Invading plants remain undetected in a lag phase while they explore suitable climates.

Area of Science:

• Ecology
• Invasive Species Biology
• Conservation Science

Background:

• Successful alien species may exhibit a lag phase, a period of quiescence before widespread invasion.
• The presence of lag phases introduces significant uncertainty into ecological risk analyses.
• Predicting invasion success and impact necessitates understanding lag phase characteristics and termination mechanisms.

Purpose of the Study:

• To quantify the prevalence and duration of lag phases in naturalized plant species.
• To investigate the influence of environmental factors and functional traits on lag phases.
• To determine if shifts in climatic space occur during the transition from lag to expansion phases.

Main Methods:

• Analysis of over 5,700 time series from 3,505 naturalized plant species across nine global regions.
• Utilized herbarium records and climate data to identify and quantify lag phases.
• Assessed shifts in species' climatic space by comparing data from lag and expansion periods.

Main Results:

• Lag phases were identified in 35% of assessed invasion events, with an average duration of 40 years (maximum 320 years).
• Phylogenetic signals for lag phases were detected in temperate regions; annual, self-fertilizing species were less prone to lags.
• Lengthy lags (>100 years) were more common in perennial plants and less frequent in self-pollinating species.
• For 98% of species with lags, climatic spaces differed between the lag and expansion phases, suggesting climate discovery or niche shifts.

Conclusions:

• Functional traits significantly influence the onset of the expansion phase.
• Climate discovery may play a role in terminating lag phases, though niche shifts and sampling issues are alternative explanations.
• Quantifying lag phases is essential for accurate ecological risk assessment and management of invasive species.