Scientists measure trees for a wide variety of reasons. When I visited the Harvard Forest last week, I measured them as part of studying carbon sequestration by plants. But you can't just go out into the woods with any old tape measure and expect to collect some significant data.
That's because where you measure the tree matters. If you want to compare the diameters of two trees, you have to make sure you're measuring them in the same place. If you measured one tree at the wide base and the other further up the trunk, where trees usually get narrower, the comparison wouldn't mean much.
That's where diameter breast height (DBH) comes in. It's a way of standardizing the measuring process.
As the name implies, DBH is meant to be a diameter measurement of a tree trunk taken at, roughly, breast height on an adult. Of course, where exactly "adult breast height" is varies greatly from person to person. So DBH has been set to a standard height—1.4 meters in the United States.
In a research forest, you'll often see some kind of marker on the trees showing where this official "breast hight" is, so people can quickly move through the woods, taking diameter measurements, without having to measure vertically on each tree. In some cases, DBH is marked with yellow spray paint. In others, metal bands. These metal bands actually help measure diameter, too. Set with springs, the bands expand as the tree does, so all researchers have to is measure the distance between two dots on the band and see how far apart the dots have moved since last time.
Read all the Dispatches from Harvard Forest
Gravitational waves are real, and scientists have detected them. In the video above, PBS Space Time explains the discovery by researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO). From the New York Times: A team of physicists who can now count themselves as astronomers announced on Thursday that they had heard and recorded the sound […]
Evil Mad Scientist Labs have released their latest set of nerdy Valentines ready for you to print, glue on cardstock, and use to win your true love’s heart.
“Bentonite Me Baby” is a brand of “detox clay” that you spread on your face, or eat, to rid your body of mysterious, nonspecific “toxins.” It is full of lead.
If you’ve been blessed enough to avoid them yourself, you’ve definitely heard the horror stories. Late night, crushing out a ton of work, writing, coding, anything, then boom – your computer crashes. The battery blows, you spill water or coffee all over the place, or it just shuts down with no explanation, and you’re screwed. […]
You travel around a lot. It might be that jet set life from New York to LA to London to Tokyo, or it might be back and forth from the coffee shop to the office, or from the kitchen to the couch. Any which way, you’re mobile and that’s the way to live. When you […]
It’s 2016 and we like our technology really small. Our phones fit in our pockets, our remotes are lighter than ever, and even our cars seem to be shrinking. So your new drone shouldn’t be an exception. This Axis VIDIUS Drone is 21% off right now and it’s so little, your biggest problem won’t be […]