Priority effects, consumer pressure, and soil resources independently alter plant diversity and resource strategies during a multi-year successional field experiment

SummaryPlant community succession is structured by priority effects, plant consumer pressure, and soil resource supply. Importantly, these drivers may interact, their effects may vary temporally, and they may influence different facets of plant community diversity by promoting different plant tradeoff strategies.In an herbaceous successional system, we manipulated priority effects by altering initial plant richness, consumer pressure via pesticide spraying, and soil resource supply via fertilization. We examined how these processes jointly influenced succession, including taxonomic diversity and functional traits, over four years.Diversity decreased in different years in response to more diverse priority effects, lower consumer pressure, and increased soil resource supply. Functionally, higher soil resource supply increased community height, SLA, and seed mass; higher consumer pressure decreased intraspecific community height, and increased interspecific SLA; priority effects led to decreased seed mass only when plots were unplanted.Our results suggest species’ resource strategies underlie plant diversity responses. Resource addition promoted resource-acquisitive species, consumer pressure disadvantaged resource-conservative species, and diversity of priority effects altered subsequent community composition through persistence of early residents, not via traits. We show that community responses to drivers of succession depend on underlying trait tradeoffs of resident species, and these tradeoffs influence community diversity across succession.