Exotic plant species pattern in selected areas of Sequoia and Kings Canyon National Parks

Invasions by alien plant species constitute a threat to natural ecosystems. Once invaders are well established in an area it is very difficult, and sometimes impossible, to eradicate them. Understanding what factors most likely contribute to the success of invaders in natural areas is critical to early detection and prevention of their uncontrolled spread.; This study analyzed the potential to predict which environmental factors influence most heavily the spread of invasive plant species in Sequoia and Kings Canyon National Parks. More precisely it revisited the idea that human disturbance is the main vehicle for the spread of such species. Transects were established along several environmental gradients and under various level of human disturbance in selected areas of Sequoia and Kings Canyon National Parks (SEKI). When a species was present, it was recorded along with the extent of its invasion and its environmental characteristics. The data were processed using multivariate statistical techniques in order to uncover dominant patterns.; Results obtained from multivariate analysis methods suggest that the spread of weeds is not always tied to a high anthropogenic disturbance. Topographical variables, such as aspect and presence of permanent or perennial streams, more greatly influence the spread of alien species for the area under investigation.