Investigating leaf lifespans with interval-censored failure time analysis

Area of Science:

• Plant Biology
• Ecology
• Statistical Modeling

Background:

• Phenological studies often use growth equations to describe leaf emergence and mortality.
• Understanding individual leaf lifespans is crucial for plant ecology and physiology.

Purpose of the Study:

• To investigate leaf lifespans using interval-censored failure time analysis.
• To compare the leaf lifespan of winter-deciduous fuchsia (Fuchsia excorticata) and annual-evergreen wineberry (Aristotelia serrata).

Main Methods:

• Employed interval-censored failure time analysis, a parametric regression model.
• Described leaf emergence and mortality using growth equations for comparison.
• Analyzed the influence of leaf emergence date, shoot height, branch order, and leaf density on leaf lifespan.

Main Results:

• Fuchsia exhibited earlier bud burst and a faster rate of leaf emergence compared to wineberry.
• Leaf mortality rates differed significantly, being highest in mid-summer for fuchsia and constant for wineberry.
• Leaf emergence timing strongly influenced leaf lifespan, with earlier emerging leaves having shorter lifespans in fuchsia and longer lifespans in wineberry.

Conclusions:

• Failure time analysis offers superior insights into plant phenology compared to traditional growth equations.
• Individual leaf-level analysis using failure time analysis reveals key ecological differences between species.
• Leaf phenology is a complex trait influenced by emergence timing and species-specific strategies.