Cattle as a dispersal agent of Acaena elongata (Rosaceae) in the cordillera of Merida, Venezuela.

Abstract

In the tropical Andean environments little is known about the relationship between weed dispersal and disturbances caused by cattle. We propose that abundance and dispersal of the Venezuelan Andean weed Acaena (Acaena elongata L.) is associated with the widespread grazing habits of cattle. We studied Acaena presence in areas with different cattle movements and grazing intensities. Acaena density increased with cattle trail density (r2 = .98, P < .001). Infestation patterns suggested dispersal by cattle along trails. Areas with greater cattle movement (0.34 trails/m) possessed the greatest density and highest number of Acaena plants (P < .001). This weed has morphological and phenological features adapted to cattle dispersal. Fruits mature during the season when cattle are less selective and travel the greatest distances.