An assessment of the problems that are presented by non-native and introduced species in maintaining native species and natural systems. Divided into two major sections, the study covers representative ecosystems in Pima County as well as representative species that have a negative impact on native species.

The study generally confirms the trends and impacts identified in the February 2001 study "Air Quality in Pima County," and suggests two types of strategies for maintaining air quality and ensuring compliance with federal air quality standards. Potential funding sources and future legislative considerations are briefly discussed.

A companion to the study issued on July 5, 2000 entitled 'Cactus Ferruginous Pygmy-Owl Investigations in Pima County.' The major objective was to determine whether pygmy-owls chose nest sites or perch trees with characteristics that differ from other available sites within a nesting territory.

The spread of invasive species creates serious environmental problems as well as economic hazards for residents and will hamper implementation of parts of the SDCP.