Looking over Dale Luthringer’s list of Pennsylvania trees I found that, due to a limited number of measurements, the tallest Mountain Laurel on the list for Pennsylvania was just 12.4 feet tall.  I knew there several mountain laurels taller than that could be found.  I had been wanting to make a measuring pole for field measurements of shrubs and dwarf trees for some time.  This was the opportunity to do both.

The Mountain Laurel site is in a area known as the “Gas Company Laurel Fields” near Clear Creek State Park in west central Pennsylvania (About 10 miles south of Cook Forest).  This property was owned by a local natural gas company and covered by laurel bushes.  The company had cleared most of the trees from the area, leaving the mountain laurel intact, and mowed part of it forming a small park-like area.   Every year as part of the Brookville Laurel Festival the area is open to the public to show off its spectacular display of laurel blooms.  A short ¼ mile dirt road loop allows people to drive around the area or they can park and walk through the laurel fields.

Overview of section of the Gas Company Laurel Fields

A measuring pole is the ideal way to get the height for a series of shorter plants - it is essentially a giant yardstick.  The complexities of the laser rangefinder/clinometer measurements are not needed.  I made a pole out of two ten-foot pieces of PVC pipe cut into five foot segments.  I fastened a length of tape from a cheap 16 foot tape measure to the pole (also cut into sections) and was off to measure the laurels. 

I ended up measuring only six of them, because their bases were entwined by poison ivy.  I will go back and get more measurements when I get some help and am wearing some latex gloves.  I took the standard measurements of height and cbh.  I measured the diameter of trunk branch that bore the tallest sprig at a breast height.  The tallest I measured was 18’ 4” in height.  Another laurel exhibited the greatest girth 15” and had a maximum crown spread of 250.”  Both the height and girth are larger than those listed in the PA database.

Laurel 001, height 9’ 6”, cbh 6’, girth 1 foot = 12”, ist branch 8”, maximum lateral spread 59.”

Laurel 002, height 12’, cbh 4”, girth 1 foot = 9”, 1^st branch 12”, maximum lateral spread 126.”

Laurel 003:   overview

Laurel 003:  close-up showing multiple trunks at base of bush

Laurel 003, height 13’ 6”, cbh 7”,  girth 1 foot = 11.1”,  1^st branch 27”, n/a.

Laurel 004:  Largest laurel in terms of girth and spread

Laurel 004, height 14’ 6”, cbh 15”, girth 1 foot = 18.5”, 1^st branch 4.5’, maximum lateral spread 130”, Max crown spread 250.”

Laurel 005:  Tallest measured at 18' 4".  Fifteen foot measuring pole provides scale.  There were five main trunks emerging from the ground in an area about two feet across.

Laurel 005:  Side view of the tallest measured laurel.  Fifteen foot measuring pole provides scale

Laurel 005, height 18’ 4”, cbh 11.75”, girth 1 foot 13.5”, 1^st branch 35”, maximum lateral spread 101”, maximum crown spread 174.”

Laurel has a typical shrub form with multiple stems emerge from the ground in a tight clump.  For shrubs or dwarf trees that are short in height, say average less than 20 feet, it seems inappropriate to measure their girth at just 4 ½ feet or breast height.  It represents too large of a portion of their total height.   The figure for cbh provides standardization for tree girth measurements and should not be abandoned, but girths should also be measured at height s more appropriate for the particular tree form or height under consideration.  CBH works well for trees of normal sizes.  It is above the root flair and gives a fair girth representative of the diameter of the tree before it has tapered significantly. 

For trees like Bald Cypress the root buttress may extend up the tree for a dozen or more feet and cbh is not really representative of the diameter of the tree trunk.  For short trees or shrubs the trunk has already tapered significantly or has split-off several branches resulting in a trunk diameter that is far to small to be representative.  A five foot tree would likely have its trunk dwindled down to almost nothing at 4 ½ feet.  For these shrubs and dwarf trees a more appropriate height would be a 1 foot or above root flair whichever is higher.  In the listing above I also provided measurement of girth at 1 foot .  I think this should become a standard measurement when dealing with these shrubs and dwarf tree specimens.

An additional consideration that we should discuss is how we deal with shrubs like these who’s normal form is that of having multiple trunks emerging from the ground in a clump.  A useful measure would be to note the number of significant trunks in the clump and the crown spread of the entire mass.  For the tallest specimen above there were five main trunks emerging from the ground in an area about two feet across and the resulting combined crown had a maximum spread of 240.”

Ed Frank

Laurel measurement Data Sheet