It's a paradox that's puzzled scientists for a half-century.

Models clearly show that the coexistence of competing species depends on those species responding differently to the availability of resources. Then why do studies comparing competing tree species draw a blank?

Competitors like black gums and red maples have coexisted for millennia in the shaded understories of eastern U.S. forests, yet species-level data offer scant proof that they respond differently to ...