Tallest & Largest Redwoods - Measuring

This page is an off-shoot of Largest Redwoods / Hyperion

Michael Taylor sent a tallest redwoods update October 2008. I saved old and new redwoods data for comparison - see how some redwoods changed from 1990s to 2008. First is the MS Word document link for the 2008 tallest coast redwood list. The info represents years invested by explorers like Atkins and Taylor. The photo below is Michael Taylor doing a preliminary measurement near Lost Man Creek: 2008. He has a knack for navigating through forest - the "Gazel of the Redwoods". Atkins and Sillett are in a photo near page end. Few people know the redwood forest like these people. Here is a feet to meter converter. And a dimension calculator is at page end:

Input :

2008 Tallest Redwoods List

Tallest Trees List / October 2008 Update / MS Word .doc

Next

A few names of tallest redwoods as recorded 2000 - 2006 in meters. A snap-shot in time from those few years. Source was Gymnosperm Database, and the trees were:

Name - park, height in meters
Hyperion - Redwood 115.55
Helios - Redwood 114.34
Icarus - Redwood 113.11
Stratosphere Giant - Humboldt 112.87
National Geographic - Redwood 112.74
Paradox Tree - - Humboldt 112.59
Federation Giant Humboldt 112.45
Mendocino Tree - Montgomery 112.01
Harry Cole Tree - Redwood 111.65
Swamp Tree - Montgomery 110.77
Pipe Dream - Humboldt 110.64
Redwood Creek Giant - Redwood 110.4
Rockefeller Tree - Humboldt 110.34
Daedalus - Redwood 110.34

Finally

Below, are redwood sizes pre-dating 2000 - another snap shot in time. Abbreviations are parks: PCRST = Prairie Creek Redwoods State Park, H = Humboldt or M = Montgomery

The table will provide the height, the diameter at breast height / DBH, and the volume of the trunk and main stems in cubic feet. These trees have been discovered and measured by several people. Chris Atkins and Michael Taylor found the bulk of the tallest redwoods.

Measuring giant redwood trunks

A few common measurements for redwoods are diameter, height and trunk volume. This section is about measuring diameter of huge redwood trees. Basically, redwood diameter is measured at DBH or diameter breast high: 4 feet & 6 inches above soil grade. But, if the redwood is on a slope:

1. Find the elevation where the trunk enters the soil on the downhill side of the redwood. Not where it enters the composting needles or leaves, but the soil..

2. Find the elevation where the trunk enters the soil on the uphill side. Unless the area is level.

3. Estimate the mid-point of the trunk between those, go up the trunk 4 feet and 6" and measure diameter there.

4. You will be including hollows or indented areas of the trunk. Don't press the tape inward against the bark at every reccession.

For a diameter mid-point, we are estimating where the center of the trunk is, above where we believe it would have sprouted when it was young or when it germinated.

You may ask ... why is the measuring tape at knee level in the photo here?

The reason is that diameter breast high or DBH, is not up at my chest. The DBH is actually near my knees because the grade and extent of the root flare is farther down out of sight. If I stood to the right side, DBH would have been near my ankles. Had I stood to the left, DBH would have been at waist level.

That tree in the photo is a redwood I call Suction Cup in Jedediah Smith redwoods. The trunk tapers quite a bit.

This is why it's hard to know if you found a redwood measured by someone else. Because if you were not around when they measured it, odds are that you will not conclude the same soil grade and DBH as they did.

Believe me - it's estimation. It is near impossible to get the same exact measurement for a redwood that you learned about.

There are at least 2 ways to measure redwood diameter - a tape measure and a laser. A tape fits the needs of most people. In part, the diameter is a matter of opinon, because a judgement has to be made about where soil grade is. Twigs and leaves do not count as soil, but humous and finely composted needles should - my system.

Some experts who are adept with instuments, can measure the irregular trunk bases of redwoods rather meticulously to determine wood volume and shape - what is sometimes referred to as the redwood's footprint on the forest floor.

Image to the left: Chris Atkins and Professor Steve Sillett setting a tripod to measure height with a laser rangefinder, in Redwood National Park - similar equipment can be used for diameter measurement.

To keep things simple, because some trunks are eliptical, measure circumference and do the math. Stick with the average. Example for redwood with 70' circumference: is 70' / π, or 70' divided by 3.14 = 22.29' diameter.

Many giant redwoods have lower trunks like volcanoes. In some cases it appears like soil grade should be near the trunk, like where my feet are in the photo. But in if all needles and twigs could be removed, it becomes apparent that soil grade is 2 to 3 feet farther down.

It helps to stand back from the redwoods and take a look from a distance. Stand 20 or 30 feet away and look around for the average soil level.

Diameter measuring can be more complicated, but those basics are adquate for most people. If a redwood or other conifer trunk branches into multiple stems below the DBH height rather than above DBH, then only the largest stem may be measured: a failure to know true size. That's one rule of one system. If there is a burl, some experts move the tape above it.

Beginners ... use the KISS principle. Estimate 4.5' above the average soil grade, measure circumference, and divide by 3.14. For convenience, here is an automatic conversion table to convert diameter, circumference and area. Fill out one field, and the others should be generated for you. Enter numbers whole or as decimals, like 4.5 for four & one half ft. or 72 for seventy two ft.

automatic generator / solver - standard unit values

Area:
Diameter:
Circumference: