WorldWideScience

Sample records for chaparral

  1. Chaparral & Fire Ecology: Role of Fire in Seed Germination.

    Science.gov (United States)

    Steele, Nancy L. C.; Keeley, Jon E.

    1991-01-01

    An activity that incorporates the concepts of plant structure and function and ecology is described. Students investigate the reasons why some California chaparral seeds germinate only after a fire has burned the surrounding chaparral. The procedure, discussion and analysis questions, expected results, potential problems, and additional activities…

  2. Particulate emissions from a mid-latitude prescribed chaparral fire

    Science.gov (United States)

    Cofer, Wesley R., III; Levine, Joel S.; Sebacher, Daniel I.; Winstead, Edward L.; Riggin, Philip J.; Brass, James A.; Ambrosia, Vincent G.

    1988-01-01

    Particulate emission from a 400-acre prescribed chaparral fire in the San Dimas Experimental Forest was investigated by collecting smoke aerosol on Teflon and glass-fiber filters from a helicopter, and using SEM and EDAX to study the features of the particles. Aerosol particles ranged in size from about 0.1 to 100 microns, with carbon, oxygen, magnesium, aluminum, silicon, calcium, and iron as the primary elements. The results of ion chromatographic analysis of aerosol-particle extracts (in water-methanol) revealed the presence of significant levels of NO2(-), NO3(-), SO4(2-), Cl(-), PO4(3-), C2O4(2-), Na(+), NH4(+), and K(+). The soluble ionic portion of the aerosol was estimated to be about 2 percent by weight.

  3. Modeling the Effects of Fire on Streamflow in a Chaparral Watershed

    OpenAIRE

    McMichael, Christine E.

    2004-01-01

    A comprehensive understanding of the effects of fire and post-fire succession on streamflow dynamics in California chaparral watersheds is needed to facilitate effective planning and management in these semi-arid shrublands. Watershed experiments have provided insights into the hydrologic effects of fire and post fire succession in chaparral watersheds, however extrapolation of these results is constrained by the small number of studies and the limited space and/or time scales examined. As i...

  4. Smoke-induced seed germination in California chaparral

    Science.gov (United States)

    Keeley, J.E.; Fotheringham, C.J.

    1998-01-01

    The California chaparral community has a rich flora of species with different mechanisms for cuing germination to postfire conditions. Heat shock triggers germination of certain species but has no stimulatory effect on a great many other postfire species that are chemically stimulated by combustion products. Previous reports have shown that charred wood will induce germination, and here we report that smoke also induces germination in these same species. Smoke is highly effective, often inducing 100% germination in deeply dormant seed populations with 0% control germination. Smoke induces germination both directly and indirectly by aqueous or gaseous transfer from soil to seeds. Neither nitrate nor ammonium ions were effective in stimulating germination of smoke-stimulated species, nor were most of the quantitatively important gases generated by biomass smoke. Nitrogen dioxide, however, was very effective at inducing germination in Caulanthus heterophyllus (Brassicaceae), Emmenanthe penduliflora (Hydrophyllaceae), Phacelia grandiflora (Hydrophyllaceae), and Silene multinervia (Caryophyllaceae). Three species, Dendromecon rigida (Papaveraceae), Dicentra chrysantha, and Trichostema lanatum (Lamiaceae), failed to germinate unless smoke treatment was coupled with prior treatment of 1 yr soil storage. Smoke-stimulated germination was found in 25 chaparral species, representing 11 families, none of which were families known for heat-shock-stimulated germination. Seeds of smoke-stimulated species have many analogous characteristics that separate them from most heat-shock-stimulated seeds, including: (1) outer seed coats that are highly textured, (2) a poorly developed outer cuticle, (3) absence of a dense palisade tissue in the seed coat, and (4) a subdermal membrane that is semipermeable, allowing water passage but blocking entry of large (molecular mass > 500) solutes. Tentative evidence suggests that permeability characteristics of this subdermal layer are altered by

  5. Seed germination and life history syndromes in the California chaparral

    Science.gov (United States)

    Keeley, J.E.

    1991-01-01

    Syndromes are life history responses that are correlated to environmental regimes and are shared by a group of species (Stebbins, 1974). In the California chaparral there are two syndromes contrasted by the timing of seedling recruitment relative to wildfires. One syndrome, here called the fire-recruiter or refractory seed syndrome, includes species (both resprouting and non-resprouting) which share the feature that the timing of seedling establishment is specialized to the first rainy season after fire. Included are woody, suffrutescent and annual life forms but no geophytes have this syndrome. These species are linked by the characteristic that their seeds have a dormancy which is readily broken by environmental stimuli such as intense heat shock or chemicals leached from charred wood. Such seeds are referred to as “refractory” and dormancy, in some cases, is due to seed coat impermeability (such seeds are commonly called hardseeded), but in other cases the mechanism is unknown. Seeds of some may require cold stratification and/or light in addition to fire related stimuli. In the absence of fire related cues, a portion or all of a species’ seed pool remains dormant. Most have locally dispersed seeds that persist in the soil seed bank until the site burns. Dispersal of propagules is largely during spring and summer which facilitates the avoidance of flowering and fruiting during the summer and fall drought. Within a life form (e.g., shrub, suffrutescent, etc.), the seeds of these species have less mass than those of species with non-refractory seeds and this possibly reflects the environmental favorableness of the postfire environment for seedling establishment. Regardless of when fire occurs, germination is normally delayed until late winter or early spring. In the absence of fire, or other disturbance, opportunities for population expansion are largely lacking for species with this syndrome. The other syndrome, here called the fire-resister or non

  6. Post-fire Erosion and Recovery in Chaparral Steeplands, Southern California

    Science.gov (United States)

    Wohlgemuth, P. M.

    2007-12-01

    In fire-prone southern California chaparral environments, wildfire is a significant disturbance event. It incinerates vegetation, alters soil properties, and renders the landscape susceptible to the agents of erosion. Accelerated erosion can cause site degradation, can extirpate refugia populations of endangered species, and can harm human communities at the wildland/urban interface. The San Dimas Experimental Forest (SDEF) is a nearly 7000 ha research preserve located in the San Gabriel Mountains. Native vegetation in the SDEF consists primarily of mixed chaparral. Management treatments following a wildfire in 1960 involved the vegetation type-conversion of some native chaparral watersheds to a mixture of perennial grasses. In 1994, a study was initiated to quantify sediment fluxes through several small (1-3 ha) headwater catchments in the SDEF under both brush and grass vegetation. Several of these watersheds burned in a prescribed fire in May 2001. The remainder burned in a wildfire in September 2002. These burns provided a unique opportunity to quantify post-fire erosion on the same sites for which there were extensive pre- fire measurements. Hillslope erosion was sampled using sheet metal collector traps with a 30 cm aperture. Seventy-five traps were placed on unbounded plots scattered throughout each of four watersheds. Sediment yield was measured behind earthen dams in 17 small watersheds. A centrally located raingage recorded precipitation amounts and intensities. During this study period, the SDEF experienced both the wettest (2005) and driest (2007) years in its 74-year history. The values for the 15-minute maximum rainfall intensity show no relation to annual erosion (hillslope or small watershed) for either vegetation type before or after fire. Both hillslope erosion and small watershed sediment yield display remarkably similar patterns of post-fire erosion response: a one to two order of magnitude increase in first-year erosion followed by a relatively

  7. Modeling the effects of fire on streamflow in a chaparral watershed

    Science.gov (United States)

    McMichael, Christine Eleana

    A comprehensive understanding of the effects of fire and post-fire succession on streamflow dynamics in California chaparral watersheds is needed to facilitate effective planning and management in these semi-arid shrublands. Watershed experiments have provided insights into the hydrologic effects of fire and post fire succession in chaparral watersheds, however extrapolation of these results is constrained by the small number of studies and the limited space and/or time scales examined. As it was not logistically or economically feasible to conduct additional field experiments for this research, an integrated remote sensing-distributed hydrological modeling strategy was utilized to advance our understanding of the effects of fire and post-fire succession on streamflow dynamics in these ecosystems. A wide range of inputs was derived for a modified version of the distributed, physically-based MIKE-SHE model using remote sensing and geographic information systems (GIS) techniques, including the development of a remote sensing-chronosequence approach for estimating the post-fire recovery sequence of chaparral leaf area index (a key input given that approximately 75% of incoming rainfall is returned to the atmosphere via evapotranspiration). The Monte Carlo-based Generalized Likelihood Uncertainty Estimation (GLUE) methodology provided the framework for model calibration, testing, and predictive uncertainty estimation. Model simulations were performed using a suite of fire size-weather regime combinations to investigate the impacts of fire on annual and seasonal streamflow dynamics. Over two-thirds of the observations (comprising over 90% of the total observed flow) in the calibration and test periods were contained within the GLUE-based predictive uncertainty bounds, an acceptable level of model performance relative to total period flow; prediction errors were generally associated with large rainfall and fire events. Model simulation results demonstrated that seasonal

  8. Isolation of Microsatellite Markers in a Chaparral Species Endemic to Southern California, Ceanothus megacarpus (Rhamnaceae

    Directory of Open Access Journals (Sweden)

    Caitlin D. A. Ishibashi

    2013-05-01

    Full Text Available Premise of the study: Microsatellite (simple sequence repeat [SSR] markers were developed for Ceanothus megacarpus, a chaparral species endemic to coastal southern California, to investigate potential processes (e.g., fragmentation, genetic drift, and interspecific hybridization responsible for the genetic structure within and among populations distributed throughout mainland and island populations. Methods and Results: Four SSR-enriched libraries were used to develop and optimize 10 primer sets of microsatellite loci containing either di-, tri-, or tetranucleotide repeats. Levels of variation at these loci were assessed for two populations of C. megacarpus. Observed heterozygosity ranged from 0.250 to 0.885, and number of alleles ranged between four and 21 per locus. Eight to nine loci also successfully amplified in three other species of Ceanothus. Conclusions: These markers should prove useful for evaluating the influence of recent and historical processes on genetic variation in C. megacarpus and related species.

  9. Using Aerial Hydromulch in Post-fire Chaparral in Southern California: Effectiveness and Consequences

    Science.gov (United States)

    Wohlgemuth, P. M.; Beyers, J. L.; Robichaud, P. R.

    2012-12-01

    High severity wildfire can make landscapes susceptible to accelerated erosion that may retard resource recovery. High levels of erosion can also threaten life, property, and infrastructure in downstream human communities. Land managers often use mitigation measures on the burned hillside slopes to control post-fire sediment fluxes both as the first step in post-fire restoration and to protect off-site human developments. Aerial hydromulch, a slurry of paper or wood fiber with tackifiers and other amendments that dries to a permeable crust, is a relatively new erosion control treatment that has not been rigorously field-tested in wildland settings. Concerns have been raised over the ability of aerial hydromulch to reduce hillslope erosion as well as its potential for negative effects on post-fire ecosystem recovery. Since 2007 we have measured sediment fluxes and vegetation development on plots treated operationally with aerial hydromulch and compared them to untreated controls after three separate wildfires in southern California. These study plots, located on steep slopes with coarse upland soils previously covered with dense mixed chaparral vegetation, were monitored with silt fences to trap eroded sediment. Meter-square quadrats were used to measure ground and vegetation cover. Although dependent on rainfall and site characteristics, surface erosion on untreated plots generally attenuated sharply with years since burning. We found that aerial hydromulch did reduce bare ground on the treated plots and that this cover persisted through the first post-fire winter rainy season. For the initial year after a fire, aerial hydromulch reduced hillslope erosion from small and medium rainstorms, but not during an extremely high intensity rainfall event. Hydromulch had no effect on regrowing plant cover, shrub seedling density, or species richness. Thus, in chaparral ecosystems aerial hydromulch appears to be an effective post-fire erosion control measure that is

  10. Short-term post-wildfire dry-ravel processes in a chaparral fluvial system

    Science.gov (United States)

    Florsheim, Joan L.; Chin, Anne; O'Hirok, Linda S.; Storesund, Rune

    2016-01-01

    Dry ravel, the transport of sediment by gravity, transfers material from steep hillslopes to valley bottoms during dry conditions. Following wildfire, dry ravel greatly increases in the absence of vegetation on hillslopes, thereby contributing to sediment supply at the landscape scale. Dry ravel has been documented as a dominant hillslope erosion mechanism following wildfire in chaparral environments in southern California. However, alteration after initial deposition is not well understood, making prediction of post-fire flood hazards challenging. The majority of Big Sycamore Canyon burned during the May 2013 Springs Fire leaving ash and a charred layer that covered hillslopes and ephemeral channels. Dry-ravel processes following the fire produced numerous deposits in the hillslope-channel transition zone. Field data focus on: 1) deposition from an initial post-wildfire dry-ravel pulse; and 2) subsequent alteration of dry ravel deposits over a seven-month period between September 2013 and April 2014. We quantify geomorphic responses in dry ravel deposits including responses during the one small winter storm that generated runoff following the fire. Field measurements document volumetric changes after initial post-wildfire deposition of sediment derived from dry ravel. Erosion and deposition mechanisms that occurred within dry-ravel deposits situated in the hillslope-channel transition zone included: 1) mobilization and transport of a portion or the entire deposit by fluvial erosion; 2) rilling on the surface of the unconsolidated deposits; 3) deposition on deposits via continued hillslope sediment supply; and 4) mass wasting that transfers sediment within deposits where surface profiles are near the angle of repose. Terrestrial LiDAR scanning point clouds were analyzed to generate profiles quantifying depth of sediment erosion or deposition over remaining dry ravel deposits after the first storm season. This study contributes to the understanding of potential

  11. Evolution of trace gases and particles emitted by a chaparral fire in California

    Directory of Open Access Journals (Sweden)

    C. E. Wold

    2012-02-01

    Full Text Available Biomass burning (BB is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 hectare prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured physical and chemical changes that occurred in the isolated downwind plume in the first ~4 h after emission. The measurements were carried out onboard a Twin Otter aircraft outfitted with an airborne Fourier transform infrared spectrometer (AFTIR, aerosol mass spectrometer (AMS, single particle soot photometer (SP2, nephelometer, LiCor CO2 analyzer, a chemiluminescence ozone instrument, and a wing-mounted meteorological probe. Our measurements included: CO2; CO; NOx; NH3; non-methane organic compounds; organic aerosol (OA; inorganic aerosol (nitrate, ammonium, sulfate, and chloride; aerosol light scattering; refractory black carbon (rBC; and ambient temperature, relative humidity, barometric pressure, and three-dimensional wind velocity. The molar ratio of excess O3 to excess CO in the plume (ΔO3/ΔCO increased from −5.13 (±1.13 × 10−3 to 10.2 (±2.16 × 10−2 in ~4.5 h following smoke emission. Excess acetic and formic acid (normalized to excess CO increased by factors of 1.73 ± 0.43 and 7.34 ± 3.03 (respectively over the same time since emission. Based on the rapid decay of C2H4 we infer an in-plume average OH concentration of 5.27 (±0.97 × 106 molec cm−3, consistent with previous studies showing elevated OH concentrations in biomass burning plumes. Ammonium, nitrate, and sulfate all increased over the course of 4 h. The observed ammonium increase was a factor of 3.90 ± 2.93 in about 4 h, but accounted for just ~36

  12. Evolution of trace gases and particles emitted by a chaparral fire in California

    Directory of Open Access Journals (Sweden)

    S. K. Akagi

    2011-08-01

    Full Text Available Biomass burning (BB is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 ha prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured post-emission chemical changes in the isolated downwind plume for ~4 h of smoke aging. The measurements were carried out on board a Twin Otter aircraft outfitted with an airborne Fourier transform infrared spectrometer (AFTIR, aerosol mass spectrometer (AMS, single particle soot photometer (SP2, nephelometer, LiCor CO2 analyzer, a chemiluminescence ozone instrument, and a wing-mounted meteorological probe. Our measurements included: CO2; CO; NOx; NH3; non-methane organic compounds; organic aerosol (OA; inorganic aerosol (nitrate, ammonium, sulfate, and chloride; aerosol light scattering; refractory black carbon (rBC; and ambient temperature, relative humidity, barometric pressure, and three-dimensional wind velocity. The molar ratio of excess O3 to excess CO in the plume (ΔO3/ΔCO increased from −0.005 to 0.102 in 4.5 h. Excess acetic and formic acid (normalized to excess CO increased by factors of 1.7 ± 0.4 and 7.3 ± 3.0 (respectively over the same aging period. Based on the rapid decay of C2H4 we infer an in-plume average OH concentration of 5.3 (±1.0 × 106 molecules cm−3, consistent with previous studies showing elevated OH concentrations in biomass burning plumes. Ammonium, nitrate, and sulfate all increased with plume aging. The observed ammonium increase was a factor of 3.9 ± 2.6 in about 4 h, but accounted for just ~36 % of the gaseous ammonia lost on a molar basis. Some of the gas phase NH3 loss may have been due to condensation

  13. Comparison of chaparral regrowth patterns between Santa Ana wind-driven and non-Santa Ana fire areas

    Science.gov (United States)

    Rachels, Diane Helen

    Wildfires are a common occurrence in California shrublands and island forests. Fire has a fundamental role in maintaining the ecosystem functions in chaparral where fire intensity and severity play important roles in the regeneration of species. In San Diego, the Cedar Fire that occurred in the fall of 2003 was unique in that one side was burned with wildfire fueled by dry, strong easterly Santa Ana winds that later died down, burning the remainder of the area under a mild westerly wind, allowing fuel-fed conditions. The objective of this study was to understand the connection between vegetation type and structure and environmental response to extreme fire events by analyzing life form regrowth in chaparral communities from the Santa Ana wind driven, Santa Ana backing, and non-Santa Ana fire types. Environmental factors of slope angle, aspect, elevation and soils were investigated in an effort to isolate shrub regrowth patterns. Fire burn characteristics, anthropogenic disturbance, fire history, and moisture availability were also analyzed to identify additional factors that may have influenced shrub regrowth. Shrub extents before the fire and six year after the fire were examined per slope aspect, slope angle, elevation, and fire characteristic categories. The closed canopy and natural features of the chaparral environment make ground based mapping very difficult. Remote sensing data and methods can be very helpful to evaluate the health of the vegetation and condition of the watershed for flood, erosion, and fire control. This study used high spatial resolution aerial imagery and a machine learning algorithm with a spatial contextual classifier to map three different areas from within the Cedar Fire perimeter. Geographic information science (GIS), field mapping, and image interpretation methods were used to identify vegetation samples for the classification and accuracy assessment of the vegetation maps. Object-based image samples were selected for the classifier

  14. Monitoring the Impacts of Severe Drought on Southern California Chaparral Species using Hyperspectral and Thermal Infrared Imagery

    Directory of Open Access Journals (Sweden)

    Austin R. Coates

    2015-10-01

    Full Text Available Airborne hyperspectral and thermal infrared imagery acquired in 2013 and 2014, the second and third years of a severe drought in California, were used to assess drought impacts on dominant plant species. A relative green vegetation fraction (RGVF calculated from 2013–2014 Airborne Visible Infrared Imaging Spectrometer (AVIRIS data using linear spectral unmixing revealed seasonal and multi-year changes relative to a pre-drought 2011 reference AVIRIS image. Deeply rooted tree species and tree species found in mesic areas showed the least change in RGVF. Coastal sage scrub species demonstrated the highest seasonal variability, as well as a longer-term decline in RGVF. Ceanothus species were apparently least well-adapted to long-term drought among chaparral species, showing persistent declines in RGVF over 2013 and 2014. Declining RGVF was associated with higher land surface temperature retrieved from MODIS-ASTER Airborne Simulator (MASTER data. Combined collection of hyperspectral and thermal infrared imagery may offer new opportunities for mapping and monitoring drought impacts on ecosystems.

  15. Chaparral Shrub Hydraulic Traits, Size, and Life History Types Relate to Species Mortality during California’s Historic Drought of 2014

    Science.gov (United States)

    MacKinnon, Evan D.; Dario, Hannah L.; Jacobsen, Anna L.; Pratt, R. Brandon; Davis, Stephen D.

    2016-01-01

    Chaparral is the most abundant vegetation type in California and current climate change models predict more frequent and severe droughts that could impact plant community structure. Understanding the factors related to species-specific drought mortality is essential to predict such changes. We predicted that life history type, hydraulic traits, and plant size would be related to the ability of species to survive drought. We evaluated the impact of these factors in a mature chaparral stand during the drought of 2014, which has been reported as the most severe in California in the last 1,200 years. We measured tissue water potential, native xylem specific conductivity, leaf specific conductivity, percentage loss in conductivity, and chlorophyll fluorescence for 11 species in February 2014, which was exceptionally dry following protracted drought. Mortality among the 11 dominant species ranged from 0 to 93%. Total stand density was reduced 63.4% and relative dominance of species shifted after the drought. Mortality was negatively correlated with water potential, native xylem specific conductivity, and chlorophyll fluorescence, but not with percent loss in hydraulic conductivity and leaf specific conductivity. The model that best explained mortality included species and plant size as main factors and indicated that larger plants had greater survival for 2 of the species. In general, species with greater resistance to water-stress induced cavitation showed greater mortality levels. Despite adult resprouters typically being more vulnerable to cavitation, results suggest that their more extensive root systems enable them to better access soil moisture and avoid harmful levels of dehydration. These results are consistent with the hypothesis that short-term high intensity droughts have the strongest effect on mature plants of shallow-rooted dehydration tolerant species, whereas deep-rooted dehydration avoiding species fare better in the short-term. Severe droughts can drive

  16. Investigating the links between ozone and organic aerosol chemistry in a biomass burning plume from a prescribed fire in California chaparral

    Science.gov (United States)

    Alvarado, M. J.; Lonsdale, C. R.; Yokelson, R. J.; Akagi, S. K.; Coe, H.; Craven, J. S.; Fischer, E. V.; McMeeking, G. R.; Seinfeld, J. H.; Soni, T.; Taylor, J. W.; Weise, D. R.; Wold, C. E.

    2015-06-01

    Within minutes after emission, complex photochemistry in biomass burning smoke plumes can cause large changes in the concentrations of ozone (O3) and organic aerosol (OA). Being able to understand and simulate this rapid chemical evolution under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use version 2.1 of the Aerosol Simulation Program (ASP) to simulate the evolution of O3 and secondary organic aerosol (SOA) within a young biomass burning smoke plume from the Williams prescribed fire in chaparral, which was sampled over California in November 2009. We demonstrate the use of a method for simultaneously accounting for the impact of the unidentified intermediate volatility, semi-volatile, and extremely low volatility organic compounds (here collectively called "SVOCs") on the formation of OA (using the Volatility Basis Set - VBS) and O3 (using the concept of mechanistic reactivity). We show that this method can successfully simulate the observations of O3, OA, NOx, ethylene (C2H4), and OH to within measurement uncertainty using reasonable assumptions about the average chemistry of the unidentified SVOCs. These assumptions were (1) a reaction rate constant with OH of ~ 10-11 cm3 s-1; (2) a significant fraction (up to ~ 50 %) of the RO2 + NO reaction resulted in fragmentation, rather than functionalization, of the parent SVOC; (3) ~ 1.1 molecules of O3 were formed for every molecule of SVOC that reacted; (4) ~ 60 % of the OH that reacted with the unidentified non-methane organic compounds (NMOC) was regenerated as HO2; and (5) that ~ 50 % of the NO that reacted with the SVOC peroxy radicals was lost, presumably to organic nitrate formation. Additional evidence for the fragmentation pathway is provided by the observed rate of formation of acetic acid (CH3COOH), which is consistent with our assumed fragmentation rate. However, the model overestimates peroxyacetyl

  17. Investigating the links between ozone and organic aerosol chemistry in a biomass burning plume from a prescribed fire in California chaparral

    Directory of Open Access Journals (Sweden)

    M. J. Alvarado

    2014-12-01

    Full Text Available Within minutes after emission, rapid, complex photochemistry within a biomass burning smoke plume can cause large changes in the concentrations of ozone (O3 and organic aerosol (OA. Being able to understand and simulate this rapid chemical evolution under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use version 2.1 of the Aerosol Simulation Program (ASP to simulate the evolution of O3 and secondary organic aerosol (SOA within a young biomass burning smoke plume from the Williams prescribed burn in chaparral, which was sampled over California in November 2009. We demonstrate the use of a method for simultaneously accounting for the impact of the unidentified semi-volatile to extremely low volatility organic compounds (here collectively called "SVOCs" on the formation of OA (using the Volatility Basis Set and O3 (using the concept of mechanistic reactivity. We show that this method can successfully simulate the observations of O3, OA, PAN, NOx, and C2H4 to within measurement uncertainty using reasonable assumptions about the chemistry of the unidentified SVOCs. These assumptions were: (1 a~reaction rate constant with OH of ~10−11cm3s−1, (2 a significant fraction (~50% of the RO2 + NO reaction resulted in fragmentation, rather than functionalization, of the parent SVOC, (3 ~1.1 molecules of O3 were formed for every molecule of SVOC that reacted, (4 ~60% of the OH that reacted with the unidentified SVOCs was regenerated as HO2, and (5 that ~50% of the NO that reacted with the SVOC peroxy radicals was lost, presumably to organic nitrate formation. Additional evidence for the fragmentation pathway is provided by the observed rate of formation of acetic acid, which is consistent with our assumed fragmentation rate. This method could provide a way for classifying different smoke plume observations in terms of the average chemistry of their SVOCs

  18. A long term monitoring of Net Ecosystem Exchanges of the chaparral ecosystem in Southern California

    Science.gov (United States)

    Rossi, A.; Oechel, W. C.; Murphy, P.; Ikawa, H.; Sturtevant, C. S.

    2012-12-01

    Arid and semiarid woody shrublands represent approximately 35% of the global terrestrial surface area and 24% of the global soil organic carbon, and 16% of the global aboveground biomass (Atjay et al., 1979; Shmida, 1985). Therefore, these areas potentially have a large contribution to the global carbon budget. However, the assessment of carbon uptake for the old-growth shrubland has remained largely unexplored. Therefore, a long-term observation of CO2 flux with the eddy covariance technique has started since 1997 at Sky Oaks Field Station in Southern California. The research site is categorized at the climatic gradient between desert and semiarid area and that experiences a Mediterranean climate. The long term record of CO2 flux showed the area has been a sink of CO2 of up to -0.2 kgCm-2yr-1. In addition to evaluating vertical carbon fluxes, we initiated a project to evaluate lateral carbon transports using litter traps, sediment fences and two small weirs adjacent to the eddy covariance site in 2011. Preliminary results indicate that the lateral carbon efflux from the system may offset the vertical influx to the shrub ecosystem. However, it is still necessary to develop the methodology to compare vertical carbon flux and the lateral carbon fluxes more accurately.

  19. Southwest U.S. Mechanically Treated Chaparral Photo Series: Species list

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Accurate, complete fuels data are critical for making fuel management decisions and for predicting fire behavior and fire effects. A fuel photo series is a useful...

  20. Quantification of Lateral Carbon Flux in a Chaparral Ecosystem in Southern California Alessandra Rossi, Walter Oechel, Patrick Murphy

    Science.gov (United States)

    Rossi, A.; Oechel, W. C.; Murphy, P.

    2013-12-01

    The lateral transport of carbon is a horizontal transfer of carbon away from the area it was withdrawn from the atmosphere (Ciais et al. 2006). Research regarding horizontal C transport has received much less attention in arid and semi-arid regions compared to other types of ecosystems. Drylands represent around 47.2% (Lal 2004) of the global terrestrial area and despite characterized by relatively low carbon flux, drylands comprise approximately 15.5% of the world's total soil organic carbon (SOC) (Eswaran et al. 2000, Schlesinger, 1991). Moreover, these dry areas contain at least as much soil inorganic carbon (SIC) as SOC (Eswaran et al. 2000). Therefore, these areas potentially have a large contribution to the global carbon budget and they deserve attention. A long-term observation of CO2 flux with the eddy covariance technique has been conducted since 1997 at Sky Oaks Field Station in Southern California, an area of Mediterranean climate at the climatic transition between semiarid area and desert. The long term record of CO2 flux showed the area has been a sink of CO2 of over -0.2 kgCm-2yr-1. In addition to evaluating vertical carbon fluxes, we initiated a project to evaluate lateral carbon transports using litter traps, sediment fences and two small weirs adjacent to the eddy covariance site. Preliminary results indicate that the lateral transfer of C in the area may offset the vertical influx to this shrub ecosystem. However, it is still necessary to develop the methodology to compare vertical carbon flux and the lateral carbon fluxes more accurately.

  1. Investigating the links between ozone and organic aerosol chemistry in a biomass burning plume from a prescribed fire in California chaparral

    OpenAIRE

    Alvarado, M. J.; C. R. Lonsdale; R. J. Yokelson; S. K. Akagi; Coe, H.; J. S. Craven; Fischer, E. V.; Mcmeeking, G. R.; Seinfeld, J. H.; Soni, T.; Taylor, J.W.; D. R. Weise; C. E. Wold

    2014-01-01

    Within minutes after emission, complex photochemistry in biomass burning smoke plumes can cause large changes in the concentrations of ozone (O3) and organic aerosol (OA). Being able to understand and simulate this rapid chemical evolution under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use version 2.1 of the Aerosol Simulation Program (ASP) to simulate the evolution ...

  2. Multiple strategies for drought survival among woody plant species

    OpenAIRE

    Pivovaroff, AL; Pasquini, SC; De Guzman, ME; Alstad, KP; Stemke, JS; Santiago, LS

    2016-01-01

    © 2015 British Ecological Society Drought-induced mortality and regional dieback of woody vegetation are reported from numerous locations around the world. Yet within any one site, predicting which species are most likely to survive global change-type drought is a challenge. We studied the diversity of drought survival traits of a community of 15 woody plant species in a desert-chaparral ecotone. The vegetation was a mix of chaparral and desert shrubs, as well as endemic species that only occ...

  3. Chapter 1 Support for Instructional Development, 1986-87.

    Science.gov (United States)

    Kaemper, Jack; Morse, Kathy

    Six of the 39 Albuquerque (New Mexico) Public Schools' Chapter 1 participating schools, as part of the school-based budgeting process, allocated a portion of their Chapter 1 resource allocation for on-site intensive staff development activities. Three schools--Alamosa, Chaparral, and Duranes--agreed to utilize the time of a Support for…

  4. 76 FR 75830 - Proposed Establishment of the Inwood Valley Viticultural Area

    Science.gov (United States)

    2011-12-05

    ... would favor grasses, montane chaparral, and woodland over mixed pine forests. Soils There are 27... (particularly Ponderosa pine) contributing to the organic component of the soil. Generally located on gently... dominates the eastern section of the Bear Creek watershed, and grasslands and blue oak foothill...

  5. Characteristic atmosphere-ocean-solid earth interactions in the Antarctic coastal and marine environment inferred from seismic and infrasound recording at Syowa Station, East Antarctica

    OpenAIRE

    Kanao, Masaki; Maggi, Alessia; Ishihara, Yoshiaki; Stutzmann, Eléonore; Yamamoto, Masa-Yuki; Toyokuni, Genti

    2013-01-01

    Several characteristic waves detected by seismographs in Antarctic stations have been recognized as originating from the physical interaction between the solid earth and the atmosphere-ocean-cryosphere system surrounding the Antarctic and may be used as a proxy for characterizing ocean wave climate. A Chaparral-type infrasound sensor was installed at Syowa Station (SYO; 39.6E, 69.0S), East Antarctica, in April 2008 during the International Polar Year (IPY2007-2008). Matching data are also ava...

  6. Models to estimate the bunch dry weight in african oil palm (elaeis guineensis jacq.), american oil palm (elaeis oleifera h.b.k. cortes) and the interspecific hybrid (e. oleifera x e. guineensis)

    OpenAIRE

    2012-01-01

    Statistical models were used to estimate the bunch dry weight through indirect nondestructive methods in African oil palm (Elaeis guineensis) American oil palm (Elaeis oleifera) and the interspecific hybrid (E. oleifera x E. guineensis); and compared with the formula proposed by Corley. The studies were conducted at Santa Barbara and Chaparral-Cuernavaca on the Unipalma plantation, located in the eastern palm region of Colombia. Ten palms were selected for each group and 30 bunches were sampl...

  7. Yucca: A medicinally significant genus with manifold therapeutic attributes

    OpenAIRE

    Patel, Seema

    2012-01-01

    The genus Yucca comprising of several species is dominant across the chaparrals, canyons and deserts of American South West and Mexico. This genus has long been a source of sustenance and drugs for the Native Americans. In the wake of revived interest in drug discovery from plant sources, this genus has been investigated and startling nutritive and therapeutic capacities have come forth. Apart from the functional food potential, antioxidant, antiinflammation, antiarthritic, anticancer, antidi...

  8. Under the canopy

    OpenAIRE

    Campbell, Conor

    2015-01-01

    non-peer-reviewed Dense islands of arboraceous clumps nestled in an expanse of meadow. I passed over chaparrals and through thickets, each one its own sheltered arcadia in a quiet place beyond civilisation . The forest I was heading towards, would frequently reappear on the horizon once I had climbed over a hill or passed through a copse or a bosk. The flatness of the meadow juxtaposed and complimented by the vertical verdancy I would soon enter. A pillared, mythologic...

  9. Impacts of chronic N input on the carbon and nitrogen storage of a postfire Mediterranean-type shrubland

    Science.gov (United States)

    Vourlitis, George L.; Hentz, Cloe S.

    2016-02-01

    Mediterranean-type shrublands are subject to periodic fire and high levels of nitrogen (N) deposition, but little is known how chronic N deposition affects carbon (C) and N storage during succession. We conducted a long-term experiment in Californian chaparral to test the hypothesis that chronic N enrichment would increase postfire C and N accumulation. The experimental layout consisted of a randomized design where four 10 × 10 m plots received 5 g N m-2 annually since 2003 and four 10 × 10 m plots served as controls. Aboveground and belowground C and N pools and fluxes were measured seasonally (every 3 months) for a period of 10 years. Added N rapidly increased soil extractable N pools and decreased soil pH; however, total soil C and N storage were not affected. Added N plots initially had significantly lower C and N storage than control plots, presumably because of nutrient losses from leaching and/or higher belowground C allocation. However, rates of aboveground N and C storage became significantly higher in added N plots after 4-5 years of exposure, thus increasing fuel buildup, which has implications for future fire intensity. This recovering chaparral stand is not yet "N saturated" after 10 years of chronic N input. However, N leaching continues to be higher in added N plots, indicating that postfire chaparral stands in high-N deposition areas can be important sources of N to groundwater/aquatic systems even if productivity is stimulated by N input.

  10. Reptile and amphibian responses to large-scale wildfires in southern California

    Science.gov (United States)

    Rochester, C.J.; Brehme, C.S.; Clark, D.R.; Stokes, D.C.; Hathaway, S.A.; Fisher, R.N.

    2010-01-01

    In 2003, southern California experienced several large fires that burned thousands of hectares of wildlife habitats and conserved lands. To investigate the effects of these fires on the reptile and amphibian communities, we compared the results from prefire herpetofauna and vegetation sampling to two years of postfire sampling across 38 burned and 17 unburned plots. The sampling plots were spread over four vegetation types and four open space areas within San Diego County. Our capture results indicated that burned chaparral and coastal sage scrub plots lost herpetofaunal species diversity after the fires and displayed a significant shift in overall community structure. Shrub and tree cover at the burned plots, averaged across the second and third postfire years, had decreased by 53 in chaparral and 75 in coastal sage scrub. Additionally, postfire herpetofauna community structure at burned plots was more similar to that found in unburned grasslands. In grassland and woodland/riparian vegetation plots, where shrub and tree cover was not significantly affected by fires, we found no differences in the herpetofaunal species diversity or community composition. At the individual species level, Sceloporus occidentalis was the most abundant reptile in these areas both before and after the fires. We saw increases in the net capture rates for several lizard species, including Aspidoscelis tigris, Phrynosoma coronatum, and Uta stansburiana in burned chaparral plots and Aspidoscelis hyperythra and U. stansburiana in burned coastal sage scrub plots. The toad, Bufo boreas, was detected at significantly fewer burned plots in chaparral after the fires. Additionally, we documented decreases in the number of plots occupied by lizards (Elgaria multicarinata), salamanders (Batrachoseps major), and snakes (Coluber constrictor, Lampropeltis getula, Pituophis catenifer, and Masticophis lateralis) in coastal sage scrub and chaparral after the fires. We discuss the individual species

  11. Estimación del área y del peso seco foliar en elaeis guineellsis, elaeis oleifera y el hibrido interespecifico e. guineensis x e. oleífera

    OpenAIRE

    Contreras, Angela P.; Corchuelo, German; Martinez, Orlando; Cayon, Gerardo

    2011-01-01

    Este trabajo se planteo can la finalidad de determinar modelos estadísticos que permitan estimar el área y el peso foliar a través de métodos indirectos (no destructivos) en Elaeis guineensis (Palma africana), Elaeis oleifera (Palma Noli), y el hibrido interespecifico E. guineensis X E. oleifera (Afrieana X Noli ). Los experimentos de campo se efectuaron en las Haciendas Santa Bárbara y Chaparral-Cuernavaca, de la plantación Unipalma, ubicadas en la zona palmera de los llanos orientales en Co...

  12. Fire risk in California

    Science.gov (United States)

    Peterson, Seth Howard

    Fire is an integral part of ecosystems in the western United States. Decades of fire suppression have led to (unnaturally) large accumulations of fuel in some forest communities, such as the lower elevation forests of the Sierra Nevada. Urban sprawl into fire prone chaparral vegetation in southern California has put human lives at risk and the decreased fire return intervals have put the vegetation community at risk of type conversion. This research examines the factors affecting fire risk in two of the dominant landscapes in the state of California, chaparral and inland coniferous forests. Live fuel moisture (LFM) is important for fire ignition, spread rate, and intensity in chaparral. LFM maps were generated for Los Angeles County by developing and then inverting robust cross-validated regression equations from time series field data and vegetation indices (VIs) and phenological metrics from MODIS data. Fire fuels, including understory fuels which are not visible to remote sensing instruments, were mapped in Yosemite National Park using the random forests decision tree algorithm and climatic, topographic, remotely sensed, and fire history variables. Combining the disparate data sources served to improve classification accuracies. The models were inverted to produce maps of fuel models and fuel amounts, and these showed that fire fuel amounts are highest in the low elevation forests that have been most affected by fire suppression impacting the natural fire regime. Wildland fires in chaparral commonly burn in late summer or fall when LFM is near its annual low, however, the Jesusita Fire burned in early May of 2009, when LFM was still relatively high. The HFire fire spread model was used to simulate the growth of the Jesusita Fire using LFM maps derived from imagery acquired at the time of the fire and imagery acquired in late August to determine how much different the fire would have been if it had occurred later in the year. Simulated fires were 1.5 times larger

  13. Evidence against a Pleistocene desert refugium in the Lower Colorado River Basin

    Science.gov (United States)

    Holmgren, Camille A.; Betancourt, Julio L.; Peñalba, M. Cristina; Delgadillo, José; Zuravnsky, Kristin; Hunter, Kimberly L.; Rylander, Kate A.; Weiss, Jeremy L.

    2014-01-01

    Aim The absence of Sonoran Desert plants in late Pleistocene-aged packrat middens has led to speculation that they survived glacial episodes either in refugia as intact associations (Clementsian community concept) or in dry microsites within chaparral or woodland according to individualistic species responses (Gleasonian community concept). To test these hypotheses, we developed a midden record from one likely refugium in north-eastern Baja California, Mexico. We also measured stomatal guard cell size in fossil leaves to further evaluate site-level individualistic responses of Larrea tridentata (creosote bush) ploidy races to climatic changes, including monsoonal history, over the late Quaternary.

  14. Infrasound Sensor Models and Evaluations

    Energy Technology Data Exchange (ETDEWEB)

    KROMER,RICHARD P.; MCDONALD,TIMOTHY S.

    2000-07-31

    Sandia National Laboratories has continued to evaluate the performance of infrasound sensors that are candidates for use by the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty Organization. The performance criteria against which these sensors are assessed are specified in ``Operational Manual for Infra-sound Monitoring and the International Exchange of Infrasound Data''. This presentation includes the results of efforts concerning two of these sensors: (1) Chaparral Physics Model 5; and (2) CEA MB2000. Sandia is working with Chaparral Physics in order to improve the capability of the Model 5 (a prototype sensor) to be calibrated and evaluated. With the assistance of the Scripps Institution of Oceanography, Sandia is also conducting tests to evaluate the performance of the CEA MB2000. Sensor models based on theoretical transfer functions and manufacturer specifications for these two devices have been developed. This presentation will feature the results of coherence-based data analysis of signals from a huddle test, utilizing several sensors of both types, in order to verify the sensor performance.

  15. Vegetation response to southern California drought during the Medieval Climate Anomaly and early Little Ice Age (AD 800–1600)

    Science.gov (United States)

    Heusser, Linda E.; Hendy, Ingrid L.; Barron, John A.

    2015-01-01

    High-resolution studies of pollen in laminated sediments deposited in Santa Barbara Basin (SBB) core SPR0901-02KC reflect decadal-scale fluctuations in precipitation spanning the interval from AD 800–1600. From AD 800–1090 during the Medieval Climate Anomaly (MCA) SBB sediments were dominated by xeric vegetation types (drought-resistant coastal sagebrush and chaparral) implying reduced precipitation in the southern California region. Drought-adapted vegetation abruptly decreased at AD 1090 and was rapidly replaced by mesic oak (Quercus) woodlands associated with an increased pollen flux into the basin. After a mesic interval lasting ∼100 years, pollen flux and the relative abundance of Quercus pollen dropped abruptly at AD 1200 when the rapid rise of chaparral suggests a significant drought similar to that of the MCA (∼AD 800–1090). This brief resurgence of drought-adapted vegetation between AD 1200–1270 marked the end of the MCA droughts. A gradual increase in mesic vegetation followed, characterizing cool hydroclimates of the Little Ice Age (LIA) in coastal southern California.

  16. Fire regimes and vegetation responses in two Mediterranean-climate regions Regímenes de incendios y respuestas de la vegetación en dos regiones de clima Mediterráneo

    Directory of Open Access Journals (Sweden)

    GLORIA MONTENEGRO

    2004-09-01

    Full Text Available Wildfires resulting from thunderstorms are common in some Mediterranean-climate regions, such as southern California, and have played an important role in the ecology and evolution of the flora. Mediterranean-climate regions are major centers for human population and thus anthropogenic impacts on fire regimes may have important consequences on these plant formations. However, changes in fire regimes may have different impacts on Mediterranean type-ecosystems depending on the capability of plants to respond to such perturbations. Therefore, we compare here fire regimes and vegetation responses of two Mediterranean-climate regions which differ in wildfire regimes and history of human occupation, the central zone of Chile (matorral and the southern area of California in United States (chaparral. In Chile almost all fires result from anthropogenic activities, whereas lightning fires resulting from thunderstorms are frequent in California. In both regions fires are more frequent in summer, due to high accumulation of dry plant biomass for ignition. Humans have markedly increased fires frequency both in the matorral and chaparral, but extent of burned areas has remained unaltered, probably due to better fire suppression actions and a decline in the built-up of dry plant fuel associated to increased landscape fragmentation with less flammable agricultural and urban developments. As expected, post-fire plant regeneration responses differs between the matorral and chaparral due to differences in the importance of wildfires as a natural evolutionary force in the system. Plants from the chaparral show a broader range of post-fire regeneration responses than the matorral, from basal resprouting, to lignotuber resprouting, and to fire-stimulated germination and flowering with fire-specific clues such as heat shock, chemicals from smoke or charred wood. Plants from the matorral have some resprouting capabilities after fire, but these probably evolved from

  17. The 2007 southern California wildfires: Lessons in complexity

    Science.gov (United States)

    Keeley, J.E.; Safford, H.; Fotheringham, C.J.; Franklin, J.; Moritz, M.

    2009-01-01

    The 2007 wildfire season in southern California burned over 1,000,000 ac (400,000 ha) and included several megafires. We use the 2007 fires as a case study to draw three major lessons about wildfires and wildfire complexity in southern California. First, the great majority of large fires in southern California occur in the autumn under the influence of Santa Ana windstorms. These fires also cost the most to contain and cause the most damage to life and property, and the October 2007 fires were no exception because thousands of homes were lost and seven people were killed. Being pushed by wind gusts over 100 kph, young fuels presented little barrier to their spread as the 2007 fires reburned considerable portions of the area burned in the historic 2003 fire season. Adding to the size of these fires was the historic 2006-2007 drought that contributed to high dead fuel loads and long distance spotting. As in 2003, young chaparral stands and fuel treatments were not reliable barriers to fire in October 2007. Second, the Zaca Fire in July and August 2007 showed that other factors besides high winds can sometimes combine to create conditions for large fires in southern California. Spring and summer fires in southern California chaparral are usually easily contained because of higher fuel moisture and the general lack of high winds. However, the Zaca Fire burned in a remote wilderness area of rugged terrain that made access difficult. In addition, because of its remoteness, anthropogenic ignitions have been low and stand age and fuel loads were high. Coupled with this was severe drought that year that generated fuel moisture levels considerably below normal for early summer. A third lesson comes from 2007 conifer forest fires in the southern California mountains. In contrast to lower elevation chaparral, fire suppression has led to major increases in conifer forest fuels that can lead to unnaturally severe fires when ignitions escape control. The Slide and Grass Valley

  18. Comparison of white-tailed kite food web dynamics among various habitats in California using stable isotope analysis

    Science.gov (United States)

    Iko, W.M.; Kester, C.L.; Bern, C.R.; Stendell, R.C.; Rye, R.O.

    2003-01-01

    The White-tailed Kite (Elanus leucurus) was once a common raptor species in the southern United States. However, by the 1930s, the species was considered on the verge of extinction until the 1940s, when a trend towards recovery was apparent. These dramatic fluctuations may be related to changes in rodent prey base due to the conversion of native wetlands to agriculture. To investigate the effects of changes in habitat, land use practices, and prey base on kite populations, we collected tissue samples from kites, their prey, and vegetation at four different locations in California: Arcata, Coastal-Coniferous Forest; Davis, mixed Urban-Agricultural; Cosumnes, Mixed Wetland-Agriculture, and Santa Barbara, Coastal-Chaparral.

  19. Use of California biomass in the production of transportation-fuel oxygenates: Estimates for reduction in CO2 emissions and greenhouse gas potential on a life cycle basis

    International Nuclear Information System (INIS)

    A set of environmental flows associated with two disposal options for thee types of California biomass - forest biomass, rice straw, chaparral - over their life cycles were studied, the emphasis being on energy consumption and greenhouse gas emissions. The two options studied were: producing ethyl-tertiary-butyl ether (ETBE) from biomass and biomass burning, and producing methyl-tertiary-butyl ether (MTBE) from natural gas. Results showed a lower (by 40 to 50 per cent) greenhouse effect impact, lower net values for carbon dioxide and fossil fuel energy consumption, and higher net values for renewable energy consumption for the ETBE option. Based on these results, the deployment of the biomass-to-ethanol ETBE option is recommended as the one that contributes most to the reduction of GHG emissions. 12 refs., 2 tabs., 5 figs

  20. A 10kW photovoltaic/hybrid system for Pinnacles National Monument

    Energy Technology Data Exchange (ETDEWEB)

    Ball, T.J. [Applied Power Corp., Lacey, WA (United States); DeNio, D. [National Park Service, Denver, CO (United States). Denver Service Center

    1997-12-31

    Visitors to the Chaparral area of the Pinnacles National Monument now can enjoy this beautiful section of the park without the constant drone of diesel generators, thanks to a recently installed photovoltaic/hybrid system. Electrical power had been supplied by two 100 KW diesel generators operating 24 hours per day. The diesels were running lightly loaded resulting in poor efficiency and high operating cost. Applied Power Corporation under contract with the National Park Service designed and supplied a 10 KW photovoltaic array, 200 KW hr battery bank and 24 KW of inverters to power the maintenance facility, visitor center and ranger residences. A new 20 KW propane generator was installed to provide supplemental power, totally eliminating the storage and transport of diesel fuel at this site. The Pinnacles PV/Hybrid system was brought on line in early 1996 and the park is now benefiting from the cost savings associated with the system.

  1. Modeling the eco-hydrologic response of a Mediterranean type ecosystem to the combined impacts of projected climate change and altered fire frequencies

    DEFF Research Database (Denmark)

    Tague, Christina; Seaby, Lauren Paige; Hope, Allen

    2009-01-01

    Global Climate Models (GCMs) project moderate warming along with increases in atmospheric CO2 for California Mediterranean type ecosystems (MTEs). In water-limited ecosystems, vegetation acts as an important control on streamflow and responds to soil moisture availability. Fires are also key...... disturbances in semiarid environments, and few studies have explored the potential interactions among changes in climate, vegetation dynamics, hydrology, elevated atmospheric CO2 concentrations and fire. We model ecosystem productivity, evapotranspiration, and summer streamflow under a range of temperature and...... climate scenarios, biomass in chaparral-dominated systems is likely to increase, leading to reductions in summer streamflow. However, within the range of GCM predictions, there are some scenarios in which vegetation may decrease, leading to higher summer streamflows. Changes due to increases in fire...

  2. FLUXNET: A new tool to study the temporal and spatial variability of ecosystem-scale carbon dioxide, water vapor, and energy flux densities

    DEFF Research Database (Denmark)

    Baldocchi, D.; Falge, E.; Gu, L.; Olson, R.; Hollinger, D.; Running,S.; Anthoni, P.; Bernhofer, C.; Davis, K.; Evans, R.; Fuentes, J.; Goldstein, A.; Katul, G.; Law, B.; Lee, X.; Malhi, Y.; Meyers, T.; Munger, W.; Oechel, W.; Paw U,K.T.; Pilegaard, K.; Schmid, H.P.; Valentini, R.; Verma, S.; Vesala, T.; Wilson, K.; Wofsy, S.

    2001-01-01

    dynamics of annual ecosystem carbon and water balances, to quantify the response of stand-scale carbon dioxide and water vapor flux densities to controlling biotic and abiotic factors, and to validate a hierarchy of soil-plant-atmosphere trace gas exchange models. Findings so far include 1) net CO2......FLUXNET is a global network of micrometeorological flux measurement site's that measure the exchanges of carbon dioxide, water vapor, and energy between the biosphere and atmosphere. At present over 140 sites are operating on a long-term and continuous basis. Vegetation under study includes...... temperate conifer and broadleaved (deciduous and evergreen) forests, tropical and boreal forests, crops, grasslands, chaparral, wetlands, and tundra. Sites exist on five continents and their latitudinal distribution ranges from 70 degreesN to 30 degreesS. FLUXNET has several primary functions. First, it...

  3. Water Repellency and Fire in Sagebrush Ecosystems of the Northern Great Basin, USA

    Science.gov (United States)

    Pierson, F. B.; Kormos, P. R.; Robichaud, P. R.; Moffet, C. A.

    2006-12-01

    Severe wildfires have occurred across the western United States over the past decade. Past management practices and fire suppression policies have left wild lands with high fuel loads resulting in larger wildfires with high burn severities. An estimated $40 million is spent every year in the United States to mitigate the effects of wildfires and reduce the risk of flash floods and debris flows. Past research in forested and chaparral- dominated communities has indicated that wildfires cause a significant increase in soil water repellency resulting in more runoff and erosion potential. Little data exists for other shrub lands and grasslands, therefore findings from forests and chaparral are extrapolated to the post-fire management of many other plant communities. A series of studies were conducted to better understand the impacts of wildfire and subsequent recovery on hillslope runoff and erosion processes within steep watersheds with coarse-textured soils and sagebrush-bunchgrass plant communities. In general, year to year changes in infiltration capacity have been larger than the impact of fire on infiltration due to natural variations in soil water repellency. Under dry conditions, soil water repellency can be greater and more persistent on unburned areas compared to burned areas. Recovery in years following fire can result in less water repellency, improved infiltration capacities and reduced runoff amounts compared to unburned conditions. However wildfires do consume organic ground cover that protects the soil surface, thus runoff can easily move down slope with greater velocity and erosion potential. These results suggest that postfire treatments within these plant communities should focus on erosion control and not on improving infiltration capacity by "breaking-up" soil water repellent layers within the soil.

  4. Final Technical Report: Response of Mediterranean-Type Ecosystems to Elevated Atmospheric CO2 and Associated Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    Oechel, Walter C

    2002-08-15

    This research incorporated an integrated hierarchical approach in space, time, and levels of biological/ecological organization to help understand and predict ecosystem response to elevated CO{sub 2} and concomitant environmental change. The research utilized a number of different approaches, and collaboration of both PER and non-PER investigators to arrive at a comprehensive, integrative understanding. Central to the work were the CO{sub 2}-controlled, ambient Lit, Temperature controlled (CO{sub 2}LT) null-balance chambers originally developed in the arctic tundra, which were re-engineered for the chaparral with treatment CO{sub 2} concentrations of from 250 to 750 ppm CO{sub 2} in 100 ppm increments, replicated twice to allow for a regression analysis. Each chamber was 2 meters on a side and 2 meters tall, which were installed over an individual shrub reprouting after a fire. This manipulation allowed study of the response of native chaparral to varying levels of CO{sub 2}, while regenerating from an experimental burn. Results from these highly-controlled manipulations were compared against Free Air CO{sub 2} Enrichment (FACE) manipulations, in an area adjacent to the CO{sub 2}LT null balance greenhouses. These relatively short-term results (5-7 years) were compared to long-term results from Mediterranean-type ecosystems (MTEs) surrounding natural CO{sub 2} springs in northern Italy, near Laiatico, Italy. The springs lack the controlled experimental rigor of our CO{sub 2}LT and FACE manipulation, but provide invaluable validation of our long-term predictions.

  5. Emissions of trace gases and aerosols during the open combustion of biomass in the laboratory

    Energy Technology Data Exchange (ETDEWEB)

    McMeeking, Gavin R.; Kreidenweis, Sonia M.; Baker, Stephen; Carrico, Christian M.; Chow, Judith C.; Collett, Jr., Jeffrey L.; Hao, Wei Min; Holden, Amanda S.; Kirchstetter, Thomas W.; Malm, William C.; Moosmuller, Hans; Sullivan, Amy P.; Wold, Cyle E.

    2009-05-15

    We characterized the gas- and speciated aerosol-phase emissions from the open combustion of 33 different plant species during a series of 255 controlled laboratory burns during the Fire Laboratory at Missoula Experiments (FLAME). The plant species we tested were chosen to improve the existing database for U.S. domestic fuels: laboratory-based emission factors have not previously been reported for many commonly-burned species that are frequently consumed by fires near populated regions and protected scenic areas. The plants we tested included the chaparral species chamise, manzanita, and ceanothus, and species common to the southeastern US (common reed, hickory, kudzu, needlegrass rush, rhododendron, cord grass, sawgrass, titi, and wax myrtle). Fire-integrated emission factors for gas-phase CO{sub 2}, CO, CH{sub 4}, C{sub 2-4} hydrocarbons, NH{sub 3}, SO{sub 2}, NO, NO{sub 2}, HNO{sub 3} and particle-phase organic carbon (OC), elemental carbon (EC), SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, Cl{sup -}, Na{sup +}, K{sup +}, and NH{sub 4}{sup +} generally varied with both fuel type and with the fire-integrated modified combustion efficiency (MCE), a measure of the relative importance of flaming- and smoldering-phase combustion to the total emissions during the burn. Chaparral fuels tended to emit less particulate OC per unit mass of dry fuel than did other fuel types, whereas southeastern species had some of the largest observed EF for total fine particulate matter. Our measurements often spanned a larger range of MCE than prior studies, and thus help to improve estimates for individual fuels of the variation of emissions with combustion conditions.

  6. Comparison of post-fire seedling establishment between scrub communities in mediterranean and non-mediterranean climate ecosystems

    Science.gov (United States)

    Carrington, M.E.; Keeley, J.E.

    1999-01-01

    I Both fire regimes and the conditions under which fires occur vary widely. Abiotic conditions (such as climate) in combination with fire season, frequency and intensity could influence vegetation responses to fire. A variety of adaptations facilitate post-fire recruitment in mediterranean climate ecosystems, but responses of other communities are less well known. We evaluated the importance of climate by comparing sites with mediterranean and subtropical climates. 2 We used paired burned and mature sites in chamise chaparral, mixed chaparral and coastal sage scrub (California), and rosemary scrub, sand pine scrub and sand-hill (Florida), to test whether (i) patterns of pre-fire and post-fire seedling recruitment are more similar between communities within a region than between regions, and (ii) post-fire stimulation of seedling establishment is greater in regions with marked fire-induced contrasts in abiotic site characteristics. 3 Post-fire seedling densities were more similar among sites within climatic regions than between regions. Both seedling densities and proportions of species represented by seedlings after fires were generally higher in California. 4 The only site characteristic showing a pre-fire-post-fire contrast was percentage open canopy, and the effect was greater in California than in Florida. Soil properties were unaffected by fire. 5 Mediterranean climate ecosystems in other regions have nutrient-poor soils similar to our subtropical Florida sites, but show post-fire seedling recruitment patterns more similar to the nutrient-rich sites in California. Climate therefore appears to play a more major role than soil characteristics.

  7. Carbon And Nitrogen Storage Of A Mediterranean-Type Shrubland In Response To Post-Fire Succession And Long-Term Experimental Nitrogen Deposition

    Science.gov (United States)

    Vourlitis, G. L.; Hentz, C. S.

    2015-12-01

    Mediterranean-type shublands are subject to periodic fire and high levels of atmospheric nitrogen (N) deposition. Little is known how N inputs interact with post-fire secondary succession to affect ecosystem carbon (C) and N storage and cycling. Thus, a field experiment was conducted in a chaparral stand located in NE San Diego County, USA that burned during a wildfire in July 2003 to test the hypotheses that rates of C and N storage would significantly increase in response to experimental N addition. The experimental layout consists of a randomized design where four-10 x 10 m plots received 5 gN m-2 (added N) in the fall of each year since 2003 and four-10 x 10 m plots served as un-manipulated controls. Aboveground biomass C and N pools and fluxes, including biomass and litter C and N pool size, litter production, net primary production (NPP), N uptake, and litter C and N mineralization were measured seasonally (every 3 months) for a period of 10 years. Belowground surface (0-10 cm) soil extractable N, pH, and total soil N and C pools and surface root biomass C and N pools were also measured seasonally for a period of 10 years, while N losses from leaching were measured over a shorted (8 year) period of time. Added N led to a rapid increase in soil extractable N and a decline in soil pH; however, total soil C and N storage have yet to be affected by N input. Added N plots initially had significantly lower C and N storage than control plots; however, rates of aboveground N and C storage became significantly higher added N plots after 4-5 years of exposure. N losses from leaching continue to be significantly higher in added N plots even with an increase in aboveground C and N storage. The impact of N enrichment on ecosystem C and N storage varied depending on the stage of succession, but the eventual N-induced increase in NPP has implications for fuel buildup and future fire intensity. While N enrichment acted to increase aboveground C and N storage, plots exposed

  8. Hierarchical distance-sampling models to estimate population size and habitat-specific abundance of an island endemic

    Science.gov (United States)

    Sillett, Scott T.; Chandler, Richard B.; Royle, J. Andrew; Kéry, Marc; Morrison, Scott A.

    2012-01-01

    Population size and habitat-specific abundance estimates are essential for conservation management. A major impediment to obtaining such estimates is that few statistical models are able to simultaneously account for both spatial variation in abundance and heterogeneity in detection probability, and still be amenable to large-scale applications. The hierarchical distance-sampling model of J. A. Royle, D. K. Dawson, and S. Bates provides a practical solution. Here, we extend this model to estimate habitat-specific abundance and rangewide population size of a bird species of management concern, the Island Scrub-Jay (Aphelocoma insularis), which occurs solely on Santa Cruz Island, California, USA. We surveyed 307 randomly selected, 300 m diameter, point locations throughout the 250-km2 island during October 2008 and April 2009. Population size was estimated to be 2267 (95% CI 1613-3007) and 1705 (1212-2369) during the fall and spring respectively, considerably lower than a previously published but statistically problematic estimate of 12 500. This large discrepancy emphasizes the importance of proper survey design and analysis for obtaining reliable information for management decisions. Jays were most abundant in low-elevation chaparral habitat; the detection function depended primarily on the percent cover of chaparral and forest within count circles. Vegetation change on the island has been dramatic in recent decades, due to release from herbivory following the eradication of feral sheep (Ovis aries) from the majority of the island in the mid-1980s. We applied best-fit fall and spring models of habitat-specific jay abundance to a vegetation map from 1985, and estimated the population size of A. insularis was 1400-1500 at that time. The 20-30% increase in the jay population suggests that the species has benefited from the recovery of native vegetation since sheep removal. Nevertheless, this jay's tiny range and small population size make it vulnerable to natural

  9. A preliminary account of aerial plant biomass in fynbos communities of the Mediterranean-type climate zone of the Cape Province

    Directory of Open Access Journals (Sweden)

    F. J. Kruger

    1977-12-01

    Full Text Available Aerial plant biomass has been sampled by harvesting on several sites in fynbos communities of the south­western Cape Province. Biomass in stands of about two years old ranged from about 2 200 kg per ha to about 7 500 kg per ha. Mature stands comprised about 11 000 to 15 000 kg per ha in heaths and 15 000 to 26 000 kg per ha in sclerophyllous scrub. The data indicate a maximum annual growth rate of 1 000 to 4 000 kg per ha early in the development of a stand, but growth rates appear to decline rapidly as communities age. Young stands are dominated by hemicryptophytes, which comprise about 2 000 to  6  000 kg per ha, or about 60 to 75 per cent of the biomass in stands of about four years old. Shrubs become prominent later, but the hemicryptophytes persist. The data indicate that the biomass, growth rates and the shape of the growth curves of fynbos communities are on the whole similar to those of analogous vegetation in other zones of mediterranean type climate. However, there are important structural differences in that analogues of the northern hemisphere (garrigue, chaparral do not have a significant component of persistent hemicrytophytes. Although Australian heath communities do have this feature, the hemicryptophytes are not as prominent as in fynbos.

  10. Field trial of systemically delivered arthropod development-inhibitor (fluazuron) used to control woodrat fleas (Siphonaptera: Ceratophyllidae) and ticks (Acari: Ixodidae).

    Science.gov (United States)

    Slowik, T J; Lane, R S; Davis, R M

    2001-01-01

    An orally delivered arthropod development-inhibitory (fluazuron) was evaluated for its potential to reduce the number of flea and tick vectors found on the dusky-footed woodrat Neotoma fuscipes Baird, a reservoir host important in disease enzootiology in northern California. Pigmented bait cubes containing fluazuron were distributed monthly to woodrat nests in a chaparral habitat for 1 yr. When compared with control woodrats, the numbers of fleas [primarily Orchopeas sexdentatus (Baker)] on treated woodrats were significantly reduced 3-4 mo after initial application, and remained so for the duration of the application period. By contrast, tick numbers were not significantly reduced on treated woodrats. After the cessation of treatments, flea indices remained lower on treated animals for up to 2 mo after application. Approximately 93% of woodrats captured in the treatment area excreted pigmented feces and 93% of distributed bait cubes were removed by woodrats, which indicates that the bait cube formulation and delivery system were highly effective. Bait cubes also were attractive to small rodents and ground-frequenting birds. The results of this study suggest that a monthly application program of fluazuron delivered by bait cube is effective in reducing woodrat flea-burdens, but is not effective, at least in the short-term, in controlling ticks. PMID:11268695

  11. Laboratory characterization of PM emissions from combustion of wildland biomass fuels

    Science.gov (United States)

    Hosseini, S.; Urbanski, S. P.; Dixit, P.; Qi, L.; Burling, I. R.; Yokelson, R. J.; Johnson, T. J.; Shrivastava, M.; Jung, H. S.; Weise, D. R.; Miller, J. W.; Cocker, D. R.

    2013-09-01

    Particle emissions from open burning of southwestern (SW) and southeastern (SE) U.S. fuel types during 77 controlled laboratory burns are presented. The fuels include SW vegetation types: ceanothus, chamise/scrub oak, coastal sage scrub, California sagebrush, manzanita, maritime chaparral, masticated mesquite, oak savanna, and oak woodland, as well as SE vegetation types: 1 year, 2 year rough, pocosin, chipped understory, understory hardwood, and pine litter. The SW fuels burned at higher modified combustion efficiency (MCE) than the SE fuels resulting in lower particulate matter mass emission factor. Particle mass distributions for six fuels and particle number emission for all fuels are reported. Excellent mass closure (slope = 1.00, r2 = 0.94) between ions, metals, and carbon with total weight was obtained. Organic carbon emission factors inversely correlated (R2 = 0.72) with average MCE, while elemental carbon (EC) had little correlation with average MCE (R2 = 0.10). The EC/total carbon ratio sharply increased with MCE for MCEs exceeding 0.94. The average levoglucosan and total polycyclic aromatic hydrocarbon (PAH) emissions factors ranged from 25 to 1272 mg/kg fuel and 1.8 to 11.3 mg/kg fuel, respectively. No correlation between average MCE and emissions of PAHs/levoglucosan was found. Additionally, PAH diagnostic ratios were observed to be poor indicators of biomass burning. Large fuel type and regional dependency were observed in the emission rates of ammonium, nitrate, chloride, sodium, and potassium.

  12. La modificacion del biotopo perihabitacional en la profilaxis de la enfermedad de Chagas

    Directory of Open Access Journals (Sweden)

    Miguel Eduardo Jörg

    1989-06-01

    Full Text Available La modification del biotopo perihabitacional consiste en crear alrededor de la vivienda humana, rural, selvática o suburbuna, un espado perimetral limpio, totalmente libre de malezas y chaparral, despojado de nidos, madrigueras o refúgios de animales silvestres y de habitáculos de animales domésticos; de suficiente magnitud para evitar que tras desinsectación, queden focos peridomiciliarios de proliferation de triatomineos, vectores del Trypanosoma cruzi, focos inmediatos y habituales de reinfestación domiciliaria por estos redúvidos hematófagos. Los trabajos de rociado entomicida y aún el mejoramiento de la vivienda se reducen extremadamente si no son complementadas con la modificación del biotopo perihabitacional. Se expone una experiencia piloto sobre un barrio de la ciudad Villa Carlos Paz, provinda Córdoba, Argentina, que en 2 anos de aplicación permitió verificar la desaparición de vinchucas en un area de baja desindad de vectores y hospedadores.

  13. Mapping potentialy asbestos-bearing rocks using imaging spectroscopy

    Science.gov (United States)

    Swayze, G.A.; Kokaly, R.F.; Higgins, C.T.; Clinkenbeard, J.P.; Clark, R.N.; Lowers, H.A.; Sutley, S.J.

    2009-01-01

    Rock and soil that may contain naturally occurring asbestos (NOA), a known human carcinogen, were mapped in the Sierra Nevada, California, using the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) to determine if these materials could be uniquely identified with spectroscopy. Such information can be used to prepare or refine maps of areas that may contain minerals that can be asbestiform, such as serpentine and tremolite-actinolite, which were the focus of this study. Although thick vegetation can conceal underlying rock and soil, use of linear-mixture spectra calculated from spectra of dry grass and serpentine allowed detection of serpentine in some parts of the study area with up to ???80% dry-grass cover. Chaparral vegetation, which was dominantly, but not exclusively, found in areas underlain by serpentinized ultramafic rocks, was also mapped. Overall, field checking at 201 sites indicated highly accurate identification by AVIRIS of mineral (94%) and vegetation (89%) categories. Practical applications of AVIRIS to mapping areas that may contain NOA include locating roads that are surfaced with serpentine aggregate, identifying sites that may require enhanced dust control or other safety measures, and filling gaps in geologic mapping where field access is limited. ?? 2009 Geological Society of America.

  14. Effects of large-scale wildfire on ground foraging ants (Hymenoptera: Formicidae) in southern California

    Science.gov (United States)

    Matsuda, Tritia; Turschak, Greta; Brehme, Cheryl; Rochester, Carlton; Mitrovich, Milan; Fisher, Robert

    2011-01-01

    We investigated the effect of broad-scale wildfire on ground foraging ants within southern California. In October and November of 2003, two wildfires burned large portions of the wildlands within San Diego County. Between January 2005 and September 2006, we surveyed 63 plots across four sites to measure the effect of the fires on the ant assemblages present in four vegetation types: 1) coastal sage scrub, 2) chaparral, 3) grassland, and 4) woodland riparian. Thirty-six of the 63 plots were sampled before the fires between March 2001 and June 2003. Mixed model regression analyses, accounting for the burn history of each plot and our pre- and postfire sampling efforts, revealed that fire had a negative effect on ant species diversity. Multivariate analyses showed that ant community structure varied significantly among the four vegetation types, and only the ant assemblage associated with coastal sage scrub exhibited a significant difference between burned and unburned samples. The most notable change detected at the individual species level involved Messor andrei (Mayr), which increased from ant samples to 32.1% in burned plots postfire. We theorize that M. andrei responded to the increase of bare ground and postfire seed production, leading to an increase in the detection rate for this species. Collectively, our results suggest that wildfires can have short-term impacts on the diversity and community structure of ground foraging ants in coastal sage scrub. We discuss these findings in relation to management implications and directions for future research.

  15. Comparisons of genetic diversity in captive versus wild populations of the federally endangered Quino checkerspot butterfly (Euphydryas editha quino Behr; Lepidoptera: Nymphalidae)

    Science.gov (United States)

    Miller, Mark P.; Pratt, Gordon F.; Mullins, Thomas D.; Haig, Susan M.

    2014-01-01

    Captive populations can play a significant role in threatened and endangered species management. An important consideration when developing and managing captive populations, however, is the maintenance of genetic diversity to ensure that adequate variation exists to avoid the negative consequences of inbreeding. In this investigation, we compared genetic diversity patterns within captive and wild populations of the federally endangered Quino checkerspot butterfly (Euphydryas editha quino Behr [Lepidoptera: Nymphalidae]), a taxon with a restricted distribution to chaparral and sage shrublands within Riverside and San Diego counties, California. Our analyses revealed that medium to high-frequency alleles from the wild populations were also present in the captive populations. While there was no significant difference in genetic diversity as quantified by expected heterozygosity, the captive populations showed tendencies toward significantly lower allelic richness than their wild counterparts. Given that alleles from the wild populations were occasionally not detected in captive populations, periodic incorporation of new wild specimens into the captive population would help ensure that allelic diversity is maintained to the extent possible. If performed in advance, genetic surveys of wild populations may provide the clearest insights regarding the number of individuals needed in captivity to adequately reflect wild populations.

  16. Risks and Benefits of Commonly used Herbal Medicines in México

    Science.gov (United States)

    Rodriguez-Fragoso, Lourdes; Reyes-Esparza, Jorge; Burchiel, Scott; Herrera-Ruiz, Dea; Torres, Eliseo

    2008-01-01

    In Mexico, local empirical knowledge about medicinal properties of plants is the basis for their use as home remedies. It is generally accepted by many people in Mexico and elsewhere in the world that beneficial medicinal effects can be obtained by ingesting plant products. In this review, we focus on the potential pharmacologic bases for herbal plant efficacy, but we also raise concerns about the safety of these agents, which have not been fully assessed. Although numerous randomized clinical trials of herbal medicines have been published and systematic reviews and meta-analyses of these studies are available, generalizations about the efficacy and safety of herbal medicines are clearly not possible. Recent publications have also highlighted the unintended consequences of herbal product use, including morbidity and mortality. It has been found that many phytochemicals have pharmacokinetic or pharmacodynamic interactions with drugs. The present review is limited to some herbal medicine that are native or cultivated in Mexico and that have significant use. We discuss the cultural uses, phytochemistry, pharmacological and toxicological properties of the following following plant species: Nopal (Opuntia ficus), Peppermint (Mentha piperita), Chaparral (Larrea divaricata), Dandlion (Taraxacum officinale), Mullein (Verbascum densiflorum), Chamomile (Matricaria recutita), Nettle or Stinging Nettle (Urtica dioica), Passionflower (Passiflora incarmata), Linden Flower (Tilia europea), and Aloa (Aloa vera). We conclude that our knowledge of the therapeutic benefits and risks of some herbal medicines used in Mexico is still limited and efforts to elucidate them should be intensified. PMID:18037151

  17. Risks and benefits of commonly used herbal medicines in Mexico.

    Science.gov (United States)

    Rodriguez-Fragoso, Lourdes; Reyes-Esparza, Jorge; Burchiel, Scott W; Herrera-Ruiz, Dea; Torres, Eliseo

    2008-02-15

    In Mexico, local empirical knowledge about medicinal properties of plants is the basis for their use as home remedies. It is generally accepted by many people in Mexico and elsewhere in the world that beneficial medicinal effects can be obtained by ingesting plant products. In this review, we focus on the potential pharmacologic bases for herbal plant efficacy, but we also raise concerns about the safety of these agents, which have not been fully assessed. Although numerous randomized clinical trials of herbal medicines have been published and systematic reviews and meta-analyses of these studies are available, generalizations about the efficacy and safety of herbal medicines are clearly not possible. Recent publications have also highlighted the unintended consequences of herbal product use, including morbidity and mortality. It has been found that many phytochemicals have pharmacokinetic or pharmacodynamic interactions with drugs. The present review is limited to some herbal medicines that are native or cultivated in Mexico and that have significant use. We discuss the cultural uses, phytochemistry, pharmacological, and toxicological properties of the following plant species: nopal (Opuntia ficus), peppermint (Mentha piperita), chaparral (Larrea divaricata), dandlion (Taraxacum officinale), mullein (Verbascum densiflorum), chamomile (Matricaria recutita), nettle or stinging nettle (Urtica dioica), passionflower (Passiflora incarnata), linden flower (Tilia europea), and aloe (Aloe vera). We conclude that our knowledge of the therapeutic benefits and risks of some herbal medicines used in Mexico is still limited and efforts to elucidate them should be intensified. PMID:18037151

  18. Assessing the representativeness of the AmeriFlux network using MODIS and GOES data

    Science.gov (United States)

    Yang, Feihua; Zhu, A.-Xing; Ichii, Kazuhito; White, Michael A.; Hashimoto, Hirofumi; Nemani, Ramakrishna R.

    2008-12-01

    The AmeriFlux network of eddy covariance towers has played a critical role in the analysis of terrestrial water and carbon dynamics. It has been used to understand the general principles of ecosystem behaviors and to scale up those principles from sites to regions. To support the generalization from individual sites to large regions, it is essential that all major ecoregions in North America are represented in the AmeriFlux network. In this study, we examined the representativeness of the AmeriFlux network by comparing the climate and vegetation across the coterminous United States in 2004 with those at the AmeriFlux network in 2000-2004 on the basis of remote sensing products. We found that the AmeriFlux network generally captured the climatic and vegetation characteristics in the coterminous United States with under-representations in the Rocky Mountain evergreen needleleaf forest, the Sierra Nevada Mountains, the Sonora desert, the northern Great Plains, the Great Basin Desert, and New England. In terms of site representativeness, our analysis suggested that Indiana Morgan Monroe State Forest, Indiana, and Harvard Forest, Massachusetts, were among the forest sites with high representativeness extents; while Audubon Research Ranch, Arizona, and Sky Oaks Young Chaparral were among the nonforest sites with high representativeness extents.

  19. USDA forest service global change research: Monitored ecosystems, northern linkages

    International Nuclear Information System (INIS)

    Foresters and natural resource managers have traditionally based long-term plans (i.e., 100+ year harvest cycles) on the assumption of stable landscapes and climate. Global climate change undercuts these assumptions and may alter or invalidate some accepted natural resource management practices and paradigms. Possible changes in biomass productivity, shifting of forest species' latitudinal or elevational limits, and rapid changes in forest community species and age class composition, all have major implications for management of the nation's forests. The USDA Forest Service is undertaking a national research program to assess rates, significant processes, and management implications of possible climatic change for the nation's forests and related resources. Pacific Region Forest Service global change research places major emphasis on understanding and monitoring forest processes in the northern boreal forest and the sub-arctic taiga of Alaska, which is potentially sensitive to climatic warming and to shifts in precipitation regime. A major terrestrial carbon pool, taiga forests and organic soils may also be important in the flux of greenhouse gases between landscape and atmosphere. Forest Service research emphasizes an ecosystem approach, incorporating landscape- and watershed-level field research with smaller-scale studies of forest ecosystem response mechanisms. Ecological monitoring is critical, and includes establishment of a monitoring mega-transect from northern latitudinal tree line to mediterranean/dry temperate forest/shrublands. Emphasis is placed on the most critical Pacific Region ecosystems: northern boreal forest (taiga), moist temperate forest, and mediterranean/dry temperate forest (chaparral/southern Ponderosa pine)

  20. Risks and benefits of commonly used herbal medicines in Mexico

    International Nuclear Information System (INIS)

    In Mexico, local empirical knowledge about medicinal properties of plants is the basis for their use as home remedies. It is generally accepted by many people in Mexico and elsewhere in the world that beneficial medicinal effects can be obtained by ingesting plant products. In this review, we focus on the potential pharmacologic bases for herbal plant efficacy, but we also raise concerns about the safety of these agents, which have not been fully assessed. Although numerous randomized clinical trials of herbal medicines have been published and systematic reviews and meta-analyses of these studies are available, generalizations about the efficacy and safety of herbal medicines are clearly not possible. Recent publications have also highlighted the unintended consequences of herbal product use, including morbidity and mortality. It has been found that many phytochemicals have pharmacokinetic or pharmacodynamic interactions with drugs. The present review is limited to some herbal medicines that are native or cultivated in Mexico and that have significant use. We discuss the cultural uses, phytochemistry, pharmacological, and toxicological properties of the following plant species: nopal (Opuntia ficus), peppermint (Mentha piperita), chaparral (Larrea divaricata), dandlion (Taraxacum officinale), mullein (Verbascum densiflorum), chamomile (Matricaria recutita), nettle or stinging nettle (Urtica dioica), passionflower (Passiflora incarnata), linden flower (Tilia europea), and aloe (Aloe vera). We conclude that our knowledge of the therapeutic benefits and risks of some herbal medicines used in Mexico is still limited and efforts to elucidate them should be intensified

  1. How well does the Post-fire Erosion Risk Management Tool (ERMiT) really work?

    Science.gov (United States)

    Robichaud, Peter; Elliot, William; Lewis, Sarah; Miller, Mary Ellen

    2016-04-01

    The decision of where, when, and how to apply the most effective postfire erosion mitigation treatments requires land managers to assess the risk of damaging runoff and erosion events occurring after a fire. The Erosion Risk Management Tool (ERMiT) was developed to assist post fire assessment teams identify high erosion risk areas and effectiveness of various mitigation treatments to reduce that risk. ERMiT is a web-based application that uses the Water Erosion Prediction Project (WEPP) technology to estimate erosion, in probabilistic terms, on burned and recovering forest, range, and chaparral lands with and without the application of mitigation treatments. User inputs are processed by ERMiT to combine rain event variability with spatial and temporal variabilities of hillslope burn severity and soil properties which are then used as WEPP inputs. Since 2007, the model has been used in making hundreds of land management decisions in the US and elsewhere. We use eight published field study sites in the Western US to compare ERMiT predictions to observed hillslope erosion rates. Most sites experience only a few rainfall events that produced runoff and sediment except for a California site with a Mediterranean climate. When hillslope erosion occurred, significant correlations occurred between the observed hillslope erosion and those predicted by ERMiT. Significant correlation occurred for most mitigation treatments as well as the five recovery years. These model validation results suggest reasonable estimates of probabilistic post-fire hillslope sediment delivery when compared to observation.

  2. Fenología de algunas especies que son alimento para la pava aliblanca Penélope albipennis

    Directory of Open Access Journals (Sweden)

    Joaquín R. Martos

    2008-12-01

    Full Text Available En la Reserva Ecológica Privada Chaparrí, Chongoyape (Lambayeque se evaluó la fenología (desarrollo vegetativo, floración y fructificación de 17 especies vegetales que alimentan a la pava aliblanca (Penélope albipennis Taczanowski. Las evaluaciones fueron mensuales entre julio 2004 y junio 2005, en tres zonas denominadas: bosque seco de planicie, bosque seco de quebrada húmeda y bosque seco de ladera. La temperatura tuvo correlación con el desarrollo vegetativo, floración y fructificación. De las 17 especies evaluadas, 6 especies (35,3% estuvieron disponibles como alimento de la pava aliblanca durante todo el año, en tanto que de las 11 especies restantes (64,7% fueron de carácter estacional; durante todo el año la pava aliblanca dispone de oferta alimenticia de alguna de las especies evaluadas.

  3. The potential economic value of a cutaneous leishmaniasis vaccine in seven endemic countries in the Americas.

    Science.gov (United States)

    Bacon, Kristina M; Hotez, Peter J; Kruchten, Stephanie D; Kamhawi, Shaden; Bottazzi, Maria Elena; Valenzuela, Jesus G; Lee, Bruce Y

    2013-01-01

    Cutaneous leishmaniasis (CL) and its associated complications, including mucocutaneous leishmaniasis (MCL) and diffuse CL (DCL) have emerged as important neglected tropical diseases in Latin America, especially in areas associated with human migration, conflict, and recent deforestation. Because of the limitations of current chemotherapeutic approaches to CL, MCL, and DCL, several prototype vaccines are in different states of product and clinical development. We constructed and utilized a Markov decision analytic computer model to evaluate the potential economic value of a preventative CL vaccine in seven countries in Latin America: Bolivia, Brazil, Colombia, Ecuador, Mexico, Peru, and Venezuela. The results indicated that even a vaccine with a relatively short duration of protection and modest efficacy could be recommended for use in targeted locations, as it could prevent a substantial number of cases at low-cost and potentially even result in cost savings. If the population in the seven countries were vaccinated using a vaccine that provides at least 10 years of protection, an estimated 41,000-144,784 CL cases could be averted, each at a cost less than the cost of current recommended treatments. Further, even a vaccine providing as little as five years duration of protection with as little as 50% efficacy remains cost-effective compared with chemotherapy; additional scenarios resembling epidemic settings such as the one that occurred in Chaparral, Colombia in 2004 demonstrate important economic benefits. PMID:23176979

  4. Spatial Modeling of Dry Ravel in Three Dimensions Development of Ravel RAT: The Ravel Risk Assessment Tool

    Science.gov (United States)

    Russel, A. M.; Miller, M. E.; Robichaud, P. R.; Wohlgemuth, P. M.

    2013-12-01

    Dry ravel describes the down slope movement of soil and rock particles due to gravity in the absence of water. Dry ravel occurs mostly in steep mountainous, semi-arid regions where slopes are greater than the ravel particle's angle of repose (the steepest angle at which the particles are stable). In these regions, vegetation can trap particles behind their stems and hold materials on slopes with their root structure. After a fire, the removal of vegetation frees the particles to roll, slide, and/or bounce down the hill. Land managers are interested in predicting post-fire dry ravel movement, as these materials can load channels and gullies with sediment that can later be transported into streams and reservoirs. Researchers have developed a spatial mass flux dry ravel model to help predict and estimate dry ravel movement. This model is being further developed using field data from four small watersheds in the San Dimas Experimental Forest in California. The model parameters being optimized include particle velocity and spatially varied burn depth. New improvements are currently being made on optimizing burn depth using Monitoring Trends in Burn Severity (MTBS) burn severity classes derived from remote sensing data from the 2002 Williams Fire, which burned three of the study watersheds. We have optimized each burn severity class to different burn depths in order to increase the accuracy of model predictions of both dry ravel production and deposition for burned chaparral vegetation.

  5. Experimentally measured morphology of biomass burning aerosol and its impacts on CCN ability

    Directory of Open Access Journals (Sweden)

    M. Giordano

    2014-05-01

    Full Text Available This study examines the morphological properties of freshly emitted and atmospherically aged aerosols from biomass burning. The impacts of particle morphology assumptions on hygroscopic predictions are examined. Chamber experiments were conducted at the UC-Riverside Center for Environmental Research and Technology (CE-CERT Atmospheric Processes Lab using two biomass fuel sources, manzanita and chamise. Morphological data was obtained through the use of an aerosol particle mass analyzer (APM, scanning mobility particle sizer (SMPS system and transmission electron microscopy (TEM. Data from these instruments was used to calculate both a dynamic shape factor and a fractal-like dimension for the biomass burning emissions. This data was then used with κ-Köhler theory to adjust the calculated hygroscopicity for experimentally determined morphological characteristics of the aerosol. Laboratory measurement of biomass burning aerosol from two chaparral fuels show that particles are non-spherical with dynamic shape factors greater than 1.15 for aerosol sizes relevant to cloud condensation nuclei (CCN activation. Accounting for particle morphology can shift the hygroscopicity parameter κ by 0.15 or more. To our knowledge, this work provides the first laboratory chamber measurements of morphological characteristics for biomass burning cloud condensation nuclei and provides experimental particle shape evidence to support the variation in reported hygroscopicities of the complex aerosol.

  6. Recent Progress and Emerging Issues in Measuring and Modeling Biomass Burning Emissions

    Science.gov (United States)

    Yokelson, R. J.; Stockwell, C.; Veres, P. R.; Hatch, L. E.; Barsanti, K. C.; Simpson, I. J.; Blake, D. R.; Alvarado, M.; Kreidenweis, S. M.; Robinson, A. L.; Akagi, S. K.; McMeeking, G. R.; Stone, E.; Gilman, J.; Warneke, C.; Sedlacek, A. J.; Kleinman, L. I.

    2013-12-01

    Nine recent multi-PI campaigns (6 airborne, 3 laboratory) have quantified biomass burning emissions and the subsequent smoke evolution in unprecedented detail. Among these projects were the Fourth Fire Lab at Missoula Experiment (FLAME-4) and the DOE airborne campaign BBOP (Biomass Burning Observation Project). Between 2009 and 2013 a large selection of fuels and ecosystems were probed including: (1) 21 US prescribed fires in pine forests, chaparral, and shrublands; (2) numerous wildfires in the Pacific Northwest of the US; (3) 77 lab fires burning fuels collected from the sites of the prescribed fires; and (4) 158 lab fires burning authentic fuels in traditional cooking fires and advanced stoves; peat from Indonesia, Canada, and North Carolina; savanna grasses from Africa; temperate grasses from the US; crop waste from the US; rice straw from Taiwan, China, Malaysia, and California; temperate and boreal forest fuels collected in Montana and Alaska; chaparral fuels from California; trash; and tires. Instrumentation for gases included: FTIR, PTR-TOF-MS, 2D-GC and whole air sampling. Particle measurements included filter sampling (with IC, elemental carbon (EC), organic carbon (OC), and GC-MS) and numerous real-time measurements such as: HR-AMS (high-resolution aerosol MS), SP-AMS (soot particle AMS), SP2 (single particle soot photometer), SP-MS (single particle MS), ice nuclei, CCN (cloud condensation nuclei), water soluble OC, size distribution, and optical properties in the UV-VIS. New data include: emission factors for over 400 gases, black carbon (BC), brown carbon (BrC), organic aerosol (OA), ions, metals, EC, and OC; and details of particle morphology, mixing state, optical properties, size distributions, and cloud nucleating activity. Large concentrations (several ppm) of monoterpenes were present in fresh smoke. About 30-70% of the initially emitted gas-phase non-methane organic compounds were semivolatile and could not be identified with current technology

  7. Diurnal Reflectance Changes in Vegetation Observed with AVIRIS

    Science.gov (United States)

    Vanderbilt, V. C.; Ambrosia, V. G.; Ustin, S. L.

    1998-01-01

    focused on day-to-day changes in water use, especially for agricultural applications. Ustin et al. showed seasonal changes in canopy water content in chaparral shrub could be estimated using optical methods. Vanderbilt et al. followed asymmetric diurnal changes in the reflectance of a walnut orchard, but could not attribute specific reflectance changes to specific changes in canopy architecture or physiology. Forests and shrub lands in California experience prolonged periods of drought, sometimes extending six months without precipitation. The conifer and evergreen chaparral communities common to the foothill region around the central valley of California retain their foliage throughout the summer and have low transpiration rates despite high net radiation and temperature conditions. In contrast, grasslands and drought resistant deciduous species in the same habitat are seasonally dormant in summer. Because of differences in the mechanisms of drought tolerance, rooting depth and physiology between different plant communities in the region, it is likely that they display differences in diurnal water relations. The presence of diverse plant communities provides an opportunity to investigate possible diurnal landscape patterns in water relations that could be observed by an airborne hyperspectral scanner. This investigation of AVIRIS data collected over forest and shrub land represents the continuation of a prior investigation involving spectral mixture analysis of diurnal effects in the same AVIRIS data set.

  8. Mercury Speciation and Trophic Magnification Slopes in Giant Salamander Larvae from the Pacific Northwest, USA

    Science.gov (United States)

    Bank, M. S.; Crocker, J.; Wachtl, J.; Kleeman, P.; Fellers, G.; Currens, C.; Hothem, R.; Madej, M. A.

    2014-12-01

    Mercury (Hg) contamination of stream salamanders in the Pacific Northwest region of the United States has received little attention. Here we report total Hg (HgT) and methyl mercury (MeHg) concentrations in larval giant salamanders (Dicamptodon spp.) and surface water from forested and chaparral lotic ecosystems distributed along a latitudinal gradient throughout Northern California and Washington. To test hypotheses related to potential effects from mining land-use activities, salamander larvae were also sampled from a reference site at Whiskeytown National Recreation Area, California, and at a nearby, upstream site (Shasta county) on Bureau of Land Management land where Hg contamination from gold mining activities has been documented. HgT concentrations in whole body larvae ranged from 4.6 to 74.5 ng/g wet wt. and percent MeHg ranged from 67% to 86%. Both HgT and MeHg larval tissue concentrations were significantly higher at the mining site in comparison to measured background levels (P low in HgT and MeHg and, in comparison, watersheds with a legacy of land-use practices (i.e., mining operations) had approximately 4.5 - 5.5 times the level of HgT bioaccumulation. Moreover, trophic magnification slopes were highest in the Shasta county region where mining was present. These findings suggest that mining activities increase HgT and MeHg exposure to salamander larvae in the region and may present a threat to other higher trophically positioned organisms, and their associated food webs.

  9. Evidence for a uniformly small isotope effect of nitrogen leaching loss: results from disturbed ecosystems in seasonally dry climates.

    Science.gov (United States)

    Mnich, Meagan E; Houlton, Benjamin Z

    2016-06-01

    Nitrogen (N) losses constrain rates of plant carbon dioxide (CO2) uptake and storage in many ecosystems globally. N isotope models have been used to infer that ~30 % of terrestrial N losses occur via microbial denitrification; however, this approach assumes a small isotope effect associated with N leaching losses. Past work across tropical/sub-tropical forest sites has confirmed this expectation; however, the stable N isotope ratio (δ(15)N) of ecosystem leaching has yet to be systematically evaluated in seasonally dry climates or across major ecosystem disturbances. We here present new measurements of the δ(15)N of total dissolved N (TDN) in small streams, bulk deposition, and soil pools across eight watershed sites in California, including grassland, chaparral, and coastal redwood forest ecosystems, with and without fire, grazing, and forest harvesting. Regardless of the dominant vegetation type or disturbance regime, average δ(15)N of TDN in stream water differed only slightly (<~1 ‰) from that of bulk soil δ(15)N, revealing a uniformly small isotope effect associated with N leaching losses even under non-steady state conditions. Rather, lower input δ(15)N compared to TDN δ(15)N in streams pointed to fractionations via gaseous loss pathways as the dominant mechanism behind soil δ(15)N enrichment. We conclude that N leaching does not impart a major isotope effect across a broad range of ecosystems and conditions examined, thereby advancing the N gas-loss hypothesis as the principal explanation for variation in bulk soil δ(15)N. PMID:26343040

  10. Habitat eradication and cropland intensification may reduce parasitoid diversity and natural pest control services in annual crop fields

    Directory of Open Access Journals (Sweden)

    Deborah K. Letourneau

    2015-10-01

    Full Text Available Abstract California’s central coast differs from many agricultural areas in the U.S., which feature large tracts of monoculture production fields and relatively simple landscapes. Known as the nations salad bowl, and producing up to 90% of U.S. production of lettuces, broccoli and Brussels sprouts, this region is a mosaic of fresh vegetable fields, coastal meadow, chaparral shrubs, riparian and woodland habitat. We tested for relationships between the percent cover of crops, riparian and other natural landscape vegetation and the species richness of parasitic wasps and flies foraging in crops, such as broccoli, kale and cauliflower, and interpreted our results with respect to the decrease in natural habitat and increase in cropland cover prompted by a local microbial contamination event in 2006. Our key results are that: (1 as cropland cover in the landscape increased, fewer species of parasitoids were captured in the crop field, (2 parasitoid richness overall was positively associated with the amount of riparian and other natural vegetation in the surrounding 500m, (3 different groups of parasitoids were associated with unique types of natural vegetation, and (4 parasitism rates of sentinel cabbage aphid and cabbage looper pests were correlated with landscape vegetation features according to which parasitoids caused the mortality. Although individual species of parasitoids may thrive in landscapes that are predominantly short season crops, the robust associations found in this study across specialist and generalist parasitoids and different taxa (tachinid flies, ichneumon wasps, braconid wasps shows that recent food safety practices targeting removal of natural vegetation around vegetable fields in an attempt to eliminate wildlife may harm natural enemy communities and reduce ecosystem services. We argue that enhancing biological diversity is a key goal for transforming agroecosystems for future productivity, sustainability and public health.

  11. Coccidioides niches and habitat parameters in the southwestern United States: A matter of scale

    Science.gov (United States)

    Fisher, F.S.; Bultman, M.W.; Johnson, S.M.; Pappagianis, D.; Zaborsky, E.

    2007-01-01

    To determine habitat attributes and processes suitable for the growth of Coccidioides, soils were collected from sites in Arizona, California, and Utah where Coccidioides is known to have been present. Humans or animals or both have been infected by Coccidioides at all of the sites. Soil variables considered in the upper 20 cm of the soil profile included pH, electrical conductivity, salinity, selected anions, texture, mineralogy, vegetation types and density, and the overall geomorphologic and ecological settings. Thermometerswere buried to determine the temperature range in the upper part of the soil where Coccidioides is often found. With the exception of temperature regimes and soil textures, it is striking that none of the other variables or group of variables that might be definitive are indicative of the presence of Coccidioides. Vegetation ranges from sparse to relatively thick cover in lower Sonoran deserts, Chaparral-upper Sonoran brush and grasslands, and Mediterranean savannas and forested foothills. No particular grass, shrub, or forb is definitive. Material classified as very fine sand and silt is abundant in all of the Coccidioides-bearing soils and may be their most common shared feature. Clays are not abundant (less than 10%). All of the examined soil locations are noteworthy as generally 50% of the individuals who were exposed to the dust or were excavating dirt at the sites were infected. Coccidioides has persisted in the soil at a site in Dinosaur National Monument, Utah for 37 years and at a Tucson, Arizona site for 41 years. ?? 2007 New York Academy of Sciences.

  12. Fire-driven alien invasion in a fire-adapted ecosystem

    Science.gov (United States)

    Keeley, Jon E.; Brennan, Teresa J.

    2012-01-01

    Disturbance plays a key role in many alien plant invasions. However, often the main driver of invasion is not disturbance per se but alterations in the disturbance regime. In some fire-adapted shrublands, the community is highly resilient to infrequent, high-intensity fires, but changes in the fire regime that result in shorter fire intervals may make these communities more susceptible to alien plant invasions. This study examines several wildfire events that resulted in short fire intervals in California chaparral shrublands. In one study, we compared postfire recovery patterns in sites with different prefire stand ages (3 and 24 years), and in another study we compared sites that had burned once in four years with sites that had burned twice in this period. The population size of the dominant native shrub Adenostoma fasciculatum was drastically reduced following fire in the 3-year sites relative to the 24-year sites. The 3-year sites had much greater alien plant cover and significantly lower plant diversity than the 24-year sites. In a separate study, repeat fires four years apart on the same sites showed that annual species increased significantly after the second fire, and alien annuals far outnumbered native annuals. Aliens included both annual grasses and annual forbs and were negatively correlated with woody plant cover. Native woody species regenerated well after the first fire but declined after the second fire, and one obligate seeding shrub was extirpated from two sites by the repeat fires. It is concluded that some fire-adapted shrublands are vulnerable to changes in fire regime, and this can lead to a loss of native diversity and put the community on a trajectory towards type conversion from a woody to an herbaceous system. Such changes result in alterations in the proportion of natives to non-natives, changes in functional types from deeply rooted shrubs to shallow rooted grasses and forbs, increased fire frequency due to the increase in fine fuels

  13. A plant distribution shift: temperature, drought or past disturbance?

    Science.gov (United States)

    Schwilk, Dylan W.; Keeley, Jon E.

    2012-01-01

    Simple models of plant response to warming climates predict vegetation moving to cooler and/or wetter locations: in mountainous regions shifting upslope. However, species-specific responses to climate change are likely to be much more complex. We re-examined a recently reported vegetation shift in the Santa Rosa Mountains, California, to better understand the mechanisms behind the reported shift of a plant distribution upslope. We focused on five elevational zones near the center of the gradient that captured many of the reported shifts and which are dominated by fire-prone chaparral. Using growth rings, we determined that a major assumption of the previous work was wrong: past fire histories differed among elevations. To examine the potential effect that this difference might have on the reported upward shift, we focused on one species, Ceanothus greggii: a shrub that only recruits post-fire from a soil stored seedbank. For five elevations used in the prior study, we calculated time series of past per-capita mortality rates by counting growth rings on live and dead individuals. We tested three alternative hypotheses explaining the past patterns of mortality: 1) mortality increased over time consistent with climate warming, 2) mortality was correlated with drought indices, and 3) mortality peaked 40–50 years post fire at each site, consistent with self-thinning. We found that the sites were different ages since the last fire, and that the reported increase in the mean elevation of C. greggii was due to higher recent mortality at the lower elevations, which were younger sites. The time-series pattern of mortality was best explained by the self-thinning hypothesis and poorly explained by gradual warming or drought. At least for this species, the reported distribution shift appears to be an artifact of disturbance history and is not evidence of a climate warming effect.

  14. Mixing State and Aging of Biomass Burning Aerosols During the 2007 San Diego Wildfires

    Science.gov (United States)

    Zauscher, M. D.; Wang, Y.; Moore, M. J.; Gaston, C. J.; Prather, K. A.

    2011-12-01

    Biomass burning aerosols (BBA) significantly affect regional and global air quality, health and climate, yet their mixing state is not fully characterized. Specifically, aerosols from burning land dominated by chaparral shrubs, such as in Southern California, are less characterized than other BBA, although fires in this area have been increasing in frequency since 1980s. During the 2007 San Diego Wildfires the size-resolved chemistry of 100-400 nm single particles was determined in real-time with an ultra-fine aerosol time of flight mass spectrometer (UF-ATOFMS). BBA, identified by having a strong potassium peak and smaller carbonaceous markers present in the mass spectra, made up 84% of all particles measured between 10/22/07 and 11/1/07. Even though levoglucosan is known as a good biomass burning tracer, only 36% of all BBA in this study had this tracer present. Positive Matrix Factorization (PMF) analysis was utilized to group different BBA chemical markers, such as potassium salts, sulfate, ammonium, oxalate and levoglucosan. A spike in ammonium was observed with the increase in relative humidity on 10/25/07 and correlated with nitric acid and nitrate, indicating that the majority of ammonium was present as NH4NO3. The presence of different potassium salts were used to identify the age of BBA. K2Cl+, indicative of fresh BBA, was only seen at the beginning of the wildfires when the size mode of particles was ~potassium salts and the presence of secondary markers, such as sulfate and oxalate. In summary, we observed the evolution of BBA undergoing four distinct aging steps based on particle size and composition: slightly fresh, slightly aged, moderately aged and aged.

  15. Pollen-based evidence of extreme drought during the last Glacial (32.6-9.0 ka) in coastal southern California

    Science.gov (United States)

    Heusser, Linda E.; Kirby, Matthew E.; Nichols, Jonathan E.

    2015-10-01

    High resolution pollen analyses of sediment core LEDC10-1 from Lake Elsinore yield the first well-dated, terrestrial record of sub-centennial-scale ecologic change in coastal southern California between ˜32 and 9 ka. In the Lake Elsinore watershed, the initial, mesic montane conifer forests dominated by Pinus, and Cupressaceae with trace amounts of Abies and Picea were replaced by a sequence of multiple, extended severe mega-droughts between ˜27.5 and ˜25.5 ka, in which halophytic and xerophytic herbs and shrubs occupied an ephemeral lake. This prolonged and extended dry interval, which corresponds with warm waters offshore, imply strengthening of the North Pacific High and persistent below-average winter precipitation. The subsequent, contrasting monotonic occurrence of montane conifers reflects little variation in cold, mesic climate until ˜15 ka. Postglacial development of Quercus woodland and chaparral mark the return to more xeric, warmer conditions at this time. A brief reversal at ˜13.1-˜12.1 ka, as reflected by an expansion of Pinus, is correlative with the Younger Dryas and interrupts development of warm, postglacial climate. Subsequent gradual expansion of xeric vegetation post - Younger Dryas denotes the establishment of a winter hydroclimate regime in coastal southern California that is more similar to modern conditions. Pollen-based reconstructions of temperature and precipitation at Lake Elsinore are generally correlative with pollen-based paleoclimatic reconstructions and foraminifera-based sea surface temperatures from Santa Barbara Basin in marine core ODP 893. The conspicuous absence of the ˜27.5-˜25.5 ka glacial "mega-drought" in the Santa Barbara Basin pollen record highlights the sensitivity of Lake Elsinore to hydroclimate change, and thus, the importance of this new record that indicates that mega-drought can occur during the full glacial when climatic boundary conditions and forcings differed substantially from the present.

  16. Airborne and ground-based measurements of the trace gases and particles emitted by prescribed fires in the United States

    Directory of Open Access Journals (Sweden)

    I. R. Burling

    2011-06-01

    Full Text Available We measured the emission factors for 19 trace gas species and particulate matter (PM2.5 from 14 prescribed fires in chaparral and oak savanna in the southwestern US, as well as conifer forest understory in the southeastern US and Sierra Nevada mountains of California. These are likely the most extensive emission factor field measurements for temperate biomass burning to date and the only published emission factors for temperate oak savanna fuels. This study helps close the gap in emissions data available for temperate zone fires relative to tropical biomass burning. We present the first field measurements of the biomass burning emissions of glycolaldehyde, a possible precursor for aqueous phase secondary organic aerosol formation. We also measured the emissions of phenol, another aqueous phase secondary organic aerosol precursor. Our data confirm previous observations that urban deposition can impact the NOx emission factors and thus subsequent plume chemistry. For two fires, we measured both the emissions in the convective smoke plume from our airborne platform and the unlofted residual smoldering combustion emissions with our ground-based platform. The smoke from residual smoldering combustion was characterized by emission factors for hydrocarbon and oxygenated organic species that were up to ten times higher than in the lofted plume, including high 1,3-butadiene and isoprene concentrations which were not observed in the lofted plume. This should be considered in modeling the air quality impacts of smoke that disperses at ground level. We also show that the often ignored unlofted emissions can significantly impact estimates of total emissions. Preliminary evidence suggests large emissions of monoterpenes in the residual smoldering smoke. These data should lead to an improved capacity to model the impacts of biomass burning in similar temperate ecosystems.

  17. Airborne and ground-based measurements of the trace gases and particles emitted by prescribed fires in the United States

    Directory of Open Access Journals (Sweden)

    I. R. Burling

    2011-12-01

    Full Text Available We have measured emission factors for 19 trace gas species and particulate matter (PM2.5 from 14 prescribed fires in chaparral and oak savanna in the southwestern US, as well as conifer forest understory in the southeastern US and Sierra Nevada mountains of California. These are likely the most extensive emission factor field measurements for temperate biomass burning to date and the only published emission factors for temperate oak savanna fuels. This study helps to close the gap in emissions data available for temperate zone fires relative to tropical biomass burning. We present the first field measurements of the biomass burning emissions of glycolaldehyde, a possible precursor for aqueous phase secondary organic aerosol formation. We also measured the emissions of phenol, another aqueous phase secondary organic aerosol precursor. Our data confirm previous observations that urban deposition can impact the NOx emission factors and thus subsequent plume chemistry. For two fires, we measured both the emissions in the convective smoke plume from our airborne platform and the unlofted residual smoldering combustion emissions with our ground-based platform. The smoke from residual smoldering combustion was characterized by emission factors for hydrocarbon and oxygenated organic species that were up to ten times higher than in the lofted plume, including high 1,3-butadiene and isoprene concentrations which were not observed in the lofted plume. This should be considered in modeling the air quality impacts for smoke that disperses at ground level. We also show that the often ignored unlofted emissions can significantly impact estimates of total emissions. Preliminary evidence suggests large emissions of monoterpenes in the residual smoldering smoke. These data should lead to an improved capacity to model the impacts of biomass burning in similar temperate ecosystems.

  18. Airborne and ground-based measurements of the trace gases and particles emitted from prescribed fires in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Burling, Ian; Yokelson, Robert J.; Akagi, Sheryl; Urbanski, Shawn; Wold, Cyle E.; Griffith, David WT; Johnson, Timothy J.; Reardon, James; Weise, David

    2011-12-07

    We measured the emission factors for 19 trace gas species and particulate matter (PM2.5) from 14 prescribed fires in chaparral and oak savanna in the southwestern US, as well as pine forest understory in the southeastern US and Sierra Nevada mountains of California. These are likely the most extensive emission factor field measurements for temperate biomass burning to date and the only published emission factors for temperate oak savanna fuels. This study helps close the gap in emissions data available for temperate zone fires relative to tropical biomass burning. We present the first field measurements of the biomass burning emissions of glycolaldehyde, a possible precursor for aqueous phase secondary organic aerosol formation. We also measured the emissions of phenol, another aqueous phase secondary organic aerosol precursor. Our data confirm previous suggestions that urban deposition can impact the NOx emission factors and thus subsequent plume chemistry. For two fires, we measured the emissions in the convective smoke plume from our airborne platform at the same time the unlofted residual smoldering combustion emissions were measured with our ground-based platform after the flame front passed through. The smoke from residual smoldering combustion was characterized by emission factors for hydrocarbon and oxygenated organic species that were up to ten times higher than in the lofted plume, including significant 1,3-butadiene and isoprene concentrations which were not observed in the lofted plume. This should be considered in modeling the air quality impacts of smoke that disperses at ground level, and we show that the normally-ignored unlofted emissions can also significantly impact estimates of total emissions. Preliminary evidence of large emissions of monoterpenes was seen in the residual smoldering spectra, but we have not yet quantified these emissions. These data should lead to an improved capacity to model the impacts of biomass burning in similar

  19. Use of Anecdotal Occurrence Data in Species Distribution Models: An Example Based on the White-Nosed Coati (Nasua narica in the American Southwest

    Directory of Open Access Journals (Sweden)

    James N. Stuart

    2013-04-01

    Full Text Available Species distributions are usually inferred from occurrence records. However, these records are prone to errors in spatial precision and reliability. Although influence of spatial errors has been fairly well studied, there is little information on impacts of poor reliability. Reliability of an occurrence record can be influenced by characteristics of the species, conditions during the observation, and observer’s knowledge. Some studies have advocated use of anecdotal data, while others have advocated more stringent evidentiary standards such as only accepting records verified by physical evidence, at least for rare or elusive species. Our goal was to evaluate the influence of occurrence records with different reliability on species distribution models (SDMs of a unique mammal, the white-nosed coati (Nasua narica in the American Southwest. We compared SDMs developed using maximum entropy analysis of combined bioclimatic and biophysical variables and based on seven subsets of occurrence records that varied in reliability and spatial precision. We found that the predicted distribution of the coati based on datasets that included anecdotal occurrence records were similar to those based on datasets that only included physical evidence. Coati distribution in the American Southwest was predicted to occur in southwestern New Mexico and southeastern Arizona and was defined primarily by evenness of climate and Madrean woodland and chaparral land-cover types. Coati distribution patterns in this region suggest a good model for understanding the biogeographic structure of range margins. We concluded that occurrence datasets that include anecdotal records can be used to infer species distributions, providing such data are used only for easily-identifiable species and based on robust modeling methods such as maximum entropy. Use of a reliability rating system is critical for using anecdotal data.

  20. Stability, Bistability, and Critical Thresholds in Fire-prone Forested Landscapes: How Frequency and Intensity of Disturbance Interact and Influence Forest Cover

    Science.gov (United States)

    Miller, A. D.

    2015-12-01

    Many aspects of disturbance processes can have large impacts on the composition of plant communities, and associated changes in land cover type in turn have biogeochemical feedbacks to climate. In particular, changes to disturbance regimes can potentially change the number and stability of equilibrial states, and plant community states can differ dramatically in their carbon (C) dynamics, energy balance, and hydrology. Using the Klamath region of northern California as a model system, we present a theoretical analysis of how changes to climate and associated fire dynamics can disrupt high-carbon, long-lived conifer forests and replace them with shrub-chaparral communities that have much lower biomass and are more pyrogenic. Specifically, we develop a tractable model of plant community dynamics, structured by size class, life-history traits, lottery-type competition, and species-specific responses to disturbance. We assess the stability of different states in terms of disturbance frequency and intensity, and quantitatively partition long-term low-density population growth rates into mechanisms that influence critical transitions from stable to bistable behavior. Our findings show how different aspects of disturbance act and interact to control competitive outcomes and stable states, hence ecosystem-atmosphere C exchange. Forests tend to dominate in low frequency and intensity regimes, while shrubs dominate at high fire frequency and intensity. In other regimes, the system is bistable, and the fate of the system depends both on initial conditions and random chance. Importantly, the system can cross a critical threshold where hysteresis prevents easy return to the prior forested state. We conclude that changes in disturbance-recovery dynamics driven by projected climate change can shift this system away from forest dominated in the direction of shrub-dominated landscape. This will result in a large net C release from the landscape, and alter biophysical ecosystem

  1. Brush-eating device promises reforestation, wood energy aid

    Energy Technology Data Exchange (ETDEWEB)

    Blackman, T.

    1981-01-01

    An invention which began as a low-ground-pressure skidder developed into a machine which clears brush, thins plantations, and can harvest wood for energy. First came the notion of an extra-low-ground-pressure log skidder. A swinging chopper was added to the front to clear the skid roads. Working in manzanita brush 10 to 12 foot tall, and with stems up to 18 inches in diameter, the Shar 20 can clear one to two and a half acres an hour. The 30 will be able to clear two to five acres an hour. The big machine will have two chopper heads rotating in opposite directions to force the chopped wood into a chipper built into the machine. Chips will be blown to a van following the harvester so they can be used for hog fuel or as feedstock for methanol production. The head spins at a relatively slow 450 rpm - a safety factor. Surrounding brush catches most of the cut material, but an occasional chunk of wood does fly several yards. Companies are paying more attention to reforestation. Clearing the land will leave a mulch-like debris on the ground. This offers some shade and helps retain soil moisture. Even when brush is harvested for energy, about 10% of the material is left on the ground. California's Department of Forestry wants to start a five-year clearing cycle for the chaparral stands, ''mowing'' a million acres a year and returning every fifth year to reclear the brush. California alone has 27 million acres of brushland not suitable for timber. A brushy acre averages from 30 to 200 tons of wood at 10% moisture content. The machines are designed to run at up to 12 mph when moving.

  2. Fire management impacts on invasive plants in the western United States.

    Science.gov (United States)

    Keeley, Jon E

    2006-04-01

    Fire management practices affect alien plant invasions in diverse ways. I considered the impact of six fire management practices on alien invasions: fire suppression, forest fuel reduction, prescription burning in crown-fire ecosystems, fuel breaks, targeting of noxious aliens, and postfire rehabilitation. Most western United States forests have had fire successfully excluded for unnaturally long periods of time, and this appears to have favored the exclusion of alien plant species. Forest fuel reduction programs have the potential for greatly enhancing forest vulnerability to alien invasions. In part this is due to the focus on reestablishing pre-Euro-American fire regimes on a landscape that differs from pre-Euro-American landscapes in the abundance of aggressive non-native species. We may be forced to choose between restoring "natural"fire regimes or altering fire regimes to favor communities of native species. Intensive grazing in many western forests may exacerbate the alien problem after fire and temporally decoupling grazing and fire restoration may reduce the alien threat. Many shrubland ecosystems such as the Intermountain West sagebrush steppe or California chaparral have a natural, high-intensity crown fire regime that is less amenable to forest restoration tactics. Historical use of prescribed fire for type conversion of shrublands to more useful grazing lands has played some role in the massive annual grass invasion that threatens these shrublands. Fuel breaks pose a special invasive plant risk because they promote alien invasion along corridors into wildland areas. Use of prescription burning to eliminate noxious aliens has had questionable success, particularly when applied to disturbance-dependent annuals, and success is most likely when coupled with ecosystem restoration that alters the competitive balance between aliens and natives. Artificial seeding of alien species as a form of postfire stabilization appears to cause more problems than it

  3. Laboratory characterization of PM emissions from combustion of wildland biomass fuels

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, SeyedEhsan; Urbanski, Shawn; Dixit, P.; Qi, L.; Burling, Ian R.; Yokelson, Robert; Johnson, Timothy J.; Shrivastava, ManishKumar B.; Jung, H.; Weise, David; Miller, J. Wayne; Cocker, David R.

    2013-09-09

    Particle emissions from open burning of southwestern (SW) and southeastern (SE) U.S. 17 fuel types during 77 controlled laboratory burns are presented. The fuels include SW 18 vegetation types: ceanothus, chamise/scrub oak, coastal sage scrub, California sagebrush, 19 manzanita, maritime chaparral, masticated mesquite, oak savanna, and oak woodland as 20 well as SE vegetation types: 1-year, 2-year rough, pocosin, chipped understory, 21 understory hardwood, and pine litter. The SW fuels burned at a higher Modified 22 Combustion Efficiency (MCE) than the SE fuels resulting in lower particulate matter 23 (PM) mass emission factor (EF). Particle size distributions for six fuels and particle 24 number emission or all fuels are reported. Excellent mass closure (slope = 1.00, r2=0.94) 25 between ions, metals, and carbon with total weight was obtained. Organic carbon 26 emission factors inversely correlated (= 0.72) with MCE, while elemental carbon (EC) 27 had little correlation with MCE (=0.10). The EC/total carbon (TC) ratio sharply 28 increased with MCE for MCEs exceeding 0.94. The average levoglucosan and total Poly 29 Aromatic Hydrocarbons (PAH) emissions factors ranged from 25-1272 mg/kg fuel and 30 1790-11300 μg/kg fuel, respectively. No correlation between MCE and emissions of 31 PAHs/levoglucosan was found. Additionally, PAH diagnostic ratios were observed to be 32 poor indicators of biomass burning. Large fuel-type and regional dependency was 33 observed in the emission rates of ammonium, nitrate, fluoride, chloride, sodium, and

  4. A plant distribution shift: temperature, drought or past disturbance?

    Directory of Open Access Journals (Sweden)

    Dylan W Schwilk

    Full Text Available Simple models of plant response to warming climates predict vegetation moving to cooler and/or wetter locations: in mountainous regions shifting upslope. However, species-specific responses to climate change are likely to be much more complex. We re-examined a recently reported vegetation shift in the Santa Rosa Mountains, California, to better understand the mechanisms behind the reported shift of a plant distribution upslope. We focused on five elevational zones near the center of the gradient that captured many of the reported shifts and which are dominated by fire-prone chaparral. Using growth rings, we determined that a major assumption of the previous work was wrong: past fire histories differed among elevations. To examine the potential effect that this difference might have on the reported upward shift, we focused on one species, Ceanothus greggii: a shrub that only recruits post-fire from a soil stored seedbank. For five elevations used in the prior study, we calculated time series of past per-capita mortality rates by counting growth rings on live and dead individuals. We tested three alternative hypotheses explaining the past patterns of mortality: 1 mortality increased over time consistent with climate warming, 2 mortality was correlated with drought indices, and 3 mortality peaked 40-50 years post fire at each site, consistent with self-thinning. We found that the sites were different ages since the last fire, and that the reported increase in the mean elevation of C. greggii was due to higher recent mortality at the lower elevations, which were younger sites. The time-series pattern of mortality was best explained by the self-thinning hypothesis and poorly explained by gradual warming or drought. At least for this species, the reported distribution shift appears to be an artifact of disturbance history and is not evidence of a climate warming effect.

  5. Seasonal Trends in Airborne Fungal Spores in Coastal California Ecosystems

    Science.gov (United States)

    Morfin, J.; Crandall, S. G.; Gilbert, G. S.

    2014-12-01

    Airborne fungal spores cause disease in plants and animals and may trigger respiratory illnesses in humans. In terrestrial systems, fungal sporulation, germination, and persistence are strongly regulated by local meteorological conditions. However, few studies investigate how microclimate affects the spatio-temporal dynamics of airborne spores. We measured fungal aerospora abundance and microclimate at varying spatial and time scales in coastal California in three habitat-types: coast redwood forest, mixed-evergreen forest, and maritime chaparral. We asked: 1) is there a difference in total airborne spore concentration between habitats, 2) when do we see peak spore counts, and 3) do spore densities correlate with microclimate conditions? Fungal spores were caught from the air with a volumetric vacuum air spore trap during the wet season (January - March) in 2013 and 2014, as well as monthly in 2014. Initial results suggest that mixed-evergreen forests exhibit the highest amounts of spore abundance in both years compared to the other habitats. This may be due to either a higher diversity of host plants in mixed-evergreen forests or a rich leaf litter layer that may harbor a greater abundance of saprotrophic fungi. Based on pilot data, we predict that temperature and to a lesser degree, relative humidity, will be important microclimate predictors for high spore densities. These data are important for understanding when and under what weather conditions we can expect to see high levels of fungal spores in the air; this can be useful information for managers who are interested in treating diseased plants with fungicides.

  6. Chemical characterization of particle emissions from controlled burns of biomass fuels using a high resolution time-of-flight aerosol mass spectrometer

    Directory of Open Access Journals (Sweden)

    L. Qi

    2012-03-01

    Full Text Available A total of forty-nine burns were conducted at the Missoula Fire Sciences Lab consisting of nine fuel types; i.e., chamise scrub oak, ceanothus, maritime chaparral, coastal sage scrub, California sage brush, Manzanita, oak savanna, oak woodland and masticated mesquite. This paper focuses on the chemical characterization of fine particle emissions collected for flaming, mixed and smoldering phases using a HR ToF-AMS. The evolution of OM/OC, H/C, O/C and N/C from fire ignition to extinction was measured to capture the transient and integrated chemical composition of the non-refractory portion of bulk particles. Real time elemental ratios and empirical formulas derived with respect to modified combustion efficiency (MCE are reported. For each fuel, the hydrogen fragment ions dominate the unit mass resolution (UMR mass spectra with no specific fragment ions attributable to an individual ecological combination. An interference ion in the UMR m/z 73, a fragment normally attributed to levoglucosan, is noted. Therefore, the results imply that C2H4O2+ (m/z 60.021 plus C3H5O2+ (m/z 73.029 are more sufficient to estimate the contribution of levoglucosan. The results did not show significant variations of levoglucosan content in the organic particle with the overall average contribution fraction ranging from 0.74% for coastal sage to 1.93% for chamise.

  7. Biomass burning fuel consumption rates: a field measurement database

    Directory of Open Access Journals (Sweden)

    T. T. van Leeuwen

    2014-06-01

    Full Text Available Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. These fuel consumption (FC rates depend on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC rates are either modeled or taken selectively from the literature. We compiled the peer-reviewed literature on FC rates for various biomes and fuel categories to better understand FC rates and variability, and to provide a~database that can be used to constrain biogeochemical models with fire modules. We compiled in total 76 studies covering 10 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter ha−1, tropical forest (n = 19, FC = 126, temperate forest (n = 11, FC = 93, boreal forest (n = 16, FC = 39, pasture (n = 6, FC = 28, crop residue (n = 4, FC = 6.5, chaparral (n = 2, FC = 32, tropical peatland (n = 4, FC = 314, boreal peatland (n = 2, FC = 42, and tundra (n = 1, FC = 40. Within biomes the regional variability in the number of measurements was sometimes large, with e.g. only 3 measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences were found within the defined biomes: for example FC rates of temperate pine forests in the USA were 38% higher than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC rates, not only between biomes but also within biomes and fuel classes. This implies that care should be taken with using averaged values, and our comparison with FC rates from GFED3 indicates that also modeling studies have difficulty in representing the dynamics governing FC.

  8. Vulnerability of birds to climate change in California's Sierra Nevada

    Directory of Open Access Journals (Sweden)

    Rodney B. Siegel

    2014-06-01

    (Pinicola enucleator, and Evening Grosbeak (Coccothraustes vespertinus. Species associated with alpine/subalpine habitats and aquatic habitats received significantly more vulnerable rankings than birds associated with other habitats. In contrast, species of foothill, sagebrush, and chaparral habitats ranked as less vulnerable than other species, and our results suggest these species may respond to climate change in the region with population increases or range expansions.

  9. Dispersal and Germination Patterns of Monterey Spineflower at Fort Ord Natural Reserve.

    Science.gov (United States)

    Chaudhry, Z.

    2014-12-01

    Some species are rare because they are restricted to certain habitats and/or have small population sizes. Monterey spineflower, a federally listed threatened annual plant, is found in open sandy regions of the California coast, in chaparral vegetation around the Monterey Bay. A model based on previous research suggests that the Monterey spineflower population at Fort Ord Natural Reserve should be rapidly increasing, but it is not. This suggests that the model may be using data that overestimates the percentage of spineflower seeds that successfully germinate. I tested three hypotheses to determine the cause of the difference in population sizes between the predicted model and the field results. First, I predicted that the spineflower seeds are blown by the wind into shrubs such as manzanita, and are unable to germinate due to the lack of a suitable environment. I tested this in two ways. A field experiment showed that seeds are easily blow by wind. Next, I took soil cores and found spineflower seeds within the manzanita shrubs. Secondly, I predicted that the germination rate used by the model (90%) was too high. However, my germination experiments did not support this hypothesis because 91% of new seeds successfully germinated. Lastly, I predicted that the newer seeds are more viable than older seeds and therefore have a higher chance of successfully germinating. After germinating seeds in a controlled environment I observed that the seeds from 2014 had a higher number of successfully germinated seeds compared to the number of successfully germinated seeds from 1995 (91% vs 33%). I conclude that the loss of seeds due to wind decreases germination expectancies and older seeds are less viable than new seeds. Therefore, Monterey spineflower is a rare plant because environmental barriers hinder seeds from dispersing to a suitable habitat and successfully germinating while seeds lose viability as they age.

  10. Modeling the Impact of Hydraulic Redistribution on Carbon Cycles Using CLM4.5 at Eight AmeriFlux Sites

    Science.gov (United States)

    Fu, C.; Wang, G.; Cardon, Z. G.

    2014-12-01

    Hydraulic redistribution (HR) has significant impacts on the terrestrial hydrological, biogeochemical, and ecological processes. Accurate modeling of HR and its impact on vegetation growth and ecosystem carbon dynamics is important for accurate simulation of regional and global carbon cycles. However, how HR influences plant, soil carbon and nitrogen dynamics remains poorly understood. In this study, we incorporate a simple HR scheme into the Community Land Model Version 4.5 (CLM4.5) including the biogeochemical model BGC. We use the modified CLM4.5-BGC model to investigate the impact of HR on the terrestrial carbon cycle at eight AmeriFlux sites where HR was detected from soil moisture measurements: a Douglas-fir site (US-Wrc) in Washington State with a Mediterranean climate, a savanna site (US-SRM) in Arizona with a semi-arid climate, and six sites along the Southern California Climate Gradient with a Mediterranean climate, with coverage of coastal sage (US-SCs), grassland (US-SCg), oak/pine forest (US-SCf), pinyon and juniper woodland (US-SCw), desert chaparral (US-SCc), and desert perennials and annuals (US-SCd). Monitored net ecosystem exchange of carbon (NEE) at the US-Wrc, US-SRM, and US-SCf sites, is used in model calibration and HR sensitivity analysis. Preliminary results from the model indicate that HR tends to increase net primary production (NPP) during dry periods and increase leaf area index (LAI) throughout the year at the US-Wrc site, while HR increased NPP and LAI during growing season and reduced NPP and LAI during dry periods at the US-SCs and US-SCg sites, with corresponding modifications to carbon storage in soil layers and in plant leaf, stem, and root carbon pools. The biogeochemical processes leading to these effects will be analyzed and presented.

  11. Dispersal by rodent caching increases seed survival in multiple ways in canopy-fire ecosystems.

    Science.gov (United States)

    Peterson, N B; Parker, V T

    2016-07-01

    Seed-caching rodents have long been seen as important actors in dispersal ecology. Here, we focus on the interactions with plants in a fire-disturbance community, specifically Arctostaphylos species (Ericaceae) in California chaparral. Although mutualistic relationships between caching rodents and plants are well studied, little is known how this type of relationship functions in a disturbance-driven system, and more specifically to systems shaped by fire disturbance. By burying seeds in the soil, rodents inadvertently improve the probability of seed surviving high temperatures produced by fire. We test two aspects of vertical dispersal, depth of seed and multiple seeds in caches as two important dimensions of rodent-caching behavior. We used a laboratory experimental approach to test seed survival under different heating conditions and seed bank structures. Creating a synthetic soil seed bank and synthetic fire/heating in the laboratory allowed us to have control over surface heating, depth of seed in the soil, and seed cache size. We compared the viability of Arctostaphylos viscida seeds from different treatment groups determined by these factors and found that, as expected, seeds slightly deeper in the soil had substantial increased chances of survival during a heating event. A key result was that some seeds within a cache in shallow soil could survive fire even at a depth with a killing heat pulse compared to isolated seeds; temperature measurements indicated lower temperatures immediately below caches compared to the same depth in adjacent soil. These results suggest seed caching by rodents increases seed survival during fire events in two ways, that caches disrupt heat flow or that caches are buried below the heat pulse kill zone. The context of natural disturbance drives the significance of this mutualism and further expands theory regarding mutualisms into the domain of disturbance-driven systems. PMID:27386076

  12. Middle Miocene carnivorans from the Monarch Mill Formation, Nevada

    Directory of Open Access Journals (Sweden)

    Kent Smith

    2016-02-01

    Full Text Available he lowest part of the Monarch Mill Formation in the Middlegate basin, west-central Nevada, has yielded a middle Miocene (Barstovian Land Mammal Age vertebrate assemblage, the Eastgate local fauna. Paleobotanical evidence from nearby, nearly contemporaneous fossil leaf assemblages indicates that the Middle Miocene vegetation in the area was mixed coniferous and hardwood forest and chaparral-sclerophyllous shrubland, and suggests that the area had been uplifted to 2700–2800 m paleoaltitude before dropping later to near its present elevation of 1600 m. Thus, the local fauna provides a rare glimpse at a medium- to high-altitude vertebrate community in the intermountain western interior of North America. The local fauna includes the remains of fish, amphibians, reptiles, birds, and 25 families of mammals. Carnivorans, the focus of this study, include six taxa (three of which are new belonging to four families. Canidae are represented by the borophagine Tomarctus brevirostris and the canine Leptocyon sp. indet. The earliest record and second North American occurrence of the simocyonine ailurid Actiocyon is represented by A. parverratis sp. nov. Two new mustelids, Brevimalictis chikasha gen. et sp. nov. and Negodiaetictis rugatrulleum gen. et sp. nov., may represent Galictinae but are of uncertain subfamilial and tribal affinity. The fourth family is represented by the felid Pseudaelurus sp. indet. Tomarctus brevirostris is limited biochronologically to the Barstovian land mammal age and thus is consistent with the age indicated by other members of the Eastgate local fauna as well as by indirect tephrochronological dates previously associated with the Monarch Mill Formation. Actiocyon parverratis sp. nov. extends the temporal range of the genus Actiocyon from late Clarendonian back to the Barstovian. The Eastgate local fauna improves our understanding of mammalian successions and evolution, during and subsequent to the Mid-Miocene Climatic Optimum

  13. Parallel Computing for Terrestrial Ecosystem Carbon Modeling

    International Nuclear Information System (INIS)

    Terrestrial ecosystems are a primary component of research on global environmental change. Observational and modeling research on terrestrial ecosystems at the global scale, however, has lagged behind their counterparts for oceanic and atmospheric systems, largely because the unique challenges associated with the tremendous diversity and complexity of terrestrial ecosystems. There are 8 major types of terrestrial ecosystem: tropical rain forest, savannas, deserts, temperate grassland, deciduous forest, coniferous forest, tundra, and chaparral. The carbon cycle is an important mechanism in the coupling of terrestrial ecosystems with climate through biological fluxes of CO2. The influence of terrestrial ecosystems on atmospheric CO2 can be modeled via several means at different timescales. Important processes include plant dynamics, change in land use, as well as ecosystem biogeography. Over the past several decades, many terrestrial ecosystem models (see the 'Model developments' section) have been developed to understand the interactions between terrestrial carbon storage and CO2 concentration in the atmosphere, as well as the consequences of these interactions. Early TECMs generally adapted simple box-flow exchange models, in which photosynthetic CO2 uptake and respiratory CO2 release are simulated in an empirical manner with a small number of vegetation and soil carbon pools. Demands on kinds and amount of information required from global TECMs have grown. Recently, along with the rapid development of parallel computing, spatially explicit TECMs with detailed process based representations of carbon dynamics become attractive, because those models can readily incorporate a variety of additional ecosystem processes (such as dispersal, establishment, growth, mortality etc.) and environmental factors (such as landscape position, pest populations, disturbances, resource manipulations, etc.), and provide information to frame policy options for climate change impact

  14. Carbon Cycling Studies in Forest and Rangeland Ecosystems of Northern and Central Coastal California

    Science.gov (United States)

    Potter, C.; Klooster, S.; Gross, P.; Hiatt, S.; Genovese, V.

    2008-12-01

    The varied topography and micro-climates of northern and central coastal California result in high biodiversity and many different levels of primary production driving regional carbon cycles. Coastal mountains trap moisture from low clouds and fog in summer to supplement rainfall in winter. This creates a favorable micro-environment for coniferous forests, including the southernmost habitat of the coast redwood (Sequoia sempervirens), which grows mainly on lower north-facing slopes in Big Sur. In rain shadows, forests transition to open oak woodland, and then into the more fire-tolerant chaparral and coast scrub. Field sites for our on-going climate change studies on the California northern and central coasts currently include the University of California Santa Cruz Campus Natural Reserve, the US Forest Service Brazil Ranch, and the University of California Big Creek Reserve. We are conducting research at each of these sites to better understand possible impacts of climate change, including: (1) biological and physical capacity of soils to capture carbon and retain plant-essential nutrients; (2) rates of plant-soil water and carbon cycling and energy flow; and (3) recovery mechanisms for disturbances such as invasive weed species, grazing, and wildfire. The NASA-CASA simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate carbon cycling for much of the central coast as far north as Mendocino County. Net primary production (NPP) of all vegetation cover was mapped at 30-meter resolution for selected years by combining MODIS and Landsat images across the region. Results show annual NPP predictions of between 200-400 grams C per square meter for coastal scrub and 800-1200 grams C per square meter for coastal evergreen forests, Net ecosystem fluxes of carbon will be presented for the region based on NASA-CASA modeling and field measurements of soil respiration fluxes.

  15. Demographic patterns of postfire regeneration in Mediterranean-climate shrublands of California

    Science.gov (United States)

    Keeley, J.E.; Fotheringham, C.J.; Baer-Keeley, M.

    2006-01-01

    This study uses detailed demographic data to determine the extent to which functional groupings, based on seedling recruitment and resprouting response to fire, capture the dynamics of postfire responses and early successional change in fire-prone ecosystems. Following massive wildfires in southern California, USA, we sampled chaparral and sage scrub vegetation in nested 0.1-ha plots from 90 sites for five postfire years. Prefire density of woody skeletons and cover and density of all postfire species were recorded. Functional types of postfire obligate seeder, facultative seeder, and obligate resprouter are broadly useful but fail to capture much of the dynamics of postfire succession in these shrublands. For the woody flora, stratifying these three regeneration modes by life-form captures important differences. Postfire obligate-seeding shrubs exhibit a single postfire seedling cohort whereas the faster growing suffrutescent species reach reproductive maturity by the second year and produce multiple seedling cohorts. Postfire obligate-resprouting shrubs reach reproductive maturity early but have very limited seedling recruitment in the early postfire years, whereas obligate-resprouting subshrubs flower the first year from resprouts and have seedling recruitment pulses in the second and subsequent postfire years. For the rich herbaceous flora, further subdivisions are needed to capture the range of variation. Herbaceous perennials are nearly all postfire obligate resprouters, and there are important demographic differences during early succession in different growth forms such as geophytes and rhizomatous grasses. Annuals lack resprouting ability and are postfire obligate seeders. Some exhibit extreme life-history specialization and are present only in the immediate postfire year(s). Others are highly specialized on fire but persist during early succession, and still others are opportunistic species widely distributed on open sites but can expand their populations

  16. San Gabriel Mountains, California, Radar image, color as height

    Science.gov (United States)

    2000-01-01

    This topographic radar image shows the relationship of the urban area of Pasadena, California to the natural contours of the land. The image includes the alluvial plain on which Pasadena and the Jet Propulsion Laboratory sit, and the steep range of the San Gabriel Mountains. The mountain front and the arcuate valley running from upper left to the lower right are active fault zones, along which the mountains are rising. The chaparral-covered slopes above Pasadena are also a prime area for wildfires and mudslides. Hazards from earthquakes, floods and fires are intimately related to the topography in this area. Topographic data and other remote sensing images provide valuable information for assessing and mitigating the natural hazards for cities along the front of active mountain ranges.This image combines two types of data from the Shuttle Radar Topography Mission. The image brightness corresponds to the strength of the radar signal reflected from the ground, while colors show the elevation as measured by SRTM. Colors range from blue at the lowest elevations to white at the highest elevations. This image contains about 2300 meters (7500 feet) of total relief. White speckles on the face of some of the mountains are holes in the data caused by steep terrain. These will be filled using coverage from an intersecting pass.The Shuttle Radar Topography Mission (SRTM), launched on February 11,2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) and the

  17. Using ecological forecasting of future vegetation transition and fire frequency change in the Sierra Nevada to assess fire management strategies

    Science.gov (United States)

    Thorne, J. H.; Schwartz, M. W.; Holguin, A. J.; Moritz, M.; Batllori, E.; Folger, K.; Nydick, K.

    2013-12-01

    strong upslope shifting of open grassland, chaparral and hardwood types, which may be initiated by increased fire frequencies, particularly where fires have not recently burned within normal fire recurrence interval departures (FRID). An evaluation of four fire management strategies (business as usual; resist change; foster orderly change; protect vital resources) across four combinations of future climate and fire frequency found that no single management strategy was uniformly successful in protecting critical resources across the range of future conditions examined. This limitation is somewhat driven by current management constraints on the amount of management available to resource managers, which suggests management will need to use a triage approach to application of proactive fire management strategies, wherein MOC landscape projections can be used in decision support.

  18. Habitat suitability of patch types:A case study of the Yosemite toad

    Institute of Scientific and Technical Information of China (English)

    Christina T.LIANG; Thomas J.STOHLGREN

    2011-01-01

    Understanding patch variability is crucial in understanding the spatial population structure of wildlife species,especially for rare or threatened species.We used a well-tested maximum entropy species distribution model (Maxent) to map the Yosemite toad (Anaxyrus (= Bufo) canorus) in the Sierra Nevada mountains of California.Twenty-six environmental variables were included in the model representing climate,topography,land cover type,and disturbance factors (e.g.,distances to agricultural lands,fire perimeters,and timber harvest areas) throughout the historic range of the toad.We then took a novel approach to the study of spatially structured populations by applying the species-environmental matching model separately for 49 consistently occupied sites of the Yosemite toad compared to 27 intermittently occupied sites.We found that the distribution of the entire population was highly predictable (AUC= 0.95±0.03 SD),and associated with low slopes,specific vegetation types (wet meadow,alpine-dwarf shrub,montane chaparral,red fir,and subalpine conifer),and warm temperatures.The consistently occupied sites were also associated with these same factors,and they were also highly predictable (AUC= 0.95±0.05 SD).However,the intermittently occupied sites were associated with distance to fire perimeter,a slightly different response to vegetation types,distance to timber harvests,and a much broader set of aspect classes (AUC = 0.90±0.11 SD).We conclude that many studies of species distributions may benefit by modeling spatially structured populations separately.Modeling and monitoring consistently-occupied sites may provide a realistic snapshot of current speciesenvironment relationships,important climatic and topographic patterns associated with species persistence patterns,and an understanding of the plasticity of the species to respond to varying climate regimes across its range.Meanwhile,modeling and monitoring of widely dispersing individuals and intermittently occupied

  19. IPLOR performance in detecting infrasound from volcanic eruptions

    Science.gov (United States)

    Ghica, Daniela; Popa, Mihaela

    2016-04-01

    Plostina infrasound array (IPLOR) is located in the central part of Romania, in Vrancea region, its current configuration consisting of 6 elements equipped with Chaparral Physics sensors deployed over a 2.5 km aperture. The array detectability observed after processing of more than 6 years of data has shown that IPLOR is more effective in measuring mainly infrasound signals produced by natural and anthropogenic impulsive sources. This can be explained by the sensors' characteristics (frequency response, dynamic range) and the large aperture of array. Among the types of events observed with IPLOR, an emphasis can be given to the Mt. Etna volcanic eruptions as one of the powerful infrasound source recorded by the array. Located at about 1320 km distance from volcano, the array has proved efficient in observing both large and small eruptions. In case of the most large eruptive episodes occurred lately (April and October 2013, December 2015), long duration infrasonic signals were detected, the initial impulsive signature of the volcanic explosion being followed by a long train of irregular waves with smaller amplitudes and higher frequency, extended over periods ranging from 6 hours to more than three days (in December 2015). For the purpose of assessing the IPLOR performance in detecting Etna eruptions, the signal interactive analysis was performed using WinPMCC, CEA/DASE version of PMCC software. The infrasound detections obtained were plotted in function of back-azimuth, velocity and frequency, showing that the detectability is dependent both on the diurnal variations of the noise around the array (during the night the human activity diminishes) and on the seasonally dependent stratospheric winds (westward propagation during summer and eastward propagation during winter). In case of the Etna eruptive episodes detected by IPLOR, the back azimuth observed is in good agreement with the expected value (230o), i.e. an average value of 232±2o could be resolved. The

  20. Interfacing models of wildlife habitat and human development to predict the future distribution of puma habitat

    Science.gov (United States)

    Burdett, Christopher L.; Crooks, Kevin R.; Theobald, David M.; Wilson, Kenneth R.; Boydston, Erin E.; Lyren, Lisa A.; Fisher, Robert N.; Vickers, T. Winston; Morrison, Scott A.; Boyce, Walter M.

    2010-01-01

    The impact of human land uses on ecological systems typically differ relative to how extensively natural conditions are modified. Exurban development is intermediate-intensity residential development that often occurs in natural landscapes. Most species-habitat models do not evaluate the effects of such intermediate levels of human development and even fewer predict how future development patterns might affect the amount and configuration of habitat. We addressed these deficiencies by interfacing a habitat model with a spatially-explicit housing-density model to study the effect of human land uses on the habitat of pumas (Puma concolor) in southern California. We studied the response of pumas to natural and anthropogenic features within their home ranges and how mortality risk varied across a gradient of human development. We also used our housing-density model to estimate past and future housing densities and model the distribution of puma habitat in 1970, 2000, and 2030. The natural landscape for pumas in our study area consisted of riparian areas, oak woodlands, and open, conifer forests embedded in a chaparral matrix. Pumas rarely incorporated suburban or urban development into their home ranges, which is consistent with the hypothesis that the behavioral decisions of individuals can be collectively manifested as population-limiting factors at broader spatial scales. Pumas incorporated rural and exurban development into their home ranges, apparently perceiving these areas as modified, rather than non-habitat. Overall, pumas used exurban areas less than expected and showed a neutral response to rural areas. However, individual pumas that selected for or showed a neutral response to exurban areas had a higher risk of mortality than pumas that selected against exurban habitat. Exurban areas are likely hotspots for puma-human conflict in southern California. Approximately 10% of our study area will transform from exurban, rural, or undeveloped areas to suburban or

  1. Fluid Substitution Modeling to Determine Sensitivity of 3D Vertical Seismic Profile Data to Injected CO­2­ at an active Carbon Capture, Utilization and Storage Project, Farnsworth field, TX.

    Science.gov (United States)

    Haar, K. K.; Balch, R. S.

    2015-12-01

    The Southwest Regional Partnership on Carbon Sequestration monitors a CO2 capture, utilization and storage project at Farnsworth field, TX. The reservoir interval is a Morrowan age fluvial sand deposited in an incised valley. The sands are between 10 to 25m thick and located about 2800m below the surface. Primary oil recovery began in 1958 and by the late 1960's secondary recovery through waterflooding was underway. In 2009, Chaparral Energy began tertiary recovery using 100% anthropogenic CO2 sourced from an ethanol and a fertilizer plant. This constitutes carbon sequestration and fulfills the DOE's initiative to determine the best approach to permanent carbon storage. One purpose of the study is to understand CO­2 migration from injection wells. CO2­ plume spatial distribution for this project is analyzed with the use of time-lapse 3D vertical seismic profiles centered on CO2 injection wells. They monitor raypaths traveling in a single direction compared to surface seismic surveys with raypaths traveling in both directions. 3D VSP surveys can image up to 1.5km away from the well of interest, exceeding regulatory requirements for maximum plume extent by a factor of two. To optimize the timing of repeat VSP acquisition, the sensitivity of the 3D VSP surveys to CO2 injection was analyzed to determine at what injection volumes a seismic response to the injected CO­2 will be observable. Static geologic models were generated for pre-CO2 and post-CO2 reservoir states through construction of fine scale seismic based geologic models, which were then history matched via flow simulations. These generated static states of the model, where CO2­ replaces oil and brine in pore spaces, allow for generation of impedance volumes which when convolved with a representative wavelet generate synthetic seismic volumes used in the sensitivity analysis. Funding for the project is provided by DOE's National Energy Technology Laboratory (NETL) under Award No. DE-FC26-05NT42591.

  2. Seismo-acoustic array installed in Vrancea seismogenic area

    Science.gov (United States)

    Ionescu, Constantin; Moldovan, Adrian-Septimiu; Moldovan, Iren-Adelina; Ghica, Daniela

    2010-05-01

    The National Institute for Earth Physics (NIEP) has installed two infrasound networks: a four-element seismo-acoustic array with an 1.2 km aperture (IPLOR) and a three-element array with a 400m aperture (IOANE). Both arrays are installed in Vrancea seismogenic area. Each array element of IPLOR consists of three sensors (a seismic 3C broad-band instrument with 1000V/m/s sensitivity, an accelerometer +/-2g EpiSensor type, and an infrasound Chaparral type sensor) and a 24-bit digitizer (Quanterra Q330). The BB sensors and accelerometers are located in 3 meters deep boreholes, while the infrasound sensors are installed in a plastic 1 mc container connected to a porous flexible pipe or plastic tube (for the central element). Inter-array communication is achieved by radio link (2.4 GHz frequency band) which transmits the data from the six-channel digitizers to the local acquisition system. Each power array element consisted of a 12 V DC source powered by the commercial power line or solar panels. The data acquisition system is based on the Seiscomp3 software; a sampling rate of 100 samples per second is applied for BB seismic instruments and accelerometers, whilst for the infrasound sensor a 20 sps rate is used. Each array element of IPLOR consists of a MBAZEL2007 microbarometer and a 24-bit digitizer. Inter-array communication is achieved by a fiber optic link. The sampling rate is 10 sps. The Vrancea seismo-acoustic array is used to identify and locate events associated with industrial blasts, to detect local and regional events, as well for the complex studies on the Vrancea seismogenic area. Moreover, the array data accelerometers are used in the early warning system for Bucharest. At NIEP, several programs are running to analyze each type of data (seismic and acoustic): for BB seismic data, a software for event detection and characterization, kindly provided by NORSAR, is applied, acceleration data recorded by the episensors are processed with a software developed

  3. West Texas array experiment: Noise and source characterization of short-range infrasound and acoustic signals, along with lab and field evaluation of Intermountain Laboratories infrasound microphones

    Science.gov (United States)

    Fisher, Aileen

    The term infrasound describes atmospheric sound waves with frequencies below 20 Hz, while acoustics are classified within the audible range of 20 Hz to 20 kHz. Infrasound and acoustic monitoring in the scientific community is hampered by low signal-to-noise ratios and a limited number of studies on regional and short-range noise and source characterization. The JASON Report (2005) suggests the infrasound community focus on more broad-frequency, observational studies within a tactical distance of 10 km. In keeping with that recommendation, this paper presents a study of regional and short-range atmospheric acoustic and infrasonic noise characterization, at a desert site in West Texas, covering a broad frequency range of 0.2 to 100 Hz. To spatially sample the band, a large number of infrasound gauges was needed. A laboratory instrument analysis is presented of the set of low-cost infrasound sensors used in this study, manufactured by Inter-Mountain Laboratories (IML). Analysis includes spectra, transfer functions and coherences to assess the stability and range of the gauges, and complements additional instrument testing by Sandia National Laboratories. The IMLs documented here have been found reliably coherent from 0.1 to 7 Hz without instrument correction. Corrections were built using corresponding time series from the commercially available and more expensive Chaparral infrasound gauge, so that the corrected IML outputs were able to closely mimic the Chaparral output. Arrays of gauges are needed for atmospheric sound signal processing. Our West Texas experiment consisted of a 1.5 km aperture, 23-gauge infrasound/acoustic array of IMLs, with a compact, 12 m diameter grid-array of rented IMLs at the center. To optimize signal recording, signal-to-noise ratio needs to be quantified with respect to both frequency band and coherence length. The higher-frequency grid array consisted of 25 microphones arranged in a five by five pattern with 3 meter spacing, without

  4. Infrasound research at Kola Regional Seismological Centre, Russia

    Science.gov (United States)

    Asming, Vladimir; Kremenetskaya, Elena

    2013-04-01

    A small-aperture infrasound array has been installed in Kola Peninsula, Russia 17 km far from the town of Apatity in the year 2000. It comprises 3 Chaparral V microbarographs placed closely to the APA seismic array sensors and equipped with pipe wind reducing filters. The data are digitized at the array site and transmitted in real time to a processing center in Apatity. To search for infrasound events (arrivals of coherent signals) a beamforming-style detector has been developed. Now it works in near real time. We analyzed the detecting statistics for different frequency bands. Most man-made events are detected in 1-5 Hz band, microbaromes are typically detected in 0.2-1 Hz band. In lower frequencies we record mostly a wind noise. A data base of samples of infrasound signals of different natures has been collected. It contains recordings of microbaromes, industrial and military explosions, airplane shock waves, infrasound of airplanes, thunders, rocket launches and reentries, bolides etc. The most distant signals we have detected are associated with Kursk Magnetic Anomaly explosions (1700 km far from Apatity). We implemented an algorithm for association of infrasound signals and preliminary location of infrasound events by several arrays. It was tested with Apatity data together with data of Sweden - Finnish infrasound network operated by the Institute of Space Physics in Umea (Sweden). By agreement with NORSAR we have a real-time access to the data of Norwegian experimental infrasound installation situated in Karasjok (North Norway). Currently our detection and location programs work both with Apatity and Norwegian data. The results are available in Internet. Finnish militaries routinely destroy out-of-date weapon in autumns at the same compact site in North Finland. This is a great source of repeating infrasound signals of the same magnitude and origin. We recorded several hundreds of such explosions. The signals have been used for testing our location routines

  5. Constraining Diffusivity and Critical Slope from Post-Fire Sediment Flux of the Day, Canyon, and Corral Fires, California

    Science.gov (United States)

    Schmidt, K. M.; Stock, J. D.; Hanshaw, M. N.; Bawden, G. W.

    2008-12-01

    months post-installation) m2day-1. Five traps in the Canyon and Corral fire sites were fit with a 0.72 critical slope and a 0.03 m2day-1 diffusivity for the time-frame of 2 months post installation, values similar to the Day fire sites. Three sites at the Canyon and Corral fires showed signs of sediment supply or process effects on their flux rates. These steepest sites (0.79-0.91 slope) were located several meters downslope from rock outcrops and had flux rates characteristic of lower slope sites in less supply-limited reaches. These low rates may represent reduced flux rates from small source lengths and close proximity to bedrock outcrops where rockfall, not grain flow, is the dominant transport process.At all sites, the largest amount of hillslope transport occurred prior to the arrival of the greatest amount of precipitation. Reductions in post-fire sediment flux and diffusivity values are consistent with field observations documenting that initially soil- mantled hillslopes were gradually stripped to bedrock and converted from transport-limited to supply-limited conditions. Furthermore, a time-series of terrestrial LiDAR surveys documented the gradual infilling of low- order valleys by as much as 1 m of sediment and that small frictional dams formed by the regrowth of vegetation provided effective traps and a mechanism to rapidly decrease diffusivity. Hence, high rates of transport in landscapes disturbed by fire can be quickly modulated through decreased sediment availability and the progressive trapping efficiency of densely spaced chaparral vegetation regrowth.

  6. Spatial variations in atmospheric CO2 concentrations during the ARCTAS-CARB 2008 Summer Campaign

    Science.gov (United States)

    Vadrevu, K. P.; Choi, Y.; Vay, S. A.

    2009-12-01

    The Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) was a major NASA field campaign designed to understand the transport and transformation of trace gases and aerosols on transcontinental and intercontinental scales and their impact on the composition of the arctic atmosphere and climate. Preceding the summer ARCTAS deployment, measurements were conducted over the state of California in collaboration with the California Air Resources Board (CARB) utilizing the airborne chemistry payload already integrated on the NASA DC-8. In situ CO2 measurements were made using a modified infrared CO2 gas analyzer having a precision of 0.1 ppmv and accuracy of ±0.25 ppmv traceable to the WMO scale. This analysis focuses on the atmospheric CO2 variability and biospheric/atmospheric exchange over California. We used multi-satellite remote sensing datasets to relate airborne observations of CO2 to infer sources and sinks. Georeferencing the airborne CO2 transect data with the LANDSAT derived land cover datasets over California suggested significant spatial variations. The airborne CO2 concentrations were found to be 375-380ppm over the Pacific ocean, 385-391ppm in the highly vegetated agricultural areas, 400-420 in the near coastal areas and greater than 425ppmv in the urban areas. Analysis from MODIS fire products suggested significant fires in northern California. CO2 emissions exceeded 425ppmv in the fire affected regions, where mostly Douglas and White Fir conifers and mixed Chaparral vegetation was burnt. Analysis from GOES-East and GOES-West visible satellite imagery suggested significant smoke plumes moving from northern California towards Nevada and Idaho. To infer the biospheric uptake of CO2, we tested the potential correlations between airborne CO2 data and MODIS normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Results suggested significant anti-correlations between the airborne CO2 data and

  7. Coupling field and laboratory measurements to estimate the emission factors of identified and unidentified trace gases for prescribed fires

    Energy Technology Data Exchange (ETDEWEB)

    Yokelson, R. J.; Burling, I. R.; Gilman, J. B.; Warneke, C.; Stockwell, C. E.; de Gouw, J.; Akagi, S. K.; Urbanski, S. P.; Veres, P.; Roberts, J. M.; Kuster, W. C.; Reardon, J.; Griffith, D. W. T.; Johnson, T. J.; Hosseini, S.; Miller, J. W.; Cocker III, D. R.; Jung, H.; Weise, D. R.

    2013-01-01

    Vegetative fuels commonly consumed in prescribed fires were collected from five locations in the southeastern and southwestern U.S. and burned in a series of 77 fires at the U.S. Forest Service Fire Sciences Laboratory in Missoula, Montana. The particulate matter (PM2.5) emissions were measured by gravimetric filter sampling with subsequent analysis for elemental carbon (EC), organic carbon (OC), and 38 elements. The trace gas emissions were measured with a large suite of state-of-the-art instrumentation including an open-path Fourier transform infrared (OP FTIR) spectrometer, proton-transfer-reaction mass spectrometry (PTR-MS), proton-transfer ion-trap mass spectrometry (PIT-MS), negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), and gas chromatography with MS detection (GC-MS). 204 trace gas species (mostly non-methane organic compounds (NMOC)) were identified and quantified with the above instruments. An additional 152 significant peaks in the unit mass resolution mass spectra were quantified, but either could not be identified or most of the signal at that molecular mass was unaccounted for by identifiable species. As phase II of this study, we conducted airborne and ground-based sampling of the emissions from real prescribed fires mostly in the same land management units where the fuels for the lab fires were collected. A broad variety, but smaller number of species (21 trace gas species and PM2.5) was measured on 14 fires in chaparral and oak savanna in the southwestern US, as well as pine forest understory in the southeastern US and Sierra Nevada mountains of California. These extensive field measurements of emission factors (EF) for temperate biomass burning are useful both for modeling and to examine the representativeness of our lab fire EF. The lab/field EF ratio for the pine understory fuels was not statistically different from one, on average. However, our lab EF for “smoldering compounds” emitted by burning the semi

  8. Library of Congress Model, Perspective View

    Science.gov (United States)

    2004-01-01

    limits urban expansion. Similarly, major transportation routes are limited to a few mountain passes. Water supply to the city and drainage away from it both follow paths largely dictated by topography. Radio, television, and cell phone transmission towers are all sited with topography in mind to maximize coverage. Its climate and scenic mountain surroundings have been a major part of the appeal of the Los Angeles region as it has grown into one of the world's largest cities over the past 150 years. But the topography that has created this environment also results from and leads to significant natural hazards. The tall mountains result from tectonic compression and uplift of Earth's crust along a kink in the San Andreas fault. (The fault is seen here as a straight boundary between the Mojave Desert and the San Gabriel Mountains.) Major earthquakes occur on the San Andreas fault every few centuries. Damaging earthquakes also occur on other faults across the region several times in a typical human lifespan. Most of these faults were first recognized by their impact upon the topographic pattern. Meanwhile, wildfires are common in the chaparral covered hills and mountains, and topography affects the fire's path (burning more readily upslope) as well as our ability to fight it. After a fire, rainfall from winter storms often strips exposed soil, accumulates it as mudflows in rugged canyons, and dumps it into the adjacent valleys which are now heavily urbanized. Topography is indeed important in the lives of the people of Los Angeles. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data substantially help in analyzing Landsat images by revealing the third dimension of Earth's surface, topographic height. The Landsat archive is managed by the U.S. Geological Survey's Eros Data Center (USGS EDC). Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched

  9. Library of Congress Model, Anaglyph

    Science.gov (United States)

    2004-01-01

    little rainfall for areas further inland, thus creating the deserts. Topography also controls the land use pattern. The mountains are mostly very rugged, which greatly limits urban expansion. Similarly, major transportation routes are limited to a few mountain passes. Water supply to the city and drainage away from it both follow paths largely dictated by topography. Radio, television, and cell phone transmission towers are all sited with topography in mind to maximize coverage. Its climate and scenic mountain surroundings have been a major part of the appeal of the Los Angeles region as it has grown into one of the world's largest cities over the past 150 years. But the topography that has created this environment also results from and leads to significant natural hazards. The tall mountains result from tectonic compression and uplift of Earth's crust along a kink in the San Andreas fault. (The fault is seen here as a straight boundary between the Mojave Desert and the San Gabriel Mountains.) Major earthquakes occur on the San Andreas fault every few centuries. Damaging earthquakes also occur on other faults across the region several times in a typical human lifespan. Most of these faults were first recognized by their impact upon the topographic pattern. Meanwhile, wildfires are common in the chaparral covered hills and mountains, and topography affects the fire's path (burning more readily upslope) as well as our ability to fight it. After a fire, rainfall from winter storms often strips exposed soil, accumulates it as mudflows in rugged canyons, and dumps it into the adjacent valleys which are now heavily urbanized. Topography is indeed important in the lives of the people of Los Angeles. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data substantially help in analyzing Landsat images by revealing the third dimension of Earth's surface, topographic height. The Landsat archive is managed by the U.S. Geological Survey

  10. Mountain Lions of the Flagstaff Uplands: 2003-2006 Progress Report

    Science.gov (United States)

    Mattson, David J.

    2007-01-01

    strong selection for rough terrain and forest or woodland cover. Females differed from males by selecting more strongly for intermediate, rather than extreme, levels of terrain roughness, by selecting more strongly for chaparral vegetation and related rocky areas during winter, and by not selecting as strongly for areas near water sources. Overall, lions collared during this study strongly avoided flat open areas in private ownership. Male but not female lions exhibited pronounced selection for National Park Service jurisdictions. Both males and females year-round avoided residential areas and a zone outward to about 1-3 km and, when within this zone, moved more slowly and with less change in direction compared to when farther away. Collared lions have so far rarely crossed paved highways of any description - orders of magnitude less often than expected by chance. We observed only 3 crossings of an interstate highway, all on I17 and none on I40. Elk comprised the majority (52%) of kills by lions in our study, followed by mule deer (46%), and small mammals (15%). Adults comprised most of the mule deer kills (68%) and mesocarnivores, primarily coyotes (n = 21), comprised 73% of smaller prey. Calf and short-yearling elk comprised the largest single category of kills (29%). In addition to kills, we documented seven instances of scavenging, involving four different lions. Females differed from males by killing more mule deer and virtually all of the mesocarnivores, and by killing fewer elk of all ages. Intervals between kills averaged between 144 hrs (young females) to 221 hours (adult females), whereas average time spent on a kill ranged from 19 hrs (adult males) to 40 hrs (young males). Carcass mass had a strong effect on likelihood that a lion would bury or relocate a kill, the percentage of edibles consumed, and overall time spent feeding. Time spent feeding and likelihoods of carcass burial and relocation all peaked at intermediate carcass masses, suggesting an optimal

  11. Coupling field and laboratory measurements to estimate the emission factors of identified and unidentified trace gases for prescribed fires

    Directory of Open Access Journals (Sweden)

    R. J. Yokelson

    2013-01-01

    Full Text Available An extensive program of experiments focused on biomass burning emissions began with a laboratory phase in which vegetative fuels commonly consumed in prescribed fires were collected in the southeastern and southwestern US and burned in a series of 71 fires at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The particulate matter (PM2.5 emissions were measured by gravimetric filter sampling with subsequent analysis for elemental carbon (EC, organic carbon (OC, and 38 elements. The trace gas emissions were measured by an open-path Fourier transform infrared (OP-FTIR spectrometer, proton-transfer-reaction mass spectrometry (PTR-MS, proton-transfer ion-trap mass spectrometry (PIT-MS, negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS, and gas chromatography with MS detection (GC-MS. 204 trace gas species (mostly non-methane organic compounds (NMOC were identified and quantified with the above instruments. Many of the 182 species quantified by the GC-MS have rarely, if ever, been measured in smoke before. An additional 153 significant peaks in the unit mass resolution mass spectra were quantified, but either could not be identified or most of the signal at that molecular mass was unaccounted for by identifiable species.

    In a second, "field" phase of this program, airborne and ground-based measurements were made of the emissions from prescribed fires that were mostly located in the same land management units where the fuels for the lab fires were collected. A broad variety, but smaller number of species (21 trace gas species and PM2.5 was measured on 14 fires in chaparral and oak savanna in the southwestern US, as well as pine forest understory in the southeastern US and Sierra Nevada mountains of California. The field measurements of emission factors (EF are useful both for modeling and to examine the representativeness of our lab fire EF. The lab EF/field EF ratio for

  12. Coupling field and laboratory measurements to estimate the emission factors of identified and unidentified trace gases for prescribed fires

    Directory of Open Access Journals (Sweden)

    R. J. Yokelson

    2012-08-01

    Full Text Available An extensive program of experiments focused on biomass burning emissions began with a laboratory phase in which vegetative fuels commonly consumed in prescribed fires were collected in the southeastern and southwestern US and burned in a series of 71 fires at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The particulate matter (PM2.5 emissions were measured by gravimetric filter sampling with subsequent analysis for elemental carbon (EC, organic carbon (OC, and 38 elements. The trace gas emissions were measured by an open-path Fourier transform infrared (OP-FTIR spectrometer, proton-transfer-reaction mass spectrometry (PTR-MS, proton-transfer ion-trap mass spectrometry (PIT-MS, negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS, and gas chromatography with MS detection (GC-MS. 204 trace gas species (mostly non-methane organic compounds – NMOC were identified and quantified with the above instruments. Many of the 182 species quantified by the GC-MS have rarely, if ever, been measured in smoke before. An additional 153 significant peaks in the unit mass resolution mass spectra were quantified, but either could not be identified or most of the signal at that molecular mass was unaccounted for by identifiable species.

    In a second, "field" phase of this program, airborne and ground-based measurements were made of the emissions from prescribed fires that were mostly located in the same land management units where the fuels for the lab fires were collected. A broad variety, but smaller number of species (21 trace gas species and PM2.5 was measured on 14 fires in chaparral and oak savanna in the southwestern US, as well as pine forest understory in the southeastern US and Sierra Nevada mountains of California. The field measurements of emission factors (EF are useful both for modeling and to examine the representativeness of our lab fire EF. The lab EF/field EF ratio for