Salamander populations are much larger in some US forests than scientists once thought. That’s really good news for vertebrates, which rely on the amphibians as a major source of food.
Researchers at the University of Missouri have estimated that the population of salamanders in forested regions of the Missouri Ozarks are 2-4 times higher than originally thought, and in other regions of the eastern US may be on average 10 times higher.
“Our lab works to identify salamanders as an influential part of the forest ecosystem and food chain,” says Ray Semlitsch, a professor of biological sciences. “Using the latest research methods, we calculated the population size of Southern Redback Salamanders in Ozark Forests and their value as a food source.
“We found that 1.88 billion salamanders inhabit one district of the Mark Twain National Forest alone, which is roughly 1,400 metric tons of biomass. For comparison, that’s equivalent to the biomass found in most whitetail deer in that region.”
There are two methods for estimating abundance. One is to simply count salamanders and plot the numbers on a grid representing the forest landscape. That is how the estimates were calculated for an influential study conducted in the 1970s.
However, Semlitsch’s group, armed with the knowledge that the majority of salamanders are underground at any given time, captured animals on the surface during intensive repeated surveys over two years and used statistical modeling to produce a more thorough accounting of variation in salamander population density.
“Our abundance models also take into account environmental factors,” Semlitsch says. “Factors such as date of collection, time since last rainfall, slope of the terrain, and forest canopy cover are plugged into the model to help predict variation in the surface population over time; that’s what makes our model so powerful.
“The hidden biodiversity of amphibians is something we don’t generally consider; we forget that salamanders are nocturnal and mostly unobserved. Therefore, I think most will be amazed at the quantities of food out there that we just don’t see.”
Semlitsch believes that future research should consider the importance of amphibians to ecosystem processes such as soil enrichment. Future forest management techniques and protection of salamanders are important to healthy forest ecosystems and should be considered in all forest management decisions, Semlitsch adds.
The study was published in the Canadian Journal of Zoology, and was funded in part by the US Forest Service cooperative Agreement with support from the Missouri Department of Conservation.
Source: University of Missouri