DOI: 10.5061/dryad.2bvq83bnm
title: Warming and shifting phenology accelerate an invasive plant life cycle

description: Numerous studies have documented changes in the seasonal timing of
 organisms’ growth and reproduction in response to climate warming. These
 changes correlate with documented changes in species’ abundance, but
 mechanisms linking these trends remain elusive. We investigated the joint
 demographic effects of advanced reproductive phenology and warming on a
 globally invasive plant (Carduus nutans) in a field experiment,
 documenting a substantial shift toward completion of the life cycle at
 younger ages. Demographic modeling projected 71% of warmed individuals
 flower as annuals, compared to 61% under current conditions. As this
 species only reproduces once, this represents a major acceleration of the
 life cycle. We project a 15% increase in this invader’s population growth
 rate. We show that rising temperatures accelerate this invasive species’
 population growth by increasing the average size of reproducing
 individuals; increasing the proportion of individuals that survive to
 reproduce; and increasing the fraction that reproduce as annuals. Major
 increases in population growth in this, and potentially many other,
 invasive species will threaten food security and require careful planning
 to avoid significant environmental and economic impacts.
description: A full description of the field experiment that produced these
 data is included in the associated article.
description: Columns within the file are as follows: PlotID: A
 unique identifier for the 10x15 cm area in which the observed plant was
 grown. This identifier is made up of the Cohort, Block, Plot, Position,
 and PlantDate, separated by “_”. Details describing each of these values
 are included below. z: Plant size
 in year <i>t</i>, measured as the natural log of the longest
 leaf length in centimeters. Rosettes were measured at the end of the
 growing season in early November. z1: Plant size
 in year <i>t</i> + 1, measured as the natural log of the
 longest leaf length in centimeters. Rosettes were measured at the end of
 the growing season in early November. Surv: Survival
 from year <i>t</i> to year <i>t</i> + 1. A value
 of 0 indicates that the individual died, while a value of 1 indicates that
 the individual survived. Repr:
 Reproduction in year <i>t </i>+ 1. A value of 0 indicates that
 the individual did not reproduce in year <i>t </i>+ 1, while a
 value of 1 indicates that the individual did reproduce in year
 <i>t </i>+ 1. age: The age
 of the individual at time <i>t</i>. Individuals measured at
 the end of their first growing season have age 0, and age increases by 1
 each year afterward. Cohort: The
 year in which the individual was planted (either 2012 or 2013).
 Block:
 The block in which the individual was planted. Values are not unique
 between years; each cohort’s block numbering starts at 1. Plot: The 2x2
 m plot in which the individual was planted. Position: The
 10x15 cm area in which the individual was planted. PlantDate: The
 seed release timing treatment to which the position was assigned. For
 plants in the 2012 cohort, the treatments were planted on the following
 dates:                 1:
 8/2/2012                 2:
 8/8/2012                 3:
 8/21/2012                 4:
 9/5/2012                 5:
 9/19/2012                 6:
 10/3/2012                 7:
 10/19/2012 For
 plants in the 2013 cohort, the treatments were planted on the following
 dates:                 1:
 8/3/2013                 2:
 8/12/2013                 3:
 8/26/2013                 4:
 9/9/2013                 5:
 9/24/2013                 6:
 10/8/2013                 7:
 10/22/2013 OTC: The
 temperature treatment to which the plot was assigned. A value of 0
 indicates the plot was at ambient temperature, while a value of 1
 indicates the plot was passively warmed using a fiber glass open top
 chamber (OTC). Pred.seeds:
 The predicted number of seed produced by the individual in year
 <i>t, </i>estimated based on the diameter of mature capitula
 harvested in late July. strata.seedl.otc: The category to which the individual belongs, among the following:                 AmbPlant: an established individual grown at ambient temperature                 AmbSeedl: a newly established rosette grown at ambient temperature                 OTCPlant: an established individual grown under passively warmed conditions in an OTC                 OTCSeedl: a newly established rosette grown under passively warmed conditions in an OTC