My Tree Leaks

This year, I discovered that my maple tree leaks.   A wet spot appeared on the sidewalk near the base of the tree.   The weather was below freezing at night and warmer in the day. The tree trunk remained below freezing during the day.  

As noted in the maple syrup discussion, we proposed: …. during “normal operation”,

(Summertime), moisture and nutrients are carried from the soil though the roots and up the tree to the leaves as a vapor. The moist soil has a high vapor pressure. Evaporation to the atmosphere creates a lower vapor pressure at the leaves.   Vapor flows between the cells and perhaps through the cells with vapor pressure as the driving force. With cold weather, the vapor condenses into a liquid. This produces a hydrostatic pressure at the maple syrup tap. This delivered liquid is then condensed by evaporation to produce maple syrup in the fall.    

Hydrostatic pressure = Pressure created by weight of fluid

We have a different condition in the spring time. Over the winter, all the liquid in the tree has frozen.   Winds create some weak points in the tree outer surface. On a warm day the frozen liquid in the thin upper branches’ thaws. The resulting hydrostatic pressure bursts through a weak point in the tree epidermis. The liquid drips to create a wet spot on my side walk. (Figure 1)     This phenomenon is not limited to maple trees.

Ruptures also occur in the epidermis of tree trunks which show up as a wet spot.   (Figure 2)   Usually these ruptures in the branches and trunks of trees heal over the summer growing season.