Plant richness, turnover, and evolutionary diversity track gradients of stability and ecological opportunity in a megadiversity center
© Guenter Fischer/Getty
Today’s biodiversity hotspots are brimming with species because they have enjoyed long periods of ecological stability.
Investigations into global biodiversity patterns have mainly focussed on diversity decline from equator to pole. But this fails to separate high productivity — whereby an ecosystem generates a lot of biomass — from environmental stability, because the tropics have both.
Now, a team that included researchers from the University of Cape Town has studied the distribution of just over 4,800 plant species across the Cape Floristic Region of South Africa, and created biodiversity maps of this extra-tropical hotspot. They compared these to maps of biome stability (how big and old an ecosystem is), climate stability over the past 140,000 years, rainfall seasonality, landscape features, and productivity.
Biome stability and low rainfall seasonality were the key drivers of biodiversity across the region — a finding that goes against theories that posit that productivity is behind species richness. It also suggests that these well-established ecosystems could be at particular risk from rapid climate change.
- PNAS 117, 20027–20037 (2020). doi: 10.1073/pnas.1915646117