As you may know, trees are used to make things like furniture, cottages and paper. Unused paper is then 'thrown in the recycling bin' and recycled (go through the same system to be reused). Deciduous tree leaves specifically, fall off in Autumn so the sticks, trunk, and remains of the tree can be used to make products with the nutrients in the wood. I think this is part of an ecosystem - hope I help! :D
Yes I think because if they swap with each other there would still be magnetic pulls from the same locations
The Himalayan mountain range and Tibetan plateau have formed as a result of the collision between the Indian Plate and Eurasian Plate which began 50 million years ago and continues today.