Tag Archives: coast redwoods

The Largest Redwoods – An Unfinished Story

1      Tree Height Versus Tree Volume

 

Tree height is an easy concept.  Measure the top and measure ground level and you have tree height.  Tree volume is more difficult to grasp.  The solid parts of a tree take up a certain amount of space, and that is the tree’s volume.  Since a tree is a tapering cylinder, cone cross section formulas can be used to estimate volumes of a tree by section.  Then sometimes the volume of the branches is estimated as well.  So tree volume is a pretty complicated business to nail down with precision.  For large redwoods the formula for a perfect cone usually gets you in the ballpark for estimating tree volume.

At some point in the near future technology may allow for rapid assessment of tree volumes in the same way the onset of laser rangefinders allowed for rapid assessment of tree height starting around the year 2000.  Think of a quadcopter with a digital camera that can measure tree height and width at various increments as it flies around and up and down a tree’s trunk.   Then think of this quadcopter moving up and down a hillside, doing these measurements for all trees over a certain size on the ridge.    This technology measures the trunk only.   Measuring limb volume is much more complex, and generally limb volume is not included when noting the volume of the largest trees.

2      The Largest Redwoods – A Very Incomplete List

 

There are lists which show the largest known redwoods in terms of volume and the tallest known redwoods in terms of height.  The height list is certainly complete or near complete as airplane based LiDAR measurements have allowed for whole forests to be measured for height.  However the largest volume list is incomplete, perhaps markedly incomplete.

Although trails have been built through and near many exemplary redwood groves, there are many areas with exemplary redwoods which have no trails.  Places such as the west side of Jedediah Smith Redwoods State Park, the Lost Man Creek area in Redwood National Park, and  the slopes above Redwood creek.    Even in areas with trails there could be very large redwoods tucked out of sight just a little bit away from the trails.

Now think about where the largest volume redwoods have been located.   Mostly in groves that have trails.  Why are so many of the largest redwoods located in Prairie Creek Redwoods?  For one, Prairie Creek has a lot of great redwood habitat with lots of alluvial flats and sheltered hillsides.  But also Prairie Creek has many trails through this habitat to make the identification of large trees easier.   What is different between Prairie Creek and the nearby groves of Redwood National Park?   Not much, at least for the groves that are relatively low in elevation.  But Prairie Creek has a much more complete trail system through its groves.

Let’s amplify this point with some statistics.

 

3      Most Redwoods Over 25,000 Cubic Feet are Yet To Be Discovered

 

If we assess the volume distribution of the top 25 giant sequoias and top 25 coast redwoods we see the relative volume between the largest and 25th largest trees in each group is similar.  In other words, each group covers the same relative range in volume.

Sequoia and Coast Redwood Top 25 Largest Trees Relative Volumes
Sequoia and Coast Redwood Top 25 Largest Trees Relative Volumes

 

So sequoias and coast redwoods have the same relative range from the largest through the 25th largest tree.   But there are many, many more mature redwoods than mature sequoias.

Species Trees/Acre Old Growth Acres Old Growth Trees
Giant Sequoia 3        38,000       114,000
Coast Redwood 8        85,000       680,000

Here the coast redwood old growth acres include only the northern redwood parks.

So there are 6X as many old growth redwoods in their prime range than the total number of old growth sequoias.  Yet the band for the top 25 trees in each species is the same?   There is only one explanation for this, and that is many, many of the largest redwoods have been missed, so far.

As a second comparison, let’s review the relative volume distribution for the twenty five largest redwoods versus the relative height distribution for the twenty five tallest redwoods.  How do those bands look?  Well they look really, really different.

Top 25 Largest and Tallest Redwoods relative volumes
Top 25 Largest and Tallest Redwoods relative volumes and relative heights

 

The 25th tallest redwood is about 95% as tall as the tallest redwood.  The 25th largest redwood is about 60% as large as the largest redwood.   Why the difference?   All or almost all of the tallest redwoods have been identified, through the use of laser rangefinder and LiDAR technology.  And many of the largest redwoods have not been found, as there is no comparable technology to quickly assess tree volume.

The current largest coast redwood tree lists have 25 trees over 24,000 cubic feet.   That is only a sample, there are probably over 100 such trees.  And almost certainly several trees are out there that are larger than 38,000 cubic feet.

So lots of discoveries to be made.   And lots of upcoming technology in the form of quad copters with smart digital imaging to assist researchers in making the discoveries.

Thanks for reading.