Andrew,
I appreciate your request for the asterisk. Just don't discount your measurement as being the most accurate one. Any way, I think the Thoreau pine just wants more attention. Big white pines can be that way you know. I look forward to a return to that tricky tree. When we return, I will have re-calibrated my lasers and clinometers. Bob ----- Original Message ----- From: "Andrew Joslin" <[email protected]> To: [email protected] Sent: Sunday, December 6, 2009 9:50:45 PM GMT -05:00 US/Canada Eastern Subject: Re: [ENTS] Settling the issue on Thoreau Experience makes for a better quality manual measurement, same as with rangefinder/clinometer measuring. Tangles in the tape are not an issue, the climber can keep track of that easily enough. It's up to the climber to do a good job setting a straight tape route through the crown, it's more or less difficult to do depending on the density of the crown structure. With experience it should be routine to get it right. To find the high tip I assess when I've reached the highest climbable point in the tree. I place the pole at the apparent high twig and then request verification from the ground that it is the highest point that they can hit with the rangefinder. It would help to have radio communication with the ground during this process, I'm not very good at yelling from the top of a tree. I use a 200' Kenson fiberglass tape, don't know what the % stretch is on a vertical measurement, research is needed. Will are you using a fiberglass tape? I think that with practice and due diligence 99.99% of manual measurement errors can eliminated. This may be a tempest in a teapot, the record shows that Will's tape drops and ENTS ground-based measurements are high percentage very close. My manual measuring inexperience probably has a lot to do with the Thoreau tree short measurement. For Thoreau's significantly off center top Will's suggestion of doing a sine calculation on an angled pole to the top twig makes tremendous sense and will likely solve most of the measuring problem for that tree. As I mentioned early in this discussion, I'd like to asterik my measurement, another manual measuring session is in order to see what's repeatable. -AJ Edward Frank wrote: > Bob, > > It is funny you mention errors in the tape drop measurement. I put a > sentence to that effect at the end of the message, but deleted it > before sending. There are several potential errors: > > 1. tangles in the tape > 2. tape caught on branches and not hanging free. > 3. misidentifying the tallest top > 4. not reaching the tallest top. > 5. top pole is titled at an angle > 6. the bottom position misidentified > 7. length of top pole mismeasured > 8. methodological errors > 9. tape stretch- not significant, but included for completeness sake. > > Most of these can be overcome with due care, but we should e aware of > them. How about it tree climbers are there other sources of error to > consider? > > Ed > > Check out my new Blog: http://nature-web-network.blogspot.com/ (and > click on some of the ads) > -- > Eastern Native Tree Society http://www.nativetreesociety.org > Send email to [email protected] > Visit this group at http://groups.google.com/group/entstrees?hl=en > To unsubscribe send email to [email protected] -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected]
