In a rapidly changing world suffering from extensive diversity loss, the most pressing questions remain largely unanswered: how can diversity exist in the first place and what are the consequences of its decline for ecosystems? In grasslands, resource niches have to date been considered the major mechanism responsible for plant coexistence and diversity. The neutral theory has recently challenged this view by attributing species coexistence solely to stochastic processes. Whereas the negative effects of plant diversity loss on primary productivity have been demonstrated numerous times in biodiversity experiments, its effects on higher trophic levels have rarely been explored. Here, we used a glasshouse experiment, simulation modelling approaches and field studies in the Jena biodiversity experiment to examine diversity maintenance, invasion and community assembly in plant communities and
effects of plant diversity loss on higher trophic levels.