Forest Bed Research Articles

Evidence for a floristically diverse rainforest on the Falkland archipelago in the remote South Atlantic during the mid- to late Cenozoic

Abstract We report the discovery of an ancient forest bed near Stanley, on the Falkland Islands, the second such ancient deposit identified on the South Atlantic island archipelago that is today marked by the absence of native tree species. Fossil pollen, spores and wood fragments preserved in this buried deposit at Tussac House show that the source vegetation was characterized by a floristically diverse rainforest dominated by Nothofagus-Podocarpaceae communities, similar to cool temperate Nothofagus forests/woodlands and Magellanic evergreen Nothofagus rainforests. The age limit of the deposit is inferred from the stratigraphic distribution of fossil pollen species transported by wind, birds or ocean currents from southern Patagonia, as well as similar vegetation types observed across the broader region. The deposit is suggested to be between Late Oligocene and Early Miocene, making it slightly older than the previously analysed Neogene West Point Island forest bed (200 km west of Tussac House). The combined evidence adds to our current knowledge of the role of climate change and transoceanic dispersal of plant propagules in shaping high-latitude ecosystems in the Southern Hemisphere during the late Palaeogene and Neogene.

Creating a new yellow and blue combination transparent film for Panax ginseng C.A. Meyer growth based on orthogonal designs

Panax ginseng C.A. Meyer originates from old-growth forest environments, where the light intensity and spectrum reaching the forest bed are influenced by the canopy and humidity. In farmlands, suitable light intensity for cultivation is achieved by controlling the light transmission rate using shading nets, while light quality is regulated by a cover of yellow or blue transparent film. Such films have a light quality distinct from that produced by old-growth forests. Herein, a large composite film was developed by alternating small pieces of yellow and blue transparent film. An orthogonal array was used to evaluate the influence of the small transparent film area (STFA), yellow transparent film (YTF) number, and blue transparent film (BTF) number on the associated changes in ginseng in a range of fluorescence-, photosynthesis-, morphology-, and crop quality-related factors. Our results showed that light intensity was influenced primarily by STFA, which caused an overall decrease, while the light quality ratio was affected primarily by YTF number, which increased the proportion of red light and decreased that of blue light, with corresponding influence on different growth parameters. Based on these observations, an improved yellow and blue combination transparent film (YBCTF) with the following characteristics was established: STFA: 15 × 15 cm, YTF: two pieces, and BTF: three pieces. The improved YBCTF facilitated efficient light energy use by the plants, and led to an increase in leaf area, the per leaf photosynthetic rate, dry root weight, and the per root single ginsenoside yield. The findings present a relatively low-cost approach for optimising the light environment of ginseng cultivated in farmland and other crops in large-scale agricultural settings.

Dating the penultimate great earthquake in south-central Alaska using tree-ring crossdating and radiocarbon wiggle-matching

A forest bed of tree stumps currently in the intertidal zone at Girdwood, south-central Alaska, records coseismic submergence during the penultimate great earthquake. Tree-ring samples from ten spruce stumps were crossdated to develop a 149-year-long ring-width chronology. Radiocarbon wiggle-matching found that single-ring ages from the chronology were offset 28 ± 7 years older than the IntCal20 calibration curve and that the last ring of the chronology dated as 1169 to 1189 CE (781–761 cal. yr. BP) at the 95% confidence level. Bark was observed on some stumps, six samples had the same year for the last growth ring, and so this wiggle-match date is also the best estimate of the date of the penultimate great earthquake. This date is in good agreement with a date for this event in a seismo-turbidite record from Skilak Lake but not with previous dates from Bayesian models of maximum- and minimum-limiting ages from coastal salt marshes. Reanalysis of the coastal salt marsh ages with the data grouped by area, context and material found that outer wood samples from stumps at coseismic submergence sites and a Bayesian limiting age model based on just herbaceous plant ages from Turnagain Arm and the Copper River area are both consistent with our wiggle-match date. Furthermore, coseismic emergence ages from Cape Suckling and Yakataga are older than the penultimate earthquake and so likely relate to an earlier uplift event in this eastern area. The rupture extent during the penultimate great earthquake appears to have been less than in the 1964 great earthquake and the interseismic interval between these two events was 785 ± 10 years.

Use of an electric heater as an idealized firebrand to determine ignition delay time of Eucalyptus globulus leaves

The Idealized-Firebrand Ignition Test (I-FIT) protocol was used to evaluate the piloted ignition delay times of fuel beds composed of leaves of Eucalyptus globulus (Labill.). The amount of fuel layer used for evaluation ranged between the fraction volume (α) of 0.03 to 0.07 which are values expected to be found in forest bed fuels. A theoretical model was developed to describe the heating and ignition of the fuel beds, based on the thermal ignition theory. The model, which was originally developed for pine needle beds, considers the penetration of radiation to the porous matrix. The model is able to accurately predict the ignition delay time for different values of α, but shows a poorer accuracy for the temperature evolution. This is explained by the large variability observed for the Eucalyptus leaves.

Evidence for a late glacial advance near the beginning of the Younger Dryas in western New York State: An event postdating the record for local Laurentide ice sheet recession

Abstract Widespread evidence of an unrecognized late glacial advance across preexisting moraines in western New York is confirmed by 40 14C ages and six new optically stimulated luminescence analyses between the Genesee Valley and the Cattaraugus Creek basin of eastern Lake Erie. The Late Wisconsin chronology is relatively unconstrained by local dating of moraines between Pennsylvania and Lake Ontario. Few published 14C ages record discrete events, unlike evidence in the upper Great Lakes and New England. The new 14C ages from wood in glacial tills along Buttermilk Creek south of Springville, New York, and reevaluation of numerous 14C ages from miscellaneous investigations in the Genesee Valley document a significant glacial advance into Cattaraugus and Livingston Counties between 13,000 and 13,300 cal yr B.P., near the Greenland Interstadial 1b (GI-1b) cooling leading into the transition from the Bölling-Alleröd to the Younger Dryas. The chronology from four widely distributed sites indicates that a Late Wisconsin advance spread till discontinuously over the surface, without significantly modifying the preexisting glacial topography. A short-lived advance by a partially grounded ice shelf best explains the evidence. The advance, ending 43 km south of Rochester and a similar distance south of Buffalo, overlaps the revised chronology for glacial Lake Iroquois, now considered to extend from ca. 14,800–13,000 cal yr B.P. The spread of the radiocarbon ages is similar to the well-known Two Creeks Forest Bed, which equates the event with the Two Rivers advance in Wisconsin.

Inferences from thermogravimetric analysis of pine needles and its chars from a pilot-scale screw reactor

Pine needles are the waste of pine forest and produced in a substantial amount every year during the fall. If not extracted from forest bed, they cause a widespread forest fire. In this study, pine needles were converted to char at different temperatures using a screw type pyrolyzer with an aim to find out the effect of thermal stress on the properties of chars and their intended end uses. The chars were evaluated for intrinsic physico-chemical transformations in comparison with the raw pine needles. Differences between chars produced in three temperatures and the raw biomass were studied by thermogravimetric analysis. It was found that the char produced at higher temperature showed a superior profile of apparent activation energy as compared with the char from low temperature. Coats–Redfern kinetics was used to compare the activation energies of chars and raw biomass, which showed that the char obtained from higher temperature had better thermal stability. From this study it can be concluded that chars produced at low temperatures in the screw reactor are useful as source of fuel, whereas the char of higher temperature is suitable for soil application and preparation of activated char.

Regional correlation of the Sonsela Member (Upper Triassic Chinle Formation) and detrital U-Pb zircon data from the Sonsela Sandstone bed near the Sonsela Buttes, northeastern Arizona, USA, support the presence of a distributive fluvial system

AbstractThe Sonsela Sandstone bed was first named as an informal unit in the lower part of the Chinle Formation in northern Arizona, USA, and it was later assigned a type section near the Sonsela Buttes, where it is composed of two prominent sandstone units separated by a predominately siltstone unit. The Sonsela Sandstone bed has been correlated to a number of specific sandstones within the thicker, formal Sonsela Member at Petrified Forest National Park in northern Arizona. Here, we present the first detrital U-Pb zircon data for the Sonsela Sandstone bed at the Sonsela Buttes to hypothesize the maximum deposition age of that unit (216.6 ± 0.3 Ma) that are consistent with the proposed lithostratigraphic correlation with the fossiliferous Jasper Forest bed of the lower part of the Sonsela Member at the Park. These results are corroborated by previous high-resolution U-Pb dates and detrital zircon provenance studies from Petrified Forest National Park and similar sections in northern Arizona and western New Mexico, USA. The hypothesized chronostratigraphic correlation of these sandstones throughout northern Arizona permits the recognition of diachronous facies distributions in the lower part of the Chinle Formation as these coarse sediments prograded from the southwest into a continental basin already receiving finer-grained fluvial sediments from the southeast. The new age data corroborate the Norian age designation for the Sonsela Member (and the Sonsela Sandstone bed) and suggest that the Sonsela Sandstone bed at the Sonsela Buttes is within the Adamanian land vertebrate estimated holochronozone.

Fire in pine grown regions of Himalayas depletes cultivable plant growth promoting beneficial microbes in the soil

Plant growth promoting microbes impact the life of trees, shrubs and other plant species in the forest. Fire in forest adversely affects the growth of plants directly by burning and heat stress and indirectly by affecting the survival of plant growth promoting microbes. Herein, we analyzed changes in the population of cultivable microbes owing to fire in the pine grown forest in the Indian Himalayan region. We found that soil in the burnt region predominantly harbored Gram-positive bacteria which lacked biofertilizer and biocontrol traits. Forest fire resulted in the loss of Gram-negative strains of genera Pseudomonas, Serratia, Enterobacter, Burkholderia, Klebsiella, and Pantoea. Similarly, we found that the rhizospheric region of grasses which came after the event of the fire in the pine forest lacked the beneficial Gram-negative strains. Furthermore, in plantae experiments in which pea (Pisum sativum) and wheat (Triticum aestivum) seedlings were treated with bacteria isolated from the burnt and unburnt forest bed showed that bacteria from the burnt region did not affect the growth of seedlings as compared to the bacteria isolated from the unburnt region which improved the growth of seedlings. Comparing the soil parameters between burnt and unburnt region showed a decrease in nutrients, and, increase in both bulk density and dispersion ratio due to the forest fire. Our results strongly indicate that forest fire reduces the population of cultivable beneficial microbes and this loss could have a negative impact on the growth of forest flora.

Monitoring of Tehri Hydroelectric Plant Induced Land Use Land Cover Change Detection in Garhwal District of Uttarakhand

The present study analyses the land use change caused by the construction of Tehri dam in Bhagirathi river. Geospatial techniques like Geographic Information System (GIS) and remote sensing have been used to make land use map using Landsat satellite image of 2000 and 2014. In Tehri district, change in land use and new developments (industrial, urban and commercial) were observed. Land use land cover change was done using two satellite images, classifying them via supervised classification and applying change detection in the classified images. Classified images had an overall accuracy of 88.57 and 88.31%. The results were validated using the ground truth points distributed all over the study. Seven main classes were identified in the study area as water, open forest, dense forest, river bed, agriculture, urban and others (which includes scrub and barren land). The increase was observed in built-up class from 2000–2014. The decrease was observed in the open, dense forest and river bed. The present study showed that the construction of the hydropower and associated construction activities had caused changes in the Tehri valley. Keywords: Change detection, land use, land cover, hydropower, Tehri, supervised classification Cite this Article Disha Punetha, Archana Sharma, Pooja Panwar. Monitoring of Tehri Hydroelectric Plant Induced Land Use Land Cover Change Detection in Garhwal District of Uttarakhand. Journal of Remote Sensing & GIS. 2018; 9(2): 1–9p.

Constraining the Late Pleistocene history of the Laurentide Ice Sheet by dating the Missinaibi Formation, Hudson Bay Lowlands, Canada

Abstract Well-dated paleorecords from periods prior to the Last Glacial Maximum (LGM) are important for validating models of ice sheet build-up and growth. However, owing to glacial erosion, most Late Pleistocene records lie outside of the previously glaciated region, which limits their ability to inform about the dynamics of paleo-ice sheets. Here, we evaluate new and previously published chronology data from the Missinaibi Formation, a Pleistocene-aged deposit in the Hudson Bay Lowlands (HBL), Canada, located near the geographic center of the Laurentide Ice Sheet (LIS). Available radiocarbon (AMS = 44, conventional = 36), amino acid (n = 13), uranium-thorium (U-Th, n = 14), thermoluminescence (TL, n = 15) and optically stimulated luminescence (OSL, n = 5) data suggest that an ice-free HBL may have been possible during parts of Marine Isotope Stage 7 (MIS 7; ca. 243,000 to ca. 190,000 yr BP), MIS 5 (ca. 130,000 to ca. 71,000 yr BP) and MIS 3 (ca. 29,000 to ca. 57,000). While MIS 7 and MIS 5 are well-documented interglacial periods, the development of peat, forest bed and fluvial deposits dating to MIS 3 (n = 20 radiocarbon dates; 4 TL dates, 3 OSL dates), suggests that the LIS retreated and remained beyond, or somewhere within, the boundaries of the HBL during this interstadial. Ice sheet models approximate the margin of the LIS to Southern Ontario during this time, which is 700 km south of the HBL. Therefore, if correct, our data help constrain a significantly different configuration and dynamicity for the LIS than previously modelled. We can find no chronological basis to discount the MIS 3 age assignments. However, since most data originate from radiocarbon dates lying close to the reliable limit of this geochronometer, future work on dating the Missinaibi Formation using other geochronological methods (e.g. U-Th, OSL) is necessary in order to confirm the age estimates and strengthen the boundaries of the LIS during this period.

Mushrooms and Yeast: The Implications of Technological Progress for Canada's Economic Growth

Whether Canadians talk about income inequality, regional growth or technological change, it is clear that economic growth is not uniformly spread across the country. Canada is not unique in this regard: modern economic growth theory shows that economies grow like mushrooms, not yeast. Instead of expanding uniformly like bread in the oven, economic growth pops up sporadically like mushrooms in the forest bed. Economic growth is a process of unpredictable “creative destruction” in which there will be winners and losers. The policy discussion around this kind of growth has often focused on the consequences for those left behind by change. It is often easier to identify those who lose from technological changes, while the winners are diffuse. Policymakers should also think more about harnessing uneven economic growth. From international trade to education policy, this Commentary shows how governments should think about the mix of targeted and economy-wide policies they should introduce to grow the Canadian economy. With increased international trade, Canadians as a whole will benefit not only from lower prices, but also from the more rapid productivity growth that will result from increased innovation by domestic firms as they seek to compete against foreign firms that can enter the Canadian market. Exchange-rate movements have many conflicting and uncertain effects on both the level and growth rate of domestic productivity. Since monetary policy cannot affect the real exchange rate in the long run, the Bank of Canada should continue to focus not on the exchange rate, but on its inflation target. Existing small business tax preferences are unlikely to promote productivity growth. Job creation is fostered not by small businesses per se, but by the young businesses that are the agents of creative destruction. The Canadian telecommunications industry is ideally suited to benefit from enhanced innovation and productivity growth in the event of a serious threat of entry by foreign firms large enough to enjoy significant scale economies. To take advantage of that possibility, the federal government should eliminate foreign ownership restrictions in the industry. Universities should also pursue independent research programs that foster basic science. Community colleges should focus on giving workers the skills they need to work with the most up-to-date technologies. With growth comes change, and it is time that Canadian policymakers think about how that change occurs and how best to use it for the benefit of Canadians.

The early Middle Pleistocene fallow deer Dama roberti: new insight on species morphology from a complete postcranial skeleton from Valdemino (northwestern Italy)

A nearly complete fallow deer skeleton from the lower levels (early Middle Pleistocene) of Valdemino Cave (northwestern Italy) is attributed to the recently described Dama roberti Breda and Lister. The dental and postcranial anatomy of this specimen is analysed in detail. Some anatomical elements show a mosaic of characters of living D. dama and Cervus elaphus, but with only a minor part resembling the latter. Each element is compared with other representatives of the fallow deer lineage, in particular to the type series of the early Middle Pleistocene D. roberti from the British Cromer Forest Bed Formation and from the French locality of Soleilhac, with its possible descendant D. dama (both the late Middle Pleistocene D. d. clactoniana and modern D. d. dama) and with its possible parent species (several representatives of the Late Pliocene–Early Pleistocene ‘Pseudodama’ group). The variability of selected characters has enabled a better morphological characterization of the species. The skeleton from Valdemino matches very precisely the morphology of the few existing postcranial elements of the D. roberti holotype and paratype. This will allow future identification of isolated postcranial bones from other localities. The Valdemino skeleton also perfectly matches the size of the type populations and confirms that D. roberti is larger than the living fallow deer D. dama. Copyright © 2014 John Wiley & Sons, Ltd.

Investigation of the mechanisms underlying the high acetylene-reducing activity exhibited by the soil bacterial community from BC2 horizon in the permafrost zone of the East Siberian larch forest bed

This study addressed a microbial composition of East Siberian larch forest bed soil and focused on major nitrogen-fixing bacterial consortia showing the highest capacity to induce acetylene reduction. The ability of a soil microbial consortium to effectively reduce acetylene was investigated using gellan gum medium. In parallel, each microbial component in the medium was analysed by a 16S rRNA gene-targeting denaturing gradient gel electrophoresis (DGGE), together with an attempt to isolate pure culture of the culturable eubacteria. Six strains of the isolated bacteria were characterized as diazotrophs, and Burkholderia xenovorans was found to be one of the major nitrogen fixer in the bacterial community cultured from the BC2 horizon soil microbiota. Co-culturing of either a diazotrophic Pseudomonas sp. with a nondiazotrophic Luteibacter sp. or a diazotrophic Luteibacter sp. with a nondiazotrophic bacterium B. xenovorans resulted in a marked elevation in acetylene reduction over that observed in the pure culture of each diazotroph. A promotion of acetylene reduction in mixed bacterial cultures, particularly when the cultures included Luteibacter, was clearly observed due to an increase in the bacterial cell population. Our study, which showed that some unculturable bacteria including anaerobic Clostridium sp. that can provide major contribution to nitrogen fixation, may provide key information useful in identifying the 'missing link' in the nitrogen cycle in the cryogenic soil ecosystem of boreal forests.

Paleobotanical and environmental implications of a buried forest bed in northern Lower Michigan, USA

Sediments and stratigraphy at the Tower Buried Forest site provide a glimpse into the immediate post-glacial environment of northern Lower Michigan, USA. At this site, sandy glacial outwash is overlain by (1) ≈37 cm of peat associated with a wetland, above which are (2) flat-lying spruce and larch logs and branches that date between ≈10 910 and 10 340 cal years BP. Above the woody materials are ≈55–75 cm of sand, interbedded with organic muck laminae, which we interpret as local alluvium. This stratigraphic sequence is overlain by muck soil materials associated with the modern wetland. Pollen and plant macrofossil analysis of the lower peat indicate that a tundra–boreal parkland had been established here, shortly after final deglaciation. Later, Picea glauca (white spruce) , Picea mariana (black spruce), Larix laricina (larch), and Abies balsamea (balsam fir) became abundant in an open boreal forest – Spaghnum peatland. Subsequent increases in Pinus (pine) and Typha (cattail) indicate drying and possibly warming conditions. At ca. 10 340 cal years BP (or a few centuries prior), nearly two millennia after final deglaciation, water flowed across the site, possibly knocking over the trees.. Interbedded sand and muck deposits above the flat-lying logs are interpreted as alluvial deposits from this event, after which the wetland became quiescent again.

The Palisades is a key reference site for the middle Pleistocene of eastern Beringia: new evidence from paleomagnetics and regional tephrostratigraphy

The Palisades, in central Alaska, is one of the most prominent exposures of Quaternary sediments on the Yukon River. Perennially-frozen silt and sand at the Palisades are presently thought to preserve paleoenvironmental records from the Holocene to ∼Marine Isotope Stage (MIS) 8 and, beneath a major unconformity, the earliest Pleistocene (∼2 Ma). We present new paleomagnetic and tephrochronologic constraints that substantially revise the age of the sediments at the Palisades. We describe 15 new tephra beds, including five beds below the prominent PAL tephra that correlate to known tephra with independent age control from other sites in eastern Beringia. These five known tephra include Chester Bluff tephra, which is present in east-central Alaska and the Yukon, and the newly named Alyeska Pipeline and Taylor Highway tephra from central Alaska; all are constrained to the middle Pleistocene. Paleomagnetic transects from the base of the bluff to the MIS 5e forest bed yield normal polarity, with the exception of a brief reversal event between Old Crow tephra (124 ± 10 ka) and the MIS 5e forest bed that is likely the first documentation of the Blake paleomagnetic event in Alaskan loess. The detailed tephrostratigraphy and paleomagnetic data collectively suggest that most of the sedimentary record at the Palisades is middle Pleistocene in age. The Palisades thus preserves a rare record of late to middle Pleistocene paleoenvironments with multiple regionally distributed tephra beds.

Radiocarbon ages of terrestrial gastropods extend duration of ice-free conditions at the Two Creeks forest bed, Wisconsin, USA

Analysis of terrestrial gastropods that underlie the late Pleistocene Two Creeks forest bed (~13,800–13,500calyr BP) in eastern Wisconsin, USA provides evidence for a mixed tundra-taiga environment prior to formation of the taiga forest bed. Ten new AMS 14C analyses on terrestrial gastropod shells indicate the mixed tundra-taiga environment persisted from ~14,500 to 13,900calyr BP. The Twocreekan climatic substage, representing ice-free conditions on the shore of Lake Michigan, therefore began near the onset of peak warming conditions during the Bølling–Allerød interstadial and lasted ~1000yr, nearly 600yr longer than previously thought. These results provide important data for understanding the response of continental ice sheets to global climate forcing and demonstrate the potential of using terrestrial gastropod fossils for both environmental reconstruction and age control in late Quaternary sediments.

Mammoth and Mastodon collagen sequences; survival and utility

Near-complete collagen (I) sequences are proposed for elephantid and mammutid taxa, based upon available African elephant genomic data and supported with LC–MALDI-MS/MS and LC–ESI-MS/MS analyses of collagen digests from proboscidean bone. Collagen sequence coverage was investigated from several specimens of two extinct mammoths ( Mammuthus trogontherii and Mammuthus primigenius), the extinct American mastodon ( Mammut americanum), the extinct straight-tusked elephant ( Elephas ( Palaeoloxodon) antiquus) and extant Asian ( Elephas maximus) and African ( Loxodonta africana) elephants and compared between the two ionization techniques used. Two suspected mammoth fossils from the British Middle Pleistocene (Cromerian) deposits of the West Runton Forest Bed were analysed to investigate the potential use of peptide mass spectrometry for fossil identification. Despite the age of the fossils, sufficient peptides were obtained to identify these as elephantid, and sufficient sequence variation to discriminate elephantid and mammutid collagen (I). In-depth LC–MS analyses further failed to identify a peptide that could be used to reliably distinguish between the three genera of elephantids ( Elephas, Loxodonta and Mammuthus), an observation consistent with predicted amino acid substitution rates between these species.

Multiple severe stab wounds to chest with cuts to the ribs. Suicide or homicide?

This paper presents the case of a 36-year-old man found dead in a forest near his home with multiple stab wounds on the chest and abdomen, while the chest wounds penetrated deep into the left pleural cavity and the lung parenchyma, completely cutting through the bone sections of four ribs along the channels of the wounds. In addition, a kitchen knife dug into the ground was found in the immediate vicinity of the corpse. The deceased was wearing a T-shirt with numerous clearly visible holes in places corresponding to the wounds and quite a large tear at the bottom. The post-mortem revealed 19 distinct wounds of the chest as well as a dozen or so superficial marks of cuts or pricks with a pointed tool on the torso. The findings of the police investigation suggested that shortly before death the man was in a bad mood and he had been telling his friends to prepare for his funeral, which was supposed to point to suicidal tendencies. Could, however, such numerous and heavy bodily injuries have been self-inflicted and would such a wounded person still be able to dig a knife into hard forest bed? If yes, in this case we are most probably dealing with aggressive self-destruction, a type of behavior sometimes observed in people suffering from serious mental disorders.

Clear increases in acetylene reduction by soil bacteria from an East Siberian Taiga forest bed under conditions mimicking the natural soil environment

In boreal forest ecosystems, nitrogen imbalance has long been discussed as a mystery with regard to its high biomass production. Under conditions widely used for the soybean nodulation bacterium Bradyrhizobium japonicum, microbiota in forest bed soil often do not show any significant acetylene reduction. However, in a recent study, soil bacterial microbiota in an East Siberian Taiga forest bed and bacteria isolated from the soil show remarkable acetylene reduction in nitrogen-poor soft-gel medium solidified with gellan gum instead of agar. Thus, we precisely investigated optimal culture conditions including compositions of the medium; appropriate conditions for the soil microbiota were determined as follows: 0.5 g L−1 D-mannitol as the carbon source, 10–15°C incubation temperature and medium pH 6.2. These culture conditions resembled the physicochemical conditions of the active layer in the East Siberian boreal forest bed on the permafrost. In fact, mannitol, which was the most appropriate carbon source, was obtained as a major sugar component of the cowberry root mats that cover the larch forest bed in this region. The most profitable concentration of D-mannitol (0.5 g L−1) for acetylene reduction was only 1/20 or 1/30 of the amount of the carbon source used in worldwide acetylene reduction assays. In a similar manner, 10–15°C, which was the most profitable incubation temperature range, was close to the reported temperature of the active layer of the bulk soil in summer. us, even in a 3.0 g L−1 gellan gum medium, an acetylene reduction assay under the imitated soil conditions led to clear increases in acetylene reduction of the bacterial communities tested. The N2-fixing potential of boreal forest bed soil had thus ever been evaluated unfairly low, because the world wide assay conditions were too far from the soil environments.

Revised Lithostratigraphy of the Sonsela Member (Chinle Formation, Upper Triassic) in the Southern Part of Petrified Forest National Park, Arizona

BackgroundRecent revisions to the Sonsela Member of the Chinle Formation in Petrified Forest National Park have presented a three-part lithostratigraphic model based on unconventional correlations of sandstone beds. As a vertebrate faunal transition is recorded within this stratigraphic interval, these correlations, and the purported existence of a depositional hiatus (the Tr-4 unconformity) at about the same level, must be carefully re-examined.Methodology/Principal FindingsOur investigations demonstrate the neglected necessity of walking out contacts and mapping when constructing lithostratigraphic models, and providing UTM coordinates and labeled photographs for all measured sections. We correct correlation errors within the Sonsela Member, demonstrate that there are multiple Flattops One sandstones, all of which are higher than the traditional Sonsela sandstone bed, that the Sonsela sandstone bed and Rainbow Forest Bed are equivalent, that the Rainbow Forest Bed is higher than the sandstones at the base of Blue Mesa and Agate Mesa, that strata formerly assigned to the Jim Camp Wash beds occur at two stratigraphic levels, and that there are multiple persistent silcrete horizons within the Sonsela Member.Conclusions/SignificanceWe present a revised five-part model for the Sonsela Member. The units from lowest to highest are: the Camp Butte beds, Lot's Wife beds, Jasper Forest bed (the Sonsela sandstone)/Rainbow Forest Bed, Jim Camp Wash beds, and Martha's Butte beds (including the Flattops One sandstones). Although there are numerous degradational/aggradational cycles within the Chinle Formation, a single unconformable horizon within or at the base of the Sonsela Member that can be traced across the entire western United States (the “Tr-4 unconformity”) probably does not exist. The shift from relatively humid and poorly-drained to arid and well-drained climatic conditions began during deposition of the Sonsela Member (low in the Jim Camp Wash beds), well after the Carnian-Norian transition.