Amphibian Cover Board Monitoring

Redback Salamander observed under a cover board.
Photo By James Fischer
I checked the cover board grids that we use to monitor amphibian populations in the Museum vicinity.  We monitor a total of 8 grids that are placed near or in critical habitats.  I observed a total of 46 Redback Salamanders (Plethodon cinereus) under the boards.  I observed a total of 32 salamanders under coniferous tree canopy and only 14 under the deciduous tree canopy.  I hypothesize this pattern is due to the difference in the forest floor under the two canopy types because the leaf phenology is different right now.  The deciduous trees' leaves are beginning to burst buds while the conifer trees are evergreen.  The forest floor under these two cover types differs a little bit.  The forest floor under the conifer cover was a little bit more damp and cooler while the deciduous forest floor was little bit drier and maybe warmer.  The lack of leaves in the deciduous cover is letting the sunlight penetrate the canopy and dry the forest floor. I wanted to know if this pattern was significantly different from a random or equal distribution.  I chose to use a chi-square analysis to detect if the observed pattern was statistically significantly different enough from the expected pattern (a random or equal number under each canopy type).  The chi-square analysis confirms that the pattern that I observed was significantly different from an equal distribution.  This statistical test does not necessarily confirm my hypothesis entirely but it tells me that I might be on the right track with my reasoning.

No comments: