The experimental orchards were located at Qiaotou town of Dongguan city,Guangdong Province,China.The litchi trees were planted between 1993 and 1994 with a distance of 3m between trees and 5m between rows.In a 2 hm 2 orchard,Desmodium intortum (Mill.Urb.),a forage legume,was planted in litchi orchard.This orchard is subsequently referred to as a complex system consisting of a litchi subsystem and a forage subsystem.In an adjacent 2 hm 2 orchard,ground cover plants (mostly weeds) were removed by farmers,an...