Interactions between invasive species and climate change: The effect on an East Texas anuran.

摘要

Leaf litter from the invasive Chinese tallow tree ( Triadica sebifera) is known to affect the survival of some aquatic amphibians. It has been reported that the effects from Chinese tallow leaf litter may be more severe on winter breeding amphibians than on species that breed later in spring and summer, possibly due to impacts on water chemistry from the leaf litter diminishing over time. Local weather conditions can play a significant role in the timing of amphibian breeding activity; therefore climate change may play a significant role in the interactions of amphibians and the invasive Chinese tallow.;The goal of this study is to investigate the interaction between Chinese tallow and southern leopard frog (Lithobates sphenocephalus) larvae when influenced by changes in climate. In Texas, Chinese tallow leaf-fall occurs from November through late December. When dropped leaves enter a wetland they are quickly leached of tannins and other solubles, affecting water chemistry, however during drought years dropped leaves may remain unleached until rainfall. Southern leopard frog breeding can occur from November through March, depending primarily on temperature. Rainfall can also play an important role in the timing of leaf leaching and anuran breeding.;To determine the relationships between invasive species, amphibian survival, and climate change I raised leopard frog tadpoles in five mesocosm treatments, each treatment with Chinese tallow leaf litter at different stages of decomposition in water. The treatments are intended to represent a gradient of scenarios where weather influences amphibian breeding phenology and timing of aquatic decomposition of Chinese tallow leaf litter. Water chemistry measurements were taken within each treatment throughout the experiment.;Tadpoles in treatments with shorter decomposition times had significantly lower survival. Treatments also had significant differences in water chemistry, supporting the hypothesis that the phenology of amphibian breeding and the timing of Chinese tallow leaf leaching are important factors affecting tadpole survival. Since leopard frog breeding phenology and the timing of leaf leaching is regulated by precipitation and temperature, climate change could have a profound and predictable impact on tadpole survival in the presence of Chinese tallow.;Shifts in the breeding phenology of many species, is believed to have occurred due to changing climate. The major threat to southern leopard frogs and other winter breeding amphibians, invaded by Chinese tallow, is a shift in breeding phenology that a warming climate could bring. Earlier breeding by amphibians will mean greater impacts of the deleterious effects of Chinese tallow.