The United Nation’s Sustainable Development Goal 15 (SDG15), known as "Life on Land," is dedicated to safeguarding, restoring, and fostering the sustainable utilization of terrestrial ecosystems while curbing the decline of biodiversity. Specifically, SDG15.1.2 pertains to the "Proportion of significant sites for terrestrial and freshwater biodiversity encompassed within protected areas, categorized according to ecosystem type." Despite its clear delineation, effectively tracking its spatial progress remains a salient challenge. In response to this challenge, we have devised a robust biodiversity monitoring framework underpinned by Earth observation big data, aimed at comprehensively monitoring the advancement of SDG15.1.2 across various spatial and temporal scales. The framework comprises seven meticulously defined indices that encapsulate species diversity, ecosystem diversity, and landscape diversity. The weighting of each index was meticulously determined through expert insights and a hierarchical analytical process, subsequently facilitating the classification of the synthesized biodiversity index into four distinct strata signifying high, medium, average, and low levels of biodiversity. Operationalized within the geographical purview of China and Southeast Asia, our proposed framework leverages spatial datasets at a 30-meter resolution, encompassing land cover, vegetation indices, aquatic features, and population distribution. The outcomes reveal the efficacy of the generated biodiversity index in effectively characterizing the spatial gradient of regional biodiversity. Furthermore, the synthesized index is seamlessly integrated with spatial data outlining protected areas, culminating in a quantitative appraisal of SDG15.1.2 at both the national and provincial (state) levels within the designated study domain. Our study significantly facilitates the national and regional evaluation of SDG15.1.2's advancement, which bears paramount importance in delineating strategic priorities for conservation initiatives, particularly in areas confronted with rapid biodiversity decline. 

biodiversity,remote sensing,big Earth data,SDG15.1.2