In recent years increasing attention has focused on plant phenology as an important indicator of the biological impacts of climate change, as many plants have shifted their leafing and flowering earlier with increasing temperatures. As data have accumulated, researchers have found a correlation between phenological responses to warming and plant performance and invasions. Such work suggests phenology may not only be a major impact of warming, but a critical predictor of future plant performance. Yet alongside this increasing interest in phenology, important issues remain unanswered: responses to warming for species at the same site or in the same genus vary often by weeks or more and the explanatory power of phenology for performance and invasions when analyzed across diverse datasets remains low.
Progress can come from explicitly considering phenology within a community context, including understanding its role in plant community assembly. In this light phenology is hypothesized as a critical trait defining species’ temporal niches and thus we may predict how the phenology and phenological cues of different species within a community will vary. Here I give an overview of these predictions and then test them using two approaches. First, I review meta-analytic findings from long-term observational data on how the phenology of plant species within diverse communities has shifted. Next I show results from experimental and observational research of 28 species in northeastern North American temperate forests; I find that species within this community show a diversified set of phenological cues. My results suggest phenology may be a critical assembly trait in many temperate communities. Therefore, shifts in phenology with global change may also fundamentally disassemble and re-assemble communities.