Controlling invasive plant infestations is very costly and often unsuccessful. Preventing invasions is more cost-effective than controlling invasive plants after they are established. Because prevention guidelines do not suggest any tools or methods to limit wind dispersal of invasive plant seeds, we investigated the influence of neighboring vegetation height on seed dispersal of a wind-dispersed (yellow salsify) and nonwind-dispersed (medusahead) species. To examine the influence of neighboring vegetation height on dispersal, seeds of both species were released in front of an artificial stand of desert wheatgrass in a modified wind tunnel. Treatments were a complete factorial design with two species, four vegetation heights (10, 30, 40, and 60 cm), three wind speeds (3, 5.5, and 10 km h−1), and three release distances from the neighboring vegetation (0, 15, and 30 cm). The ability of medusahead and yellow salsify seeds to disperse was influenced by the height of neighboring vegetation. Increasing height of neighboring vegetation decreased the number of yellow salsify seeds dispersing across neighboring vegetation. The greatest percentage of medusahead seeds dispersed across the neighboring vegetation was at the shortest height. Based on these results, we suggest that maintaining or promoting tall vegetation neighboring invasive plant infestations may reduce wind dispersal of seeds. More research is needed to investigate the influence of varying heights, densities, structural attributes, and composition of vegetation neighboring infestations and the dispersal of invasive plants.
Nomenclature: Medusahead, Taeniatherum caput-medusae (L.) Nevski; yellow salsify, Tragopogon dubius Scop; desert wheatgrass, Agropyron desertorum Fisch. Ex Link J.A. Schultes;