Forest Ecology

infestations - infestations occur when vermin (such as rats) or insects (such as grasshoppers) swarm over an area. Infestations usually have bad consequences, such as the spread of disease, from disease-carrying rats, or the destruction of farmers' crops, by grasshoppers eating them up.
glaciation - glaciation means the covering of a landscape with ice. It can also mean an ice age.
succession - succession is the many stages that land goes through as it is colonized by plants.