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:''This article outlines the basic procedures for measuring trees for scientific and champion tree purposes. It does not cover timber assessment for production purposes, which is focused on marketable wood volumes rather than overall tree size.'' Tree height is the vertical distance between the base of the tree and the tip of the highest branch on the tree, and is difficult to measure accurately. It is not the same as the length of the trunk. If a tree is leaning, the trunk length may be greater than the height of the tree. The base of the tree is where the projection of the pith (center) of the tree intersects the existing supporting surface upon which the tree is growing or where the acorn sprouted.〔Frank, Edward Forrest. September 19, 2005. Base of Tree.〕〔Frank, Edward Forrest. January 12, 2010. The Really, Really Basics of Laser Rangefinder/Clinometer Tree Height Measurements. http://www.nativetreesociety.org/measure/really_basic_3a.pdf Accessed March 4, 2013.〕 If the tree is growing on the side of a cliff, the base of the tree is at the point where the pith would intersect the cliff side. Roots extending down from that point would not add to the height of the tree. On a slope this base point is considered as halfway between the ground level at the upper and lower sides of the tree. Tree height can be measured in a number of ways with varying degrees of accuracy. Tree height is one of the parameters commonly measured as part of various champion tree programs and documentation efforts. Other commonly used parameters, outlined in Tree measurement include height, girth, crown spread, and volume. Additional details on the methodology of Tree girth measurement, Tree crown measurement, and Tree volume measurement are presented in the links herein. American Forests, for example, uses a formula to calculate Big Tree Points as part of their Big Tree Program〔American Forests Measuring Guidelines. http://www.americanforests.org/bigtrees/big-tree-measuring-guidelines/ Accessed March 4, 2013.〕 that awards a tree 1 point for each foot of height, 1 point for each inch of girth, and ¼ point for each foot of crown spread. The tree whose point total is the highest for that species is crowned as the champion in their registry. The other parameter commonly measured, in addition to the species and location information, is wood volume. A general outline of tree measurements is provided in the article Tree Measurement with more detailed instructions in taking these basic measurements is provided in "The Tree Measuring Guidelines of the Eastern Native Tree Society" by Will Blozan.〔Blozan, Will. 2004, 2008. The Tree Measuring Guidelines of the Eastern Native Tree Society. http://www.nativetreesociety.org/measure/Tree_Measuring_Guidelines-revised1.pdf Accessed March 4, 2013.〕〔Blozan, Will. 2006. Tree Measuring Guidelines of the Eastern Native Tree Society. Bulletin of the Eastern Native Tree Society, Volume 1, Number 1, Summer 2006. pp. 3-10. http://www.nativetreesociety.org/bulletin/b1_1/bulletin1_1.htm〕 ==Maximum heights== The tallest tree in the world is a coast redwood (Sequoia sempervirens) growing in Northern California that has been named Hyperion. In September 2012, it was measured at 379.65 ft (115.72m) tall.〔Monumental Trees - The thickest, tallest, and oldest trees in North America. http://www.monumentaltrees.com/en/records/northamerica/ Accessed March 5, 2013.〕 There are 7 other coastal redwoods known to be over 370 feet (112 meters) in height, and 222 specimens over 350 feet.〔Tallest Coast Redwoods. http://landmarktrees.net/redwoods.html Accessed March 5, 2013.〕 There are only five species known to grow over 300 feet in height worldwide.〔World Rucker Index. http://www.ents-bbs.org/viewtopic.php?f=235&t=3573 Accessed March 4, 2013.〕 There are historical accounts of extremely tall and large trees. In the northeastern United States, for example, there are frequent stories published in newspapers and magazines dating from the 1800s telling of extremely tall white pines (Pinus strobus).〔Historical Accounts of White Pine Heights - A Compilation. http://www.nativetreesociety.org/historic/nwhite_pine_heights.htm Accessed March 5, 2013.〕 One extraordinary account in the Weekly Transcript, North Adams, Mass., Thursday, July 12, 1849 reads: "A Large Tree. --- Mr. D. E. Hawks, of Charlemont, cut a Pine tree a short time since, of the following dimensions. It was 7 feet through 10 feet from the stump, and 5 feet through 50 feet from the stump. Twenty-two logs were taken from the tree, the average length of which were 12 feet. Fourteen feet of the tree were spoiled in falling. The extreme length of the tree from the stump to the top twigs was 300 feet! ---- Greenfield Gazette." In 1995 Robert Leverett and Will Blozan measured the Boogerman Pine, a white pine in Great Smokey Mountains National Park, at a height of 207 feet in 1995 using ground based cross triangulation methods.〔Rucker, Colby. Feb 2004. Tallest Examples of Eastern Native Tree Species. http://www.nativetreesociety.org/bigtree/webpage_tall_tree_list.htm Accessed March 5, 2013.〕 This the highest accurate measurement obtained for any tree in the eastern United States within modern times. The top of the tree was lost in Hurricane Opal in 1995 and it currently stands at just under 190 feet in height.〔Boogerman Pine, GSMNP. http://www.nativetreesociety.org/fieldtrips/gsmnp/boogerman/boogerman.htm Accessed March 5, 2013.〕 It is possible that some white pines in the past reached heights of well over 200 feet given the much larger area of primary forest prior to the timber boom in the 1800s, however, based on what grows today, it is highly unlikely they ever reached the heights in some of these historical accounts. These reported heights are likely just a mixture of personal and commercial bravado by the lumbermen of the time. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tree height measurement」の詳細全文を読む スポンサード リンク
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