Amphibian Coverboard Experiment Monthly Check -- October 2011

Spotted Salamander (Ambystoma maculatum) discovered under a
cover-board just as it emerged from it's mole-like tunnel.
Photo by James Fischer  
I observed an amphibian at 57.6% of the cover-board (CB) stations yesterday.  This is the highest proportion of stations that detected an amphibian ever observed during our monthly visits to this site over the past 2.5 years!  This is exciting news but I want to tell you about another interesting observation that I made.

A yellow-hued Spring Peeper (Pseudacris crucifer) camouflaged
among newly fallen autumn leaves.
Photo by James Fischer  
The CB grid spans across two stands of trees, one stand is dominated by deciduous trees while the other are evergreen trees.  The CB stations under the deciduous trees detected more amphibians than the stations under the evergreen canopy.  This puzzled me while I was traversing the grid from station to station.  I walk the grid a systematic fashion so that it takes less time.  I walk the grid along the lines within the grid from the evergreen stand to the deciduous stand and back again.  But that question kept bugging me. Why were more amphibians observed under the CB's in the deciduous stand rather than the conifer stand?  I think I may know but I need to tell you about another pattern that I observed whilst walking the line.  This was a new pattern for me this season.  I was wearing my sunglasses while I was in the deciduous stand and not in the evergreen stand.  Okay, if I lost you, please keep reading because there is a reason why this is important.

Just as I was beginning to get frustrated with having to pull out my sunglasses from my pocket each time I entered into the deciduous stand, the light hit my eyes and my skin began to feel warm!  Yes, it was noteworthy moment but not the kind you may be thinking of.  I began to think that the amount of sunlight penetrating the forest floor could have been one factor causing this pattern.  It is now autumn in southern New England and many of the leaves have already fallen from the deciduous trees allowing more of the sunlight to reach the forest floor.  The CB's under the deciduous trees should be warmer than their evergreen counterparts, which explains why so many amphibians were observed under these boards.  But lets not rush to this conclusion too quickly!  There could be several other explanations.  I'll offer another possible process just to demonstrate how complex a walk in the woods can sometimes be to biologists and ecologists.

Northern Two-lined Salamander  (Eurycea bislineata) found
under a cover-board near a spring seep.
Photo by James Fischer
Another explanation could be that the leaf litter on the forest floor could also be warmer and more importantly dryer under the deciduous trees while the conifer stand could be cooler and moister.  The amphibians in the deciduous stands would seek out shelter that offers a moister environment.  The amphibians inhabiting the evergreen stand would not have to seek out these micro-habitats.  Moisture is very important to a group of organisms that breathe through their skin.  Moist skin allows for more oxygen to transpire than drier skin.  Amphibians breathe through their skin as an adaptation which has allowed them to lower their metabolism as they evolved which means they require less energy to live.

Who knew flipping cover-boards and a walk in the woods could be so complex...

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