Afforestation is the process of introducing trees and tree seedlings to an area that has previously not been forested. Afforestation can be done through tree planting and seeding naturally or artificially. Similarly, reforestation can be considered a form of afforestation because like afforestation, reforestation is the alteration of a non-forested area to a forested area through tree planting and seeding. The difference is that reforestation is the restoration of an area that has been deforested.
There are many reasons for restoring an area via afforestation and reforestation, however they vary based on the area. Generally it is done for either conservation or industrial-commercial purposes.
Afforestation, reforestation and other forms of conservational forestry methods are often thought to be used for stopping the effects of climate change by reducing atmospheric carbon. The issue is which type of tree sequesters the most amount of carbon and does this have a positive or negative effect if any at all? The tree types that are widely discussed are old growth vs young-growth forests. Old growth forests are said to have massive carbon storage capabilities however these trees are capturing carbon incredibly slowly or unable to capture any more. With reforestation, this process is ‘solved’ by cutting down old growth and planting young-growth trees. Unfortunately, when an old growth forest is cut down, a lot of the stored carbon gets released into the atmosphere thus preventing a net positive effect. Afforestation is being thought of as a solution to the reforestation issue. By planting a new young-growth forest in an area that hasn’t previously had a forested, this could be a viable option for sequestering more carbon from the atmosphere. However, planting trees in an area previously unforested could impact the original ecosystem negatively such as reducing soil moisture in an area and forcing many species to leave their preferred habitats.
Some issues that can arise from afforestation and reforestation is climate change, anthropogenic changes to landscape and increased wood demand. Climate change can have some major effects on the growth and health on newly planted trees. Drought and major temperature fluctuations can cause serious seedling mortality to an area that has been newly planted, ultimately slowing down the restoration process. To reduce the effects of climate change on the restoration process, drought and shade tolerant species are used.
Increasing wood demand is another problem. The rate at which trees are being planted is much slower than the rate of those being cut down for production. The trees need time to grow and without a properly timed planting seasons going hand in hand with deforestation, there can be a potential stasis for the ever increasing wood demand.
Climate change is also changing the success of pests like the mountain pine beetle. In North America, as temperatures rise in the west and winters are becoming warmer, the pine beetle populations aren't dying out as they are supposed to in the winter. Figures 2 and 3 below show the difference between tree cover gain and loss in British Columbia from 2001 to 2014 taken from the global forest watch interactive map. The pink dots represent tree cover loss and the blue dots represent tree forest gain.