Type: report

Article abstract: This project evaluated the potential for grazing to enhance conservation values in grasslands and coastal sage scrub habitats while simultaneously reducing fire hazard from non-native annual grasses. There are important limitations to using the existing literature to answer the primary questions. A review of the literature reveals that potential trade-offs among management goals and the limitations and the possibilities of grazing are not well described or understood (see the literature review conducted as part of this project, https:// sdmmp.com/view_article.php?cid=SDMMP_CID_187_625051ca1fb35). While there are good examples of meeting similar goals with livestock grazing, the literature includes findings that: a) grazing may cause harm to shrublands or other sensitive resources; b) there are limitations to what grazing can achieve and potential trade-offs among management goals, but those limitations are neither well described nor understood; and c) there is a need for improved adaptive management and monitoring to facilitate managing livestock to optimize achievement of management goals. Rancho Jamul Ecological Reserve (RJER) and Hollenbeck Canyon Wildlife Area (HCWA) have good information about geology, vegetation structure, species of special concern, and current grazing use in the literature, but soils and vegetation change information is mostly lacking. The conceptual models for Ecological Site Descriptions (ESDs) and State and Transition Models (STMs) require soil information, in particular as linked to how and why vegetation changes, that is not available for the study site. These models have been widely applied in some rangelands but have not been well-developed in San Diego County and the rest of Southern California. Reliable vegetation reference conditions (potential natural vegetation states) are also not available. This information is essential for answering the study questions and evaluating the efficacy of grazing practices to meet study objectives. To address these needs, we identified Ecological Sites (ES) based on landform and soil characteristics, and ES-specific management-scale STMs to better describe spatial and temporal processes and to place the role of management within the context of other drivers (pgs. 14-19). We used a ground-up, plot-based process to do this. Our classifications are built from empirical plot-based quantitative data. We provide descriptions of vegetation states for each ecological site (ES), and a