Hauling field gear up Gothic Mountain…
Human activities have doubled the amount of biologically-available nitrogen on Earth, much of which is emitted to the atmosphere and falls to the ground far from its source. This blanket of fertilizer, called ?atmospheric nitrogen deposition, has well-studied ecological effects near sources of nitrogen emissions, but much less is understood about the elevated, yet low-level, deposition that occurs more broadly. In particular, it is unclear how low-level nitrogen fertilization indirectly affects relationships among plants, herbivores and predators, especially across the long timespans over which nitrogen deposition occurs. I propose to study how long-term, low-level nitrogen deposition impacts a community composed of plants, arthropods and black bears. My previous research showed that bears can indirectly benefit plants by eating ants and suppressing positive relationships between ants and herbivorous insects, but that the effects of bears weakened under short-term nitrogen enrichment. Here, I will extend this ongoing experiment to a total of 18 years to evaluate how long-term exposure to low-level nitrogen enrichment affects these relationships. I will also study spatial and temporal variation in bear consumption of ants. This work will aid our understanding of the repercussions of nitrogen pollution and inform the management of both nitrogen deposition and bears.