The document discusses various aspects of forests and trees including: 1) Earthworms can live up to 16 years. One ton of small animals can live in a hectare of forest. 2) Humus is made of organic materials. Forest soil has four layers - litter, humus, roots/gravel, and gravel/minerals. 3) A tree's age can be determined by counting its rings. Rainforest trees differ from temperate trees in their ring patterns.