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Invasive Growth

Posted from Camarillo, California, United States.

Most of our students are recovering from this year’s trip by catching up on their other classes and their sleep.  We are still in the midst of entering all the vegetation data we collected this year, but some of it has been fully entered.  Chief among these are data from our individual tree growth study.

Tree 18 (tallow, Triadica sebifera, tag 1518) from our tree growth study on Trail C at Woodlands on March 26, 2107. We spray paint all our monitored trees green to make sure our managers don’t accidentally kill these particular invading individuals during their routine management efforts.

Monitoring Invaders Individual Growth

For the past several years, we have been trying to get a better handle on the exact growth rates of our invaders.  Doing so will allow us to better estimate how quickly a stand of unimpeded invaders might get to their “mature” canopy height.  While we sacrificed about one-third of our monitored individuals this past year to more precisely estimate standing biomass and correlate growth annual growth rings to allometric measures (DBH, height, etc.), we still have more than 60% of our individuals living and growing along Woodlands Trail’s Trail C.

Below are our most updated estimates of actual growth rates:

Diameter at Breast Height (1.5m above the ground)

Height of the Tree Apex

Our DBH measurements are the best estimate of growth given the fact we can consistently measure it easily and accurately.  While our estimates of height are good, many of these individuals are now more than 7 or 8 meters tall.  As such, accurately measuring the very top of these taller trees is difficult and introduces error into our numbers in recent years.  This may well explain the relative decrease in growth in height from this year’s measurements (the “2016” is the change between March 2016 to March 2017).

Note: some iPhones are having problems rendering our graphs.  As such, here they are in stagnant (non-html) image formats:

 

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