Forest gardening was also being used as a food production system in various parts of the world over this period. Forest gardens originated in prehistoric times along jungle-clad river banks and in the wet foothills of monsoon regions.[citation needed] In the gradual process of families improving their immediate environment, useful tree and vine species were identified, protected and improved, whilst undesirable species were <answer>eliminated</answer>. Eventually superior foreign species were selected and incorporated into the gardens.
What did these gardeners do about unwanted species?
eliminated