In the 1930s, researchers began to challenge the negative notions about wildland fires and argued that fire was essential to many plant and animal communities. For example, in drier ecosystems around the world where there is not enough moisture to help in the decay of dead plants, fire is required to break down and help recycle the nutrients. This concept is fire dependence and applies to natural communities that are adapted to and rely on the effects of fire to make the environment more hospitable for that community's plants and animals. For example, fire kills some large plants and prepares the soil for seeding by making nutrients more available for plant uptake. As a result, competition is reduced from other species that would have absorbed needed nutrients or shade out sunlight the new plants require.
Fire history is described as how often fires occur in a given geographical area.
Trees actually record fire history. Each year a tree adds a layer of cells, increasing the width of its trunk. When a fire passes through a forest, trees may be only scorched. A layer of charcoal remains on a living tree and, in time, is enveloped by a layer of new growth, creating fire scars. These fire scars provide a record that scientists can use to determine when in the history of the scarred tree a fire occurred.