Bahlai, C., C. Hart, M. Kavanaugh, J. White, R. Ruess, T. Brinkman, H. Ducklow, D. Foster, W. R. Fraser, H. Genet, P. Groffman, S. K. Hamilton, J. Johnstone, K. Kielland, D. Landis, M. C. Mack, O. Sarnelle, and J. Thompson. Future trajectories of ecosystems in the U. S. Long Term Ecological Research Network: Cascading effects. Ecosphere (in press).

Ecosystems across the U.S. are changing in complex and unpredictable ways and analysis of these changes requires coordinated, long-term research. This paper is a product of a synthesis effort of the U.S. National Science Foundation funded Long Term Ecological Research (LTER) network addressing the LTER core research area of “populations and communities.” This analysis revealed that each LTER site had at least one compelling “story” about what their site would look like in 50 to 100 years. As the stories were prepared, themes emerged, and we grouped the stories into five separate papers along five themes: state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the cascading effects theme and includes stories from the Kellogg Biological Station (agricultural and freshwater), Bonanza Creek (Boreal), Palmer (Antarctic) and Harvard Forest (temperate forest) sites and includes a wide array of unforeseen chains of events that result from a variety of actions or changes in ecosystems. While climate change is having important direct effects on boreal forests, indirect effects mediated by fire activity – severity, size, and return interval have large cascading effects over the long term. In the temperate forests of the northeast, legacies of human management and disturbance affect the composition of current forests, which creates a cascade of effects that interact with the climate-facilitated invasion of an exotic pest. In Antarctica, declining sea ice creates a cascade of effects including declines in Adelie and increases in Gentoo penguins, changes in phytoplankton, and consequent changes in zooplankton populations. Exotic species invasion of lady beetle are likely to have important future effects on pest control and the conservation of native species in agricultural landscapes. New studies of zebra mussels, a well-studied invader, have established links between climate, the heat tolerance of the mussels and harmful algal blooms. Collectively, the stories highlight the need for long-term studies to sort out the complexities of different types of ecological cascades. The diversity of sites within the LTER network facilitates the emergence of overarching concepts about trophic interactions as an important driver of ecosystem structure, function, services and futures.

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Regional or Synthesis

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