Explaining that it was a gradual process, the book says: “Man has persistently interfered with the natural vegetation, mainly in order to expand his farming and pasture area, but also to obtain building materials and fuel for his fire. ”
Raamatus räägitakse, et see on järkjärgulise tegevuse tagajärg: „Inimesed on pidevalt sekkunud looduskeskkonda, peamiselt selleks, et laiendada põlluharimis - ja karjakasvatuspiirkonda, ent ka selleks, et hankida ehitus - ja küttematerjali. ”