Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2007
Publication Date: 11/1/2007
Citation: Davies, K.W., Sheley, R.L. 2007. Influence of neighboring vegetation height on seed dispersal: implications to invasive plant management. Weed Science 55:626-630
Interpretive Summary: Invasive plants are rapidly invading previously uninfested rangelands at an alarming rate. However, no methods to limit wind dispersal of seeds have been developed. This study evaluated the potential influence of neighboring vegetation height on reducing wind dispersal. Seeds from a wind-dispersed and non wind-dispersed species were released in a modified wind tunnel in front of vegetation of differing height. Wind speeds and distance from neighboring vegetation were also varied. Both species dispersal varied with neighboring vegetation height regardless of distance from vegetation barrier or wind speed. The wind-dispersed species dispersal decreased drastically as neighboring vegetation became taller than the seed release height. These results suggest maintaining or promoting tall vegetation around invasive plant infestations can reduce invasive plant seed dispersal.
Technical Abstract: Invasive plants are spreading rapidly into previously uninfested rangelands. 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 [Tragopogon dubius Scop.]) and non wind-dispersed (medusahead [Taeniatherum caput-medusae (L.) Nevski]) 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 (Agropyron desertorum (Fisch. Ex Link) J.A. Schultes) 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•hr-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 (P < 0.0001). Increasing height of neighboring vegetation decreased the number of yellow salsify seeds dispersing across neighboring vegetation (P < 0.0001). The greatest percentage of medusahead seeds dispersed across the neighboring vegetation at shortest height (P < 0.0001). Results suggest maintaining or promoting tall vegetation neighboring invasive plant infestations may reduce wind dispersal of seeds. Our results also suggest that more research is needed to investigate the influence of varying heights, densities, and composition of vegetation neighboring infestations and the dispersal of invasive plants