+ Traversing Swanton Road (revised 02/22/2016) By James A. West Abstract: Situated at the northwest end of Santa Cruz County and occupying circa 30 square miles of sharply contrasted terrain, the Scott Creek Watershed concentrates within its geomorphological boundaries, at least 10-12% of California's flora, both native and introduced. Incorporated within this botanical overview but technically not part of the watershed sensu strictu, are the adjacent environs, ranging from the coastal strand up through the Western Terrace to the ocean draining ridge tops..... with the Arroyo de las Trancas/Last Chance Ridge defining the western/northwestern boundary and the Molino Creek divide, the southern demarcation. Paradoxically, the use/abuse that the watershed has sustained over the past 140+ years, has not necessarily diminished the biodiversity and perhaps parallels the naturally disruptive but biologically energizing processes (fire, flooding, landslides and erosion), which have also been historically documented for the area. With such a comprehensive and diverse assemblage of floristic elements present, this topographically complex but relatively accessible watershed warrants utilization as a living laboratory, offering major taxonomic challenges within the Agrostis, Arctostaphylos, Carex, Castilleja, Clarkia, Juncus, Mimulus, Pinus, Quercus, Sanicula and Trillium genera (to name but a few), plus ample opportunities to study the significant role of landslides (both historical and contemporary) with the corresponding habitat adaptations/modifications and the resulting impact on population dynamics. Of paramount importance, is the distinct possibility of a paradigm being developed from said studies, which underscores the seeming contradiction of human activity and biodiversity within the same environment as not being mutually exclusive and understanding/clarifying the range of choices available in the planning of future land use activities, both within and outside of Swanton. {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} Although synthetic in origin, Swanton Road, like its fluid counterpart Scott Creek, traverses a substantial part of the watershed and reveals an informative cross-section of the region’s flora. Without leaving the tarmac, one can journey the entire length of “Old Highway One” and observe/study some of Santa Cruz County’s rarest, most horticulturally desirable, and just plain overlooked plant life! The Scott Creek Watershed and its environs, is more than an aggregation of 1 600+ native species (subspecies, varieties and forms), representing 282+ genera and 90+ families: it is that rare occurrence, a living window into California’s evolutionary past, still relatively undeveloped by human activity and spared the habitat degradation that has befallen much of the coastal ecology elsewhere in our state. Momentarily putting aside the nostalgic and visually arresting aspect of the watershed, it is paradoxical that an area logged, ranched/grazed and farmed for the past 130+ years, could still yield species new to science and sustain habitats that serve as refugia for taxa rare elsewhere in the state. Because there is such a high percentage of the Golden State’s native flora, at least (10- 12%) and still counting, concentrated within 30 square miles, this area is perhaps the ideal primer for students investigating, for example: (#1) the underlying evolutionary mechanisms, which from an ecological perspective, define the interrelationships between four taxa within one genus (Stachys) sharing the same watershed, ranging from site specific, (a) Stachys chamissonis/hydrologically active year round habitat/China Ladder Marsh, (b) Stachys ajugoides/seasonally wet, often poorly drained depressions, (c) Stachys rigida var. quercetorum/mesic to xeric (edge of chaparral) habitats and (d) Stachys bullata, highly adaptive, ranging from coastal marshes, coniferous/oak woodlands, riparian corridor and occasionally extending up to chaparral..... (#2) reproductive isolating mechanisms and native [Bombus sp] versus introduced [Apis sp] species of Hymenoptera, comparing their overall versatility as pollinating vectors and the potential consequences of population collapse due to disease, parasites and/or pesticides of the introduced species relative to habitat loss thru agricultural conversion and/or urbanization of the native species. What percentage of our native plant species are flexible enough in their basic floral structures, to allow for indigenous replacement vectors with albeit less effective capacities for pollen transference to offset the possible loss of the primary pollinator and what are the long term implications, for speciation in a changing environment?..... (#3) the roles of mammals, birds and insects, intentional or otherwise, as pollinators /dispersers of seeds and the co-evolutionary mechanisms involved..... [a] which plant species are generalists when pollinating vectors are concerned and which species have co- evolved with specific vectors: e.g., Castilleja subinclusa subsp. franciscana with hummingbirds but Castilleja affinis sensu lato generally being bee pollinated even though this polyploid/polyphyletic complex shows evidence of Castilleja subinclusa subsp. franciscana in its ancestry?..... [b] where flower color and scent are present: e.g., Lupinus arboreus and its hybrids with Lupinus variicolor, do both of these traits have equal value in the formation of the fertile hybrid or does one of these two attractants, visual/olfactory, exert a greater influence in the hybrid formation?..... (#4) chemical signatures (foliage and/or floral scents) as taxonomic markers, used in conjunction with other morphological features, to differentiate locally problematic species/hybrid complexes of Castilleja (densiflora aff. Orthocarpus noctuinus Eastw.), Layia (L. gaillardioides and L. hieracioides), Madia (M. exigua, M. gracilis and M. sativa), Mimulus = Erythranthe (guttata complex), Monardella (villosa complex), Pseudognaphalium (gianonei, pro.sp.nov.), Sanicula (gianonei, pro.sp.nov. and pseudo- laciniata, pro.sp.nov.), Trillium (chloropetalum complex, see pages 177-178 of this essay) and Stachys (evolutionary/phylogenetic relationships between S. ajugoides, S. bullata, S. chamissonis and S. rigida var. quercetorum based on a comparative analysis of their chemical signatures)..... (#5) creating a digital library/herbarium documenting the watershed’s flora at all stages of development (e.g., cotyledon configuration, seed structure and patterning), note: CalPoly/Swanton Pacific Ranch has implemented this concept and its ongoing development can be viewed on the Ranch's website..... (#6) habitat stability versus human induced 2 disruptions and the resulting increase/decrease in patterns of biodiversity: e.g., n/ne slopes overlooking Scott Creek, between Scott Creek and Little Creek Bridges, with particular emphasis on the forested slopes overlooking Swanton Pacific/Calpoly orchard down to Mill Creek confluence with Scott Creek and the e-facing slopes overlooking Swanton Valley, between the confluences of Big and Little Creeks with Scott Creek..... (#7) palynological (pollen) studies involving core samplings taken throughout the watershed to ascertain historic changes within the local species composition..... specifically, from a hydrological, palynological and ecological perspective, do a comparative study of the benched/perched marshes at the sw edge of the Western Terrace aka coastal prairie, between the Cowboy Shack Gulch and Lasher Marsh Gulch drainages: (a) to determine, if possible, the age(s) of the marshes which act as "islands of biological diversity", (b) differences between current and pre-european occupancy native species composition, (c) doing an inventory of shared and marsh specific taxa, (d) role, if any, the underlying syncline plays in water storage/distribution patterns within this section of the Western Terrace, (e) what influence, has the eolian sand deposits played in shaping the vegetational mosaics throughout this portion of the coastal prairie, (f) the cumulative impact of agriculture, both grazing and row crops, have played in modifying/fragmenting the "native vegetation", its persistence along the non-cultivated margins and the repository capacity of Juncus tussocks to act as mini-refugia and (g) the ecological importance from a biodiversity perspective, of the east/west alignment of the lower portions of the marsh draining gulches between the coastal prairie and highway 1, having mesic and xeric biotic profiles mirroring each other..... (#8) the geomorphic origins of the “vertical grasslands” and their value as refugia for rare taxa and holding succession in abeyance, using Lidar mapping to define these areas of concentrated biodiversity coupled with in situ digital photography and biota inventories, generating a baseline for in depth reasearch projects..... (#9) slope orientation and the resulting changes in vegetation patterns (mesic versus xeric) within the same drainage system and one of the underlying mechanisms needed to establish localized biodiversity, using the ocean draining gulch systems between the Lasher Marsh Gulch and Scott Creek Marsh, as examples..... (#10) the importance of cyclical riparian scouring to reinvigorate the established, long-lived vegetation and increase species diversity by uncovering seeds deposited and buried decades before in sandbars and adjacent stream banks paralleling the co-evolutional value of fire within the chaparral ecosystem..... (#11) study