Ability of introduced species to compete with native vegetation

Plant competition should be considered from the viewpoint of short-term establishment, long-term survival, and perpetuation of stands. Competition during the establishment stage may be reduced by the application of herbicides or mechanical treatments (mowing, plowing) to the native vegetation until the desired species become established. When high yields are desired, competition from weeds may be eliminated on a continuous basis by regular or periodic treatments.

Long-term perpetuation of stands of introduced species will depend on their ability to reproduce either vegetatively (for example, by suckers, runners, stolons, or rhizomes) or by seed. Some fast growing exotic species are not able to perpetuate themselves on the site and may need to be replanted after a number of years. However, some exotics have become invading pests (Opuntia spp., Prosopis spp., Nicotiana glauca, Parkinsonia spp., Euphorbia spp., Jatropha spp.).

Competition within mixtures, when mixtures are desired, can be reduced by using species with different root systems (for example, shallow-rooted species mixed with deep-rooted ones) as well as including species that have different seasonal patterns of growth.

Competition may also be reduced by selecting species according to their adaptability to microhabitats such as mounds, depressions, flat areas, or sloping areas. Diverse topography will create diversity in the resulting vegetation composition. Doing this, however, requires skill and experience and is not always practical for large-scale programs.