摘要：Continuing destruction of habitats—and especially tropical forests—the introduction of plant and herbivorous animal species outside their native ranges, and global climate disruption all contribute to the extinction of plant species. What can we do to prevent this? Do we have enough basic information to make effective conservation decisions? First, how many plant species are there? This question has an easy element—how many species we know now—and a much more difficult one—how many do we not know. Second, where are the concentrations of plant species? Third, where are the species we do not yet know? Fourth, what plant species have gone extinct, and where did they live? A related question is which species are threatened with extinction and where do they live? Fifth, how well can we map threats to species? For habitat loss, remote sensing provides satellite images globally and very frequently. It does so at a resolution that often displays individual trees and bushes. Sixth, supposing we had detailed answers to the previous questions, what are we doing to protect species? How well does the existing network of protected areas encompass species, especially those with the smallest ranges? Does that network allow for species moving upslope as the climate heats up? How well are managers doing in removing introduced species? Although answering these questions must be a scientific priority, we cannot wait until we have all the answers. We can, and indeed must, act on what we know already.
关键词：biodiversity;climate disruption;extinction;hotspots;introduced species
