California Department of Fish and Wildlife(CDFW) statewide analyses of biological richness by 2.5 square mile hexagons, for ACE-II project, September 18, 2015 update. Four indices of biological richness were developed: total native species richness based on species range maps, rare species richness and rarity-weighted richness based on rare species occurrence data, and sensitive habitat presence. The four indices were combined in a weighted-additive model framework, giving each layer equal weight, to produce the biological index surface.Biological richness indices represent relative values scaled from 0-1 (i.e., percentages) across the state. Hexagons with a high biological index score represent those areas with high species richness, high levels of rarity and irreplaceability, and/or sensitive habitats. See the ACE-II Project Report for a detailed description of data inputs and analyses at https://nrmsecure.dfg.ca.gov/FileHandler.ashx?DocumentID=24326. An abbreviated summary is provided in the Supplemental Information below.