鈥淚 speak for the trees 鈥� let 鈥榚m grow! But nobody listens too much, don鈥檛 you know.鈥� In the world of Dr Seuss, a short, orange creature called the Lorax argues lyrically on behalf of trees. But in real life, rhyming couplets aren鈥檛 enough and making a case for trees often involves putting a price on them.
Imagine, for example, that a builder damages a tree. Deciding how much the construction firm should be fined involves valuing it. But that can be a contentious task. Are you valuing the raw wood? The service the tree provides by sucking pollution out of the air? The cost of replacing the tree for insurance purposes? There isn鈥檛 a single approach that perfectly encapsulates these different ways a tree can have worth. But the one most commonly used by local authorities in the UK is the Capital Asset Value for Amenity Trees (CAVAT), which estimates the value of a tree as a public amenity 鈥� roughly speaking, how it creates good vibes and accentuates a sense of place.
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The CAVAT method works by first determining a basic price for the tree based upon the width of the trunk, which is a good measure of the tree鈥檚 age. It then adjusts that value based on various factors, such as the expected lifespan of the tree, the number of people who might enjoy it and attributes that contribute to or diminish the sense of place. A beautiful form of branches is a plus whereas a carpet of squashy, smelly fruit can be a minus.
Here, Kieron Dock of Forest Research, the research agency of the UK Forestry Commission, and Chris Neilan, the forester who invented CAVAT, calculate the value of 7 famous trees. It was really just for fun. But it does illustrate that putting a price on a tree is a tricky business. 听Is any one of these trees really any more valuable than the others? CAVAT serves its purpose, but we also need听 other methods to get a fuller sense of how much our trees are worth.
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1. Old Tjikko, Sweden
拢24,445
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This Norway Spruce may look a little scraggly, but then so would you if you were 9550 years old. Old Tjikko, as it is known locally, is cheating a bit because it鈥檚 a clonal organism: a succession of different individual trees that have grown in the exact same spot from the same ancestor. It is the third oldest clonal tree in the world. Even so, CAVAT considers it to be worth relatively little, largely because it doesn鈥檛 have a full and attractive canopy.
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2. Ta Prohm strangler figs, Cambodia
拢798,216
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If these exotic-looking tree roots look vaguely familiar, it is probably because they featured in the 2001 movie Tomb Raider. The ruins it adorns are those of a monastery and university founded in the late 12th century. There is some disagreement over the exact species of the tree, but we鈥檝e assumed it is a strangler fig.
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3. General Sherman, California
拢11,152,563
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It鈥檚 not just that this tree is tall 鈥� though at 83 metres, it most certainly is. It is also exceedingly thick and it maintains that girth nearly all the way up, as all giant sequoias do. That鈥檚 largely why it has such a huge CAVAT value. This one is more than 5-metres wide even at 18 metres above the ground, making it the largest single stem tree by volume on earth.
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4. Angel oak, South Carolina
拢872,849
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Some people claim that this is America鈥檚 oldest tree east of the Mississippi river. That鈥檚 not true but at roughly 500 years old, it has been around a long time. What makes this tree special is its incredible fanning branches 鈥� the longest is 57 metres. That, and the local legends that say the ghosts of slaves can be seen hanging out around the tree. The reason it鈥檚 worth so much, according to CAVAT, is largely its huge girth.
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5. Berkeley Square tree, London
拢750,000
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Local councils regularly use CAVAT to value their trees. The London Plane at the centre of this square emerged in 2008 as probably the UK鈥檚 most valuable street tree. There are dozens of other large trees worth more than 拢500,000 in London鈥檚 metropolitan area, but none has yet out-valued this one.
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6. Major Oak, Sherwood Forest, UK
拢574,430
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Legend has it that the outlaw Robin Hood and his band of merry men slept in the branches of this tree after a hard day robbing the rich and giving to the poor. The tree gets its name from a description of it written by an 18th-century antiquary who happened to be an army Major. Though considerably bigger than the Angel Oak (see above), a large section of the tree has fallen away, which brings down its CAVAT value. An elaborate system of scaffolding now supports the remaining branches.
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7. Wawona Tunnel Tree, California
拢9,465,164
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In 1881, two brothers were paid $75 to enlarge a scar in this giant sequoia into a tunnel. It was envisaged as a tourist attraction, designed to draw more visitors to the fledgling Yosemite National Park. It worked: during the early 20th-century countless visitors were photographed driving cars through the tree. The valuation applies to the trees as it stood in 1969; just before it fell under the weight of an intense snowfall.
