The impact of invasive species on native vegetation is a major threat to biodiversity all over the world - a threat ranked second only to habitat destruction. Other negative effects of weed invasions include reduced ecosystem services, loss to agricultural production and impacts on human health. This work covers the discipline of risk assessment as applied to the invasion ecology of plants. Taking a global context, it synthesizes theories on plant invasions, introduces a variety of models for weed risk assessment, and addresses procedures for ranking invasive species on a range of scales to determine weeds of national significance. It shows how the application of risk assessment to weed invasion may help reduce weed impact and thereby improve living conditions for people throughout the world. This text is aimed at invasions ecologists, botanists, quarantine officers, policy-makers and community groups wanting to know more about this developing discipline.

This book is open access under a CC BY-NC 2.5 license. This book provides an unprecedented synthesis of the current status of scientific and management knowledge regarding global rangelands and the major challenges that confront them. It has been organized around three major themes. The first summarizes the conceptual advances that have occurred in the rangeland profession. The second addresses the implications of these conceptual advances to management and policy. The third assesses several major challenges confronting global rangelands in the 21st century. This book will compliment applied range management textbooks by describing the conceptual foundation on which the rangeland profession is based. It has been written to be accessible to a broad audience, including ecosystem managers, educators, students and policy makers. The content is founded on the collective experience, knowledge and commitment of 80 authors who have worked in rangelands throughout the world. Their collective contributions indicate that a more comprehensive framework is necessary to address the complex challenges confronting global rangelands. Rangelands represent adaptive social-ecological systems, in which societal values, organizations and capacities are of equal importance to, and interact with, those of ecological processes. A more comprehensive framework for rangeland systems may enable management agencies, and educational, research and policy making organizations to more effectively assess complex problems and develop appropriate solutions.