If only some roots have been killed, the tree may decline slowly for no obvious reason. If the whole root system is damaged, the tree can die quickly, or fail over time as the roots decay. Underground, it can be a different story, with potentially catastrophic damage to the root system. If the lightning goes to the earth through the roots, there may well be no symptoms of a strike visible above ground. This may be due to the strike causing a serious disruption to the tree’s metabolism or because it’s been unable to fend off fungal disease or insect pests after being weakened by the strike. Lightning can cause unexpected tree deaths well after the strikeįor some trees when there is a small or no lightning scar, the tree appears to be fine only to die suddenly between two and 12 months later. But you and I know a secret – its trunk is hollow but strong. If you go past today, you will see no evidence of wounds or scars. As more years passed, its trunk broadened and the scar eventually grew over. Over the following years, I observed the long, narrow lightning scar deepening as the wood decayed. Many of us thought it would die, but it defied the odds. There is a splendid variegated elm growing at Melbourne University’s Burnley Campus which was struck by lightning almost 30 years ago. Unlucky trees can explode from a strong lightning hit. Trees can often recover from strikes like this, if the scar and decay are not too great. The wood behind the scar often decays over time, leaving a hollow behind. You’ll notice the lightning scar on trees like these, as it’s very visible. Such a strike often kills the tree’s living tissues in a strip running along a large branch, vertically down the trunk to the ground, or even ending a metre or two above the ground. Sometimes, lightning will strike one side of a tree. You may well notice the tree will appear to be undamaged and continue to grow well. You can sometimes see the sooty residue left on parts of the tree after a strike like this. If the trunk of the tree is very wet from rain, the lightning will course through the water and dust on the trunk down to the earth, causing little damage to the tree itself. Trees are not very good conductors of electricity. It would be an excellent idea not to be under a tree when this happens.ĭry lightning has set Tasmania ablaze, and climate change makes it more likely to happen again The sap inside the tree instantly turns to steam, which can cause it to literally explode, or lose great strips of wood and bark. For a tree unlucky enough to be hit by one of these events, it’s all over.
Strikes can be up to a million volts, generating temperatures up to 20,000℃. The damage done depends on the tree species, whether it was sheet or forked lightning, how wet it was and where the lightning hits the earth and dissipates.
The lightning strike pictured hit a tree in Sydney’s Royal Botanic Gardens. In fact, the effects can vary enormously. You’d think a lightning strike would be game over for most trees. When lightning strikes, they are more likely to be struck. How do these rules apply from the perspective of a tree? Old trees are often the tallest thing around. Lightning never strikes in the same place twice. Don’t shelter under a tree during a thunder storm. Most of us are used to the rules we were told about lightning and trees from childhood. And that means our tallest trees will be hit more often. As storms intensify in our new climate, we’re likely to see more lightning strikes. These all contribute to trees falling or dropping large branches.īut there’s something you might not think of as linked to climate change. This is what we can expect as our climate changes, with storm events more frequent, wind speeds stronger and rainfall heavier.
The huge storms many Australians have experienced recently have damaged or toppled old trees which had withstood the vagaries of our weather for the past century or more.
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