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How Tall and Large Can Redwoods Grow

 

1      Maximum Height of Redwood Trees

Over the past twenty years the redwood groves on public lands have been systemically surveyed for tree height using both ground based rangefinders as well as airplane based LiDAR pulse measurements. The resulting point in time data has identified 220 individual trees at or over 350 feet in height on public lands.   It is possible there are a few other trees over 350 feet on private lands (half the remaining old growth redwood forest is on private land but the public lands generally have the better redwood habitat).

This is a graph of the distribution of height for these trees.

 

Distribution of height for 220 tallest redwoods
Distribution of height for 220 tallest redwoods

 

As you can see redwoods over 360 feet are rare, just 51 trees. And redwoods over 370 feet are exceedingly rare, just 8 trees. Then the two tallest trees are about 377 and 380 feet in height.

There apparently are factors in play that are limiting tree height. From the demonstrated heights the trees have a hard time obtaining 370 feet. There are several studies on theoretical redwood maximum height that have come up with heights a little over 400 feet. These studies take into account the energy required to draw water up to the top of the tree as well as the water which can be extracted from atmospheric fog.   However there are no trees now in excess of 380 feet.

While it is true what remains is just five percent of the original redwood old growth the parks themselves are in some of the best areas for big and tall trees. Also many of the parks have been around for quite some time now, and in some cases there is a fifty year growth record that can be referenced for some of the tallest trees.   For example in 1964 National Geographic published research on very tall trees along Redwood Creek in the area that became Redwood National Park. At that time the three tallest trees in that area were 364 – 368 feet in height. In the fifty years since 1964 none of these three trees have reached 370 feet in height. There is a physiological limiter on tree height that seems to be around the 370 foot mark.

As another example, the Humboldt Rockefeller forest is noted as having many of the tallest redwoods. This forest has been protected for over eighty years. At this point in time no tree has reached 375 feet in that old growth forest. There are dozens of trees over 360 feet in the Rockefeller forest area but none have reached 375 feet. Again some type of physiological maximum appears to exist for tree height around the 370 foot mark.

2      Example – Humboldt State Park 373 ft Redwood

 

To review a specific tree, let’s take a look at this 373 foot redwood.   This is a magnificent tree in the Humboldt Rockefeller forest whose most recent published height measurement is 372.73 feet. As you can see it also has a large diameter – over 17 feet.   Based on lists of the largest redwoods, this is the largest volume redwood of those over 370 feet.

Base of 373 foot redwood. Diameter is over 17 feet
Base of 373 foot redwood. Diameter is well over 17 feet

When I found this tree in the forest I immediately knew what tree it was and it just took my breath away. It is an impressive tree in an incredible forest setting.

Who is that tiny guy in the forest

 

View up toward the crown
View up toward the crown

 

The first published height for this tree, shortly after it was identified as one of the tallest trees, was 368.6 feet in 2000.   Then the most recent published height was 372.7 feet in 2013. So that is a growth rate of 4.1 inches per year or one foot every three years. So does that mean this tree can get to 380 feet in twenty years and 400 feet in eighty years?  I would say 380 feet is a good possibility but 400 feet is a stretch.

3      Example – Redwood National Park 371 Ft Redwood

This beautiful tall redwood grows on a bench along Redwood Creek. It is another one of the extremely rare 370 footers – the latest published height I have found is 371 feet from 2013.

This tree could not be in a more pleasant setting.

Published measurements over time indicate this tree has grown about eight feet in the last fifty years. This works out to be two inches per year.  In recent years the height gain per year has been more than the fifty year average. Does that mean this tree will be a 380 footer in a few years and a 400 footer in thirty years?  Again 380 seems possible, even probable, and 400 would be a stretch.  There is no confirmed record of a current or historic 400 foot redwood tree.

 

371 foot redwood in Redwood National Park
Trunk of 371 foot redwood tree in Redwood National Park

 

371 redwood tree and its neighbors. Standing tall along the bench like the Golden State Warriors
371 redwood tree and its neighbors. Standing tall along the bench like the Golden State Warriors

 

It is possible factors could be in play to increase or decrease redwood growth rates.   For example the increase in atmospheric carbon could be helping the forest get taller as there is more energy provided for photosynthesis. Or if there is a decrease in foggy summer mornings that might have a negative effect. These types of changes are being evaluated and quantified by current redwoods researchers.

Also any tree that gets high above its neighbors has a top that is less protected from wind. All the tallest trees will eventually lose part of their crown to wind. However they could still keep on adding wood to their surface area over time, allowing them to become the largest volume redwoods. And it is possible their crowns could “reiterate” (grow back) after breaking off.

So how tall can a redwood tree grow?   My guesstimate is 400 feet.

4      Maximum Volume of Redwood Trees

It is more difficult to assess the volume of a redwood tree than to measure its height. Trees have different shapes at the bottom and then taper off at different rates as height increases. Then the volume of the branches and limbs needs to be taken into account as well.

As a rule of thumb the volume of a redwood can be estimated using the formula for the volume of a perfect cone.   It works pretty well for some of the big volume redwoods:

Large tree volumes versus cone formula

In the last five years no new tallest redwoods have been identified.   But there have been some new top ten largest redwoods found and preliminarily measured.   There are areas of the redwood parks that have not been fully explored for the largest redwoods. Generally these are off trail hillside areas in the northern redwood parks.

There are also some differences of opinion on what to include for volume when a redwood tree has a complex trunk with partial fusions. This is particularly true for the two largest trees listed above.

This is a point in time distribution of the thirty largest by volume redwoods. It is incomplete because not all the redwood range has been surveyed for volume and new discoveries are being made.

Distribution of volumes among largest redwoods
Distribution of volumes among largest redwoods

As you can see there are very few redwoods over 35,000 cubic feet. It is possible a few historic redwood trees may have exceeded 45,000 cubic feet and rivaled the 52,500 cubic feet in the largest known living tree – the General Sherman sequoia. Possibilities are the Crannell Creek Giant and Lindsey Creek tree.     There is more unknown out there for tree volume, the current profile of top redwood trees by volume is not as complete as the profile of top redwood trees by height. It’s just harder to come up with a volume measure for a redwood, although if diameter and height are known a volume range can be inferred.

5      Humboldt Largest Redwood

 

The largest known volume redwood in Humboldt is about number ten on the list of the largest redwoods by volume. It is a powerful presence in the forest.

Largest volume Redwood in Humboldt
Largest volume Redwood in Humboldt

It sits in a forest growing on an alluvial flood plain. This tree lost maybe thirty feet from its top decades or centuries ago. At one time it was probably one of the tallest trees but now has aged into one of the largest ones.

Forest surrounding largest tree in Humboldt. Many, many big, big trees.
Forest surrounding largest tree in Humboldt. Many, many big, big trees.

A large volume redwood probably adds more wood per year than a tallest redwood since it has more surface area to cover. I am sure attempts are being made to measure redwood volume over time. A new technology I have noticed here and there are ground based LiDAR sensors tied into remote power generation stations. This would be an effective way to use technology to measure something that is difficult to measure.

So how large can a redwood tree become? The current maximum is around 45,000 cubic feet, there may have been a few larger than that in the past. And in the future there could again be 50,000 cubic foot redwoods.  No doubt.

Thanks for reading.

 

 

 

 

 

Tall Trees in Mendocino County

1      Mendocino County, California, USA

Mendocino County is noted for its wineries, microbreweries, and  coastline but also retains some remnant redwood forests.   On one hand these forests are not as extensive as the ones further north but on the other hand their smaller size makes them easier to thoroughly explore. Also since they are remnants of the once great coastal redwood strip they are surrounded by rangeland which provides a contrast in views as well as interesting winding drives up, over, and around the coastal ranges to get to these groves.

I visited two of these groves on a late winter weekend, the weather was spectacular. Unusually clear with temperatures near 70 in the sunny open areas and then mid 50’s in the redwood forest valleys.

2      Hendy Woods State Park

This park and its redwood groves have nine lives.   The original titled owner was Joshua Hendy who was a 49’er (1849 Gold Rush, not the football team) who kept about 100 acres of his best redwoods uncut. Eventually though this land was purchased by lumber companies but the locals kept pressure on to keep the 100 acre grove uncut and in the end the grove and the area around it were incorporated into a California state park.   Then more recently California wanted to reduce or cease operations at the park but again local pressures and more comprehensive economic studies served to keep this park in the state park system.

There is some construction work going on around the redwood grove parking area so until sometime this Spring (2015) visitors need to park in the camping area then take a short half mile walk downhill to the redwood groves.

The groves are adjacent to grasslands dotted with oak trees. Here you can see the entrance to the redwood grove, with a tall tree sticking into the sky right where the forest starts.

Tall redwood at entrance into the grove
Tall redwood at entrance into the grove

 

Because it is surrounded by open land, the grove itself is not quite as dark and imposing as some of the northern groves.   Here is a typical view early on in the trail.

 

Discovery Trail Big Hendry Grove
Discovery Trail Big Hendry Grove

 

For sure there are some large and tall redwoods in this grove.   The 2010 tall trees list shows six trees in this grove between 340 and 345 feet in height.  That’s really tall, even for redwood trees.

This large redwood appears to be the “king of the forest”. It has a 17 foot diameter trunk and is a little over 300 feet tall.   That’s about 23,000 cubic feet of wood if you apply the volume for a cone formula ( pi r squared h/3) which provides a decent estimation of the total wood volume in a redwood tree.   Not quite a top 20 by volume redwood (which requires about 27,000 cubic feet) but very large indeed.

 

Hendy Discover Tree Base View
Big Hendy Grove large tree
Hendy Discover Tree Upper Trunk View
Big Hendy Grove large tree upper trunk view

 

The trails are very well marked and the hiking is easy. At places there were open areas which I am sure are used for ranger programs and school field trips.

 

Big Hendy Grove Discover Trail Upper and Back Loop Junction
Big Hendy Grove Discover Trail Upper and Back Loop Junction

 

At the exit of the grove there is a nice live oak prairie.   Then you can turn back around and see the forest you just walked through. Pretty cool.

 

Big Hendy Woods Discover Trail Exit at Navarro River Meadow
Big Hendy Woods Discover Trail Exit at Navarro River Meadow

 

View of Big Hendy Grove from Navarro River Meadow
View of Big Hendy Grove from Navarro River Meadow

 

 

3      Montgomery Woods State Natural Reserve

This reserve is known for its abundance of tall redwoods in a small area.   According to the tall trees list four of the top fifty and seven of the top one hundred tallest redwoods can be found in this reserve.

Starting from the parking area there is a short but relatively steep (250 feet elevation gain) trail up to the reserve which is at the headwaters of Montgomery Creek. Then the redwoods are in a relatively flat flood plain along the creek. There is a 1.3 mile stretched oval trail that loops through the reserve on either side of the creek.   The flood plain is surrounded by steep hillsides which help protect the redwoods from the wind.  In a way this park reminded me a little bit of Pennsylvania state parks with glacial flooding history, such as Cooks Forest or McConnells Mills.  Of course Montgomery has much taller and larger trees.

This park could give you a stiff neck as you look up to the tops of the tall redwoods, with their upper crowns lit up by the bright afternoon sunshine.  One way to assess the tallest trees is to see which ones are still lit up in the late afternoon sun.   Those could be good ones to measure if you have a laser rangefinder.

 

Incredibly tall Montgomery Reserve redwoods with tops lit up by late afternoon sun
Incredibly tall Montgomery Reserve redwoods with tops lit up by late afternoon sun

 

Then to even things out you can try to find early blooms in the redwood sorrel or watch the water flow down Montgomery Creek.

 

Early blooming redwood sorrel (February 22)
Early blooming redwood sorrel (February 22)

 

Montgomery creek outflow below Montgomery Grove
Montgomery creek outflow below Montgomery Grove

 

Even on a no rain weekend you need to pick your way carefully to avoid small pockets of water in some areas.   But generally the trail is a little elevated and there are also boardwalks and foot bridges through the wettest areas.   Here are trunk photos of a couple nice trees in the grove.

 

Tall redwoods in Montgomery grove
Tall redwood in Montgomery grove
Another nice redwood in the Montgomery grove. That's me by the tree.
Another nice redwood in the Montgomery grove. That’s me by the tree.

 

This is the biggest (by volume) tree in the grove, it is about 361 feet tall with a 17.3 foot diameter.

 

Big tall redwood in Montgomery Grove.  On some days I would get wet standing where I am but not on this day.
Big tall redwood in Montgomery Grove. On some days I would get wet standing where I am but not on this day.

 

If approaching this park from US 101 / Ukiah you go up and over the coast range from the valley side to the Pacific side. The drive is winding and scenic.   Here is a view near the summit of the coast range.

Coast range between Montgomery Reserve and Ukiah
Coast range between Montgomery Reserve and Ukiah

 

Montgomery Reserve is a popular park with a strong reputation for great redwoods which is well deserved.