If you have the funding, look into ground-based LiDAR. http://gees.usc.edu/GEER/10-07-2004%20Meeting/Kayen_lidar.pdf http://www.blackwell-synergy.com/links/doi/10.1111/j.0021-8901.2004.00925.x/abs/ http://www.esajournals.org/perlserv/?request=get-abstract&issn=1051-0761&volume=014&issue=03&page=0873 http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?_handler_=HandleInitialGet&journal=cjfr&volume=34&calyLang=fra&articleFile=x03-225.pdf
Essentially, it is a precision laser that rotates on one axis while the beam is shifted transverse to the rotation axis via prism. The sensor detects the reflection and determines the distance by 1/2 travel time. The instrument that I heard about recently had a vertical displacement of +/- 40 degrees and 0.25 arc-sec resolution, and 400 meter range (if I remember correctly). By establishing a network of several points using a theodolite, and then placing the LiDAR on those observed points, you could triangulate positions of all stems and their diameters within your plot to about 1 arc-sec accuracy. The downside, in addition to the breath-taking price of the instrument, is the unbelievable volume of data accumulated in each observation. Sorting and triangulating would be a huge undertaking. But as a result, you would have a complete 3 dimensional model within the parameters of the instrument and the stations you select. ---chris Christopher J Wells, Geographer National Wetlands Research Center, USGS 700 Cajundome Blvd Lafayette, LA 70506 Office: 337 266 8651 Cell: 337 288 0737 [EMAIL PROTECTED] [EMAIL PROTECTED] Sent by: "Ecological Society of America: grants, jobs, news" <[email protected]> 06/24/2007 09:35 AM Please respond to [EMAIL PROTECTED] To [email protected] cc Subject Re: Ficus challenges to tree diameter-biomass relationships Hello, Flint, I am just brainstorming-- 1. Use radiation-- a. Very weak gamma source on one side of the tree and a Geiger counter on the other side b. Measure sound attenuation from one side of the tree to the other (some distance away from it). c. Put an ultrasound probe on the tree and measure reflection times. 2. Use immersion to get volume-- Not the whole tree. Put a cylinder around the bottom and fill it with something. Then weigh how much stuff you put in the cylinder. Ping pong balls might work nicely 3. Measure bremsstrahlung radiation from the beta decay of C14 in the tree. This might be an innovative way of measuring the mass of many objects that contain carbon and are hard to put on a scale. For very old trees, a correction for age might be necessary. For thick forest, you would need to subtract background. IF this has never been done, and IF feasible, it might make a nice research project. Ernie Rogers In a message dated 6/23/2007 10:01:58 P.M. Mountain Daylight Time, [EMAIL PROTECTED] writes: Date: Fri, 22 Jun 2007 18:09:48 -1000 From: Flint Hughes <[EMAIL PROTECTED]> Subject: Ficus challenges to tree diameter-biomass relationships MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Hello, We are in search of useful feedback on how best to measure the diameter of Ficus (F. macrocarpa, F. benjamina, and F. macrophylla) trees in order estimate their aboveground biomass using allometric models. Does anyone have any ideas on how to estimate Ficus biomass given the plant morphological eccentricities (extensive aerial roots and the lack of a solid stem trunk to wrap a diameter tape around) that this species presents? Does anyone happen to have or know of Ficus-specific tree models? Thanks in advance for any help you might be able to provide and I will post a summary of any useful responses. Best Wishes, Flint ************************************** See what's free at http://www.aol.com.
