How Fast Do Growing Redwoods Reach Exceptional Heights

 

1       Redwood Tree Height

 Redwood trees are noted for reaching exceptional heights.  This is the only species of tree that currently has numerous individual trees over 100 meters in height.  But even for redwoods, 100-meter trees are relatively uncommon, with about 1,900 individual trees exceeding this height.  Then there are only 40 or so redwoods over 110 meters in height, with the current demonstrated maximum height about 116 meters.

This table recaps the counts for tall redwood trees by Park and Area.

Summary 100 Meter Redwood Trees

2       Redwood Tree Height vs Age In Old Growth Forests

In 2009 and 2010 redwood research plots were established in old growth forests across the current redwood range, sixteen in all.  Each plot is one hectare (10,000 square meters) and is shaped in a long narrow 10-meter X 100-meter rectangle, with two tall redwoods near each end.   These plots were put in to monitor redwood tree and redwood tree forest health over time.  As part of this research, the tree heights are measured every so often, and the tree ages were established by core samples up the trunk to allow the thin increment borer to reach the center of the trunk if possible.  A few redwoods outside the plots are also included in the longitudinal study.

All of this is detailed in the fine research paper: 

Carroll AL, Sillett SC, Kramer RD (2014) Millennium-Scale Crossdating and Inter-Annual Climate Sensitivities of Standing California Redwoods. PLoS ONE 9(7): e102545. doi:10.1371/journal.pone.0102545

From Appendix F in the research paper, the tree heights and ages can be plotted.  I have generated this plot and table from the information in Appendix F.

SESE Plots Heights vs Age
SESE Plots Tree ID to Likely Tree Name

From this graph we can see the youngest 100-meter redwood is about 500 years old.  Then the tallest redwoods cover a broad age range, from about 700 years old to about 2,000 years old.  The growth structure of these trees is covered in Appendix K of the same paper.  Some of the older trees lost some height but then grew tall again, this is termed reiterated growth.   Then other trees have continued to grow without much crown breakage.  The very oldest trees tend to be a little shorter and include many reiterations.  So, if you happen to measure a redwood tree as 100 meters in height, it is almost certainly over 500 years old.

3       Redwood Tree Height vs Age in Second Growth Forests

Redwood tree forests were timbered starting around 1850.  After timber operations left an area the redwoods began to grow again from the ground up, either as new growth from stump roots or growth from seedling sprouts.  These second growth forests are in both managed timber lands and in parks and reserves.  In parks and reserves the second growth redwoods have been thinned over time to help the forests more quickly mature.  The tallest second growth redwoods are about 285 feet tall and about 160 years old.  How long will it be before these trees reach 100 meters in height?  It is likely much sooner than 500 years.

Navarro North Fork Tallest Tree (LiDAR indicated height 275 feet, age about 160 years. From Google Earth Street View.

For example, in Navarro Redwoods the tallest trees are 250-275 feet tall and growing on average eight inches per year.  These trees are definitely ahead of the growth versus age curve in old growth forests, where 80-meter trees are between 190 and 400 years old.   Then the 80-meter redwoods in Navarro are increasing height at more than double the rate of 80-meter old growth redwoods.

Tall Navarro trees with LiDAR indicated growth rates. Trees are approximately 160 years old.

This is an estimate of growth curves for second growth redwoods in optimal habitats.  It is predicted 160 year old second growth redwoods in optimal growing areas will on average reach 100 meters in height at age 400 years (240 years from now).  There will likely be a few very fast-growing second growth trees that reach 300 feet in 30 years and 328 feet (100 meters) in 100 years.

Estimated Height Growth Curve for Second Growth Redwoods in Optimal Habitats

Thanks for reading.

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