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
To demonstrate the Magnus effect, YouTuber PeterSripol grabbed a couple of KFC buckets and tricked out an RC plane. The resulting trial and error is mostly the latter.
One of the weirdest places in Antarctica is Blood Falls, a five-story cascade of blood-red liquid pouring from Taylor Glacier. Researchers finally traced its source: a saltwater lake millions of years old trapped under the glacier.
Fetal lambs survived for weeks in an experimental artificial womb, and scientists hope that the breakthrough could lead to new treatments for premature babies and perhaps the dreamed-of machine utopia where humans are kept mindlessly writhing in translucent plastic sheaths filled with psuedoamniotic liquid. Physicians at the Children’s Hospital of Philadelphia placed fetal lambs into […]
If you want to work in tech, but don’t have any desire to code web apps to help businesses sell things to other business, you might want to consider a career in cybersecurity. Judging from the apparent complete infiltration of Russian hackers in American cyberspace, it seems fair to speculate that there’s a major shortage of […]
All moms are different. But all moms like getting flowers on Mother’s Day, and that’s a fact (not, however a fact we can document in any fashion.) Instead of getting chewed out for forgetting to call her on the second Sunday of May, you can take care of it ahead of time with Teleflora’s flower […]
Yeah, Bluetooth audio is pretty common these days, so why should you care about these earbuds? Look how happy that woman up above looks. She’s got FRESHeBUDS in. Boom. There’s your reason. She’s also at the beach and it appears to be a very nice day.But for the sake of promotion, wireless earbuds are fast becoming the […]