International seed trading provides a significant introductory pathway for weed seeds, and many globally established weeds originated as contaminants in agricultural lots. Management of these trade systems helps minimize losses is an important means preventing future biological incursions. Forage crop lots could be considered higher risk than arable vegetable crops, they have been found to perc...

Blue oak savannas were found to be substantially more diverse at all scales from localized point diversity to the community scale, than higher elevation shrubland and coniferous forests in the southern Sierra Nevada. Also, alien plants were more diverse and represented a substantial fraction of the understory flora in these blue oak savannas, comprising threefourths of the species at the smalle...