Scotts Creek, in Santa Cruz County, Calif., supports the southernmost extant population of Coho Salmon (Oncorhynchus kisutch) in North America. In 1997, the California Department of Fish and Game (now Fish and Wildlife) conducted an extensive habitat typing survey of mainstem Scotts Creek, describing all habitat units from the top of the estuary to the limit of anadromy approximately 12 km upstream. I repeated this survey in 2013 to (1) assess changes in the quantity and quality of instream habitat, (2) compare the current condition to goals and standards established in the federal Central California Coast (CCC) Coho Salmon Recovery Plan, and (3) identify opportunities for possible future restoration. A comparison of the two surveys revealed an overall increase in mean canopy cover, mean bank vegetation, mean percentage instream cover, pool depth diversity, and percentage riffles since 1997, and decreases in mean residual pool depth, percentage flatwater, and number of primary pools. Overall, the percentage of the total mainstem classified as pool habitat did not change between the two survey periods. Results for individual habitat metrics were more variable when the stream was broken into discrete reaches delineated by major tributary junctions. Although a large woody debris (LWD) survey was not conducted as part of the 1997 survey, contrasting our results with data collected during intervening years indicated that instream LWD has become more abundant, primarily due to increases in hard-wood species (i.e., red alder [Alnus rubra] and California bay [Umbellularia californica]). When compared to habitat goals established in the federal CCC Coho Salmon Recovery Plan, Scotts Creek has adequate canopy cover and percentage pools, but is lacking in percentage riffles, instream cover, key pieces of LWD per100 m, and percentage primary pools.

Swanton Pacific Ranch is an educational and research facility owned by the Cal Poly Corporation and managed by the Cal Poly State University (Cal Poly) College of Agriculture, Food and Environmental Sciences. Located about 180 miles north of campus and just 14 miles north of Santa Cruz, California on Highway 1, the property was first leased to and then donated to Cal Poly by the late Albert E. Smith in 1993. The rancho’s original inhabitants included Native Americans, Spaniards, Mexicans, as well as various European immigrants and their descendants; currently, the staff, faculty, and students of Cal Poly occupy the land. Each of these groups used the land’s rich environment for a variety of purposes from subsistence to financial and intellectual pursuits. Over time, researchers and local historians have discussed specific aspects of the Swanton Pacific Ranch and its environs, particularly concerning its occupants, land use (e.g. businesses, farming, research), and land features (e.g. geology, botany). The following work offers a more cohesive, descriptive narrative of the land and its people organized chronologically from prehistory to the present.

Six geomorphic study reaches were established in 2002 along a forested mountain stream (gradients range from 0.02 to 0.05) on Cal Poly's Swanton Pacific Ranch in Santa Cruz County, California. These study reaches are a component of paired and nested watershed studies in the approximately 500 hectare Little Creek watershed. The overall goal of this study was to monitor water quality and channel conditions before, during, and after a selective harvest of redwood. A selective harvest occurred in the North Fork of Little Creek in Summer 2008. In August 2009, approximately 90% of the Little Creek Watershed was burned in the Lockheed Fire. Channel change was evaluated by measuring ground profiles using traditional survey methods. Cross section and longitudinal profiles are surveyed annually every summer in the six study reaches. Change is assessed through evaluation of cross sections and longitudinal profiles, analysis of bed elevation and cross-sectional area change data, and analysis of residual pool characteristics and longitudinal profile variability. Changes in the channel during this time have been relatively small and are typically associated with movement or introduction of coarse woody debris to the stream channel. However, during the study period no large stream flow events occurred (return interval at the closest USGS gauging station does not exceed 5 years). Historically, large debris flow events have occurred in this watershed, with well documented events in 1955 and 1998. The survey data is an important tool for understanding change detection in channel characteristics before and after harvesting, and following fire disturbance.

Forest roads and stream channels are mapped using a variety of remote sensing and ground-based techniques. In densely forested areas, conventional remote sensing methods provide limited terrain information, while ground-based surveys can be time-consuming, difficult, and expensive. Light Detection and Ranging (LiDAR) is an airborne remote sensing technology used to create high-resolution digital elevation models (DEMs) of the earth’s surface. This study tests the accuracy of forest road and stream channel features mapped using LiDAR in the steep, forested terrain of California’s Santa Cruz Mountains. A conventional total station survey was used to determine centerline position and elevations along a four-kilometer forest road, and along six thirty-meter stream channel study reaches. A 1.5 m LiDAR DEM was suitable to accurately map the location of the forest road and channel features. Ninety five percent of the LiDAR-derived road length was located within 2.2 m normal to the field-surveyed centerline and LiDAR-derived road slopes were not significantly different from field-surveyed slopes. Stream channel features derived from the LIDAR DEM were located within 2.7 m normal to the field-surveyed thalweg, while the LiDAR-derived slopes measured within 0.49 percent of field-surveyed slopes. These findings indicate that LiDAR can provide accurate terrain measurements that are suitable for resource management and assessment.

This thesis conducts historical research into Swanton Pacific Ranch in the County of Santa Cruz, an interdisciplinary facility for education and research managed by Cal Poly’s College of Agriculture, Food and Environmental Sciences. The study seeks to determine whether there have been discernable changes in vegetation alliances (communities), spatially or in type, within a 110-acre Study Area from the early twentieth century to the present day and how the changes compare with other similar historical analyses in California. Historical farming and ranching uses of the area are researched, and two family case studies are presented as paradigms of potential changes to vegetation as well as the connectivity with the larger socioeconomic context of Italian immigration into California. Examination of the vegetation alliances over the course of the historical study period utilizes several types of historical imagery, including twentieth-century aerial photography, ground level photography and nineteenth-century maps. This thesis diverges from scholarship that posits substantial alteration of ecological systems by anthropogenic activities by arguing that the primary alliances and geospatial borders of the vegetation in the Study area have remained essentially stable, i.e., unchanged at a macro level, since at least the early twentieth century, and that this stability has persisted despite long-term agricultural activities. This thesis contributes to the historiography of Swanton Pacific Ranch by providing a preliminary exploration of the botanic resources and the attendant anthropogenic agricultural activities on the land that may have affected those resources. It provides a framework for further study of Ranch resources as well as the cultural context of the agricultural history of the North Coast-Santa Cruz region.

Efforts to sequester soil carbon (C) should consider soils intrinsically capable at C retention. Of the mineral soil orders, Mollisols have minimum requirements for soil organic C (SOC; over 0.06 %) and basic saturation (over 50 %). In the U.S., grasslands comprise 93% of the vegetation mapped above Mollisols. Soils beneath the southern extent of Sequoia sempervirens (redwood) forests in central California are mapped as Molliols. It widely accepted that redwood forests harbor considerable biomass C, but the extent to which aboveground C is retained in the soil is not well understood. This study aimed to: (i) to gather baseline soils data (bulk density, pH, basic saturation, cation exchange capacity, SOC, total nitrogen, structure, depth) for an iconic and understudied ecosystem, the southern extent of coast redwood forests and to compare said properties to those in adjacent grasslands, (ii) to identify taxonomic classifications of said soils, (iii) to investigate the influence of vegetative gradation on soil properties between these ecosystems using auger sampling, (iv) to compare levels of basic cations between the forest floor and mineral horizons and, (v) to characterize the total C and active C pools within these ecosystems and to explore interpretations of these pools. In sites randomly selected across two regions, Swanton Pacific Ranch (SPR) and Landels-Hill Big Creek Reserve (LHBCR), soil was collected and described in 24 profiles beneath redwoods and compared to 19 profiles in nearby grasslands. Auger samples at fixed depths were collected in a complimentary study from 5 randomized transects that transitioned through mixed-evergreen forest (and across ecotones) between redwoods and coastal grasslands at SPR. Mineral soil samples were analyzed for SOC, permanganate oxidizable C (POXC), C/N ratio, pH, extractable basic cations, and cation exchange capacity. Samples of forest litter were analyzed for basic cation composition. Multivariate regression models of profile data found higher values of pH, C/N, and CEC in redwoods than in grasslands, and lower values of bulk density in redwoods than in grasslands. Redwood soils were conducive to mollic epipedon formation (21 of 24 profiles in the redwoods as Mollisols) and generally had high base levels, for which extractable calcium from the forest floor was the main driver. Along the transects, multivariate regression returned generally consistent and graded patterns for C/N ratios, POXC/SOC ratios, and pH; these variables were generally highest in the redwood forest and decreased sequentially across mixed-evergreen forest and into the grassland Our look at soil C pools focused on the fraction of SOC that was POXC. Observed higher ratios of POXC/SOC in redwoods than in the grasslands at SPR was corroborated by the transect study; at LHBCR, the regression model provided no evidence for a significant difference in POXC/SOC ratios between communities. Differences in POXC fractions across plant communities and localities were postulated as the result (and combination) of contrasting ecologies, and different management strategies and disturbance histories. The data collected in this study does not provide clear mechanisms to explain these discrepancies, and further research is needed; disharmonious interpretations of POXC across the literature suggested that the replacement of operationally defined C fractions with pools tied to a particular stabilization mechanism would provide clearer insights across ecosystems to land managers. Our estimates of SOC in the top 1 m of soil showed redwood soils stored as much or more C than soils in the neighboring grasslands, at SPR, 144 (± 21) and 123 (± 25) tons SOC per ha in the top 1 m of redwoods and grasslands, respectively, and at LHBCR, 221 (± 23) and 126 (± 24) tons SOC per ha in the top 1 m of redwoods and grasslands, respectively. The carbon densities provided in this study can be used as a baseline to measure changes to SOC and POXC pools in response to future activities to sequester C in our study regions and/or to assess losses from recent 2020 wildfires. We are curious to see how the breadth of information gathered in this study can provide refinement for following questions that will hopefully one day, direct considerate and conscientious management in response to the environmental challenges ahead.