College

College of Agricultural, Food, and Environmental Sciences

Department

Natural Resources Management and Environmental Sciences Department

Degree Name

BS in Environmental Management and Protection

Date

7-2019

Advisor(s)

Yiwen Chiu

Abstract/Summary

Across the western United States, researchers are increasingly working with beaver (Castor canadensis) for process-based stream and watershed restoration. One recently-developed geographic information system-based tool, the Beaver Restoration Assessment Tool (BRAT), analyzes opportunities for beaver-assisted restoration (BAR) at a landscape-scale. However, this tool benefits significantly from human dimensions-inclusive, basin-centralized beaver knowledge for proper interpretation. Unfortunately, this information is scattered or absent in most semi-arid and arid southern California basins. This study thus sought to gather and produce this information through an explorative, benefits-maximizing approach to landscape-scale BAR opportunities assessment in one of these basins, the Salinas River. 49.2 km of beaver dam field surveys, an emailed survey and interviews completed by 39 riparian organizations and residents, and a BRAT model run produced: an ANOVA-driven statistical determination of beaver damming hotspot areas, a beaver damming consistency range map, seven computer assisted qualitative data analysis themes, and BRAT dam capacity and management outputs. When combined, these products revealed basin beaver dam dynamics, population behavior, ecosystem impacts, and human dimensions information that, despite their high-level nature, improved the quality and applicability of assessment recommendations. Ultimately, this study demonstrates how integrating a qualitative data component in landscape-scale BAR assessments is valuable for understanding basin-specific BAR opportunities and considerations, especially for basins without extensive prior beaver research efforts. Study findings also support literature that suggests the current BAR field’s focus on beaver damming, and not other beaver activities, may be too restrictive for maximizing its potential in California basins similar to the Salinas River. Perhaps most interestingly, study findings suggest that beaver may be more prevalent in southern California rivers and their tributaries than has been commonly understood. That beaver extensively utilize the Salinas River basin warrants further research efforts in this basin, in addition to surveys and studies in other major southern California basins, to better understand their prevalence and potential ecosystem tradeoffs within these hydrologic regions. To this point, in these basins where beaver need no reintroduction, California beaver advocacy groups may better promote proactive beaver management by adjusting education and communication strategies to emphasize these potential tradeoffs. In doing so, they have an opportunity to impart a healthier understanding among human communities of local ecosystem complexities.

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