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
Dip your dollar into liquid anhydrous ammonia, dry it, and repeat. The surface tension of the boiling and evaporating ammonia shrinks the bill. Caveat: It could prove difficult to use a mini-dollar and mutilating a bill may even be illegal. (Applied Science via Weird Universe)
In many states in America, legislatures have erected punitive, vindictive barriers for women seeking contraception, requiring them to get prescriptions for safe, widely taken medications.
Designer Art Donovan writes, “I’m always looking for new and unique inspiration for my lighting commissions and the latest, cutting edge scientific devices offer a boatload of great design inspiration. From the cool, new ‘James Webb Space Telescope’ to the myriad of complex details in the L.H.P.C. at Cern- it’s a cornucopia of rich imagery.”
If you want a quality vaping experience, it’s usually going to cost you. Vaporizers that deliver a fast, controlled burn will set you back up to $300, which is why the FEZ Vaporizer (now just $99) is an absolute steal.The FEZ dry herb pen does everything that more expensive models handle at a reduced price. It heats up […]
Taking pictures can be challenging. There are a million factors that can influence each shot you take – and unless you’re a trained photographer, you often just focus, click…and cross your fingers.Of course, you can take some of the ambiguity out of your picture-taking with this Hollywood Art Institute Photography Course & Certification package, now […]
Experienced shutterbugs with DSLR cameras have boatloads of lens options for capturing the moment. Unfortunately, smartphone photographers often get stuck with their one crummy lens, which means limited zoom and focus for their final image.Step up your smartphone’s photographic power with the Acesori 5-Piece Smartphone Camera Lens Kit, now just $9.99 in the Boing Boing Store.Magnetic rings easily […]