agroforestry vs silviculture

agroforestry

noun
  • An agricultural approach of using the interactive benefits from combining trees and shrubs with crops and/or livestock. 

silviculture

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

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