Globally we are experiencing a biodiversity crisis and potentially a sixth mass extinction event. Plant specimens are one of the best, most concrete records of biodiversity that we can create. Despite this, the rate of plant collecting has declined steeply since World War II. Now more than ever, plant collections are vital, both for the purpose of quantifying the plant biodiversity in an area and for discovering previously unrecognized diversity. In Chapter 1, we conducted a floristic survey of the Cal Poly Swanton Pacific Ranch. The Swanton Pacific Ranch (SPR) is located north of the small town of Davenport California, in Santa Cruz county. SPR is 3,200 acres and contains areas of salt marsh, coastal bluff, coastal prairie, riparian forest, redwood forest, mixed conifer forest and chaparral in approximate ascending order of elevation. The property extends over an elevational gradient from 0 m to 420 m (1400 ft). We documented 634 taxa at SPR. In total, 974 specimens were collected during this project, 405 specimens in 2017 and 569 in 2019. We reviewed 211 historic specimens. We vouchered 546 taxa between 2017 and 2019 and observed but did not collect 6 taxa. 53 taxa are represented from historic collections and were not relocated. There are 30 taxa listed as historically present from personal observations of the authors but without vouchers. Though these do not have the same value as a physical specimen, we believe that all information is valuable and have included them with a clear indication of the source of the record. There were 465 native and 169 non-native taxa documented in the study area. There were 93 families represented, with Asteraceae, Poaceae and Fabaceae be ing the top three most speciose respectively. There were 83 taxa noted as locally rare following Neubauer, of these 16 taxa have a California Native Plant Society (CNPS) rare plant rank. We vouchered one new taxon for Santa Cruz County, Senecio aphanactis, which has a CNPS rare plant rank of 2B.2 In Chapter 2, we describe a new combination in the Sanicula crassicaulis species complex. During the project detailed in Chapter 1, we observed and collected several specimens that keyed to Sanicula crassicaulis Poepp. ex. D.C. but were notably distinct from other S. crassicaulis that we collected in the area. On further investigation, we found that these plants match the type specimen of S. nudicaulis Hook & Arn., described in 1839 and later synonymized with S. crassicaulis. This taxon is distinguished primarily by its long, sinuate marginal leaf trichomes, in contrast to the short, straight marginal trichomes of S. crassicaulis. Additionally, the length of the most proximal prickles on the schizocarps is about the same as the length of the most distal rather than the distal prickles being much longer as in S. crassicaulis and the angle of attachment of the prickles is more or less perpendicular as opposed to acute in S. crassicaulis. The known range of this taxon is between the San Francisco Bay Area and Santa Barbara County, generally near the coast. Here we recognize this taxon as a variety in S. crassicaulis, Sanicula crassicaulis var. nudicaulis. We provide a diagnosis, a map of the known range of the taxon and a key to the varieties of S. crassicaulis. Overall this project has significantly increased or knowledge and documentation of the flora of both SPR and Santa Cruz county. In addition to the immediate benefits of this study (a complete species list for SPR, the discovery of a new taxon, and the mapping of all rare species at SPR) we have also contributed almost 1,000 physical specimens to the Cal Poly Hoover herbarium which may be used in future taxonomic and ecological studies.

Two locations on Scott Creek, located 12 miles north of Santa Cruz California, are being considered for the installation of a streamgage to measure discharge. Each location offers unique considerations and challenges in gage construction and discharge measurement capabilities. A detailed flood frequency analysis was completed using a direct watershed comparison, direct equations developed by Waananen and Crippen, a Log Pearson Type III Frequency Distribution, a regional analysis, and two-station comparisons. Final results indicate a 100-year recurrence interval of 6,310 ft3/s at the Upper Scott Creek location and 6,520 ft3/s at the lower location. A detailed indirect measurement revealed that the Lower Scott Creek gage location can only maintain a discharge of 2,500 ft3/s, or a 10-year frequency event, before bank overflow. Therefore, a cableway spanning the width of the design flow cannot be constructed and stage readings at extreme peak events will not accurately represent the true hydrograph. A bridge at the Upper Scott Creek gage location will provide a means for measuring high flow events; however, the channel is in a state of disequilibrium due to debris jams within the 140 foot reach above the bridge. This site is also problematic due to the occurrence of channel avulsion which is scouring and incising a new channel which threatens to undermine the left bank wingwall of the bridge. Remediation measures have been proposed, including the installation of a cross-vane and wing-deflectors, to mitigate negative effects of erosion and reestablish a natural channel condition. The upstream location has been selected as the preferred alternative given the remediation measures are successful.