Forest generally goes through process of growth by sequestering carbon and releasing it. Photosynthesis is the chemical process by which plant use sunlight and absorbed CO2 to convert nutrients into sugars and carbohydrates. Carbon dioxide (CO2) is one of the nutrients essential to building the organic  chemicals that comprise leaves ,roots -contain  carbon, but  the proportion in each part varies enormously depending on  the plant species and the individual specimen's age and growth pattern. Nonetheless as more photosynthesis occurs, more CO₂ is converted into biomass, reducing carbon in the atmosphere and sequestering (storing) it in plant tissue (vegetation) above and below ground.

Forests are vitally important for global carbon cycle. The total areas of the world's forest is about 3.952 billion ha (more or less same as 1948), which is about 30% of the total land area of the world. It is estimated that the world's forest store 283 Gt of of carbon in the ecosystem as a whole including dead wood, litter and soil up to depth of 30 cm. Nepal's  forest cover nearly 40% of the total land area of the country . Forests of Nepal store 897 million metric tons of carbon in the year 2005. On the other hand, forest are long lived plants that develop a large biomass, thereby capturing a large amount of carbon over a growth cycle for many decades. Similarly, revitalizing degraded forest land and their soils in the global terrestrial ecosystem can sequesters 50-70% of historic loss.

Forest ecosystem consists of not only trees but also soils. Of the total global terrestrial carbon, about two thirds, excluding those sequestered from rocks and sediments are stored in forested areas in the form of standing biomass, under storey biomass, leaf and forest debris, and soil. Of the different land uses globally, forest vegetation including tropical, temperate, Boral, and savanna forests accounts for over 90% of carbon in plants and about 52% in the soil, from only 43% of the land.