Upper thermal limits predict herpetofaunal responses to forest edge and cover

Abstract

Amphibians and reptiles are sensitive to changes in the thermal environment, which varies considerably in human‐modified landscapes. Although it is known that thermal traits of species influence their distribution in modified landscapes, how herpetofauna respond specifically to shifts in ambient temperature along forest edges remains unclear. This may be because most studies focus on local‐scale metrics of edge exposure, which only account for a single edge or habitat patch. We predicted that accounting for the combined effect of multiple habitat edges in a landscape would best explain herpetofaunal response to thermally mediated edge effects. We (1) surveyed herpetofauna at two lowland, fragmented forest sites in central Colombia, (2) measured the critical thermal maximum (CTmax) of the species sampled, (3) measured their edge exposure at both local and landscape scales, and (4) created a thermal profile of the landscape itself. We found that species with low CTmax occurred both further from forest edges and in areas of denser vegetation, but were unaffected by the landscape‐scale configuration of habitat edges. Variation in the thermal landscape was driven primarily by changes in vegetation density. Our results suggest that amphibians and reptiles with low CTmax are limited by both canopy gaps and proximity to edge, making them especially vulnerable to human modification of tropical forest. Abstract in Spanish is available with online material.

Observations on Vertebrates at Padang Chong Forest Reserve, Perak

“…This may due to the fact that amphibians require the cool moist conditions of forest floor microhabitats, but increasing sunlight penetration on the forest floor in the forest edge may provide drier and warmer forest floor microhabitats that cause amphibians tend to avoid the forest edge [20,21]. Beside, rich in reptile's species may due to their tolerance for higher temperatures and by behavioural means, where most reptiles regulate their body temperature via basking under the sun and move into shades when their body temperature drops or ambient temperature starts increasing more than they can tolerate [22]. Study also found that amphibians show stronger impact toward edge effect compare to reptiles, as edge effect decrease the abundance of amphibian's species higher than reptile's species [23].…”

Stand structure as the proximate driver of endemic biodiversity and ecosystem functions in tropical mosaic landscapes

“…We found that low LAI was correlated with high butterfly species richness, likely because light provides favorable conditions for nectar collection, basking, mating, and other activities butterflies love to engage in (Vlasanek et al, 2013). Conversely, high LAI was also correlated with high amphibian species richness, presumably due to a more humid microclimate suitable for tropical amphibian forest species (Veselka et al, 2023). The use of combined metrics such as multidiversity is useful to deal with these different responses.…”