Environmental Factors Influencing Wood Frog (Lithobates
sylvaticus) Tadpole Size in a Glaciated Landscape
Amanda Smith, Dr. James Church and Dr. Mandy Little
University of Wisconsin-Stout
Introduction
Results
 L. sylvaticus populations are a significant contributor in
maintaining a balanced food chain; therefore L. sylvaticus is
important to maintain a functional wetland.
pH was the only environmental variable to be positively correlated with
SVL (Figure 1). Out of the 40 ephemeral ponds surveyed, only half collected
L.sylvaticus tadpoles. The mean SVL was 13.7 mm (± 8.19). Minimum SVL
was 8.33 mm and maximum was 20.2 mm.
 Isolated ephemeral wetlands are a significant habitat for
amphibians in the forested landscape.
 Is there an environmental characteristic of wetlands correlated
with L. sylvaticus tadpole body size?
 Objective: evaluate environmental variables as it relates to the
assessment of tapole body size.
 Environmental variables: temperature, pH, and dissolved,
chlorophyll-a and canopy cover
Figure 1. Correlation of pH and SVL. Each dot represents an ephemeral pond that had L.
sylvaticus tadpoles during the time of surveying. The figure indicates a strong positive
correlation between pH and SVL.
Discussion
Methods
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Chippewa Moraine State Recreation Area
40 ephemeral ponds
One sample period in May 2013
Four minnow traps per pond
24 incubation period
Snout-vent length (SVL)
 pH was the only significant factor having a strong correlation with SVL. We
believe factors affecting pH are most likely litter inputs in addition to
geological wetland characteristics.
 Studies examining types of leaf litter have indicated that tadpole size may be
determined by both the species of amphibian and species of tree (Stoler and
Reylea, 2011, p.867).
 The pH of wetlands can serve as a proxy for the relationship between
immediate upland landscapes, most often acidifying Pinaceae family, and the
SVL of L. sylvaticus. As pH increases, SVL increases; thus more basic wetlands
are more likely to have sustainable populations due to larger amphibians.
 While our study focuses on L. sylvaticus, it is important to realize the
potential implications of our results on other wetland species such as
aquatic macro-invertebrates that are essential contributors to water quality.
 Future studies designed to evaluate multiple species of animals and plants of
wetlands would promote a better understanding of biodiversity functions of
wetland ecosystems. With expansive research we believe conservation
policy could be greatly beneficial to the greater watersheds.
Literature Cited
Stoler, A.B. and Relyea, R.A. (2011). Living in the litter: the influence of leaf litter
on wetland communities. Oikos, 120, 862-867.
Tadpole Photo: Photo by Rick Relyea,
http://www.myscience.us/wire/stressed_out_tadpoles_grow_larger_tails_to_es
cape_predators-2013-umich “Stressed-out tadpoles grow larger tails to escape
predators”
WI map: http://www.mappery.com/Wisconsin-Counties-Map