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Test excavation of floor fill deposits in the first room in Bear Den Cave, Sequoia National Park, produced fossiliferous sediments down to at least 40 cm depth. Radiocarbon analysis of charcoal from this layer indicates an early-middle Holocene age of 7220 CAL BP. The fossil accumulation represents prey recovered from generations of ringtail (Bassariscus astutus) dung. Microvertebrate remains include salamanders, lizards, snakes, and mammals. The recovery of Aneides ferreus/vagrans from early-middle Holocene deposits in Bear Den Cave is a first for this species group. Equally interesting is the recovery of Plethodon sp. Neither taxa live in the Sierra Nevada today. The fossil-rich deposits of Bear Den Cave indicate that future paleoecological studies will be productive in Sequoia National Park.
Densities of fecal indicator bacteria (FIB) represented by total coliforms, E. coli and enterococci were measured within tidal channels of the Ballona Wetlands (Los Angeles County) to see if the wetlands act as a sink or source for these bacteria and to measure increases in FIB densities during wet weather. Samples were collected on 10 days over a 1-yr period beginning February 2003 at four sites within the wetlands and one site in Ballona Creek opposite the west tide gate. Incoming flood and outgoing ebb tides were sampled during each sampling event at each station. Water from Ballona Creek may be a significant source of indicator bacteria in the wetlands. Within the tidal channels, densities for total coliforms typically ranged from 103–104 MPN/100 ml, but ranged up to 106 during runoff events. Densities of E. coli and enterococci were orders of magnitude less than those measured for total coliforms, generally ranging from 101–104 for E. coli, and 101–105 for enterococci; greater densities were associated with runoff events. Densities of FIB tended to be up to three times greater during flood than ebb tide conditions depending on the tidal range. This result suggests that more FIB may be entering the wetlands on flood tides than leaving during ebbs, so that these bacteria either are being destroyed, sinking into the tidal channel sediments and plant surfaces, or both. This hypothesis needs to be tested by further identifying other possible FIB sources within the wetlands, and increasing the study design's statistical power to better characterize the flux of these bacteria entering and leaving the wetlands.
Interactive effects of red brome grass (Bromus rubens) density and time of establishment on the early survival and growth of blackbrush (Coleogyne ramosissima) seedlings were quantitatively investigated. Seeds of Coleogyne and Bromus were collected from Cold Creek of the Spring Mountains in southern Nevada. A series of pot trial experiments were conducted in a controlled environmental glasshouse. In mixed culture pots when Coleogyne seedlings planted four weeks later than Bromus at medium and high density levels, survival of Coleogyne seedlings (experimental populations) was greatly reduced compared to single Coleogyne seedlings that grew alone (control population). Significant interactions were detected between neighboring Bromus density and time of planting for shoot height, root/shoot ratio, leaf length, and shoot water potential of experimental Coleogyne populations. When Bromus density was examined independently, all measured growth parameters of experimental Coleogyne populations were significantly reduced compared to the control population. When time of planting was examined independently, shoot height, root/shoot ratio, shoot biomass, leaf length, and water potential of experimental Coleogyne populations were significantly reduced. Results of this study revealed that some Coleogyne mortalities occurred in the absence of interspecific competition, and that growth among surviving seedlings were significantly reduced under conditions of increased density of neighboring Bromus and early Bromus establishment.
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