In the past twenty years it has become possible to systemically search old growth redwood forests for tall trees. Overhead LiDAR data can identify very tall trees. Then follow up measurements with laser range finders can identify height accurately within a foot or so. If more accuracy is required then advanced climbing techniques followed by the use of a measuring pole and direct tape drop can accurately measure height with a precision of a centimeter or so.
For trees on slopes or mounded trees there is still some judgement involved when determining true ground level. So not everyone will agree on the exact height of certain very tall redwoods.
2 Average Annual Height Changes in Redwood Trees
Using published sources the height of the one hundred tallest known redwoods in 2000 can be compared to the 2012 height for the exact same trees. When doing this comparison several interesting observations can be made.
First, ALL one hundred tallest known redwoods from 2000 were still standing in 2012. Assuming each individual tree has a one in a thousand chance of toppling in a given year there is a 70 percent chance at least one tree would fall during this period. But none did. So a quiet interval for the redwoods, versus the 1990’s when two of the tallest redwoods fell (Telperion and Dyerville Giant).
Second, just six of the one hundred tallest known redwoods lost height from 2000 to 2012. So very little die back of the tops.
Third, about one third of the one hundred tallest trees grew at an average rate of six inches or more per year. That’s a pretty good growth rate for an old growth redwood tree.
3 Some Tables Concerning Height Changes
This table shows twelve year height changes by individual tree, with the starting heights sorted from low to high as move from left to right. Here note some of the tallest redwoods had pretty good growth rates but overall there is a slightly negative association between starting tree height and height change.
This table shows the average height change in feet per year by park. Note the low tree count for Redwood National Park, many of the tallest redwoods in RNP were unidentified in the year 2000.
On average these tallest redwoods gained three inches in height per year.
This table shows detail for areas of Humboldt Redwoods State Park. Note the fastest growth area is the even aged very tall stand of redwoods in Harper Flat. Here the redwoods averaged almost five inches of growth per year.
4 Height Changes for a Few Specific Redwoods
Here are examples of trees with negative of zero change in height.
These three top ten tallest redwoods all had about the same average annual increase in height per year between 2000 and 2012, about 3.5 inches.
This is Nugget in Redwood National Park, it increased in height a bit more between 2000 and 2012 than the other top ten redwoods, about 4.25 inches per year.
There were two redwood trees on Harper Flat that grew a whopping seven feet between 2000 and 2012. This tree is one of them.
The two tallest redwoods, Hyperion and Helios, are not included in these tables as their discovery year was after 2000. In general Hyperion is growing relatively slowly compared to the other tallest redwoods while Helios is growing at a rate similar to Laurelin, Paradox, and Stratosphere Giant.
Hyperion did pick up the pace a bit after 2012.
I read a Humboldt State dendrochronology (tree ring) study which indicated redwoods are putting on more mass now than at any other time in the past one thousand years. This is also exhibited in the general height increase of all the tallest redwoods from 2000 to 2012.
There is an association between alluvial flats built up from by stream flood deposits and tall redwood trees. The tall redwoods spread their roots through this nutrient rich soil, often in multiple iterations as alluvial soil builds up from flooding events over the centuries. However these streams are not an important source of water for these redwood trees. Instead high amounts of annual rainfall as well as year round fog drip provide the water for these giants. However there is another way rich soil can accumulate to support the growth of tall redwoods.
2 Tall Redwoods and Schist Filled Benches
If you have been on the hillsides above redwood creeks you may have noticed several things.
First, the hillsides can be very steep, with gradients often between 20 and 40 percent.
Second, there are convex (slightly bowl shaped relative to the slope) benches that occur at different elevations on these hillsides.
Third, these benches have a dark, fine soil. That dark fine soil is called schist and when you stand on these benches you are standing on a pile of schist. Schist is great soil to support redwood tree growth. In the Redwood Creek Basin the soil on the hillsides (all of it) creeps about 2 millimeters per year and can also flow up to 200 millimeters during a very heavy rain event. The convex shape of the hillside benches induces the capture of the creeping schist soil. Presto, you have the perfect growing medium for a redwood.
If a redwood grows on a schist bench in an area that is within reach of fog year round it can grow very tall. As tall as any redwood that grows in the alluvial flats.
Hyperion grows on a schist bench. By all accounts Helios and Orion also grow on schist benches.
Much of the alluvial flat soil is schist that has washed, flowed, or crept down the hillside, mixed with the flowing creek, and then left on the flats above the creek banks as the waters receded. To some extent this occurs every year during the transition from the wet to the dry season. One type of schist soil is called greywacke. There is a redwood on the upper Bull Creek flats in Humboldt Redwoods that is named Graywacke after this soil type.
3 Schist in Northern California Is Formed by Plate Tectonics
A lot of geology is hard for me to follow but apparently the schist associated with northern California redwood forests was induced by tectonic fracturing and shearing of underlying bedrock. There is a tremendous amount of tectonic activity in the northern California redwood belt, as this is the location of the Mendocino Triple Junction where three large tectonic plates meet. There is a subduction zone a short distance offshore which induces giant (9.0 magnitude) earthquakes every 300-500 years (the last one was in 1700). Off the major faults are many minor faults, and the some of the notable redwood creeks follow these minor faults. Examples are Redwood Creek following Grogan Fault and Lost Man Creek following Lost Man Fault.
The tectonic activity and associated periodic earthquakes have created the benches on the hillsides and contributed to the unstable nature of the soil formations. The soil formations then creep over time, allowing for the collection of the soil in the convex benches.
4 Schist in Northern California Needs Flooding for Active Transport
Heavy rains induce the hillside schist soils to flow over the underlying bedrock. This can help the convex hillside benches “fill up” with soil as well as transport soil down to the creeks. Once in the creek the schist soil mixes in with the fast moving floodwaters. Then as the flood waters become less turbid and start to recede the schist falls out of solution and adds soil to the alluvial flats along the creek.
5 The Formula for Tall Redwoods in Northern California
A unique set of circumstances have combined to create the spectacular redwood forests in northern California. These forests would not be as impressive or even exist at all if even one of these ingredients was missing:
High annual rainfall
Some fog to provide moisture during the dry season
Temperatures above freezing year round
Incredibly rich schist soils which are the product of tectonic activity
Flooding rainfalls to move the soil into the convex benches and build the alluvial flats
Forests with tall redwoods need earthquakes and floods to thrive over the millennia.
6 It is Difficult to Measure the Height of Redwoods on Hillsides
Exceptional redwoods have been noted and measured in the northern California redwood forests for over fifty years. Looking through the data the redwood dimensions are defined in these ways:
Diameter (or circumference which we recall from trignometry is pi x diameter). This is by far the easiest dimension to measure as you walk up to the trunk and use a tape wrap or rangefinder to do the measurement.
Height. This can be difficult as the top of the tree needs to be hit at a distance with a rangefinder, then the height differential between the measure point and the point where the trunk meets soil needs to be determined.
American Forestry Points: Trunk circumference inches plus height in feet plus one fourth average crown spread in feet. So here the crown spread has been added as an additional measurement to base circumference and height.
Mass or volume. This is exceedingly difficult to measure and requires multiple measure points along the trunk as well as some kind of estimate of wood in the limbs and branches. Based on the overall shape of the redwood formulas for different geometric cone forms can be used as an estimate.
When a tall redwood is on a hillside all these measurements become more difficult.
For diameter the determination of average breast height (4.5 feet) measure point can involve some judgement as the point where the trunk meets soil can be ten feet higher on the up slope side of the tree versus the down slope side of the tree.
For height the elevation differential between measure point and trunk elevation can become difficult. Many hillside redwood tops will measure around five hundred feet in height from a measure point on the flats but how high is the tree base above the flat? The GPS can become a little erratic on a remote forested hillside and GPS altitude readings are usually a little off. So even if you get coordinates right at the trunk that may or may not be correct for altitude.
Also LiDAR has had its problems measuring trees on slopes. If a tree leans to the downhill the height will be overestimated. But there are also many redwood trees that lean a little uphill. This is due to the downslope buttressing seen in many hillside redwoods. Redwoods leaning uphill will have an underestimated LiDAR height. By the way, this hillside buttressing is an area of controversy in determining the ground level for hillside redwoods.
Demonstrated LiDAR errors for redwoods heights are up to five percent. This would result in an 18 foot or so error for a very tall redwood.
It is possible the tallest redwood is not Hyperion but rather a hillside redwood that has been missed so far. It is very easy to walk right by a tall hillside redwood. There is a chance a redwood or two growing out of a schist bench on a steep hillside slope could be taller than Hyperion. As one redwood explorer has commented, “chance has potential”.
7 Views of Tall Redwoods Growing on Schist Filled Hillside Benches
8 Views of Tall Redwoods Growing on Schist Filled Alluvial Flats
Please note this section involves speculation but is based on a known geologic event.
The Bull Creek Giant stands as the king of the redwood forests along Bull Creek in what will become Humboldt Redwoods State Park in northern California. Its top leaves quiver in the evening breeze 390 feet above its 21 foot diameter base. It is nine in the evening, and wispy fingers of fog are starting to flow up the Eel River and into Bull Creek Canyon. The forest is very green and damp from the ample winter rains.
Suddenly a pulse moves through the ground underneath the giant redwood. Then a few seconds later the ground starts to rumble, then shake, then lurch. The shaking continues for one minute….two minutes…..three minutes……four minutes and gets worse and worse minute by minute. The root ball of the giant starts to twist in relation to the axis of the tree. This induces a circular motion at the top of the tree with ever increasing centrifugal force. Suddenly the top sixty feet of the tree snap off and crash to the earth. Now the shaking starts to decrease in intensity and then ends rather quickly. There will be many strong aftershocks during the upcoming hours and days but the main event is over. For the third time in its lifetime the Bull Creek Giant has endured a 9.0 magnitude Cascadia subduction earthquake. This time the redwood did not get off damage free. It is no longer the tallest tree on Earth.
2 Original American Villages in Areas That Will Become Eureka, Arcata, Orick, and Crescent City – January 26, 1700
Please note this section involves speculation though it is based on oral traditions and a known geologic event.
Groups of native, or original, Americans have lived along the Pacific Northwest coast for over ten thousand years. In the oral traditions of these peoples are stories of past giant earthquakes followed by walls of water coming in off the ocean. At 9 PM the inevitable happens and another great quake occurs. The ground shakes violently, knocking people off their feet and caving in walls and roofs. The people who are able to do so act on their oral traditions and immediately start walking to higher ground. The people who are trapped in debris or otherwise unable to move to higher ground are tragically drowned twenty minutes later by a great upheaval of water originating a few hundred miles offshore.
3 Redwood Forests – 2016
The present day remaining old growth redwood forests are very special. They give us a view into what forests looked like many millions of years ago and are also places of great scenic beauty. These trees are very long lived and well able to withstand a lot of what nature dishes out. Be it forest fires, winter storms with hurricane force winds, flooding rainfalls, and even 9.0 magnitude earthquakes, many redwood trees endure. But many are damaged in some way by these events, and sometimes these trees come crashing down to the ground, the whole entire tree, all at once.
I would like to speculate the 9.0 magnitude Cascadia subduction earthquakes occurring every five hundred years or so have effects on redwood forests in ways that have not yet been documented. These effects could include the following:
Even aged reiterations in crowns: The 9.0 magnitude earthquakes cause tops of trees to whipsaw and snap off. This effect has been documented in the Forest of Nisene Marks at the epicenter of the 1989 Loma Prieta earthquake. Perhaps there are clusters of reiterations in cadence with the timing of the past large earthquakes in 1700 AD, 1310 AD, 810 AD, 400 AD, and 170 BC.
Twisted redwoods: The cause of twisting in some trunks is not well understood. Perhaps one influence is the reorientation of the axis of the tree due to twisting of the roots caused by the large intermittent earthquakes.
Bends in trunks: Some redwoods have a pronounced bend in the trunk. These could originate with leans induced by rapid subsidence due to earthquakes followed by the trees then growing straight sections.
Even aging of downed redwoods: Once redwood trees fall they still persist on the ground for hundreds of years. Core samples can be taken from a sample of downed redwoods and the rings cross dated to the core samples taken from many standing redwoods. In this way the last growth year of the downed redwoods can be determined. I predict the year 1699 will come up much more often than by chance.
4 Eureka, Arcata, Orick, and Crescent City – 2016
When you drive along Route 101 in and near the towns of Eureka, Arcata, Orick, and Crescent City you will see blue signs with a symbol of a person moving uphill from a large wave. These signs will say “Tsunami Hazard Zone” or “Tsunami Evacuation Route” or “Tsunami Evacuation Site”, or something similar. Should a large earthquake occur while you are along 101 or other low lying areas in or near these towns heed these signs. The people living in these areas are well aware of the risks associated with major earthquakes and know to get to higher ground immediately, most likely by walking as the roads will be damaged and gridlocked. It is very doable as there are many hills and getting to one hundred foot elevation should be safe enough. Then they know to wait there until the all clear, most likely several hours later as there will probably be multiple tsunamis, with the first starting 15 to 30 minutes after the initial earthquake.
According to numerous credible websites there is a ten percent chance a major (8.7 to 9.2 magnitude) Cascadia subduction earthquake will occur in the next fifty years. The full threat of these earthquakes was not realized until 2005, and many buildings and infrastructure have earlier construction or remodel dates. For this reason as well as the sheer size of the event the primary impact of Cascadia subduction earthquakes will be damage to buildings and infrastructure. However the tsunami threat to low lying areas is also of great concern.
Since 2005 a lot of good work has gone into threat identification and preparation for the inevitable upcoming event.
NASA maintains a global canopy height map on its website. This map is comprised of airplane based LIDAR mapping (2.4% of land mapped for canopy height) and satellite based “spectroradiometer” equipment (97.6% of land area mapped for canopy height). The canopy height is appropriately in shades of progressively darker green with the darkest green indicating at least eighty percent of the tree canopy in the area is over 70 meters (230 feet). All the dark green areas in northern California are old growth redwood stands. The average tree height in old growth stands in northern California is 250-300 feet, with maximum demonstrated individual tree height at 380 feet. To see more on this subject see my posting on “Distribution of Tree Height in an Old Growth Redwood Forest”.
Below is a portion of the Global Canopy Height map that includes the area from Fortuna to Klamath. The dark green (old growth redwood) forests have been noted from north to south. The old growth forests include Prairie Creek Redwoods and Redwood National Parks. No surprises there. However there are five additional areas with large enough tracts of old growth redwoods to be discernable on the global canopy height map.
You can click on the map to see a larger version.
2 Lesser Known Areas With Old Growth Redwood Forests
From north to south here are some comments on the lesser known areas with old growth redwoods forests.
Six Rivers National Forest High Prairie Creek Section and Yurok Redwood Experimental Forest
This area is low elevation and is protected from the ocean by a large ridge and has riparian zones along High Prairie Creek. These are perfect conditions for large and tall redwoods and indeed there are many large tree crowns in this area as seen on Google Earth.
This area does not have any public access and most requests for special access will be declined.
This could be the best area for old growth redwoods between Prairie Creek Redwoods State Park and Jedediah Smith Redwoods State Park and the trees in this forest are representative of the redwoods found in those parks.
Private Holdings – GDRC and HRC
The GDRC dominates timber holdings north of Eureka while HRC has extensive holdings around Eureka and south. Both these companies provide detailed publicly available management plans and holdings maps. Most of their holdings are managed second growth but they do have some old growth forests. Any old growth areas of three acres or more are voluntarily and permanently protected from harvesting and road construction by both of these companies.
I am not familiar with the access requirements for these areas but certainly written permission would be required from the respective company.
Some folks call this the “mysterious Headwaters Reserve”. It was the scene of some famous forest protection protests in the 1990’s and culminated in 1999 with a $380 million purchase of 7,000 acres from the owning lumber company, of which 3,000 acres are old growth redwoods. The purchase was 100% taxpayer funded, $250 million from the Federal government and $130 million from the state of California. The Reserve is managed by the Bureau of Land Management.
The Reserve does have public access though it is limited. There is a north approach which requires a five mile hike or bike from a parking area to reach the heart of the reserve. Then there is a south approach from near Fortuna that requires a reservation and meeting up with a representative of the reserve.
This reserve contains a few redwoods in the 360 feet height range. This is exceptionally tall, there are less than sixty redwoods throughout their range that are over 360 feet in height. Undoubtedly there are exceptionally large diameter and volume trees in this reserve as well.
3 Record Breaking Redwoods Outside the Redwood State and National Parks?
Any of the lesser known areas highlighted above could hold a record breaking tall redwood tree. It is not likely but there is a chance. As one well known redwood explorer writes – “chance has potential”.
Based on the existing information on tallest redwoods, a super tall redwood can grow anywhere from near sea level to around 900 feet in elevation. That covers a lot of ground. As long as the soil is good, there is some protection from wind from surrounding trees and hills, and there are year round water sources (nearby creeks, springs, and fog drip) a very tall redwood is a possibility.
Then to increase the possibility there needs to be a forest of trees growing in conditions for super tall redwoods. Each of the lesser known areas outlined above contains such a forest, as confirmed by the NASA global canopy height map.
For the same reasons there could also be very large (over 20,000 cubic feet) redwoods in these areas as well.
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:
Acres Old Growth Redwoods
# Redwood Trees > 100 cm per Hectare
# Acres per Hectare
# Old Growth Redwood Trees
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.
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.
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:
Expected Pct of Trees Less Than
HRSP Expected Trees
RNP Expected Trees
HRSP + RNP Expected Trees
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.
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.
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.
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.
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.
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.
Recently eight of so interpretive information signs have been put up along the trail. They are well done. Here is one of them.
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.
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.
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.
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.
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.
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:
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Then to even things out you can try to find early blooms in the redwood sorrel or watch the water flow down Montgomery Creek.
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.
This is the biggest (by volume) tree in the grove, it is about 361 feet tall with a 17.3 foot diameter.
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.
Montgomery Reserve is a popular park with a strong reputation for great redwoods which is well deserved.