Comparative Experimental Study of Seed Dispersal on Animals

Studies of the plants Achyranthes aspera, Bidens sp. and Petiveria alliacea establish examples of seed attachment and detachment on dispersal surfaces that occur continuously during movement of a dispersal agent. In uniform one—species stands, dynamic saturation points for the dispersal surfaces were demonstrated. A parameter termed the retention rate (R) was determined for each species in various habitats, and was used to calculate mean distances of dispersal. Within and around established populations of Achyranthes, for example, the mean dispersal distance ranged from < 5 m to > 2.4km, showing that settlement is selective and depends on the structure of existing vegetation. This relationship is also affected by the vertical distribution of seeds on the disperser.