CSBR: Natural History Collections: Safeguarding the world's largest dendrochronological collection The Laboratory of Tree-Ring Research (LTRR) at the University of Arizona holds the world's largest and most diverse collection of wood specimens used for dendrochronological (tree-ring dating) research. The estimated two million tree-ring specimens collected over the past century are used to understand past climate and ecosystem dynamics, refine predictions regarding future environments, inform policy for hazard mitigation and resource management, and to study and date a broad range of human and environmental interactions. Many of these unique, irreplaceable specimens are currently at-risk, stored beneath the university football stadium bleachers. They require cataloging, labelling, and re-boxing prior to transfer into a new state-of-the-art repository. Techniques and tools will be developed to assist in this cataloging and to maximize accessibility to the international scientific community and the public. Best practices developed through this process will be made available to other tree-ring laboratories around the world. In addition, the project will enhance the existing LTRR public outreach program by developing new resources such as STEM and sensory resource kits in collaboration with local schools. This project will safeguard the approximately 60,000 specimens that constitute the "modern studies" portion of the tree-ring collection, making them physically available, secure and electronically accessible via web resources. The specimens will be cataloged using the open source Tellervo software, which conforms to the Tree Ring Data Standard (TRiDaS) developed by the international research community. Tellervo will be further developed to include new curation interfaces to improve the efficiency of the cataloging workflow. To enable data to be provided to established biodiversity portals like iDigBio (iDigBio.org) and the Global Biodiversity Information Facility (GBIF.org), fields will be mapped from TRiDaS to the DarwinCore standard and delivered using GBIF's Integrated Publishing Toolkit (IPT). A dedicated web portal will also be developed for Tellervo enabling users to query the rich information associated with dendrochronological data beyond the core specimen collection information. Such information combined with full accessibility will enhance next generation studies in tree-ring science. The new curation, DarwinCore data export, and web portal tools developed during this project will be made available to numerous laboratories already using Tellervo, facilitating international adoption of a standardized procedure for collection, data and specimen storage for tree-ring research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.