Richard in Canada asked:
How much heavier do deciduous trees get when they grow leaves in the summer?
There are 177 000 leaves on a 48 foot Maple tree which has an area of about 1/6th of an acre - a lot of leaf area. A leaf weighs between 1 and 5g where 5g is for a big leaf like a horse chestnut so if you multiply 5g by 177 000 you get about 1 tonne, about the same as a small family car, not a huge weight as the wood of the tree will weigh a lot more than this. The big problem that leaves pose is their surface area because they trap wind the means that the wind exerts a big force on the tree which is much more difficult to deal with than their actual weight.