A Mossy Misconception

On 05/18/15, our Science class went outside to examine a tree as part of Project Learning Tree, where I unexpectedly came across a misconception!---"Moss always grows on the North side of a tree.” I love nature and learning to survive in nature with nothing but nature. One of my interests is navigation using only natural resources. I always thought that if I happened to get lost in the woods, I could look for a tree with moss or lichen growing on it. Whatever side that moss is growing on is North, and from there I would have an idea of which way to go. During our Adopt-A-Tree exercise, while we were observing our tree, I noticed that it had moss and lichen growing on it. As I walked around the tree, I also noticed that the moss and lichen grew all the way around the tree, and I wondered, “I thought moss ALWAYS grows on the North side of the tree.” So I did some research. Dan Johnson, assistant professor of forest-biology in the college of natural resources at the University of Idaho, says this concept would make sense since the North side of a tree gets more sunlight than the other parts of the tree, it should be cooler, more damp, and have more shade—perfect conditions for mosses.” First of all, he says moss would then grow on the North side of a tree in the Northern hemisphere, and on the South side of a tree in the Southern hemisphere. However, anything can create those conditions, such as the shade from one tree on another. Also, if an area is very damp, moss can grow all around the tree and higher up than the moss we might regularly see at the bottom of a tree. He does not recommend using moss growth to navigate.

So then I started wondering why the Sun would hit the South side of a tree in the Northern hemisphere and the North side on the Southern hemisphere. The UCSB Science Line says that because of the Earth's tilt, we get more direct sunlight to the South in the Northern hemisphere and more direct sunlight to the North in the Southern hemisphere; therefore rooms facing South have more sunlight than rooms facing North. I always thought that since the sun rises in the East and sets in West, plants that need full sunlight should be planted on the Eastern side of a house. (Or is that a misconception?) From what I'm understanding, the Sun will always be brighter to our South because the US is above the Tropic of Cancer (which is below us), where the sun's rays hit most directly for us in the Summer Solstice. But the land from the Tropic of Cancer to the Equator will have the Sun to its North and South as the Earth moves around the Sun from Summer to the Fall Equinox (where the Sun's rays will hit directly over the Equator). Therefore, for us here in the US, plants would get the most amount of sunlight facing South...or Southeast? The more I learn, the more I need to learn!

Anyway, this survival myth is still busted! The air within 60 centimeters (just about 2 ft.) off the ground is always moist since water is constantly evaporating from the ground. Natural Navigator.com says, “If you manage to find a near vertical smooth surface that is not close to the ground and it has moss growing on it then there is likely to be only one reason for it staying moist: it is in the shade in the middle part of the day when he sun is doing most of its drying. It is very likely to be the Northern side in Northern latitudes.” However, if water is hanging from overhanging branches, even on a South side, moss will thrive. In a thick forest, where light doesn't penetrate that far in, or in damp areas near standing water for example, moss can also be found on all sides of trees, branches, and rocks. As Leon Pantenburg explains in his Blog, “There are apparently so many variables about where and when moss grows in a forest that a firm rule can't be established.” So using moss or lichen as a GPS apparently cannot be trusted. There are just too many variables.

Here is a video of the moss and lichen on a tree in my yard. I tried to upload the video on here, but it didn't work. So you can just see it by clicking on this link:

https://drive.google.com/file/d/0B4vdbHnciHMTbEpQVFVHUXVNY1E/view?usp=sharing

You can see in this video, there is lichen and mold growing mostly on the North side, but there is still some on the South side, and just a little on the West and East side. The lichen growing on the South side looks like it could be due to that branch being in the shade of the trunk to its right. So even if moss and lichen did grow mostly on the North side, it is not just on that side and can still be misleading where it grows on different parts of the North side. So, in conclusion, there is some useful truth to the concept behind this myth, so I would take moss growth into consideration for navigation, but I would not solely rely on it.

NORTH SIDE

WEST SIDE

SOUTH SIDE

EAST SIDE

Also, Check out Leon Pantenburg's blog on why this myth is busted. He has some great pictures of moss growing on all sides of a tree, even on the tops of them!

http://survivalcommonsense.com/busting-the-finding-directions-by-tree-mossfeed/

So what about using a stick as a sundial to tell direction or time of day? Or using a leaf, a needle, and water to tell direction? So many questions and possible misconceptions to explore!!!

References:
McCarthy, E. (2014 , April 21). Does Moss Really Only Grow on the North Side of Trees. Retrieved from: http://www.mentalfloss.com

UC Regents. (2015). Why Does Moss Only Grow on the North Side of Trees Answer. Retrieved from: http://scienceline.ucsb.edu

Gooley, T. (2013. October 18). Moss on the North Side of Trees. Retrieved from: http://www.naturalnavigator.com

Pantenburg, L. (2014, October 27). Survival Myth Busted: finding directions by tree moss. Retrived from: http://www.survivalcommonsense.com