Enabling ecological survey data integration with the Humboldt Extension to Darwin Core

In the face of the global biodiversity crisis, accessibility to biodiversity data that are maximally effective for downstream use in science, conservation, and policy is paramount. The Darwin Core standard has played a central role in providing a standardised structure and vocabulary for biodiversity data. However, early iterations of the standard were not optimised to capture the sampling context of biodiversity surveys – survey methods, scope, and sampling effort – which is essential for the correct interpretation and potential reuse of such data. To address this limitation, we present the Humboldt Extension to Darwin Core, a ratified standard designed to accommodate datasets that contain such contextual information. Building upon an initial, previously developed framework, we significantly improved, fully tested, and ratified a final standard, following a community process defined by biodiversity information standards (TDWG), an international standards organisation. The resulting Humboldt Extension adds 55 terms that enrich the Darwin Core, providing the terms needed to capture and share multiple types of biodiversity survey data. We illustrate the benefits of implementing the Humboldt Extension with three case studies and demonstrate how richer data can be used in research, modelling, and to inform decision-making. We urge the uptake and use of this Extension to facilitate the reuse and synthesis of monitoring data, particularly structured surveys and inventories, for science, conservation, and policy.