Is nitrogen deposition manna for herbivores?

Background/Question/Methods While much research has focused on the influence of nitrogen deposition on individual plants and plant communities, much less work has addressed how nitrogen deposition may affect consumers. Nitrogen deposition has the potential to strongly influence individuals, populations, and community composition of herbivores if deposition affects the quality or quantity of plant tissue available. Insect herbivores may be particularly sensitive to deposition-induced changes in host plant quality due to their sensitivity to leaf nitrogen content. We review the recent literature on nitrogen deposition impacts on plant-herbivore interactions and discuss potential community and ecosystem level implications.

Results/Conclusions Nitrogen deposition can lead to strong positive impacts on individual insect performance, probably due to deposition-induced improvements in host-plant chemistry. These improvements include increased nitrogen and decreased carbon-based defensive compound concentrations. Evidence to date suggests that deposition may also positively affect insect populations. These positive impacts of nitrogen deposition on herbivory may in turn affect biodiversity and biogeochemical processes. In addition, interactions between nitrogen deposition and other global-scale changes may lead to non-additive effects on patterns of herbivory.