strategies for reducing negative effects of herbivory at the restoration sites, including caging, mowing, and acoustic playbacks of predator sounds. We found extremely strong consumer effects at sites with extensive stands of exotic forbs upland of the high marsh; uncaged restoration plants suffered heavy herbivory and high mortality, while most caged plants survived. Brush rabbits (Sylvilagus bachmani) were by far the most frequent consumers of these high marsh plants. Our work thus provides the first evidence of mammal consumers affecting salt marsh restoration success. Mowing of tall exotic forb cover adjacent to the marsh at one restoration site greatly reduced consumption, and nearly all monitored plantings survived at a second restoration site where construction had temporarily eliminated upland cover. Playbacks of predator sounds did not significantly affect restoration plantings, but restoration efforts in marsh communities vulnerable to terrestrial herbivory may benefit from concurrent restoration of predator communities in the upland habitats surrounding the marsh. A landscape approach is thus critical for recognizing linkages between terrestrial and marine vegetation.
湿地恢复为了解植被动态提供了显著的机会，并通过严格的恢复实验为未来项目的成功提供信息。盐沼恢复通常侧重于物理因素，如泥沙动态和海拔。尽管有许多关于盐沼受到强烈自上而下影响的证据，但消费者对盐沼恢复项目的潜在影响很少被量化。最近，美国加利福尼亚州中部埃尔克霍恩沼泽国家河口研究保护区的重大恢复项目提供了一个机会，可以研究食草动物如何影响恢复的成功。我们通过比较笼养和非笼养植物来量化消费者的影响强度，并比较了不同物种和地点的影响。我们使用摄像机陷阱来检测哪些食草动物最常见，以及它们的丰度如何在空间上变化。除了描述消费者的影响，我们还测试了在恢复地点减少食草动物负面影响的管理策略，包括笼养、修剪和播放捕食者声音的录音。我们发现，在有大量外来草本植物生长的高沼泽地区，消费者的影响非常强烈；非笼养的恢复植物受到严重的食草动物侵害和高死亡率，而大多数笼养植物幸存下来。刷尾兔（Sylvilagus bachmani）是这些高沼泽植物最频繁的消费者。因此，我们的工作首次提供了哺乳动物消费者影响盐沼恢复成功的证据。在一个恢复地点，对靠近沼泽的高大外来草本植物进行修剪，大大减少了植物的消耗量，几乎所有监测到的植物都在第二个恢复地点存活下来，在那里，建筑工程暂时消除了高地的覆盖物。播放捕食者的声音并没有显著影响恢复植物的生长，但在容易受到陆地食草动物影响的沼泽社区进行恢复工作时，可能需要同时恢复沼泽周围高地栖息地的捕食者群落。因此，采用景观方法对于认识陆地和海洋植被之间的联系至关重要。
