Sericea lespedeza is an invasive legume native to eastern Asia. Although it was initially introduced for forage and erosion control, it has since become a widespread problem, especially in prairie and rangeland areas, forming dense monocultures and outcompeting more palatable native plants. While much work has been done on identifying methods of controlling sericea, less is known about the biology of the plant itself. One particular knowledge gap concerns the methods by which sericea seeds are dispersed. As sericea is considered a significant threat to biodiversity in Oklahoma, an understanding of how it spreads may help to identify areas that may be impacted in the future. It has been suggested that water, specifically overland flow, may play a role in sericea’s dispersal. To test this hypothesis, we set out 27 transects at Oklahoma State University’s Range Research Station, and the Joseph H. Williams Tallgrass Prairie Preserve, with six seed traps per transect. Each transect consisted of six seed traps located downslope from a patch of sericea. Slope and sericea density varied for each transect, from 2° to 16° slope, and 10% to nearly 100% upslope sericea.
Results/Conclusions
Slope, sericea patch size, and distance from the patch interacted to influence the number of seeds captured in a trap (poisson GLMM; p < 0.05). More sericea seeds were trapped near larger patches of Sericea, with the highest amounts being found on medium slopes and closest to the patch. Furthermore, the majority of seeds were found at trap distances directly adjacent to the source patch at all sericea levels, and on low and medium slopes, with smaller numbers of seeds being found up to 7.62m away. Additionally, seed fall in general increased through October and November, and decreased towards December. Our results suggest that while most seeds tend not to disperse very far from their source, particularly on low to medium slopes, they are nevertheless capable of moving substantial distances, if only in small numbers. Further work on tracking sericea seed movement in relation to rainfall amount and intensity is currently in progress.