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. ”
يوضح الكتاب نفسه ان الامر حدث تدريجيا ،‏ قائلا :‏ « بقي الانسان يدمِّر الحياة النباتية ليوسِّع اماكن الزراعة والرعي بصورة رئيسية ،‏ وليحصل ايضا على مواد البناء والحطب » .‏