Understanding the forces that shape plant communities has been a core question in ecology since its start. Numerous theories have developed over this time, examining how static and variable resources may influence community assembly. Additionally, over the last 50 years new, often complementary theories have been developed to help understand how certain species become invasive in particular habitats. At the same time plant phenology has received increasing attention in recent decades, promoting the development of many geographically large-scale databases in addition to previously-available long-term records. Here we develop several of the major theories of community and invasion ecology into their main phenological predictions and present early results from tests with North American datasets.

Results/Conclusions

Our hypotheses on the role of phenology in structuring plant communities focus on time as a pivotal niche axis. We extend the niche partitioning, priority effects and storage effect models into their phenological applications. A temporally-explicit version of the niche complementary model suggests species should partition time across a growing season, while the related vacant niche model suggests exotic plants may target growth during periods when native plants are less active, resulting in differing phenologies for native versus exotic species. Additionally, basic ecological co-existence models predict priority effects—where species establishing earlier in the season benefit by sequestering resources first—could also be important to the success of invasive plants. Storage effect models, which combine priority effects with variable success through time, suggest varying phenologies within and across growing seasons may also help assemble communities. We test some of these predictions using leaf-burst and flowering data throughout the United States. Our results support priority effects for exotic species in some areas of North America and suggest large-scale datasets of plant phenology may provide a powerful way to test the main theories of invasion biology.