Courtesy : Bachelor of Science Forestry (Botany, Zoology, forestry) Latest
Evolutionary history
The first known forests on Earth arose in the Late Devonian (approximately 380 million years ago), with the evolution of Archaeopteris, which was a plant that was both tree-like and fern-like, growing to 10 metres (33 ft) in height. It quickly spread throughout the world, from the equator to subpolar latitudes; and it formed the first forest by being the first species known to cast shade due to its fronds and by forming soil from its roots. Archaeopteris was deciduous, dropping its fronds onto the forest floor, the shade, soil, and forest duff from the dropped fronds creating the first forest. The shed organic matter altered the freshwater environment, slowing its flow and providing food. This promoted freshwater fish.# ISO certification in India
Ecology
Main article: Forest ecology
Temperate rainforest in Tasmania’s Hellyer Gorge
Forests account for 75% of the gross primary productivity of the Earth’s biosphere, and contain 80% of the Earth’s plant biomass.# ISO certification in India
The world’s forests contain about 606 gigatonnes of living biomass (above- and below-ground) and 59 gigatonnes of dead wood. The total biomass has decreased slightly since 1990, but biomass per unit area has increased.
Forest ecosystems can be found in all regions capable of sustaining tree growth, at altitudes up to the tree line, except where natural fire frequency or other disturbance is too high, or where the environment has been altered by human activity.# ISO certification in India
The latitudes 10° north and south of the equator are mostly covered in tropical rainforest, and the latitudes between 53°N and 67°N have boreal forest. As a general rule, forests dominated by angiosperms (broadleaf forests) are more species-rich than those dominated by gymnosperms (conifer, montane, or needleleaf forests), although exceptions exist.# ISO certification in India
Forests sometimes contain many tree species within a small area (as in tropical rainforests and temperate deciduous forests), or relatively few species over large areas (e.g., taiga and arid montane coniferous forests). Forests are often home to many animal and plant species, and biomass per unit area is high compared to other vegetation communities. Much of this biomass occurs below ground in the root systems and as partially decomposed plant detritus. The woody component of a forest contains lignin, which is relatively slow to decompose compared with other organic materials such as cellulose or carbohydrate.# ISO certification in India
The biodiversity of forests varies considerably according to factors such as forest type, geography, climate, and soils – in addition to human use. Most forest habitats in temperate regions support relatively few animal and plant species, and species that tend to have large geographical distributions, while the montane forests of Africa, South America, Southeast Asia, and lowland forests of Australia, coastal Brazil, the Caribbean islands, Central America, and insular Southeast Asia have many species with small geographical distributions. Areas with dense human populations and intense agricultural land use, such as Europe, parts of Bangladesh, China, India, and North America, are less intact in terms of their biodiversity. Northern Africa, southern Australia, coastal Brazil, Madagascar, and South Africa are also identified as areas with striking losses in biodiversity intactness. # ISO certification in India