Global Vegetation I. Natural Vegetation Natural vegetation is the plant cover that would exist naturally in a region with no human disturbance or alteration. However, humans have altered the vegetation of the Earth's surface dramatically over the past 10,000 years, erasing in some areas all vestiges of natural vegetation. Instead, we now have human-influenced vegetation in most parts of the Earth, such as areas used for agriculture, grazing, and urbanization.
Some areas appear to be untouched by humans, such as regions protected in national parks.
In reality, even these areas have been affected by management practices . For example, wildfires have been aggressively suppressed in most national parks, under the assumption that wildfires are bad for forests. In reality, wildfires are a necessary component of forest ecosystems. Because we've removed wildfires by suppression, we've considerably altered the composition of forests in the U.S. Life-forms of plants refer to their structure, size, and shape, and often help indicate the environmental properties of an area. Biomes are further broken down into formation classes , which use the dominant life-form of the indicator plants.