A stage specific ecological trap: Consequences of a biphasic lifestyle in an unassuming habitat

Background/Question/Methods Invading exotic habitats are the focus of many new studies; however, few have focused on the consequence of these habitats as ecological traps in relation to animal life history.  The concept of ecological and evolutionary traps is important when considering how invading habitats can change the reliability of information for species. One of the most invasive exotic plants in central and eastern U.S. is the Asian Amur honeysuckle (Lonicera maackii). In addition to other competitive attributes (i.e. resource use); Amur honeysuckle produces phenolic compounds that are allelopathic; thereby reducing numbers of native plants.  Furthermore, from unpublished data on Amur honeysuckle and studies of other invasive species, these compounds are known to negatively effect the growth and survival of larval amphibians.  However, as honeysuckle produces a monoculture, it changes the microclimate that is alluring to migrating adult amphibians that use humidity and temperature as a cue for optimal foraging, movement and reproduction.
Does Amur honeysuckle cause an ecological trap? 

We sampled terrestrial amphibians using pitfalls (10 L buckets buried in ground) installed on all ends of three drift fences arranged into a Y-shape array (12 M each).  We placed six arrays in high density invasion and six in low density invasion.  We recorded humidity and temperature in all plots during sampling periods.

Results/Conclusions

In our field sampling, we found that amphibians, particularly adults, are more common in honeysuckle-choked areas.  However, larval and juvenile populations are uncommon and often not present in dense honeysuckle habitats.  Microclimate data collected in our plots indicate that humidity is greater and less variable and temperature is less variable in invaded compared to uninvaded plots.  Allelopathy may enable Amur honeysuckle to have a bottom-up (plant or algae resource effect) impact on amphibians.  The trap caused by honeysuckle can come from a stage specific impact where the larval form has lower survival.  Amphibians might have faulty information about the environment; therefore further study could focus on distinction between habitat selection and habitat quality.  Future studies will focus on larval amphibian communities inside invaded habitats and adult movements in and out of these habitats.