Dear student, (a)- A forest is a highly complex, constantly changing environment made up of a variety of living things (wildlife, trees, shrubs, wildflowers, ferns, mosses, lichens, fungi and microscopic soil organisms) and non-living things (water, nutrients, rocks, sunlight and air). Trees are the biggest part of this complex community. (b)- Afforestation means to plant trees in an area where there were no trees before. Reforestation means re - planting of trees where trees have been cut down.Reforestation usually occurs naturally. Regards