1) Conversion 2) Desert greening 
planting new forests on lands that have not been recently forested.
• (n.) The act of converting into forest or woodland.
The process or act of changing land into forest by planting trees, seeding, etc. on land formerly used for something other than forestry. This can obviously be contrasted with deforestation.
The establishment of a forest, stand or tree crop on an area not previously forested, or on land from which forest cover has very long been absent.
The act or process of establishing a forest, especially on land not previously forested. 
Planting of new forests on lands which, historically, have not contained forests.
Planting trees on land not previously used for forestry. :: Coillte (5th Edition) 
Planting trees where there were none before.
Af·for`es·ta'tion noun The act of converting into forest or woodland. Blackstone. 
planting new forests on lands that have not been recently forested.
process of establishing a forest.
[n] - the conversion of bare or cultivated land into forest (originally for the purpose of hunting)
afforest, afforestation 1. To convert (bare or cultivated land) into forest, originally for the purpose of providing hunting grounds. 2. To convert (open land) into a forest by planting trees or their seeds.
Planting of new forests on lands that historically have not contained forests.
noun the conversion of bare or cultivated land into forest (originally for the purpose of hunting)
Planting of trees in areas that have not previously held forests. (Reafforestation is the planting of trees in deforested areas.) Trees may be planted (1) to provide timber and wood pulp; (2) to provide firewood in countries where this is an energy source; (3) to bind soil together and prevent soil erosion; and (4) to act as windbreaks....
The establishment of a forest or stand of trees in an area where the preceding vegetation or land use was not forest.
Planting of new forests on lands that historically have not contained forests.