•Information on the vertical and horizontal structure of habitat is critical for biodiversity assessment.•Airborne laser scanning (ALS) offer descriptions of the three-dimensional distribution of vegetation.•We develop and apply a forest structure index across the forested area of Alberta.•We demonstrate how the index can be used to predict avian species richness. Most efforts to link remote sensing to species distributions and movement have focused on indirect estimates of traits based on components of physiological and functional biodiversity. Such a view reflects one perspective on the general needs (habitat) of species. However, information on the vertical and horizontal structure of habitat may play a critical role in defining what a suitable habitat is. The development and application of highly accurate airborne laser scanning (ALS) systems, which are capable of describing the three-dimensional distribution of vegetation, have significant potential value in deriving quantitative relationships between species distributions and their habitat structure. In this paper we review the use of ALS for biodiversity studies, and propose a three-dimensional index which captures the three main components of vertical and horizontal vegetation structure: height, cover, and complexity. Once developed, we apply the index across the forested area of the Canadian province of Alberta, and compare and contrast the differences across natural subregions and land cover types. We also demonstrate how the index can be used with biodiversity data, in this case examining patterns in avian species richness. We conclude with a discussion on the potential use of the habitat structure index with other biodiversity-related research.