What is the process called when forests are established in an area where there was no previous tree cover?

The process being described is called afforestation, which refers to the establishment of a forest or stand of trees in an area where there was no previous tree cover. This can occur in areas that were previously bare land, such as grasslands or deserts, or in lands that have been degraded but not forested in the past.

Afforestation is often undertaken for various reasons, including to combat climate change by sequestering carbon dioxide, to enhance biodiversity, to improve soil quality, and to regenerate ecosystems. This is distinct from reforestation, which involves replanting trees in areas that have been deforested or where trees have been cut down. Deforestation, conversely, is the process of clearing forests, and agroforestry involves integrating trees with agricultural practices. Thus, the correct answer captures the unique aspect of planting trees in previously non-forested areas.