Patterns and theory of the globe's terrestrial diversity: Does conservation matter?

Background/Question/Methods

I use theory and global data on terrestrial vertebrates and their ecoregions supplied by WWF. How large a loss of species and generic diversity do we face at the global scale? Theory and known patterns of global biodiversity predict the losses. But island biogeography theory cannot because globally extinct species cannot immigrate from the past to recolonize the future. At what rate will the mass extinction proceed? Do the processes that produce diversity result in different extinction rates? Does global warming play a part? What are the effects of exotic species globally and locally? Can conservation biology affect the ultimate outcomes? Will integration of conservation projects with human populations help?

Results/Conclusions

Species-area curves at the global scale are much steeper than those at any other scale. That steepness predicts much more extensive losses than those predicted by local or island SPARs. Adding climate data to area does not remove the extreme threat of area loss. If climate acts through energy flow, losses will amount to at least 65% and as much as 99% depending on how much land and productivity we remove from nature. If climate acts through temperature, the losses will be slightly ameliorated. Species extinction lags area loss and climate change by an unknown amount of time so we cannot yet predict how long diversity will take to relax to its new steady state. Extinction proceeds in three stages. Life instantaneously loses any species deprived of all its appropriate habitat. Then it loses species reduced to sink populations. Finally, it loses species because ordinary extinction processes proceed faster than speciation processes. Because ordinary extinction may be very slow, relaxation may be long delayed. But extinction is now proceeding at rates that are orders of magnitude higher than usual. We do not yet know whether the high rates indicate anything beyond the loss of all habitat or all source habitat. But global climate change in the context of habitat isolates must be contributing to the rate increase. Meanwhile exotic species actually increase local diversities and do very little to reduce long-term global diversities. To reduce the impending long-term losses, conservation must reduce the amount of land that people utterly remove from nature. It must integrate conservation projects with human populations, practicing reconciliation ecology by rebuilding useful habitat heterogeneity in human dominated landscapes.