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This guide details key methods and concepts in measuring Michigan's forests, focusing on tree measurements such as percent crown coverage and board foot calculations. It emphasizes the significance of forests, land ownership, and the vital roles they play in our environment. You'll learn to pace for accurate measurements, construct a densitometer, and understand basic timber metrics, including diameter at breast height and volume estimations. Perfect for budding forestry enthusiasts or anyone interested in environmental science!
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Forestry Measurements Written by: Heather Dombroski July 2005
Pre-reading • Website reading • http://forestry.msu.edu/uptreeid/History/Modern.htm • After your finished take a look at “Facts About Today's Michigan Forests”
Let’s Review • What are our most popular trees? • Who owns the most forested land in Michigan? • Where is the majority of our forest? • Why are forests important?
Pacing • How far is one step? that is your pace • Everyone's will be different, you must remember yours • We’ll measure out 1 chain (66ft) • You will practice walking this distance to get an average pace measure
Percent Crown Coverage • From a point looking up, what % of the sky is covered (no light gets through) • Our measurement tool is called a densitometer • We will be making our own and using them outside http://www.extension.umn.edu/distribution/naturalresources/images/3474-38.jpg
Densitometer • Hold it above your face just an inch or so, you see several squares, their either covered or not • Count the ones covered • Multiply this number by 4 to get 100% canopy cover • From spot one move 5 paces rerecord, repeat until you have 8 readings This represents 25%
What is a Board Foot? • 12”long X 12”wide by 1” thick • This is the measurement marketable timber is sold by (144 cubic inches per bd ft) • So if we have a 2X4 that’s 8ft long, how many Bd ft is that? • 2inch x 4inch (8ft x 12in/ft) = 768 cubic/in • 768/144 = 5.33 bd ft 12” 1” 12”
Practicing Bd ft • We cut a 1 ½ x 8 on our sawmill in the bullpen, its 10ft long. What’s the bd ft? • 1.5x8 (10ft x 12in/ft) = 1440 cubic ft • 1440/144 = 10 Bd Ft
Diameter at Breast Height • This is 4 ½ feet from the level ground • This helps us decide marketable timber • The sectional area is also called Basal area • We will use both; • diameter tape and • the Biltmore stick http://www.extension.umn.edu/distribution/naturalresources/images/3474-57.jpg
Height in logs or bolts • Logs - 16ft marketable section of a hardwood tree • Bolts –8ft marketable section of a coniferous tree • This is measured until a break in the bole (trunk) on hardwoods or 8” diameter • And measured up to a 4” diameter on pines http://www.efi.fi/fine/kidscorner/images/plants/tree_tall2.jpg
Measuring Marketable Timber • We use # of logs and DBH to figure Marketable timber or volume • By looking at the “How much Lumber is in that Tree” handout we see there is more than one way to figure this amount
Aging Trees • Taking a core sample • Counting sections of limbs on conifers • Tree cookies http://www.efi.fi/fine/kidscorner/images/plants/tree_tall2.jpg
Density of Trees per Acre • Usually estimates by 1/10 acre plots • Done in several random areas of a stand • These areas are then averaged • 1/10 plot = a circle with a 37.2ft radius At higher densities, the growth rates of individual trees slow down because there are more trees competing for the site's limited resources. 37.2
