Savannas are a ‘battleground’ between two contrasting life forms, C3 trees and C4 grasses, with each side keeping the other in check. However, over the last few decades, the balance between grasses and trees has been tipping in favour of trees in savannas across the world, with negative impacts on biodiversity and a range of ecosystem services.

Rising atmospheric CO2 has been strongly implicated in driving increased tree densities because it boosts tree growth and enhances their survival through fire and herbivory. However, the response of the C4 grasses has received much less attention but may be significant in determining tree-grass dynamics into the future. In my talk, I’ll assess the responses of both sides of this ecological battle to rising CO2, and discuss implications for the future of the savanna biome.