Insights in plant ecology from Bromus tectorum invasion in the Great Basin, USA

Abstract

Species invasion is a widespread occurrence that adversely affects native ecosystems. This dissertation examines Bromus tectorum invasion in the Great Basin to increase scientific understanding of invasion dynamics and to provide rigorous information to enhance land management. First, a conceptual model of invasion, the Triangle Model for Evaluating Species Invasion, is presented. Components and utility of the invasion triangle are described in detail, and two example case studies are presented. Second, the framework provided by the triangle model is used to organize an evaluation of factors that influence B. tectorum invasion in the Great Basin. Data presented are from a large scale, multi-year, observational study on the relative influence of biological characteristics, environmental conditions, anthropogenic disturbance, grazing, and fire on B. tectorum invasion. Third, a hypothesis of invasion that states `species may induce changes in their environment that increase invasiveness' is examined. Specifically, the ability of plant species to induce changes in a subsequent generation of plants through alteration of the soil environment via soil nutrient dynamics, soil microbial community, and allelopathic deposition is examined in a greenhouse study. Although these projects examine invasion on substantially different scales, all provide original and practical information on species invasion.