Forests are now considered to be collections of trees as a whole, or large areas of trees. Tropical rainforest is found around the equatorial regions, and has perhaps the greatest number of kinds of life of any habitat, and a major role in taking in carbon dioxide and releasing oxygen. Temperate forests are also important.
The definition of old growth forests varies from group to group. Scientists use it to mean a forest of at least 150 years old and is composed of large living and dead trees that support a large diversity of other organisms while environmental groups have interpreted it to mean forests with large trees and minimal to no human influence.[1] While being established ecosystems, old growth forests are not immune to the effects of disturbance. On larger scales, old-growth forests are in a steady state, where the structure and composition of the forest can buffer the effects of a disturbance.[2] Because of the resilience to severe disturbances, such as windstorms and fire, treefalls are the most notable instances of disturbances in mature forests. Gap dynamics occur where a surplus of light and space in the area where a mature tree fell facilitates the growth of young trees and understory sun plants. [3]
In California, Indians burned old-growth forest with such regularity that there are more old-growth forests today than there was in 1850.[4] Despite these burning efforts, the Indians in the area utilized fire to keep undergrowth and brush down so that they could support the growth of other plants and the attraction of animals used for food.[5] It was after that fire suppression was implemented that it was seen that brush and dried materials built up, and combined with suppression, fires grew to become more severe in intensity, area, and duration.[6] Because of the more intense fires, legislation has been passed that encourages more frequent prescribed burns.[7] Prescribed burns have been found to be more effective at reducing wildfire severity when compared to conventional methods, reducing tree mortality by up to 72% in some areas of California as brush is continually removed rather than being allowed to build up as fuel for larger fires.[8] This demonstrates the importance of understanding the natural system during conservation. Not every area of the Earth was a idyllic mature forest prior to human influence. Natural disturbances were allowed to be carried out that reset and maintain certain ecosystems in a dynamic stasis, such as the more xeric environments of California.
The word 'forest' did not used to mean 'a place of trees', however. 'Forest' was a Norman French word, brought to England after 1066. It had the meaning of 'a place of deer (for hunting)'. The Normans designated large areas as 'forest', so that the king and his nobles could hunt there. 'Forest Law' applied, with severe penalties for those 'Saxons' caught killing, or attempting to kill, 'beasts of the chase' (deer, wild boar, etc.). An English forest did not have to be tree-covered: some were mainly wooded forests, like The New Forest, others were mainly moorland, like The Forest of Bowland. Sherwood Forest at the time the Robin Hood legend is set was in fact mainly heathland (heather etc.) and had relatively few, small woods.
Categories: [Trees] [Environment]