A Possible new largest diameter Douglas fir in Portland! * (Update: April 22, 2014, the largest diameter Douglas fir in Portland resides on Powell Butte, see follow-up blog post).
Big tree enthusiast, photographer, and outdoorsman Darvel Lloyd recently told me about a very large old Douglas fir he had found while hiking in Mt. Tabor park. Yesterday, Nov. 6, 2013 Darvel Lloyd and I decided to measure this old tree, and found what may be the largest circumference Douglas fir in the city! Using an elastic tape measure we got a reading of about 19 ft circumference, or 6.04 feet average diameter at breast height for an old rugged looking Douglas fir on the southern end of Mt Tabor Park. This tree was on quite a bit of a slope so the measurement was tricky. The top of this old tree had long ago been blown off, but it now has a healthy vibrant crown. There may well be thicker diameter Douglas fir trees in Forest Park, and the outlying parks of Portland, but as it stands the largest heritage Douglas fir trees officially recognized within city limits are all a trifle under 6 feet diameter, making this old Mt. Tabor tree a potential new record! Preliminary measurements with my inclinometer showed it to be about 166 feet high.* I brought along a 100 ft open tape reel, and Darvel and I measured down hill, a distance of 200 feet from the tree to get a measurement reference for my inclinometer. The hill was quite steep, about 58 feet of rise over 200 feet distance, so I will go back to the site to get several more height readings from different angles.
An interesting side note was a rare naturally regenerated Douglas fir seedling just 20 feet down the hill of the big tree! Darvel told me the park is entirely void of seedlings, so this is an encouraging find! We also measured several other large Douglas fir and found them to be in the 4.5 to 5.5 feet diameter range. A large fir just across from the Parking lot, and west of the covered picnic area was at least 5.5 feet DBH, and from a quick preliminary measurement I took it was about 160 feet tall. Several other trees Darvel and I measured in the park agreed very well with the Google Earth 3D heights to within a couple to several feet. So I think it’s safe to say the Google heights are often 95% accurate or more.
The tallest tree in Mt Tabor park that I have been able to locate using Google Earth is a 185 footer located in the bottom of the gulch on Salmon Way.
Using my inclinometer, I measured the tallest tree from 4 separate vantage points, and they all were within a couple to a few feet of the Google Earth measurement of 185 ft. This tree is only approx. 42 inches, or 3.5 feet in diameter. However, I am expecting that taller trees could be located in this park along the sides of the hills, or in this same ravine. I am hoping to find a 200 footer!