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Dendritic Seismographic Sensor Network

An arborist device to survey a tree's root structure
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I'm currently working as a tree worker and in my little expereince with the field I've learned that alot of damage done to trees that ultimately leads to their decline is due to the difficulty in finding out where a tree's root system lies before landscaping or construction work is done around the tree. Mostly, the time/cost of the work in finding a tree's root system outweighs the benefits in preserving a tree as viewed from a developer's perspective. Especially when you are already doing additional landscaping (why not just plant a new tree when the old one dies?).

There are currently only 3 ways to deal with this: one is to ignore it and cut the roots to make way for utilities, irrigation, etc. This will result in tree decline/death. The second is to use a high pressure air knife to excavate the roots starting from the trunk and working towards the construction site. This is messy and time consuming, but effective. The final is to use ground penetrating radar (GPR) to survey the land from the tree to the construction area to find the roots. I believe this is more expensive, probably much more time consuming and the data is difficult to interpret as the radar signature for earth and root and man made object varies very slightly (and some materials prohibit wave penetration very far). It does have he advantage of being unobtrusive and doesn't require digging down 1 to 3 feet of soil to find all the roots which a lax/quick excavation may miss.

So my idea came from a mixture of my reaction to a GPR presentation and day-to-day experience with removing trees. What about GPR in reverse, so to speak? I noticed that when standing 'near' (by the dripline)a tree undergoing removal, there is an perceptable vibration in the ground as the chainsaw bites into the trunk of the tree. I wondered if there would be some way of analyzing that vibration on a seismographic network spread out around the tree. I propse you would place some sort of non-destructive 'thumper' (ala dune) on the trunk to produce vibrations through the trunk at varying amplitudes and frequencies and pick these vibrations up from the siesmographic network that you've spread out around the tree. I imagine the big trick is going to be filtering out the noise and tuning it to such precision that you'll be able to 'see' (difference between baseline earth vibration and earth-with-root-through-it-vibration) the basic 2D root structure as it is propagated through the earth. I imagine some pretty hefty controlled testing will be required to filter out the fact that sensor A will be getting vibration 'noise' from the root structure all the way across the tree that sensor B is there to detect! Perhaps some fancy 'noise comparison' software that find the similar noise frequency and edit it out?

So there's no real benefit to this compared to GPR in that when all is said and done and the funding and kinks have been worked out, you just sent up your fancy network in the morning, break for lunch as you collect the data, and analyze the data in the afternoon. GPR seems to take about the same amount of time and you're just exchanging walking-the-radar-around-slowly-time for installing-the-sensor-net-time. Perhaps it would be a good comparison model for GPR to stand up against. But it was pretty fun to contemplate:).

glemieux, Apr 21 2007

Root system architecture of urban trees http://www.treelink...02/jan/01Stokes.pdf
Background. Pilot study comparing GPR with actual root systems (after excavation). Unfortunately, they've redrawn the GPR images themselves. [jutta, Apr 21 2007]

Pipe finder http://www.schonste...=Pipe%2Band%20Cable
I think they send out a signal through the pipe. [ye_river_xiv, Jan 09 2012]

Post hole diggers. http://www.tanaka-u...dex.php?section=187
Statistical soil sampling is a common idea... [ye_river_xiv, Jan 09 2012]

Soil Resistivity. http://en.wikipedia...stivity_measurement
[ye_river_xiv, Jan 09 2012]

[link]






       Interesting idea! My first aproach would be to water it with something radioactive, then measure where the tree roots lift the heavy above ground level after the rest of the water has seeped away - but that has its own problems.   

       Realistically, figuring out what's what from vibration waves and figuring out what's what from reflected GPR waves is probably similar, no?
jutta, Apr 21 2007
  

       There is a very similar technique for cable detection, or buried pipes: a coil is used to send a high frequency test signal along them (from a known point above ground), and a receiving coil is used to detect where the signals go. When the object is deeper it is more difficult to pinpoint.
Ling, Apr 21 2007
  

       Bun, if for no other reason than being only the third person to use the word "Dendritic" in an idea, and only the second to put it in the title. Cool idea to boot.
gardnertoo, Apr 21 2007
  

       //there's no real benefit to this//   

       [marked-for-tagline]
pertinax, Apr 23 2007
  

       This sounds almost like you're seeking out a more practical solution to your particular problem.   

       I suggest taht you might find some assistance in the annals of soils engineering, prospecting, and/or archaeology.   

       I've noted that pipes are located by attaching a device to the above-surface portion of a pipe, and then wandering around with an instrument that locates that signal elsewhere in the environment. The principle is a bit outside of my expertise, but I assume that all your trees have a trunk, and roots that extend from it, which should be able, in one way or another, to better propagate the signal than soil, seeing as how the roots are composed of solid, and continuous structures, whereas soil contains solids, liquids, and a lot of discontinuous material.   

       You might also consider soil resistivity. Seeing as how trees must contain water in a continuous flow from the roots to the leaves, it should be possible to track the progress of electrical signals through the tree and into the surrounding terrain. This may or may not be preferable to sound waves.   

       I also would suggest you consider the application of post-hole diggers. These have a way of finding roots, although you may not be able to prove what tree they come from until the damage is done, I presume that a few post holes might prove the presence of roots early enough that some construction plans could be altered before significant damage occured to the tree.   

       You may also wish to consider some mathematical modeling for the spread of the roots. I suggest that any generalized tree might grow in a pattern that can be statistically interpreted to be similar to the inverse square law, or perhaps some maximum root length could be predicted based on the age of the tree. We might examine fractal patterns, and the drainage of the area in an attempt to better estimate the overall pattern of the roots as well.
ye_river_xiv, Jan 09 2012
  
      
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