It’s not just in the forest canopy that our team of researchers is studying the subtropical forests of China. They also want to find out what is going on at ground level. Which species are to be found in the herb layer? Are they the same species as in the tree layer, or are there unwelcome intruders? Once they have become established, they can have serious consequences for the ecosystem. The big question is: Does higher species diversity provide protection against invasion by exotic plants?