California Plant Research Articles

Impact of Field Border Plantings on Rodents and Food Safety Concerns

Author(s): Sellers, Laurel; Long, Rachael; Baldwin, Roger A.; Jay-Russell, Michele; Li, Xunde; Atwill, Edward Rob; Engeman, Richard M. | Abstract: This one-year study focused on the impact of hedgerows of native California plants on rodents and food safety in adjacent crops in the Sacramento Valley. Deer mice, house mice, California voles, and western harvest mice were live trapped in four different walnut orchards at zero, 10, 75, 175-m transects from hedgerows. The abundance and richness of rodents was compared to control sites with conventionally managed field edges that were mowed or sprayed for weed control. Unique rodent capture data showed two peaks in activity: 1) in the middle of the orchard regardless of field border type, and 2) in the hedgerow across all seasons with winter being the most active overall. Fewer captures were recorded in the conventional field border, likely because they lacked vegetative structure. Deer mice were the most prevalent species captured throughout the study (g96% of unique captures). House mice and California voles were almost always found in hedgerows and not in adjacent crops. Fecal samples from captured rodents showed a low prevalence of Escherichia coli (non-O157 STEC 1.4%, n = 438; O157 STEC 0%, n = 434) and Salmonella (0.92%, n = 434). Giardia (28.6%, n = 210) and Cryptosporidium (23.8%, n = 210) were more prevalent in captured rodents, but the distribution was not affected by field-edge habitat.

Exergetic efficiency of NF, RO and EDR desalination plants

Exergetic analysis of a 2250gpm brackish water desalination plant in California was performed using its operational data. The plant contains nanofiltration, reverse osmosis and electrodialysis reversal units subject to the same source water. The correct definition of exergetic efficiency for such systems was discussed. The effect of feed salinity was also used for further illustrating the difference in the second-law efficiency definitions. The preferred definition can be used to determine the specific energy consumption and makes thermodynamic sense. The nanofiltration, reverse osmosis and electrodialysis reversal units had efficiencies of 0.087%, 0.066% and 0.078%, respectively, which are very low. Various energy recovery devices including a pressure retarded osmosis unit (having infinite area) were applied to the system to see relative increase in second-law efficiency. For the preferred definition, it was seen that the nanofiltration unit had the best efficiency. In terms of alternative designs using energy recovery devices, the pressure retarded osmosis option had efficiencies approximately equal to the hydro-turbine while the highest efficiency occurred through the use of a pressure exchanger at the plant inlet salinity. Therefore, it does not seem to be a practical energy recovery method for the investigated desalination systems.

The construction of technology and place: Concentrating solar power conflicts in the United States

There is sufficient space in the United States to site large-scale renewable energy technologies, yet siting decisions are often highly contentious with conflicting land-use values. This paper examines conflicts surrounding large-scale solar power siting through the lens of place-making and the co-shaping of place and technology. It traces the place-based conflicts over the Ivanpah solar power plant in California over five years, from designed to operational, in order to understand the evolving public engagement process in issues of place. Place-making can aid in understanding conflicts over renewable energy siting by interpreting stakeholder values. Through the place-making process, both the place and technology were shaped but could only be bent so far until they became something else entirely, making the negotiation of trade-offs difficult and the object of the negotiation a moving target. Moving forward, the challenge should be addressed that the technology and place must be sufficiently concrete to engage the public in siting decisions but accomplished early enough to avoid polarization and to facilitate mutual accommodation. Innovative forms of place-based participation are needed that would help citizens to debate the properties and trade-offs of energy systems in constructive ways downstream without damaging or breaking trust.

Experimental studies of adaptation in Clarkia xantiana. III. Phenotypic selection across a subspecies border.

Sister taxa with distinct phenotypes often occupy contrasting environments in parapatric ranges, yet we generally do not know whether trait divergence reflects spatially varying selection. We conducted a reciprocal transplant experiment to test whether selection favors "native phenotypes" in two subspecies of Clarkia xantiana (Onagraceae), an annual plant in California. For four quantitative traits that differ between subspecies, we estimated phenotypic selection in subspecies' exclusive ranges and their contact zone in two consecutive years. We predicted that in the arid, pollinator-scarce eastern region, selection favors phenotypes of the native subspecies parviflora: small leaves, slow leaf growth, early flowering, and diminutive flowers. In the wetter, pollinator-rich, western range of subspecies xantiana, we expected selection for opposite phenotypes. We investigated pollinator contributions to selection by comparing naturally pollinated and pollen-supplemented individuals. For reproductive traits and for subspecies xantiana, selection generally matched expectations. The contact zone sometimes showed distinctive selection, and in ssp. parviflora selection sometimes favored nonnative phenotypes. Pollinators influenced selection on flowering time but not on flower size. Little temporal variation in selection occurred, possibly because of plastic trait responses across years. Though there were exceptions and some causes of selection remain obscure, phenotypic differentiation between subspecies appears to reflect spatially variable selection.

Following the fuel: How portable biomass energy generation may help rural communities

Following the fuel: How portable biomass energy generation may help rural communities

Late Summer Fog Use In The Drought Deciduous Shrub, Artemisia californica (Asteraceae)

Coastal fog affects many California plant species and can be critically important to species that experience periodic drought. Drought-deciduous species in particular rely on water availability to maintain their leaves during the summer. To determine fog water use in drought-deciduous plants, this study manipulated access to fog drip and measured the water relations of the common shrub, Artemisia californica, near Santa Barbara, CA. Measuring the stable isotope ratio of hydrogen and oxygen, this study found that A. californica uses fog water in the late summer months when fog is present. This additional water increased plant water content but had no effect on pre-dawn xylem pressure potential. While climatic variability inhibits reliable fog input to A. californica in Santa Barbara, this species can use fog water opportunistically and benefits from large fog events during the summer drought.

Antibacterial activity of native California medicinal plant extracts isolated from Rhamnus californica and Umbellularia californica.

BackgroundAntimicrobial resistance (AMR) is a major threat to global public health. Medicinal plants have long been used as remedies for infectious diseases by native cultures around the world and have the potential for providing effective treatments for antibiotic-resistant infections. Rhamnus californica (Rhamnaceae) and Umbellularia californica (Lauraceae) are two indigenous California plant species historically used by Native Americans to treat skin, respiratory and gastrointestinal infections. This study aimed to assess the in vitro antimicrobial activity of methanolic extracts of leaves and bark of R. and U. californica against methicillin-resistant Staphylococcus aureus (MRSA) and other Gram-positive and Gram-negative bacteria.MethodsMethanolic extracts of leaves and bark of R. and U. californica were prepared by soxhlet extraction and evaluated for their antimicrobial activity against Bacillus cereus, Streptococcus pyogenes, Mycobacterium smegmatis, Staphylococcus aureus, MRSA, Escherichia coli and Pseudomonas aeruginosa using disc diffusion and minimal inhibitory concentration (MIC) assays. Chemical profiling of the extracts was performed using standard methods.ResultsAll extracts inhibited the growth of MRSA and other Gram-positive bacteria with MICs of 3.3-6.0 mg/ml. Gram-negative organisms were unaffected by these extracts. U. californica extracts (leaves and bark) had the lowest MIC values. Chemical profiling detected the presence of quinones, alkaloids, flavonoids, cardenolides, tannins and saponins in these extracts. Our study is the first to report the antimicrobial properties of R. and U. californica and illustrates their promising anti-MRSA potential.ConclusionsOur results give scientific credence to the traditional medicinal uses of these plants by the indigenous peoples of California. Further investigation of the secondary metabolites responsible for the antimicrobial activity of these extracts against MRSA is warranted.

S.P. Harrison (2013) – Plant and Animal Endemism in California

S.P. Harrison (2013) – Plant and Animal Endemism in California

Three New Subspecies ofMonardella(Lamiaceae) from Southern California, U.S.A.

Continuing work on the flora of California after the publication of The Jepson Manual: Vascular Plants of California has led to the discovery of three new Monardella Benth. (Lamiaceae) subspecies: M. australis Abrams subsp. gabrielensis Elvin & A. C. Sanders, M. australis subsp. occidentalis Elvin, R. A. Burgess & A. C. Sanders, and M. sinuata Elvin & A. C. Sanders subsp. gerryi Elvin, A. C. Sanders & R. A. Burgess. Monardella australis subsp. gabrielensis occurs in the central and western San Gabriel Mountains of the Transverse Ranges, and M. australis subsp. occidentalis occurs on Pine Mountain Ridge in the Western Transverse Ranges and the San Rafael Mountains of the adjacent southern portion of the South Coast Ranges. The two new subspecies of M. australis are most similar to the autonymic subspecies, but both differ in their bract and leaf morphology, pubescence on the stems and calyces, stature, and distribution. Monardella sinuata subsp. gerryi occurs in the Las Posas and Camarillo Hills in the coastal plain of Ventura County in the South Coast Region. The new subspecies is most similar to M. sinuata subsp. sinuata but differs in its stem, leaf, bract, and glomerule size and in its pubescence, nutlets, and ecological setting. Monardella neglecta Greene is transferred to a new rank as a subspecies of M. purpurea Howell, as M. purpurea subsp. neglecta (Greene) Elvin & A. C. Sanders. It is a diminutive, glabrous, serpentine endemic on the Marin and Tiburon peninsulas in northern California. A taxonomic assessment of names within the M. villosa Benth. complex results in the synonymy of M. franciscana Elmer to M. villosa subsp. villosa. Monardella villosa subsp. subserrata (Greene) Epling is recognized as the upland and interior taxon in this species. A lectotype is designated for M. purpurea Howell and recognized for both M. franciscana Elmer and M. neglecta Greene.

Whole-Genome Sequence of "Candidatus Liberibacter solanacearum" Strain R1 from California.

The draft whole-genome sequence of “Candidatus Liberibacter solanacearum” strain R1, isolated from and maintained in tomato plants in California, is reported. The R1 strain has the genome size of 1,204,257 bp, G+C content of 35.3%, 1,101 predicted open reading frames, and 57 RNA genes.

Origins of Plant Diversity in the California Floristic Province

Recent biogeographic and evolutionary studies have led to improved understanding of the origins of exceptionally high plant diversity in the California Floristic Province (CA-FP). Spatial analyses of Californian plant diversity and endemism reinforce the importance of geographically isolated areas of high topographic and edaphic complexity as floristic hot spots, in which the relative influence of factors promoting evolutionary divergence and buffering of lineages against extinction has gained increased attention. Molecular phylogenetic studies spanning the flora indicate that immediate sources of CA-FP lineages bearing endemic species diversity have been mostly within North America—especially within the west and southwest—even for groups of north temperate affinity, and that most diversification of extant lineages in the CA-FP has occurred since the mid-Miocene, with the transition toward summer-drying. Process-focused studies continue to implicate environmental heterogeneity at local or broad geographic scales in evolutionary divergence within the CA-FP, often associated with reproductive or life-history shifts or sometimes hybridization.

Assessing invasion threats: novel insect-pathogen-natural enemy associations with native New Zealand plants in southern California

The potential for novel pests to attack indigenous plants can be examined in non-native ranges of these plants. We used perennial native New Zealand plant species growing in botanic gardens and on public spaces in southern California to explore new associations between these plants, the bacterium Xylella fastidiosa, and its vector, the invasive insect pest, Homalodisca vitripennis (the glassy-winged sharpshooter), both of which are not yet present in New Zealand. Further, we examined the biocontrol potential of egg parasitoids against H.vitripennis on New Zealand plant hosts in southern California. We make the case for the inclusion of biocontrol as an early-response strategy against H.vitripennis should this pest invade New Zealand, and outline the steps required to make biocontrol part of a rapid-response management plan should an incursion and localized establishment occur.

Predicting invasive plants in California

Preventing plant invasions or eradicating incipient populations is much less costly than confronting large well-established populations of invasive plants. We developed a preliminary determination of plants that pose the greatest risk of becoming invasive in California, primarily through the horticultural industry. We identified 774 species that are invasive elsewhere in Mediterranean climates but not yet invasive in California. From this list, we determined which species are sold through the horticulture industry, whether they are sold in California and whether they have been reported as naturalized in California. We narrowed the list to 186 species with the greatest potential for introduction and/or invasiveness to California through the horticultural trade. This study provides a basis for determining species to evaluate further through a more detailed risk assessment that may subsequently prevent importation via the horticultural pathway. Our results can also help land managers know which species to watch for in wildlands.

Huge Solar Plant in California versus Affordable Solar Appliances for the Poor

Huge Solar Plant in California versus Affordable Solar Appliances for the Poor

Genetic and ecotypic differentiation in a Californian plant polyploid complex (Grindelia, Asteraceae).

Studies of ecotypic differentiation in the California Floristic Province have contributed greatly to plant evolutionary biology since the pioneering work of Clausen, Keck, and Hiesey. The extent of gene flow and genetic differentiation across interfertile ecotypes that span major habitats in the California Floristic Province is understudied, however, and is important for understanding the prospects for local adaptation to evolve or persist in the face of potential gene flow across populations in different ecological settings. We used microsatellite data to examine local differentiation in one of these lineages, the Pacific Coast polyploid complex of the plant genus Grindelia (Asteraceae). We examined 439 individuals in 10 different populations. The plants grouped broadly into a coastal and an inland set of populations. The coastal group contained plants from salt marshes and coastal bluffs, as well as a population growing in a serpentine grassland close to the coast, while the inland group contained grassland plants. No evidence for hybridization was found at the single location where adjacent populations of the two groups were sampled. In addition to differentiation along ecotypic lines, there was also a strong signal of local differentiation, with the plants grouping strongly by population. The strength of local differentiation is consistent with the extensive morphological variation observed across populations and the history of taxonomic confusion in the group. The Pacific Clade of Grindelia and other young Californian plant groups warrant additional analysis of evolutionary divergence along the steep coast-to-inland climatic gradient, which has been associated with local adaptation and ecotype formation since the classic studies of Clausen, Keck, and Hiesey.

ULTIMATE TROUGH® - Fabrication, Erection and Commissioning of the World's Largest Parabolic Trough Collector

A first Ultimate Trough® (UT) collector demonstration loop was successfully integrated in an existing solar power plant in California and is now put into operation. Its huge dimensions of one Solar Collector Assembly (SCA) with an aperture of 7.5 m and a length of 247 m makes it the largest parabolic trough collector ever built and operated. It is expected that this collector reduces the solar field cost by 20 to 25%.The fabrication and erection of a collector with the present dimensions exceeds present knowledge and experience. To provide safety for the design of upcoming solar thermal power plants with the same collector, it was decided to demonstrate all fabrication and erection procedures as they will be applied in series production.The paper describes the part manufacturing, as well as site assembling procedures, transportation and new developed erection tools. Furthermore, it gives an overview on the assembly process on site.The UT collector is designed to avoid complex and costly SCE alignment procedures in the field. The principles and results of the new SCE alignment method are presented.With this new parabolic trough collector a major step towards solar field cost reduction has been achieved. The development process has reached the final step, and the Ultimate Trough has reached market maturity. It is now planned to be applied for commercial collector field applications.

Supplementary data for: Field Testing Diorhabda elongata (Coleoptera: Chrysomelidae) From Crete, Greece, to Assess Potential Impact on Nontarget Native California Plants in the Genus Frankenia

Supplementary data for: Field Testing Diorhabda elongata (Coleoptera: Chrysomelidae) From Crete, Greece, to Assess Potential Impact on Nontarget Native California Plants in the Genus Frankenia

Plant and animal endemism in California

Plant and animal endemism in California

Relationship between phosphate scales and silica fouling in wastewater RO membrane systems

Precipitation of calcium phosphate scale on reverse osmosis (RO) membranes continues to be a major challenge for wastewater recycling facilities. In most cases, antiscalant is dosed in combination with sulfuric acid because calcium phosphate solubility improves at lower pH. Several waste water RO plants in California that have attempted to reduce the costly acid dosing have experienced fast scale formation that has offset any savings with downtime and expensive cleaning chemicals. Online cleanings were attempted by reducing the pH to 6 for 1 week in order to reduce downtime; however, they did not fully restore flux in the tail elements and performance progressively declined over time. When these membranes were autopsied, silica was surprisingly the predominant deposit on the membrane surface, even though brine silica concentrations were only in the range of 130–160 ppm. An extensive study was conducted to simulate these conditions in a laboratory setting. Tests were conducted using various antiscalants av...

Climate interacts with soil to produce beta diversity in Californian plant communities

Spatially distinct communities can arise through interactions and feedbacks between abiotic and biotic factors. We suggest that, for plants, patches of infertile soils such as serpentine may support more distinct communities from those in the surrounding non-serpentine matrix in regions where the climate is more productive (i.e., warmer and/or wetter). Where both soil fertility and climatic productivity are high, communities may be dominated by plants with fast-growing functional traits, whereas where either soils or climate impose low productivity, species with stress-tolerant functional traits may predominate. As a result, both species and functional composition may show higher dissimilarity between patch and matrix in productive climates. This pattern may be reinforced by positive feedbacks, in which higher plant growth under favorable climate and soil conditions leads to higher soil fertility, further enhancing plant growth. For 96 pairs of sites across a 200-km latitudinal gradient in California, we found that the species and functional dissimilarities between communities on infertile serpentine and fertile non-serpentine soils were higher in more productive (wetter) regions. Woody species had more stress-tolerant functional traits on serpentine than non-serpentine soil, and as rainfall increased, woody species functional composition changed toward fast-growing traits on non-serpentine, but not on serpentine soils. Soil organic matter increased with rainfall, but only on non-serpentine soils, and the difference in organic matter between soils was positively correlated with plant community dissimilarity. These results illustrate a novel mechanism wherein climatic productivity is associated with higher species, functional, and landscape-level dissimilarity (beta diversity).