Cats have a natural instinct to climb. Unfortunately, this sometimes means that cats wind up stuck at great heights in trees. While it is comforting to think of kindly firefighters climbing up to save the cat, in reality this rarely happens. Usually, it becomes your responsibility to scale the tree and save the cat --- even if the cat is not your own. There are ways to prevent cats from climbing your trees, however. Simple household items and precautionary measures are all you need to remedy this tricky situation.
Keep your cat indoors. This is the simplest precautionary method to prevent a cat-up-a-tree rescue. Provide your cat with "cat furniture" for climbing inside your home. Not only does this keep your cat out of your trees, it also protects it from predators or getting hit by a car.
Create a chicken wire cone on the tree. Start the cone 6 feet up the tree trunk, or at whatever height you want a cat to stop climbing the tree. When creating the cone, attach the narrow end to the trunk, fanning the large end of the cone out pointing up into the foliage of the tree. This cone should be large enough in size that the cat cannot jump over it, and angled so that the cat cannot climb it. This discourages the cat from climbing above the cone, keeping it at a reasonable height in the tree.
Cover the trunk of the tree in aluminium foil, beginning at the height you do not wish cats to climb beyond. Wrap the layer of foil as high as you think is necessary to prevent the cat from jumping past it in an attempt to get up the tree. Aluminium foil's surface has a feel that is unappealing to cats, making many cats unlikely to climb or even walk on it.
Apply a layer of cling wrap to the tree's trunk at a height that you wish the cat to stop climbing. Continue the cling wrap high enough that the cat cannot jump past it to climb the tree. Like aluminium foil, cling wrap is unappealing to cats. As they dislike the feel of it, they do not climb past the cling wrap to climb the tree.
If using aluminium foil or cling wrap on your tree, remember to replace it periodically. The foil and wrap will deteriorate due to weather and animals, and replacing it keeps it effective.