The effects of Chinese tallow (Triadica sebifera) on development and survivorship of anuran larvae

Chinese tallow (Triadica sebifera) is an invasive exotic deciduous tree species. The current range of the species includes coastal prairie and lowland areas of the southeastern United States. The species is common in riparian areas and is known to create mono-specific stands in areas where it is not controlled by herbicides or other management practices. Chinese tallow is commonly found in wetlands of East Texas, with leaf litter entering aquatic ecosystems. Leaf litter from tallow breaks down quickly, releasing nutrients and other compounds into aquatic environments. Chinese tallow leaf litter has been found to negatively impact some invertebrates and decomposers, but there is little research investigating the impacts from Chinese tallow leaf litter on aquatic vertebrates. I compared the effects of tallow, red maple (Acer rubrum), and swamp chestnut oak (Quercus michauxii) leaf litter on survival, and rate of development for four species of anuran larvae. Tadpoles were raised in mesocosms that differed only in the type of leaf litter. Pseudacris fouquettei and Lithobates sphenocephalus had lower survival within the tallow pools. Pseudacris fouquettei were smaller in Chinese tallow mesocosms than the two native species, while L. sphenocephalus tadpoles were larger in mesocosms with Chinese tallow than either of the two native species. Hyla versicolor showed significant developmental and morphological differences in Chinese tallow; however, survivorship was not significantly different among leaf treatments. Leaf litter treatment did not affect survivorship, developmental rate, or morphology in Incilius nebulifer. The anurans tested also vary in timing of breeding season with L. sphenocephalus and P. fouquettei breeding in winter and early spring while I. nebulifer and H. versicolor breed in the spring and summer. Timing of breeding may influence how each species survives and develops within an environment with Chinese tallow leaf litter. Pseudacris fouquettei and L. sphenocephalus are among the earliest breeding species in east Texas and had the lowest survival within the experimental mesocosms, while the later breeders showed no negative effect of the tallow treatment compared to other leaf litter treatments. Because Chinese tallow leaf litter breaks down faster than that from native tree species, the negative effects of the tallow leaves may be short lived in the aquatic environment, therefore posing a greater threat to species that breed soon after leaf fall.