Salamander Demography at Isolated Wetlands within Mature and Regenerating Forests

Abstract

Geographically isolated wetland and surrounding landscape features affect the ecology and life history of amphibian species. We used multistate mark recapture methods and data from over 30,000 captures of adult Ambystoma opacum to explore how survival, breeding, and movement probabilities differed among wetlands surrounded by regenerating 20-year-old clearcuts and mature 100-year-old forest stands. Survival varied among ponds and years but did not differ between regenerating and mature forest habitats. Both sexes at all ponds incurred dramatic mortality during the non-breeding season of a drought year (2001–2002). Females that skipped one or more breeding opportunities had higher breeding probabilities the following year than did successive breeders. Females exiting into regenerating forests had lower breeding probabilities at two of the three ponds. Breeding salamanders tended to make local movements from regenerating to mature forests, particularly when exiting the pond basin. Landscape movements between ponds were generally low, with few individuals moving from mature to regenerating forest habitats. We conclude that clearcuts continue to negatively impact some demographic parameters of salamanders 20 years post-cutting, but other environmental factors may mitigate these effects, and that populations are probably capable of complete recovery, particularly if some mature forest is retained.

Comparing Genetic and Field-Based Estimates of Population Connectivity in Marbled Salamanders, Ambystoma opacum

“…These focal ponds are part of a karst-depression wetland in the Shenandoah Valley [27] with little microtopography among ponds and are well-known for their role in biodiversity and biogeographic patterns of organisms. The three differ in the extent of regenerating forest (clear cut in 1980) and mature forest (at least 100 years old) that encircle each pond [28]. Within the clear cuts, white pines were planted at higher density than they occur within the mature forest.…”

“…They live primarily underground the remainder of the year, with limited movement [12]. pond [28]. Within the clear cuts, white pines were planted at higher density than they occur within the mature forest.…”

“…We used field estimates of movement from a capture mark recapture (CMR) study of adult Ambystoma opacum in years 1999-2003 [28]. Movement probabilities were averaged across males and females and breeders and nonbreeders among ponds.…”

Variation in Flatwoods Salamander Survival Is Unrelated to Temperature and Rainfall

“…URVIVAL rates are known to vary over the course of an individual's lifetime and among individuals within a population (Roff, 1992;Cooch, 2002;Ebenman and Persson, 2012). Mortality risk is intrinsically tied to environmental conditions and body size and can therefore show considerable variability through time and across a population (Laurie and Brown, 1990;Forsman, 1991;Sorci and Clobert, 1999;Kunz and Ekman, 2000;Church et al, 2022). For instance, in amphibians, regulating temperature and water balance is more challenging for smaller individuals, making them susceptible to prolonged periods of drought, temperature extremes, and food deprivation (Ash et al, 2003;Knapp et al, 2003;Rothermel and Semlitsch, 2006;Tilghman et al, 2012).…”