Spring and autumn phenology in an understory herb are uncorrelated and driven by different factors

Premise Climate warming has altered the start and end of growing seasons in temperate regions. Ultimately, these changes occur at the individual level, but little is known about how previous seasonal life-history events, temperature, and plant-resource state simultaneously influence the spring and autumn phenology of plant individuals. Methods We studied the relationships between the timing of leaf-out and shoot senescence over 3 years in a natural population of the long-lived understory herb Lathyrus vernus and investigated the effects of spring temperature, plant size, reproductive status, and grazing on spring and autumn phenology. Results The timing of leaf-out and senescence were consistent within individuals among years. Leaf-out and senescence were not correlated with each other within years. Larger plants leafed out and senesced later, and size had no effect on growing season length. Reproductive plants leafed out earlier and had longer growing seasons than nonreproductive plants. Grazing had no detectable effects on phenology. Colder spring temperatures delayed senescence in two of three study years. Conclusions The timing of seasonal events, such as leaf-out and senescence in plants can be expressed largely independently within and among seasons and are influenced by different factors. Growing season start and length can often be dependent on plant condition and reproductive status. Knowledge about the drivers of growing season length of individuals is essential to more accurately predict species and community responses to environmental variation.

Automated summary

Climate warming has affected the timing of growing seasons in temperate regions, but little is known about how previous seasonal life-history events, temperature, and plant-resource state simultaneously influence the phenology of plant individuals. In this study, the relationships between leaf-out and shoot senescence were studied in a natural population of the understory herb Lathyrus vernus over 3 years. It was found that plant size, reproductive status, and spring temperature all had effects on spring and autumn phenology.