Symposium 1 (PT 1). Tree rings from national forest inventories: a timely opportunity to assess tree growth across space and through time
Tree-ring time series provide long-term, annually resolved information on the growth of individual trees. However, public tree-ring archives contain a considerable portion of data collected from trees that have been selected with specific research questions in mind (e.g., for climate reconstruction). This makes these archives a biased representation of the sensitivity of forest ecosystems to ongoing climate variation (e.g. temperature, precipitation), including non-stationarity (i.e., global warming and associated changes to Earth’s climate). Many public collections also lack the tree and forest information needed to quantify forest-level growth, making it very difficult to scale-up tree-level information to ecosystem estimates of biomass accumulation and carbon sequestration. National forest inventories (NFIs), by comparison, are systematic observatories of forest ecosystems designed specifically for large-scale inference. Yet, this spatial information comes at relatively low temporal (e.g. decadal) resolution and hampers the investigation of forest responses to annual climate variability as well as seasonal and climate extremes. When tree-ring data are collected in NFIs (or other statistically designed) forest plot networks, multiple influences on tree growth can be captured in an unbiased and representative way—not just climate, but also competition, disturbance processes, and other environmental factors (atmospheric CO2 concentration, N deposition)—which is critical to parse their effects and understand how they may interact. A systematic effort to sample tree rings in NFIs can yield unprecedented temporal and spatial resolution of the drivers of forest and carbon dynamics. This symposium aims to showcase the latest work on the development and applications of tree rings collected from NFIs and forest plot networks. Applications of NFI tree-ring data may include retrospective analyses of spatial variations in productivity and climate sensitivity, efforts to improve carbon accounting, examinations of climate change impacts, and assessments of mitigation potential critical for Earth’s habitability.