Climate Change Impacts on Seedling Establishment for a Threatened Endemic Thistle, Cirsium pitcheri

Abstract

A study was conducted to assess the effects of predicted climate change on seedling emergence, growth, and survival for the federally listed threatened species Cirsium pitcheri in the region proximal to Chicago, Illinois, U.S.A. Three geographically distant extant populations that could potentially serve as donors to re-introduced Illinois populations were tested to determine the influence of local adaptation on seed response to climate scenarios at two future time points. For all three populations, temperature was shown to be the most critical factor impacting future growth. All populations performed worst at the 2095 temperature for four measured growth metrics: length of longest adult leaf, number of adult leaves, dry shoot mass, and dry root mass. Growth performance at the 2095 conditions did not correlate with climate familiarity but did reflect the genetic diversity of the parent population. Predicted changes in average precipitation did not produce a significant effect on any growth metric, possibly reflecting a limitation in the study conditions. Seedling emergence and survival were tied to seed mass, a trait influenced by maternal effects and correlated with the level of inbreeding depression in the parent population. These results suggest managing populations to maintain high genetic diversity could be an important factor in tolerating temperature stress associated with climate change.

Seed size and capitulum position drive germination and dormancy responses to projected warming for the threatened dune endemic Cirsium pitcheri (Asteraceae)

“…For germination trials tracking cumulative seed germination, we plated a randomized subsample of 20 seeds from a given capitulum position and site of origin onto Petri dishes lined with dampened, sterilized germination paper, and randomly assigned Petri dishes to one of three temperature treatments (20/10, 25/10, and 30/10°C day/night, hereafter "20, 25, and 30°C"). These temperatures fall within ranges previously tested for C. pitcheri (Chen & Maun, 1998, 1999Staehlin & Fant, 2015) and simulate predicted temperature scenarios that are expected to influence its range (Hayhoe et al, 2010;Vitt et al, 2010).…”

“…Habitat and other environmental changes induced by climate change are expected to further exacerbate dune plant population declines (Frosini et al., 2012; Seabloom et al., 2013; Staehlin & Fant, 2015). While plants growing in dune ecosystems are adapted to withstand environmental stresses like resource limitation, low moisture, high temperatures, and periodic burial (Brown & McLachlan, 2002; Hamzé & Jolls, 2000; Martínez & Psuty, 2004), the increased intensity and frequency of natural and anthropogenic ecosystem perturbances predicted by climate models may significantly reduce the appropriate climate envelopes for dune plant species (Frosini et al., 2012; Seabloom et al., 2013).…”

“…Population viability models for C. pitcheri predict its extinction time to be <20 years (Havens et al., 2012; Jolls et al., 2015). Factors like shoreline development (USFWS, 2002), lake level fluctuations (Staehlin & Fant, 2015), and seed predation by the non‐native weevil, Larinus planus (Fabricius, 1792) (Havens et al., 2012; Louda & O'Brien, 2002) are expected to contribute to C. pitcheri population declines across its range. Further population declines are also expected due to climate change as temperatures in the Great Lakes region rise (Hayhoe et al., 2010) and early life stages, like seed germination and seedling emergence, are impacted (Staehlin & Fant, 2015).…”

“…Factors like shoreline development (USFWS, 2002), lake level fluctuations (Staehlin & Fant, 2015), and seed predation by the non‐native weevil, Larinus planus (Fabricius, 1792) (Havens et al., 2012; Louda & O'Brien, 2002) are expected to contribute to C. pitcheri population declines across its range. Further population declines are also expected due to climate change as temperatures in the Great Lakes region rise (Hayhoe et al., 2010) and early life stages, like seed germination and seedling emergence, are impacted (Staehlin & Fant, 2015). However, despite the bleak predictions for C. pitcheri population persistence, little is known about the impact of climate change on C. pitcheri seed dormancy‐break patterns and how seed attributes affect the timing and probability of seed germination in the context of climate change.…”

“…With an ephemeral between-year soil seed bank, a combination of sand burial and multiple episodes of low temperature (cold) stratification is required to break seed dormancy (Chen & Maun, 1999;Hamzé & Jolls, 2000). Studies investigating C. pitcheri seed germination have demonstrated that seed attributes like mass and source influence seed dormancy (Hamzé & Jolls, 2000), as well as seedling emergence (Staehlin & Fant, 2015) and survival in dune environments (Chen & Maun, 1999).…”