A Science for Everyone

Measuring Forest Canopy

I like foresters – they have some fun tools.  In grade school, I learned how to use an increment borer to determine a tree’s age and it’s rate of growth.  Later, I learned how those tools, coupled with beams in cliff houses and other old dwellings in the American Southwest helped develop the specialized science of dendrochronology – determining dates by the study of growth rings in trees.  It turns out that it also provides a lot of information about past climate and weather.

This week, I got my hands on a spherical densiometer.  It’s a simple little tool, designed to measure the density of the forest canopy.  Fits in a shirt pocket, and shows that it was developed by a forester in the correction factor – you multiply your count by 1.04.  Others might try for a 1:1 reading – but a forester deals with Scribner scale, Doyle scale and International scale for measuring logs, and knows that what is correct with one method gives a different answer if you change methods.  1.04 is close enough in forestry.

I want to get a better handle on canopy because of a comment Joe Zacek made over 40 years ago in a conversation with Tim Wiersum.  Joe was a range scientist – one of the best – and Tim was trained as a forester.  They were closing in on a magic number in forest canopy figures . . . and figured that somewhere between 25 and 30 percent canopy would provide 100% of harvestable timber and 80% of potential grass.  I figured it was all a matter of sunlight – but as I’ve grown older, I’ve noticed that the open areas tend to have a bit more soil moisture in the Spring. 

Other studies have been done on canopy (or crown density) and the spread of fires.  I’m certainly no expert, but using the densiometer on the old road shows me that a road that made a good firebreak 70 years ago isn’t anymore. 

It’s a simple little tool – but if I can carry it in my pocket, improve grass growth, timber growth and fire safety, I’m going to enjoy using it.  A real forester might be better, but I’m happy with the tool. And things just might get better as I use it.

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