Over the last four decades, annual rainfall has reduced in West African rainforests at 4% per decade. This has consequences for the survival and growth of young plants in tropical forests, and ultimately affects the diversity and distribution of tropical tree species.
I tested how 23 Ghanaian tree species respond to drought, and what plant characteristics determine this. I compared the species drought survival with the annual rainfall at which these species grow in nature. I found that across species, drought survival was enhanced by less biomass allocation to leaves, a low leaf area per unit plant mass, and dense and tough leaf and wood tissues that allow tree seedlings to overcome drought. Tree species that occur in high rainfall areas experience less survival and growth under drought conditions. My findings suggest that species in the wettest forests will disappear first under decreasing rainfall, leading to significant loss of biodiversity.