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Todd E. Dawson - One of the best experts on this subject based on the ideXlab platform.

  • Fog as a source of nitrogen for redwood trees evidence from fluxes and stable isotopes
    Journal of Ecology, 2015
    Co-Authors: Pamela H Templer, Todd E. Dawson, Holly A Ewing, Kathleen C Weathers, Vanessa K Boukili, Stefania Mambelli, Amanda M Lindsey, Jeramy Webb, Mary K Firestone
    Abstract:

    Author(s): Templer, PH; Weathers, KC; Ewing, HA; Dawson, TE; Mambelli, S; Lindsey, AM; Webb, J; Boukili, VK; Firestone, MK | Abstract: © 2015 British Ecological Society. A defining feature of the redwood forest in coastal California is the presence of Fog in the summer months, a time when there is typically little rainfall. Our goal was to determine the role of summer Fog in canopy transformation of nitrogen, nitrogen uptake by trees and photosynthesis within a coastal redwood forest ecosystem. We measured horizontal and vertical inputs of nitrogen, the isotopic composition of nitrogen in a variety of atmospheric sources (summer Fog, winter rain and throughfall throughout the year), nitrogen pools (soil solution) and plant tissue (roots and foliage), as well as rates of photosynthesis and nitrogen uptake by trees. Throughfall nitrogen fluxes were greater at the forest edge compared to the interior both within the canopy (sampled 10m above-ground) and onto the forest floor (sampled 1m above-ground; Pl0.05). Similarly, soil solution NO3- and total inorganic nitrogen were greater at the forest edge compared to the interior (P=0.0014 and 0.009, respectively). Whereas natural abundance δ15NO3 values were not significantly different between winter rain (measured as bulk precipitation) and summer Fog Water (average δ15N=-1.2±0.680/00), δ15NH4 values were significantly greater in Fog Water (11.4±2.70/00) compared to rain (1.2±0.90/00). We found no difference in δ15N in roots from forest edge trees compared to interior trees. In contrast, nitrogen concentrations and δ15N in foliage from forest edge trees were significantly greater compared to interior trees (Pl0.0001), suggesting that the leaves of forest edge trees may be obtaining a greater proportion of their nitrogen from Fog compared to those of the interior trees. Natural abundance 13C of leaf sugars and rates of photosynthesis were significantly higher at the forest edge compared to the interior during the Fog season (Pl0.05), but not different between locations in the rain season (Pg0.05). Nitrification in the forest floor, rather than the canopy, is the primary source of NO3- in these soils throughout the year. Synthesis. Summer Fog provides nitrogen directly and indirectly to redwood trees, especially those at the forest edge, and affects the physiologic function of redwood trees. Summer Fog provides nitrogen directly and indirectly to redwood trees, especially those at the forest edge, and affects the physiologic function of redwood trees.

  • Polystichum munitum (Dryopteridaceae) varies geographically in its capacity to absorb Fog Water by foliar uptake within the redwood forest ecosystem.
    American Journal of Botany, 2010
    Co-Authors: Emily B. Limm, Todd E. Dawson
    Abstract:

     Premise of the study : Fog provides a critical Water resource to plants around the world. In the redwood forest ecosystem of northern California, plants depend on Fog absorbed through foliar uptake to stay hydrated during the rainless summer. In this study, we identifi ed regions within the redwood ecosystem where the fern Polystichum munitum canopy most effectively absorbs Fog drip that reaches the forest fl oor.  Methods : We measured the foliar uptake capacity of P. munitum fronds at seven sites along 700 km of the redwood forest ecosystem. We quantifi ed the canopy cover of P. munitum at each site and estimated how much Water the fern canopy can acquire aboveground through Fog interception and absorption.  Key results : Throughout the ecosystem, nocturnal foliar uptake increased the leaf Water content of P. munitum by 7.2%, and we estimated that the P. munitum canopy can absorb 5 ± 3% (mean ± SE) of intercepted Fog precipitation. Strikingly, P. munitum had the highest foliar uptake capacity in the center of the ecosystem and may absorb 10% more of the Fog its canopy intercepts in this region relative to other regions studied. Conversely, P. munitum had no foliar uptake capacity in the southern end of the ecosystem.  Conclusions : This study shows the fi rst evidence that foliar uptake varies within species at the landscape scale. Our fi ndings suggest that the P. munitum at the southern tip of the redwood ecosystem may suffer most from low summertime Water availability because it had no potential to acquire Fog as an aboveground Water subsidy.

  • Foliar Water uptake: a common Water acquisition strategy for plants of the redwood forest
    Oecologia, 2009
    Co-Authors: Emily B. Limm, Kevin A. Simonin, Aron G. Bothman, Todd E. Dawson
    Abstract:

    Evaluations of plant Water use in ecosystems around the world reveal a shared capacity by many different species to absorb rain, dew, or Fog Water directly into their leaves or plant crowns. This mode of Water uptake provides an important Water subsidy that relieves foliar Water stress. Our study provides the first comparative evaluation of foliar uptake capacity among the dominant plant taxa from the coast redwood ecosystem of California where crown-wetting events by summertime Fog frequently occur during an otherwise drought-prone season. Previous research demonstrated that the dominant overstory tree species, Sequoia sempervirens , takes up Fog Water by both its roots (via drip from the crown to the soil) and directly through its leaf surfaces. The present study adds to these early findings and shows that 80% of the dominant species from the redwood forest exhibit this foliar uptake Water acquisition strategy. The plants studied include canopy trees, understory ferns, and shrubs. Our results also show that foliar uptake provides direct hydration to leaves, increasing leaf Water content by 2–11%. In addition, 60% of redwood forest species investigated demonstrate nocturnal stomatal conductance to Water vapor. Such findings indicate that even species unable to absorb Water directly into their foliage may still receive indirect benefits from nocturnal leaf wetting through suppressed transpiration. For these species, leaf-wetting events enhance the efficacy of nighttime re-equilibration with available soil Water and therefore also increase pre-dawn leaf Water potentials.

  • Fog Water and ecosystem function heterogeneity in a california redwood forest
    Ecosystems, 2009
    Co-Authors: Holly A Ewing, Todd E. Dawson, Kathleen C Weathers, Pamela H Templer, Mary K Firestone, Amanda M Elliott, Vanessa K Boukili
    Abstract:

    Fog is thought to influence ecological function in coastal forests worldwide, yet few data are available that illuminate the mechanisms underlying this influence. In a California redwood forest we measured Water and nitrogen (N) fluxes from horizontally moving Fog and vertically delivered rain as well as redwood tree function. The spatial heterogeneity of Water and N fluxes, Water availability, tree Water use, and canopy N processing varied greatly across seasons. Water and N fluxes to soil (annual average of 98% and 89%, respectively) across the whole forest occurred primarily in the rain season and was relatively even across the whole forest. In contrast, below-canopy flux of Fog Water and N declined exponentially from the windward edge to the forest interior. Following large Fog events, soil moisture was greater at the windward edge than anywhere else in the forest. Physiological activity in redwoods reflected these differences in inputs across seasons: tree physiological responses did not vary spatially in the rain season, but in the Fog season, Water use was greater, yet Water stress was less, in trees at the windward edge of the forest versus the interior. In both seasons, vertical passage through the forest changed the amount of Water and form and concentration of N, revealing the role of the tree canopy in processing atmospheric inputs. Although total Fog Water inputs were comparatively small, they may have important ecosystem functions, including relief of canopy Water stress and, where there is Fog drip, functional coupling of above- and belowground processes.

  • the contribution of Fog to the Water relations of sequoia sempervirens d don foliar uptake and prevention of dehydration
    Plant Cell and Environment, 2004
    Co-Authors: Stephen S O Burgess, Todd E. Dawson
    Abstract:

    Fog is a defining feature of the coastal California redwood forest and Fog inputs via canopy drip in summer can constitute 30% or more of the total Water input each year. A great deal of occult precipitation (Fog and light rain) is retained in redwood canopies, which have some of the largest leaf area indices known (Westman & Whittaker, Journal of Ecology 63, 493–520, 1975). An investigation was carried out to determine whether some fraction of intercepted Fog Water might be directly absorbed through leaf surfaces and if so, the importance of this to the Water relations physiology of coast redwood, Sequoia sempervirens. An array of complimentary techniques were adopted to demonstrate that Fog is absorbed directly by S. sempervirens foliage. Xylem sap transport reversed direction during heavy Fog, with instantaneous flow rates in the direction of the soil peaking at approximately 5–7% of maximum transpiration rate. Isotopic analyses showed that up to 6% of a leaf's Water content could be traced to a previous night's Fog deposition, but this amount varied considerably depending on the age and Water status of the leaves. Old leaves, which appear most able to absorb Fog Water were able to absorb distilled Water when fully submersed at an average rate of 0.90 mmol m2 s−1, or about 80% of transpiration rates measured at the leaf level in the field. Sequoia sempervirens has poor stomatal control in response to a drying atmosphere, with rates of Water loss on very dry nights up to 40% of midday summer values and rates above 10% being extremely common. Owing to this profligate Water use behaviour of S. sempervirens, it appears that Fog has a greater role in suppressing Water loss from leaves, and thereby ameliorating daily Water stress, than in providing supplemental Water to foliar tissues per se. Although direct foliar absorption from Fog inputs represents only a small fraction of the Water used each day, Fog's in reducing transpiration and rehydrating leaf tissues during the most active growth periods in summer may allow for greater seasonal carbon fixation and thus contribute to the very fast growth rates and great size of this species.

Jana Olivier - One of the best experts on this subject based on the ideXlab platform.

  • Fog as a Fresh-Water Resource: Overview and Perspectives
    AMBIO, 2012
    Co-Authors: Otto Klemm, Anne Lummerich, Tseggai Gherezghiher, David Corell, Pilar Cereceda, Robert S Schemenauer, Victoria Marzol, Johan Heerden, Dirk Reinhard, Jana Olivier
    Abstract:

    The collection of Fog Water is a simple and sustainable technology to obtain fresh Water for afforestation, gardening, and as a drinking Water source for human and animal consumption. In regions where fresh Water is sparse and Fog frequently occurs, it is feasible to set up a passive mesh system for Fog Water collection. The mesh is directly exposed to the atmosphere, and the Foggy air is pushed through the mesh by the wind. Fog droplets are deposited on the mesh, combine to form larger droplets, and run down passing into a storage tank. Fog Water collection rates vary dramatically from site to site but yearly averages from 3 to 10 l m^−2 of mesh per day are typical of operational projects. The scope of this article is to review Fog collection projects worldwide, to analyze factors of success, and to evaluate the prospects of this technology.

  • Fog Water harvesting along the west coast of south africa a feasibility study
    Water SA, 2002
    Co-Authors: Jana Olivier
    Abstract:

    Many parts of the West Coast of South Africa experience severe Water shortages throughout the year. Despite the meager rainfall, however, the region is subject to a high incidence of Fog which might provide Water for Water-poor communities. This paper investigates the Fog Water potential of the area. Since Fog Water collection rates are to some extent dependent upon the spatial and temporal characteristics of Fog, these aspects were investigated. Pilot Fog collectors were erected at six West Coast sites and the Water collection rates measured over a three to four year period. It was found that the incidence of Fog is mostly confined to the coastal zone below the 200 m contour line with Fog frequency decreasing with latitude within this zone. The highest Water collection rates were recorded at Cape Columbine where volumes in excess of 2.5 /m 2 of collecting surface can be expected to be collected per day. Of this, approximately 90% is due to Fog deposition alone, while rainfall contributes to the remaining 10%. The quality of the Water is good and fit for human consumption.

  • the implementation of Fog Water collection systems in south africa
    Atmospheric Research, 2002
    Co-Authors: Jana Olivier, C J De W Rautenbach
    Abstract:

    Two Fog Water collection systems (FWCS) have been implemented in South Africa. Both are located in areas where communities experience acute Water shortages but which are prone to frequent Fog episodes. The first was located at a high elevation site at the Tshanowa Junior Primary (JP) School in the Soutpansberg located in the Northern Province and the other near a small rural community at Lepelfontein along the West Coast. The former represents a mountainous site, while the latter is located on a low level coastal plain. The principal aim of the projects was to implement operational FWCSs to supply the communities with Water. During the period 1999 to 2001 the total recorded cloud Water yields at the Tshanowa JP School and Lepelfontein Water collection sites were in the region of 72 422 and 148 691 1, respectively. This is equivalent to just over 2 1m -2 day -1 at the Tshanowa JP School and 4.6 1 m -2 day -1 at the Lepelfontein site. Despite the relatively low average daily yields recorded, the total Water volume collected on a particular day may be considerable. In fact, at both sites the maximum daily yield exceeded 3800 1. Fog deposition accounted for around 25% and 88% of the total Water yield measured at the Tshanowa JP School and Lepelfontein sites, respectively. Both experiments indicated that Fog Water collection holds considerable potential as an alternative Water source in the mountainous regions and along the West Coast of South Africa.

Jeffrey L Collett - One of the best experts on this subject based on the ideXlab platform.

  • Ship-borne observations of sea Fog and rain chemistry over the North and South Pacific Ocean
    Journal of Atmospheric Chemistry, 2019
    Co-Authors: Taehyun Park, Jeffrey L Collett, Gyutae Park, Keyhong Park, Seokwon Kang, Seung-myung Park, Yongjoo Choi
    Abstract:

    Clouds, Fogs, and rain can serve as useful integrators of both atmospheric aerosols and soluble trace gases. To better understand the chemical characteristics of sea Fog and rain in the North and South Pacific Ocean, Fog and rain were measured aboard the R/V ARAON in 2012 and 2014, respectively, as part of the Ship-borne Pole-to-Pole Observations (SHIPPO) project. The mean sea Fog pH (3.59) was lower than the mean rain pH (4.54), reflecting greater inputs of non-sea-salt (nss)-SO_4^2−. For the collected rain, nss-Ca^2+ and nss-Mg^2+ from mineral dust particles were the major contributors to acidity neutralization. NO_3^− concentrations, which are derived from scavenging of gaseous nitric acid and aerosol nitrate, were higher than NH_4^+ concentrations, indicating that terrestrial and/or local anthropogenic NO_3^− sources outweighed contributions from anthropogenic or biological oceanic NH_3/NH_4^+ sources. The ratio of Cl^−/Na^+ in the sea Fog was slightly lower than that in the sea Water due to HCl volatilization from scavenged sea-salt particles. The ratio of NH_4^+/ nss-Ca^2+ was lower in the rain than in the sea Fog, revealing the influence of mineral dust particles at altitudes above the sea Fog layer. The average sea Fog Water TOC concentration, 13.2 ppmC, was much higher than the measured TOC concentrations in marine Fogs and clouds in other remote environments, likely due to continental influence; the TN and TOC concentrations in the Fog Water were much higher than those in the rain. The sea Fog and rain chemical properties measured during research cruises like these enhance our understanding of wet deposition and cloud condensation nuclei sources and processes in the Pacific Ocean.

  • total and monomethyl mercury in Fog Water from the central california coast
    Geophysical Research Letters, 2012
    Co-Authors: Peter Weisspenzias, D Fernandez, Jeffrey L Collett, Cruz Ortiz, Paul R Acosta, Wesley Heim, John P Ryan, Russell A Flegal
    Abstract:

    0.04 ng L 1 respectively. Using estimates of Fog Water deposition from 6 sites in the region using a standard Fog Water collector (SFC), depositions of HgT and MMHg via Fog were found to range from 42–4600 and 14–1500 ng m 2 y 1 ,w hich accounted for 7–42% of HgT and 61–99% of MMHg in total atmospheric deposition (Fog, rain, and dry deposition), estimated for the coastal area. These initial measurements suggest that Fog precipitation may constitute an important but previously overlooked input of MMHg to coastal environments. Preliminary comparisons of these data with associated chemical, meteorological and oceanic data suggest that biotically formed MMHg from coastal upwelling may contribute to the MMHg in Fog Water. Citation: Weiss-Penzias, P. S., C. Ortiz Jr., R. P. Acosta, W. Heim, J. P. Ryan, D. Fernandez, J. L. Collett Jr., and A. R. Flegal (2012), Total and monomethyl mercury in Fog Water from the central California coast, Geophys. Res. Lett., 39, L03804,

  • Fog Water chemistry in shanghai
    Atmospheric Environment, 2011
    Co-Authors: Chenyu Yang, Xinjun Wang, Jianmin Chen, Jeffrey L Collett
    Abstract:

    With the aim of understanding the Fog chemistry in a Chinese megacity, twenty-six Fog Water samples were collected in urban Shanghai from March 2009 to March 2010. The following parameters were measured: pH, electrical conductivity (EC), ten inorganic major ions (SO 2� 4 ,N O � 3 ,N O � 2 ,F � ,C l � ,N a þ ,K þ , Ca 2þ ,M g 2þ ,N H þ ) and four major organic acids (CH3COO � , HCOO � ,C 2O 2� 4 , MSA). The total ionic concentration (TIC) and EC of Fog samples were one or two orders of magnitude higher than those often found in Europe, North America and other Asian countries. Pollutants were expected to be mainly from local sources, including factories, motor vehicle emissions and civil construction. Non-local sources such as moderate- and long-range transport of sea salt also contributed to pollution levels in Fog events as indicated by back trajectory analysis. The pH of the Fog Water collected during the monitoring period varied from 4.68 to 6.58; acidic Fogs represented about 30.8% of the total Fog events during this period. The Fog Water was characterized by high concentrations of SO 2� 4 (20.0% of measured TIC), NO � 3 (17.1%), NH þ (28.3%) and Ca 2þ (14.4%). SO 2� 4 and NO � 3 , the main precursors of Fog acidity, were related to burning fossil fuels and vehicle emissions, respectively. NH þ , originating from the scavenging of gaseous ammonia and particulate ammonium nitrate and ammonium sulfate, and Ca 2þ , originating from the scavenging of coarse particles, acted as acid neutralizers and were the main cause for the relatively high pH of Fogs in Shanghai. The ratio of (SO 2� 4 þ NO

  • speciation of mercury ii and methylmercury in cloud and Fog Water
    Aerosol and Air Quality Research, 2011
    Co-Authors: D R Bittrich, Jeffrey L Collett, Shawn P Chadwick, Christopher L Babiarz, H Manolopoulos, Andrew P Rutter, J J Schauer, David E Armstrong, Pierre Herckes
    Abstract:

    The fate of oxidized mercury (Hg) in clouds and Fogs is affected by the complexation of oxidized Hg(Ⅱ) with other chemical species present in cloud and Fog Water. Metal complexation often influences the types of reactions available to a metal in an aqueous system. The influence of pH, major inorganic ions, and organic acids on the complexation of Hg(Ⅱ) and methylmercury (MeHg) was examined for a range of cloud and Fog Water compositions. Fog Water was collected in the San Joaquin Valley, CA and rain Water was collected at Devil's Lake State Park, WI to provide additional measurements of the chemical conditions of atmospheric media. A thermodynamic model was used to determine the speciation of Hg(Ⅱ) and methylmercury (MeHg) over a range of atmospherically-relevant cloud and Fog compositions. The speciation of Hg(Ⅱ) in cloud and Fog Water was highly dependent on pH. For conditions found in most clouds and Fogs, the chloride ion was the most important major ion controlling Hg(Ⅱ) complexation, even under conditions of relatively low chloride content. However, Hg(OH)2(subscript (aq)), and HgClOH(subscript (aq)) were found to dominate over HgCl2 in locations with high pH due emissions of agricultural ammonia; i.e. San Joaquin and Sacramento Valleys, CA. At concentrations relevant to typical cloud and Fog Waters, carboxylic acids (e.g. formate and acetate) did not play a significant role in Hg(Ⅱ) speciation. Methyl mercury was speciated as MeHgCl in most locations, except for the locations with high pH, where MeHgOH dominated. These results provide constraints over potential reaction pathways that may transform oxidized Hg(Ⅱ) in clouds and Fogs.

  • Water soluble atmospheric organic matter in Fog exact masses and chemical formula identification by ultrahigh resolution fourier transform ion cyclotron resonance mass spectrometry
    Environmental Science & Technology, 2010
    Co-Authors: Lynn Mazzoleni, Brandie M Ehrmann, Xinhua Shen, Alan G Marshall, Jeffrey L Collett
    Abstract:

    The detailed molecular composition of Water-soluble atmospheric organic matter (AOM) contained in Fog Water was studied by use of electrospray ionization ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. We identified 1368 individual molecular masses in the range of 100−400 Da from negative-ion spectra obtained after reversed-phase extraction with a hydrophilic solid phase sorbent. The detected organic anions are multifunctional with a variety of oxygenated functional groups. We observe organic nitrogen, organic sulfur, and organic nitrogen−sulfur compounds as well as many species with only C, H, and O elemental composition. Analysis of the double bond equivalents (DBE = the number of rings plus the number of double bonds to carbon) suggests that these compound structures range from highly aliphatic to aromatic with DBE values of 1−11. The compounds range in their extent of oxidation with oxygen to carbon ratios from 0.2 to 2 with an average value of 0.43. Several homologou...

Christopher J Still - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Fog drip versus Fog immersion on the physiology of Bishop pine saplings
    Functional plant biology : FPB, 2017
    Co-Authors: Sara A Baguskas, Douglas T Fischer, Jennifer Y King, Carla M. D'antonio, Christopher J Still
    Abstract:

    Fog-drip to the soil is the most obvious contribution of Fog to the Water budget of an ecosystem, but several studies provide convincing evidence that foliar absorption of Fog Water through leaf wetting events is also possible. The focus of our research was to assess the relative importance of Fog drip and Fog immersion (foliar wetting) on leaf gas-exchange rates and photosynthetic capacity of a coastal pine species, Bishop pine (Pinus muricata D.Don), a drought-sensitive species restricted to the Fog belt of coastal California and offshore islands. In a controlled experiment, we manipulated Fog Water inputs to potted Bishop pine saplings during a 3 week dry-down period. Ten saplings were randomly assigned one of two Fog treatments: (1) Fog drip to the soil and canopy Fog immersion, or (2) Fog immersion alone. Five saplings were assigned the ‘control’ group and received no Fog Water inputs. We found that Fog immersion alone significantly increased carbon assimilation rates and photosynthetic capacity of saplings as soil moisture declined compared with those that received no Fog at all. The highest carbon assimilation rates were observed in saplings that also received Fog drip. Soil moisture was 40% higher in the Fog immersion compared with the control group during the dry-down, indicating a reduced demand for soil Water in saplings that had only leaves wetted by canopy interception of Fog. Leaf-level physiology is more strongly enhanced by Fog drip compared with Fog immersion, although the results of this study provide evidence that foliar absorption is a viable mechanism by which Bishop pines use Fog Water and that it can enhance instantaneous plant carbon gain and potentially whole plant productivity.

  • coastal Fog during summer drought improves the Water status of sapling trees more than adult trees in a california pine forest
    Oecologia, 2016
    Co-Authors: Douglas T Fischer, Christopher J Still, Sara A Baguskas, Carla M Dantonio, Jennifer Y King
    Abstract:

    Fog Water inputs can offset seasonal drought in the Mediterranean climate of coastal California and may be critical to the persistence of many endemic plant species. The ability to predict plant species response to potential changes in the Fog regime hinges on understanding the ways that Fog can impact plant physiological function across life stages. Our study uses a direct metric of Water status, namely plant Water potential, to understand differential responses of adult versus sapling trees to seasonal drought and Fog Water inputs. We place these measurements within a Water balance framework that incorporates the varying climatic and soil property impacts on Water budgets and deficit. We conducted our study at a coastal and an inland site within the largest stand of the regionally endemic bishop pine (Pinus muricata D. Don) on Santa Cruz Island. Our results show conclusively that summer drought negatively affects the Water status of sapling more than adult trees and that sapling trees are also more responsive to changes in shallow soil moisture inputs from Fog Water deposition. Moreover, between the beginning and end of a large, late-season Fog drip event, Water status increased more for saplings than for adults. Relative to non-Foggy conditions, we found that Fog Water reduces modeled peak Water deficit by 80 and 70 % at the inland and coastal sites, respectively. Results from our study inform mechanistically based predictions of how population dynamics of this and other coastal species may be affected by a warmer, drier, and potentially less Foggy future.

  • evaluating patterns of Fog Water deposition and isotopic composition on the california channel islands
    Water Resources Research, 2007
    Co-Authors: Douglas T Fischer, Christopher J Still
    Abstract:

    Fog deposition is an important Water source for endemic conifer species during the annual summer drought along the California coast ( and in other coastal and montane areas). We present a new design for a passive Fog collector that is useful both for characterizing Fog regimes ( timing and quantity of deposition) and for collecting Fog Water for subsequent isotopic analysis. The new collector both mimics vegetation collection efficiency and minimizes isotopic fractionation under a range of Fog conditions. Low construction cost and collector durability allow widely distributed installation and greater insight into spatially heterogeneous Fog patterns. We installed 21 Fog collectors throughout a stand of Bishop pines ( Pinus muricata D. Don) on Santa Cruz Island. In general, there was greater Fog deposition with increasing elevation and decreasing frequency farther inland. Within these broad patterns, there was large spatial and temporal variability in Fog deposition. Monthly samples of Fog and rain Waters reveal differences in stable isotope composition ( delta O-18 and delta D) large enough to serve as tracers of different Water sources moving through the ecosystem.

Douglas T Fischer - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Fog drip versus Fog immersion on the physiology of Bishop pine saplings
    Functional plant biology : FPB, 2017
    Co-Authors: Sara A Baguskas, Douglas T Fischer, Jennifer Y King, Carla M. D'antonio, Christopher J Still
    Abstract:

    Fog-drip to the soil is the most obvious contribution of Fog to the Water budget of an ecosystem, but several studies provide convincing evidence that foliar absorption of Fog Water through leaf wetting events is also possible. The focus of our research was to assess the relative importance of Fog drip and Fog immersion (foliar wetting) on leaf gas-exchange rates and photosynthetic capacity of a coastal pine species, Bishop pine (Pinus muricata D.Don), a drought-sensitive species restricted to the Fog belt of coastal California and offshore islands. In a controlled experiment, we manipulated Fog Water inputs to potted Bishop pine saplings during a 3 week dry-down period. Ten saplings were randomly assigned one of two Fog treatments: (1) Fog drip to the soil and canopy Fog immersion, or (2) Fog immersion alone. Five saplings were assigned the ‘control’ group and received no Fog Water inputs. We found that Fog immersion alone significantly increased carbon assimilation rates and photosynthetic capacity of saplings as soil moisture declined compared with those that received no Fog at all. The highest carbon assimilation rates were observed in saplings that also received Fog drip. Soil moisture was 40% higher in the Fog immersion compared with the control group during the dry-down, indicating a reduced demand for soil Water in saplings that had only leaves wetted by canopy interception of Fog. Leaf-level physiology is more strongly enhanced by Fog drip compared with Fog immersion, although the results of this study provide evidence that foliar absorption is a viable mechanism by which Bishop pines use Fog Water and that it can enhance instantaneous plant carbon gain and potentially whole plant productivity.

  • coastal Fog during summer drought improves the Water status of sapling trees more than adult trees in a california pine forest
    Oecologia, 2016
    Co-Authors: Douglas T Fischer, Christopher J Still, Sara A Baguskas, Carla M Dantonio, Jennifer Y King
    Abstract:

    Fog Water inputs can offset seasonal drought in the Mediterranean climate of coastal California and may be critical to the persistence of many endemic plant species. The ability to predict plant species response to potential changes in the Fog regime hinges on understanding the ways that Fog can impact plant physiological function across life stages. Our study uses a direct metric of Water status, namely plant Water potential, to understand differential responses of adult versus sapling trees to seasonal drought and Fog Water inputs. We place these measurements within a Water balance framework that incorporates the varying climatic and soil property impacts on Water budgets and deficit. We conducted our study at a coastal and an inland site within the largest stand of the regionally endemic bishop pine (Pinus muricata D. Don) on Santa Cruz Island. Our results show conclusively that summer drought negatively affects the Water status of sapling more than adult trees and that sapling trees are also more responsive to changes in shallow soil moisture inputs from Fog Water deposition. Moreover, between the beginning and end of a large, late-season Fog drip event, Water status increased more for saplings than for adults. Relative to non-Foggy conditions, we found that Fog Water reduces modeled peak Water deficit by 80 and 70 % at the inland and coastal sites, respectively. Results from our study inform mechanistically based predictions of how population dynamics of this and other coastal species may be affected by a warmer, drier, and potentially less Foggy future.

  • evaluating patterns of Fog Water deposition and isotopic composition on the california channel islands
    Water Resources Research, 2007
    Co-Authors: Douglas T Fischer, Christopher J Still
    Abstract:

    Fog deposition is an important Water source for endemic conifer species during the annual summer drought along the California coast ( and in other coastal and montane areas). We present a new design for a passive Fog collector that is useful both for characterizing Fog regimes ( timing and quantity of deposition) and for collecting Fog Water for subsequent isotopic analysis. The new collector both mimics vegetation collection efficiency and minimizes isotopic fractionation under a range of Fog conditions. Low construction cost and collector durability allow widely distributed installation and greater insight into spatially heterogeneous Fog patterns. We installed 21 Fog collectors throughout a stand of Bishop pines ( Pinus muricata D. Don) on Santa Cruz Island. In general, there was greater Fog deposition with increasing elevation and decreasing frequency farther inland. Within these broad patterns, there was large spatial and temporal variability in Fog deposition. Monthly samples of Fog and rain Waters reveal differences in stable isotope composition ( delta O-18 and delta D) large enough to serve as tracers of different Water sources moving through the ecosystem.