Effects of Experimental Canopy Manipulation on Amphibian Egg Deposition

Abstract

Although effects of forest management on amphibians are relatively well studied, few studies have examined how these practices affect egg deposition by adults, which can impact population recruitment. We quantified the effects of 4 canopy tree‐retention treatments on amphibian oviposition patterns in clusters of 60‐L aquatic mesocosms located in each treatment. We also related aquatic and terrestrial biophysical parameters in treatment plots to oviposition patterns. Cope's gray treefrogs (Hyla chrysoscelis) deposited more egg masses in clear‐cut and 25–50% tree‐retention treatments than in controls. In contrast, mountain chorus frogs (Pseudacris brachyp***hona) deposited more egg masses in unharvested control and 75% retention treatments than in clear‐cut or 25–50% retention treatments. Spotted salamanders (Ambystoma maculatum) only deposited eggs in 75% retention treatments and controls. The number of egg masses deposited by mountain chorus frogs was positively related to canopy cover and negatively related to water temperature, pH, and dissolved oxygen, whereas we noted the opposite relationships for Cope's gray treefrogs. We did not detect a relationship between the number of egg masses deposited by any species and the distance of mesocosms to either the nearest mature closed‐canopy forest or to the nearest natural amphibian breeding pool. The impacts of the silvicultural treatments we studied were species‐specific and depended on the amount of trees removed. In areas where protection of spotted salamander and mountain chorus frog breeding habitat is a priority, we recommend harvests retain at least 75% of the canopy. Our results also suggest that retention of 25–50% of canopy trees surrounding amphibian breeding pools has little conservation benefit.

Responses of the woodland salamander Ensatina eschscholtzii to commercial thinning by helicopter in late-seral Douglas-fir forest in northwest California

“…This result is consistent with a reduction in canopy, an action that incurs more light reaching the ground thereby increasing temperatures and lowering moisture (e.g., Rambo and North, 2009). While the effects of canopy reduction on amphibians can vary by species (e.g., Felix et al, 2010), there is little debate that the overall effects on woodland salamanders is negative (Tilghman et al, 2012). Surface activity, while vital for foraging and reproduction, can none-the-less be substantially reduced because of the physiological constraints on these salamanders (Feder, 1983;Homyack et al, 2011).…”

Wetland Reserve Program Enhances Site Occupancy and Species Richness in Assemblages of Anuran Amphibians in the Mississippi Alluvial Valley, USA

“…Thus, wetlands with extensive canopy cover may be a deterrent to occupancy by several species of anurans. Five of the 11 species detected (American Bullfrog, Spring Peeper, Blanchard's Cricket Frog, Green Frog, and Cope's Gray Treefrog) had similar estimates of occurrence in both (Skelly et al 1999;Binckley and Resetarits 2007;Felix et al 2010). In the MAV, the American Bullfrog, Green Frog, and Blanchard's Cricket Frog are associated with permanent or long hydroperiod sloughs and large swale wetlands that have large patches of open water.…”

Matrix context and patch quality jointly determine diversity in a landscape‐scale experiment

“…). While most species prefer open‐canopy ponds, and more species coexist in these areas, it is clear that some species prefer closed‐canopy ponds (Felix et al , Earl et al ). Therefore, in order to maximize biodiversity at the landscape scale, management strategies that preserve both closed‐ and open‐canopy ponds are needed.…”