It is interesting how, as scientists, we frame questions in very scientific terms. Biodiversity is only a word concocted by someone or some group of people concerned with our environment. There is something that is missing from the scientific literature. It is ignored because it cannot be framed within the scientific rubric. That is okay.
Science is science.
Scientists argue about numbers, whatever they might be. I would argue that the whole issue of the environment and biodiversity is trying to be answered in a manner that will not ultimately solve the problem. We, most especially in our western, scientific, capitalist, exploitist society have lost a connection with our environment and indeed with all living and non-living entities. I do not pretend to have the answer as to how to accomplish this seemingly monumental task. To that I would say consider the world climate that we live in.