Salamander Populations 63 



DISCUSSION 



As far as we know, this is the longest series of continuous 

 quantitative observations on any amphibian populations. Other 

 multiple-year studies include 13 years for Savannah River Ecology 

 Laboratory studies (Pechmann et al. 1991) and the same duration for 

 Taricha rivularis in California (Twitty 1966). In the former, changes 

 could be explained by drought, and the latter was completed long 

 before the supposed general decline of amphibian populations. 



Our observations bear on some of the suggested causes for long- 

 term declines in amphibian populations. There is considerable evidence 

 that the observed dieback and decline of spruce-fir forests in the 

 southern Appalachians is due to atmospheric pollution (Bruck 1988, 

 Dall et al. 1988, Zedaker et al. 1988). As the salamander populations 

 have remained essentially in steady states, acid rain and ozone depletion 

 cannot be universal causes of all declines in amphibian populations. 



As the great majority of records of population declines are based 

 on anecdotal evidence, we remain skeptical of the generality of these 

 declines until similar long-term records are produced. We are also 

 convinced that over-collecting by biological supply companies and by 

 some herpetologists has been underrated as a possible cause of observed 

 declines. 



ACKNOWLEDGMENTS— Vie thank successive officials of the 

 Great Smoky Mountains National Park for permission to carry out 

 the study at Heintooga. We also thank Wayne Swank, Director, Coweeta 

 Hydrologic Laboratory for permission to carry out the studies there. 

 Without the dedicated efforts of the hundreds of students in our classes, 

 as well as those of the teaching assistants, the data could not have 

 been collected. 



LITERATURE CITED 



Barringer, M. 1990. Where have all the froggies gone? Science 247:1033- 

 1034. 



Blaustein, A. R., and D. B. Wake. 1990. Declining amphibian populations: 

 a global phenomenon? Trends in Ecology and Evolution 5:203-204. 



Beebee, T. J. C, R. J. Flower, A. C. Stevenson, S. T. Patrick, P. G. 

 Appleby, C. Fletcher, C. Marsh, J. Natkanski, B. Rippey, and R. W. 

 Batterby. 1990. Decline of the natterjack toad Bufo calamita in 

 Britain: paleoecological, documentary and experimental evidence for 

 breeding site acidification. Biological Conservation 53:1-20. 



Bruck, R. I. 1988. Research site: Mount Mitchell (southern Appalachians). 

 Decline of red spruce and Fraser fir. United States Department of 

 Agriculture Forest Service, General Technical Report 120: 133-143. 



