HUMAN HAZARDS A sustainable use of a forest is essential since uncontrolled and unchecked exploitation can cause irreversible damage such as loss of biodiversity, soil erosion, flooding and climate change. Forest exploitation In the past people rarely considered the importance of forest maintenance. Forests have been devastated whenever people needed open land for farming or fuel: the once huge forests of in Lebanon have almost completely disappeared; vast forests in China were destroyed during and after World War II; the forest trees of North American east coast were cut down by the new to use the timber; rainforests in the Amazon basin are still being for cropland. Each year, around 13 million hectares are deforested worldwide. 96% of this annual deforestation occurs in tropical regions. cedar settlers cleared Damage to forests Forests are subject to fragmentation, atmospheric pollution, and degradation, as well as the occasional forest fires. The most serious problems are:ù the effect of harmful substances, such as increased concentrations of ozone and nitrogen oxide; progressive soil acidification, which leads to root system fragility and reduced stability in the event of storms; a higher risk of extreme weather (storms, rain and droughts) due to global warming; • acid rain due to air pollution; forest fires. Forest fire prevention Forest fires constitute a serious and increasing threat throughout Europe, and in particular in Greece, Spain, France, Italy and Portugal. Larger and more damaging (i.e. ‘megafires’ ) are destroying large areas. For this reason, it is necessary to have wildland fire policies and practices carefully designed to reduce the risk of wildfire in extreme weather events (dry periods or strong winds), not only in normal weather conditions. wildfires 1 MORE A megafire is a wildfire that is beyond the capacity of the extinction system, either because of its high flame lengths or their high speed of propagation. According to official statistics, a megafire contains a burned surface area greater than 500 hectares of forest. 1 Forest quality management It is also important to guarantee the quality of a forest. The long-used practice of cutting only a few trees at a time from a particular wood is now being opposed because it resulted in taking the best trees and leaving inferior to take over the forest. Nowadays, individuals and companies have learned better harvesting techniques to improve the forest quality. The most commonly used method of tree improvement involves locating superior specimens of the species first. Then, branches are collected from their and are onto in nurseries, where they grow until they are old enough to bear seeds. Finally, the selected seeds with the best characteristics are planted. specimens crowns grafted rootstocks