Distribution of Tree Height in an Old Growth Redwood Forest

1      Old Growth Redwoods

 

Old growth redwoods – that phrase invokes a lot of different feelings in people. Certainly in the present the phrase describes the large never cut forests in the redwood parks. Forests full of giant trees, some by rivers or streams and others along hillsides. Forests covered with needles and sorrel and forests covered with ferns. Forests with deer moving through them to reach the creeks, all the while shadowed by mountain lions. Forests with black bear dens. Remote and rugged but never more than a few miles from a highway.

Two parks with many acres of old growth redwoods as well as the ten tallest trees in the world are Humboldt Redwoods State Park and Redwood National Park.   Each parks contains hundreds of thousands of old growth redwood trees.   Here is the math:

Park Acres Old Growth Redwoods # Redwood Trees > 100 cm per Hectare # Acres per Hectare # Old Growth Redwood Trees
HRSP                    17,000 50 2.47                            344,130
RNP                    19,640 50 2.47                            397,571

 

The redwood density figure is a general rounding of the findings in a redwood plots study underway at Humboldt State University.

If that number seems too high, well…. Here are two pictures.   These are from the Redwood Creek Overlook on Bald Hills Road in Redwood National Park.   The old growth forests and patches are very distinctive.   If you go to that overlook and put a strong pair of binoculars on those forests it is an impressive site.   Many big and tall trees all growing along Redwood Creek and the surrounding feeder creeks and hillsides. I can’t imagine a more spectacular forest. It is kind of intimidating.

Redwood Creek Overlook looking west northwest.
Redwood Creek Overlook looking west northwest.

 

Redwood Creek Overlook west southwest view
Redwood Creek Overlook west southwest view

 

2      Height Distribution for the Tallest Trees

 

Thorough ground based searches combined with LiDAR technology have given a pretty complete picture of tree height in all parks with the exception of the Headwaters Reserve. The tallest redwoods, those over 365 feet, are all in Humboldt Redwoods State Park and Redwood National Park, with the exception of two trees in the exceptional Montgomery Woods Reserve. Then all the trees over 370 feet (there are only ten or so) are in Humboldt Redwoods State Park and Redwood National Park.

 

Trees over 350 feet.  Each line represents a tree.
Trees over 350 feet. Each line represents a tree.

 

There are two things that are apparent when viewing these graphs. First, the distribution patterns are very similar between the parks. And second, there are a lot more tall trees in HRSP than in RNP. Based on this data paired with the history of each park the explanation is certainly this: In Humboldt most of the forests with the tallest trees are intact. In Redwood National Park most of the forests with the tallest trees have been thinned or removed.

 

3      Height Distribution for Old Growth Redwood Trees

 

Noting the steepness of the curve on the tall trees graph it is evident there is some type of “bell shaped” distribution where there are many trees of a certain height, say 350 feet, then the trees get fewer and fewer at 360 feet and even more scarce at 370 feet.

Using this information and the total number of old growth redwoods we can infer the number of trees of certain heights:

Std Deviations Expected Pct of Trees Less Than HRSP Expected Trees RNP Expected Trees HRSP + RNP Expected Trees
2 97.725%                      7,829                      9,045                              16,874
3 99.865%                          465                          537                                1,001
4 99.997%                            11                            13                                      23
4.5 99.99966%                              1                              1                                        3
5 99.99997% 0.0981 0.1133 0.21

Looking at the results of expected trees versus actual tree populations, it is evident four standard deviations describes 368 feet or so redwoods, while 4.5 standard deviations describes the very tallest redwoods (380 feet).

Then with some calculations and interpolation, we can arrive at three standard deviations corresponding to a 338 foot redwood tree.   This then results with the following very approximate distribution of tree height in old growth redwood forests in Humboldt Redwoods State Park and Redwood National Park.

Std Dev Height Feet
4.5 383
4 368
3 338
2 308
1 278
0 248
-1 218
-2 188
-3 158
-4 128
-4.5 113

 

So the average old growth redwood in Humboldt and Redwood NP is 250 feet tall.  Remember this covers all old growth trees at all elevations that are at least 3.28 feet in diameter.

Then there are 1,000 trees over 338 feet in height.

What do you think?

 

4      Old Growth Redwood Groves Close Ups

 

For some closer in views of old growth, here are pictures from two of my favorite areas in the redwood parks.   There are views like this all over the redwood parks.

 

Humboldt Bull Creek outflow
Humboldt Bull Creek outflow

 

Redwood NP Lost Man Creek area
Redwood NP Lost Man Creek area

 

Thanks for viewing and reading.

 

Montgomery Redwoods Hike

 

1      Tall trees In A Small Area

 

Montgomery Woods State Natural Reserve is a very scenic spot with a high concentration of very tall redwood trees.   The tall trees list shows 17 trees in this reserve over 350 feet in height. The tallest redwood in the reserve (Mendocino Redwood) is about 368 feet tall and is the 11th or so tallest tree in the world.   The tall trees over 350 feet are found throughout the reserve – in the lower, middle, and upper flats. But that is a small area – a long stretched oval about 1.5 miles around and only 150 or so yards wide.

I had the fortune to recently hike through this reserve with Jerry Beranek. Jerry is a noted redwood photographer and writer who has published several books. His book “Coast Redwood – Tree of Dreams and Fortune” is a must have for any redwood enthusiast. It contains many great pictures of redwood trees as well as lots of information on the trees, plants, and animals that coexist with redwoods.

Jerry points out Montgomery Reserve may have been a lake at one time. A landslide could have backed up the creek for several centuries or thousands of years, allowing the shallow lake to form. Then the natural dam let go, the lake drained, and the rich soil was populated by redwoods which grew tall in the protected valley on the north side of a coast range mountain. As he mentions the redwoods needed to “stretch” to get up above the rim of the bowl and get more sunlight.

This picture is from the area at the start of the grove after hiking up the hill from the parking lot. You can see the evidence for a long ago earthen dam (I am standing on it) as well as the beauty of the grove. Montgomery Creek winds through the flat area with tall redwoods uniformly distributed throughout.

Start of lower flat in Montgomery Redwoods
Start of lower flat in Montgomery Redwoods

 

2      Fire Event in 2008

 

There was a large fire in this reserve in 2008 that burned the undercover (it has since fully recovered) and some of the hardwoods on the slopes above the flat (they didn’t make it). This fire was part of a group of wildfires that occurred in July that were very destructive to Mendocino County. Most of the redwoods came out ok as one of their specialties is fire survival given their thick bark. However a few of the hollow redwood trees sustained significant damage including one really big one that burned for days like a giant smokestack and then collapsed. As part of the collapse event one huge branch splintered into three sections as it crashed to earth. Each of the three sections entered the ground at about the same angle. These branch sections are still buried in the earth – three big widow makers. They are pictured below.

Congruent near simultaneous ground entry for broken sections of a single large redwood branch
Congruent near simultaneous ground entry for broken sections of a single large redwood branch

 

3      A Big Tree and a Tall Tree

 

The biggest and fourth tallest tree in the reserve is the Montgomery Giant, with a diameter of 17 feet and a height of 361 feet. Jerry and his buddies did some climbing in this reserve in the 1980’s. In 1981 Jerry climbed the Montgomery Giant and measured its height via tape drop at 357 feet. While at the top an even taller tree in the distance was noted as the tallest tree in the reserve. This tree was assigned the name Mendocino Redwood in the 1990’s and for a few years it was the tallest known tree (before the Stratosphere Giant was identified).

Here are two pics of the Montgomery Giant. The first is a mid to upper trunk view. Then the second is of Jerry and I having a discussion on how to get a fish line over the lowest branch in the tree.

Montgomery Giant mid and upper trunk view
Montgomery Giant mid and upper trunk view

 

Montgomery Giant - we are discussing the methods used to get a weighted fish line over the lowest branch of a tall redwood
Montgomery Giant – we are discussing the methods used to get a weighted fish line over the lowest branch of a tall redwood

4      Finishing Up the Hike

 

Jerry, like some other redwood enthusiasts, hikes with a tripod and camera. Here he is checking light while setting up for a photo.

 

Jerry Beranek setting up for a photo along the trail
Jerry Beranek setting up for a photo along the trail

 

Recently eight of so interpretive information signs have been put up along the trail. They are well done. Here is one of them.

One of a group of very well executed information signs recently added along the loop trail
One of a group of very well executed information signs recently added along the loop trail

 

Montgomery Redwoods Reserve is a great hike. This was my second hike there and both times I was lucky to hike with someone knowledgeable about the reserve. Jerry’s knowledge of and experiences in the redwood forests are impressive, interesting, and entertaining.