Taking inspiration from the emerging field of macrosystems ecology, this session focuses on ecological insights gained from the information contained in the annual rings formed by trees. Specifically, we show how tree-ring science (dendrochronology) is used to investigate biological, geophysical, and sociocultural patterns and processes – and their interactions – across a wide range of scales. The session begins with two talks at the cellular and organismal scale that offer insight into tree physiology – the intertwined carbon and water dynamics of tree growth – with an eye to the global scale at which forest ecosystems play an important feedback role in the coupled biosphere-climate system. Two talks at the community and landscape scale follow, on the lasting effects that rare disturbance events can have on forest communities and on the “wicked” problem of wildfire. The session then turns to coupled human-natural systems, where tree rings offer centennial- to millennial-length perspectives on human uses of landscapes, how human societies influence disturbance regimes and are influenced by climate variation, and on the vulnerability of the ecosystem services provided by forested landscapes in the face of climate change. We then highlight two frontiers of tree-ring science in time and space: the use of Bayesian stochastic antecedent modeling to investigate ecological memory in forest ecosystems, and a new, representative tree-ring data network collected in the permanent forest inventory plots of the U. S. D. A. Forest Service’s Interior West-Forest Inventory and Analysis Program. The use of extensive tree-ring data to indicate future landscape suitability for boreal forests of eastern Canada - ecological forecasting - is a new and innovative reversal of climate-tree growth relationships. The session closes by circling back to the process of carbon sequestration, but at the global scale – an outlook talk on the challenges of upscaling from tree-ring samples to global-scale carbon accounting. With new technology, powerful statistics, and the accumulation of large data and knowledge, 21st century dendrochronology is uniquely poised to advanced our understanding of the challenges posed to “hierarchical ecological systems comprising biological, geophysical, and social components” across a broad range of biological, temporal, and spatial scales.