Summary: Bennett et al. (2011)

Invasive, exotic, introduced, are all words used to describe a species that has been brought into an area of which it originally did not belong.  Like adding anything to a system that was not meant to contain the addition, the addition will most definitely have an affect on the system.  Whether that affect on the system is for better or for worse is to be determined.  There has been many studies conducted and observations made in regards to that exact question, what are the effects on an ecosystem or environment as a result of an introduced species?  Looking at just one specific study done on Holcus lanatus, a species of grass introduced to California in the United States, results determined that this introduced species does have a negative impact on the local communities in which the grass is found.  The study was conducted both in the greenhouse and out in the field in which the species is found, measuring growth rate, size, herbivory, competition and the soil (Bennett et al. (2011)).  the results proved that the presence of H. lanatus affects the plant community in that it interferes with "the germination, growth, and establishment" of E. glaucus, the native plant (Bennett et al. (2011)).  While growth rate was reduced due to competition and soil was affected by the H. lanatus's strong roots above and below ground, the size the plants reached were directly related to "mammalian herbivory" whom appeared to show no preference in one plant over the other.  This study provides one small example into the many factors hat need to be taken into consideration when evaluating a specific area, the continued survival of species in the area and possible restoration and continued management projects.