It is often useful to look back in time in an attempt to interpret the nature of previous events that may be similar to what we expect to experience in the future and measure how the things we are interested in have responded in the past. This can often be a challenge in biological systems as they are, by their very nature in a constant state of change, with these changes themselves having legacies that persist for very different time scales. From the seasons experienced in temperate climates and the impact this has on the life cycles of different species, to the seemingly random formation of a gap in a forest canopy after a storm, to the chance death of a deer in a specific part of a forest, providing temporary food for a complex community of organisms, confined to that specific location. Change is inherent, a fundamental and integral part of every biological system that drives the machinery of evolution, forcing species to enter into a eternal arms race; adapt or suffer the consequences. But this can be a tall order, and the rate of change is expected to be faster than mechanisms of adaption are keep pace with. This step change in the pace and unpredictability of global change poses unique challenges, but we can learn a significant amount from studying the way in which species have adapted before and attempting to measure how robust or resilient they are. So how do we look back in time and what accurate and reliable record do we have of the past?
Every living tree holds within it a piece of this puzzle, annually recording in every ring its own unique story, a combination of genetic inheritance and a lifetime of environmental exposure. Collectively, many trees build up the pages of a book that can be pieced together to tell a story, cell by cell, ring by ring, chapter by chapter. It is this story that can help us answer the questions of how previous climate has affected our forests, and enable us to make informed decisions on how best to deal with the challenges we face today.