Attributes That Confer Invasiveness and Impacts Across the Large Genus Bromus: Lessons from the Bromus REEnet Database

Abstract

Bromus (L.) species are cool-season grasses of temperate regions and tropical high elevations. Some species in the genus Bromus have been widely introduced into new areas of the globe and are invasive in the Western United States, while others occur only in their native ranges. We developed a database with information about traits of Bromus species and their interactions with biotic and abiotic features of their environments. Using the collected data, we looked for correlations among wide introduction, weediness, a suite of traits including taxonomic section, year, life span, seed awn length, average seed mass, polyploidy, human use and cultivar availability, and climate factors. Annual Bromus species were often destructive crop weeds, ruderal weeds, and environmental (natural habitat) weeds. Long awn length was associated with wide introduction and weediness in annual Bromus grasses. Perennial Bromus grasses generally remained confined to their native regions unless they were polyploid species cultivated for hay, forage, and revegetation, and few were invasive. Invasiveness in Bromus species was associated with the ability to grow at high and low temperature and precipitation levels and with human activities. Most research focuses on highly invasive species such as Bromus tectorum L. (downy brome or cheatgrass) and cultivated species such as Bromus inermis Leyss. (smooth brome), while information about most other species is more limited. Information about Bromus species in a central location facilitates comparisons among species and provides data that can be used for modeling, prediction, management, and control of Bromus grass invasions.