Intermediate Pond Sizes Contain the Highest Density, Richness, and Diversity of Pond-Breeding Amphibians

Abstract

We present data on amphibian density, species richness, and diversity from a 7140-ha area consisting of 200 ponds in the Midwestern U.S. that represents most of the possible lentic aquatic breeding habitats common in this region. Our study includes all possible breeding sites with natural and anthropogenic disturbance processes that can be missing from studies where sampling intensity is low, sample area is small, or partial disturbance gradients are sampled. We tested whether pond area was a significant predictor of density, species richness, and diversity of amphibians and if values peaked at intermediate pond areas. We found that in all cases a quadratic model fit our data significantly better than a linear model. Because small ponds have a high probability of pond drying and large ponds have a high probability of fish colonization and accumulation of invertebrate predators, drying and predation may be two mechanisms driving the peak of density and diversity towards intermediate values of pond size. We also found that not all intermediate sized ponds produced many larvae; in fact, some had low amphibian density, richness, and diversity. Further analyses of the subset of ponds represented in the peak of the area distribution showed that fish, hydroperiod, invertebrate density, and canopy are additional factors that drive density, richness and diversity of ponds up or down, when extremely small or large ponds are eliminated. Our results indicate that fishless ponds at intermediate sizes are more diverse, produce more larvae, and have greater potential to recruit juveniles into adult populations of most species sampled. Further, hylid and chorus frogs are found predictably more often in ephemeral ponds whereas bullfrogs, green frogs, and cricket frogs are found most often in permanent ponds with fish. Our data increase understanding of what factors structure and maintain amphibian diversity across large landscapes.

Species interactions and the effects of climate variability on a wetland amphibian metacommunity

“…Predicting how communities will respond to climate change requires a strong understanding of the role that species traits and species-interactions have in structuring responses (Ives 1995, Urban 2004, Gilman et al 2010, Zarnetske et al 2012, Anderson et al 2015. Our results provide a direct demonstration of why it is important to consider these interacting components and provide a template for estimating interaction strengths in occurrence time-series data.…”

“…Similarly, the pig frog has a breeding season that spans approximately 6-7 months and its larvae require at least one year to complete development (Lamb 1984). Because species traits have an important role in defining optimal conditions for each species (Wilbur 1987, Pechmann et al 1989, Skelly et al 1999, Paton and Crouch 2002, Babbitt et al 2003, Anderson et al 2015, Semlitsch et al 2015, they are also likely important in understanding the effects of changing climate. Despite being locally abundant in some locations, the pig frog is a species of concern throughout parts of its distribution and large knowledge gaps remain in our understanding of its ecology (Lamb 1984, Ugarte et al 2007, Hammerson et al 2008.…”

“…In wetland systems, a major determinant of community structure is hydroperiod, which can range from highly ephemeral wetlands that remain inundated for short periods of time to permanent wetlands (Pechmann et al 1989, Snodgrass et al 2000a, Semlitsch et al 2015. Habitat suitability for individual species is influenced by interactions between the physical characteristics of the wetland (i.e., soil composition, geomorphology, hydrology) and climate (Kupferberg 1996, Pounds et al 1999, Brooks 2004, Jackson et al 2014.…”

Integrating life-history traits and amphibian upland habitat use in a Neotropical hotspot

“…predators (Semlitsch et al, 2015). Thus, the protection of large ponds are unlikely to help sustain most amphibian populations.…”

“…Besides benefits in the conservation of semi-aquatic animals, protective buffers may also provide a number of ecosystem services, including the improvement of water quality by removing sediments and pollutants (Lovell and Sullivan, 2006). To maintain present levels of biodiversity, regulation policies should guarantee the protection of wetlands small as 0.1 ha (Semlitsch and Bodie, 1998;Semlitsch et al, 2015).…”