Tag Archives: tallest redwood tree

Groves of Tall Redwoods – Changes over Decades, Centuries, and Millennia

1       Tall Redwood Groves – Recent Changes in Height

Redwood tree height measurement came into its own in the 1990’s.  Skilled researchers and naturalists combined laser rangefinder technology, LiDAR height estimation, hiking and climbing skill, and direct tape drop from the canopy to create a nearly complete inventory of tall redwood trees throughout their range (with the exceptions of Six Rivers National Forest and Headwaters Reserve, which have not been thoroughly assessed). From this it was determined redwoods over 100 meters (328 feet) in height were uncommon, totaling about 2,000 trees.  And redwoods over 350 feet (106.7 meters) in height were very uncommon, totaling about 230 trees.  Each tall tree is remeasured every five years or so, with the tallest trees having more frequent measurements.

 I don’t have direct access to the 15-25 years of longitudinal height data for tall redwoods but through research I was able to find height information for the tallest known trees in the year 2000 as well as their remeasured heights as of 2015.  There were 129 trees over 350 feet on the 2000 list, indicating many more 350-foot redwoods were yet to be identified, particularly in Redwood National Park.  Here are the height changes for these 129 trees in inches growth per year (parks with smaller tree counts are excluded) on the left axis and 2015 height on the right axis (line).

On the chart the trees are grouped by Bull Creek (Humboldt Redwoods along Bull Creek), Eel River (Humboldt Redwoods along Eel River including Rockefeller Loop), Montgomery (Montgomery Woods State Natural Reserve) and Redwood (Redwood National Park).

Height Change (left axis and bars) and 2015 Height (right axis and line)

It is evident in all four areas most trees had height increases over fifteen years.  Nine trees lost height, a few in each area.  Median height growth was about three inches per year.  Over the past few years two of the trees in the data have fallen.

The chart also includes tree height in 2015.  Correlation between 2015 height and height change is 0.53, correlation between 2000 height and height change is 0.02.  So height change was not related to initial starting height.

Here is summary data related to the chart.

Height Changes Summary

This data indicates the canopy of very tall redwood trees increased three feet from 2000 to 2015.   The canopy in 2000 was the result of several thousand years of forest development. Then why did the tallest existing redwood trees increase on average another three feet in height from 2000 to 2015?  Some potential contributing factors:

  • More sun reaching the leaves of edge habitat trees due to cutting of nearby trees from 1860-1979.
  • Fire suppression
  • Increased atmospheric CO2 providing more energy for photosynthesis

2       The Future of These Tall Trees

Based on plot information, 350-foot tall redwoods are between 700 and 2000 years old, with the median age 1180 years.  It is very likely almost all of the current 350-foot tall redwoods will fall over the next 1000 years, being replaced by grow in from trees currently under 350 feet and trees yet to sprout.

Let’s test this against the known 350-foot trees to fall in the last 30 years in Humboldt Redwoods State Park.

Humboldt Redwoods Fallen Trees

It can be expected about ten percent of the tallest redwoods will fall every 100 years, with 3-4 trees falling each decade.

Before falling many trees will lose and regain height over time.  About two thirds of the 350-foot redwoods in study plots have reiterated tops.

3       What is the Maximum Height for Redwoods

The current tallest tree is about 381 feet tall.  There are four trees around 375 feet tall or taller, and all four are gaining height.  Then the data shows the canopy for very tall trees in general is increasing by about one foot every five years.

So will there be 385-foot redwoods in 20 years?  Could be.

Will there be 390-foot redwoods in 50 years, and 400-foot redwoods in 100 years?  Maybe.  The theoretical maximum height based on tree structure and physics has been calculated to be 425 feet.  There is no reliable historic record for a redwood tree over 400 feet in height.  One was measured right at 400 feet about fifty years ago along Wilson Creek by an expert timber cruiser.

Will some second growth Douglas Fir beat all the redwoods and get to 400 feet first?  Maybe, but then again the reliable historic maximum height for Douglas Fir is 393 feet.

Thanks for reading.

Record Breaking Redwoods Outside the Redwood National and State Parks?

1      Tall Forests – NASA Canopy Height Mapping

 

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.

 

NASA Global Canopy height map - Eureka to Klamath
NASA Global Canopy height map – Eureka to Klamath

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.

Yurok Experimental Forest and Six Rivers NF near Klamath
Yurok Experimental Forest and Six Rivers NF near Klamath (Google Earth view)

 

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.

 

Headwaters Reserve

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.

Headwaters Reserve low elevation north section (close in Google Earth view)
Headwaters Reserve low elevation north section (close in Google Earth view)

 

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.

Thanks for reading.