Figure 1 - uploaded by Danny J Gustafson
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Trillium pusillum var. pusillum mean counts (±1SE) based on single leaf (A), triple leaf (B), and flowering (C) individuals starting the year after Hurricane Hugo (1989). Coefficients of variation (CV) for each plot over 26 censuses are listed down the right-hand side of the panel and refer to the temporal variability of each size class. Hurricanes (H), Tropical Storms (TS).
Source publication
Hurricane Hugo was a category five storm in September of 1989 that significantly impacted natural areas along the Carolina coastal plain through wind damage and storm surge flooding. Francis Beidler Forest, an Audubon wildlife sanctuary in Four Holes Swamp, suffered severe damage to its forest canopy. In response to concerns that the rare spring ep...
Contexts in source publication
Context 1
... average number of single leaf, triple leaf, and flowering T. pusillum var. pusillum per 25 m 2 plots varied over the 29 years of demographic surveys (Figure 1). Within any given census year, there were significantly more single leaf plants than flowering plants (Table 2). ...
Context 2
... peak flowering occurred in 1991 while single and triple leaf total peaked in 1997 (Table 3). Coefficient of variation across census periods indicated a decrease in temporal variation from a high of 256% in the single leaf plants, to 169% in the triple leaf plants, and 61% in flowering plants (Figure 1). There was a significant positive association between the number of single leaf plants and number of named storms the previous two (r=0.631, ...
Context 3
... Honnay et al. 2005). There were significantly more three leaf than flowering individuals during two blocks of time (1996)(1997)(1998)(1999)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016), which could reflect flowering individuals regressing to the three leaf, an increase in the number of single leaf individuals transitioning to the three leaf stage, or some combination (Figure 1). Our data consists of subplot level (1 m 2 ) and not individual plants; therefore, we cannot address the transition probabilities among the single leaf, triple leaf, and flowering stages. ...
Citations
... Small populations are known to be more susceptible to intrinsic and extrinsic stochastic processes relative to large populations (Matthies et al. 2004). Extrinsic stochastic processes in the form of extreme weather events (Menges et al. 2011;Gustafson et al. 2021), disease (Barrett et al. 2008;Fraedrich et al. 2008), or fire (Menges et al. 2006) can also have greater proportional effects on small populations relative to large populations. ...
Understanding the effects of seed predation, dispersal, and recruitment on the population dynamics of rare plant species is essential for generating effective management strategies. Unfortunately for most rare plants, the parameterization of these processes is limited and generally not included in demographic analyses. This exclusion can lead to biased estimates of vital rates and overall population growth rates, as well as limit inferences about inter-population processes like colonization and demographic rescue that can affect population viability. Based on previous empirical studies from Fort Liberty (formerly Fort Bragg) North Carolina (USA), we constructed a spatially explicit demographic model that accounts for pre-dispersal seed predation, dispersal, and habitat suitability for Lindera subcoriacea (bog spicebush), a rare shrub in the southeastern United States. We demographically modeled three scenarios: S1 did not include any of the three parameters; S2 accounted for seed predation and dispersal; and S3 included all three of the parameters. Results suggested that pre-dispersal seed predation, dispersal, and habitat suitability negatively impact the population growth rates of bog spicebush relative to the naïve demographic model. After 100 annual time steps, scenarios S1, S2, and S3 led to a 96%, 49%, and 1% increase in population size, respectively. In addition, over the course of 100 years, results of scenarios S2 and S3 demonstrated limited increases in site occupancy, with newly occupied areas located < 1 km from previously occupied habitat. Our results suggest additional parameterization of plant demographic models may be an informative endeavor and warranted, even in the absence of empirical data.
