afforestation vs silviculture

afforestation

noun
  • The act or process of creating a new forest where none had existed before, or reforestation of areas long deforested. 

silviculture

noun
  • The care and development of forests in order to obtain a product or provide a benefit; forestry. 

How often have the words afforestation and silviculture occurred in a corpus of books? (source: Google Ngram Viewer )