Sometimes it means species per square acre, other times species evenness, richness, Shannon index, Simpsonās index, or Hill number. In practice, usually only mammals, birds, trees, and shrub species are measured, ignoring the smaller plants, animals, and fungi.
Are any of these just total number? Because from a long-term perspective, since extinction is irreversible (at this point), then you can always re-establish density, etc. Nitpick: acre is an area measure, so square acre is incorrect.
Buncha pedantics: The problem with that is itās easy to add more āweedyā species to increase biodiversity per local area, even as you decrease global biodiversity. The real number is global extant species but we arenāt perfectly coordinated to know what this specific place should do best relative to what everywhere else is doing. Aaand you canāt totally re-establish density with reduced genetic diversity if it gets bad enough, but you are correct. Its the irreversible damage that is most concerning.
Are any of these just total number? Because from a long-term perspective, since extinction is irreversible (at this point), then you can always re-establish density, etc. Nitpick: acre is an area measure, so square acre is incorrect.
Total number is richness.
Buncha pedantics: The problem with that is itās easy to add more āweedyā species to increase biodiversity per local area, even as you decrease global biodiversity. The real number is global extant species but we arenāt perfectly coordinated to know what this specific place should do best relative to what everywhere else is doing. Aaand you canāt totally re-establish density with reduced genetic diversity if it gets bad enough, but you are correct. Its the irreversible damage that is most concerning.
Thanks for noticing that! Iāll fix it.