Earth Sciences Commons^™

Modeling Spatial And Temporal Variation In Natural Background Specific Conductivity, John Olson, Susan M. Cormier

John Olson

Predicting Combined Effects Of Land Use And Climate Change On River And Stream Salinity, John Olson

John Olson

Disentangling Climatic And Anthropogenic Controls On Global Terrestrial Evapotranspiration Trends, Jiafu Mao, Wenting Fu, Xiaoying Shi, Daniel M. Ricciuto, Joshua B. Fisher, Robert E. Dickinson, Yaxing Wei, Willis Shem, Shilong Piao, Kaicun Wang, Christopher R. Schwalm, Hanqin Tian, Mingquan Mu, Altaf Arain, Philippe Ciais, Robert Cook, Yongdiu Dai, Daniel Hayes, Forrest M. Hoffman, Maoyi Huang, Suo Huang, Deborah N. Huntzinger, Akihiko Ito, Atul Jain, Anthony W. King, Huimin Lei, Chaoqun (Crystal) Lu, Huimin Lei, Anna M. Michalak, Changhui Peng, Shushi Peng, Benjamin Poulter, Kevin Schaefer, Elshin Jafarov, Peter E. Thornton, Weile Wang, Ning Zeng, Zhenzhong Zeng, Fang Zhao, Qiuan Zhu, Zaichun Zhu

Chaoqun (Crystal) Lu

We examined natural and anthropogenic controls on terrestrial evapotranspiration (ET) changes from 1982 to 2010 using multiple estimates from remote sensing-based datasets and process-oriented land surface models.A significant increasing trend of ET in each hemisphere was consistently revealed by observationally-constrained data and multi-model ensembles that considered historic natural and anthropogenic drivers. The climate impacts were simulated to determine the spatiotemporal variations in ET. Globally, risingCO2 ranked second in these models after the predominant climatic influences, and yielded decreasing trends in canopy transpiration and ET, especially for tropical forests and high-latitude shrub land. Increasing nitrogen deposition slightly amplified global ET via …

Toward “Optimal” Integration Of Terrestrial Biosphere Models, Christopher R. Schwalm, Deborah N. Huntzinger, Joshua B. Fisher, Anna M. Michalak, Kevin Bowman, Philippe Ciais, Robert Cook, Bassil El-Masri, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul Jain, Anthony W. King, Hiumin Lei, Junjie Liu, Chaoqun (Crystal) Lu, Jaifu Mao, Shushi Peng, Benjamin Poulter, Daniel Ricciuto, Kevin Schaefer, Xiaoying Shi, Bo Tao, Hanqin Tian, Weile Wang, Yaxing Wei, Jia Yang, Ning Zeng

Chaoqun (Crystal) Lu

Multimodel ensembles (MME) are commonplace in Earth system modeling. Here we perform MME integration using a 10-member ensemble of terrestrial biosphere models (TBMs) from the Multiscale synthesis and Terrestrial Model Intercomparison Project (MsTMIP). We contrast optimal (skill based for present-day carbon cycling) versus naïve (“one model-one vote”) integration. MsTMIP optimal and naïve mean land sink strength estimates (−1.16 versus −1.15 Pg C per annum respectively) are statistically indistinguishable. This holds also for grid cell values and extends to gross uptake, biomass, and net ecosystem productivity. TBM skill is similarly indistinguishable. The added complexity of skill-based integration does not materially change …

Global Methane And Nitrous Oxide Emissions From Terrestrial Ecosystems Due To Multiple Environmental Changes, Hanqin Tian, Guangsheng Chen, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Bowen Zhang, Kamaljit Banger, Bo Tao, Shufen Pan, Mingliang Liu, Chi Zhang, Lori Bruhwiler, Steven Wofsy

Chaoqun (Crystal) Lu

Greenhouse gas (GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today, posing serious risks for ecosystem health. Methane (CH4) and nitrous oxide (N2O) are the two most important GHGs after carbon dioxide (CO2), but their regional and global budgets are not well known. In this study, we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH4 and N2O fluxes as driven by multiple environmental changes, including climate variability, rising atmospheric CO2, increasing nitrogen deposition, tropospheric ozone pollution, land use change, and nitrogen fertilizer use. The estimated CH4 …

Taphonomy Of The Joanna Track Site, Cretaceous Glen Rose Formation: Is The Shrimp Mightier Than The Dinosaur?, Michael Blair, Benjamin Dattilo, Lydia Mark, James Farlow, Jerry Jacene, Shelley Mcfadin

Benjamin F. Dattilo

Dinosaur trackways are common in the Cretaceous Glen Rose Formation of central Texas. While the trackways in Dinosaur Valley State Park are well known, many other sites can be found in this region. Recently, a new track site was discovered during construction in Glen Rose, Texas. The Joanna Track Site features tridactyl tracks which have been partly obliterated by invertebrates burrowing through the thick mud which buried them.

We measured and described the interval from 0.3 m below the track layer through 2.7 m above it in a vertical outcrop directly adjacent to the track site. Samples were collected in …

Microstratigraphic Analysis Of Burrow-Reworked Dinosaur Track Bed At Joanna's Track Site, Cretaceous Glen Rose Formation, Glen Rose, Texas, Michael Blair, Benjamin Dattilo, Anthony Martin, James Farlow

Benjamin F. Dattilo

Although dinosaur trackways are common in the Cretaceous Glen Rose Formation of Texas, the recently discovered Joanna track site illustrates a unique ichnological relationship where dinosaur tracks were disrupted by invertebrate burrows made long after burial. In an effort to document the precise sequence of events, we described the interval from 0.3 m below the track layer through 2.7 m above it in a vertical outcrop adjacent to the track site, focusing on the 70-cm of strata immediately above the track horizon. An 8-meter N-S cross-section of this 70-cm interval was power-washed, examined for trace fossils, body fossils, and lithology …

Dinosaur Tracksites Of The Paluxy River Valley (Glen Rose Formation, Lower Cretaceous), Dinosaur Valley State Park, Somervell County, Texas., James O. Farlow, Mike O'Brien, Glenn J. Kuban, Benjamin F. Dattilo, K. T. Bates, Peter L. Falkingham, L. Pinuela, Amanda Rose, A. Freels, C. Kumagai, Courtney Libben, Justin Smith, J. Whitcraft

Benjamin F. Dattilo

In 1940 R.T. Bird of the American Museum of Natural History collected segments of a sauropod and a theropod trackway from a site in the bed (Glen Rose Formation; Lower Cretaceous) of the Paluxy River, in what is now Dinosaur Valley State Park (Glen Rose, Texas, USA). However, Bird left undocumented thousands of other dinosaur footprints from this and other Paluxy tracksites. In 2008 and 2009 our international team carried out fieldwork to create detailed photomosaics of extant Paluxy tracksites, using GIS technology to combine these with historic maps and photographs. We also made photographs, tracings, LiDAR images, and measurements …

The Curse Of Rafinesquina: Negative Taphonomic Feedback Exerted By Strophomenid Shells On Storm-Buried Lingulids In The Cincinnatian (Katian, Ordovician) Series Of Ohio, Rebecca Freeman, Benjamin Dattilo, Aaron Morse, Michael Blair, Steve Felton, John Pojeta

Benjamin F. Dattilo

Thousands of lingulid brachiopods were found clustered beneath hundreds of individual valves of the strophomenid brachiopod Rafinesquina in the Upper Ordovician of Ohio. This association suggested a relationship between the two brachiopods, but the nature of this relationship was unclear. We utilized serial thin sectioning to examine these brachiopods and to determine the origin of the bed in which they were found. Sedimentary structures, mixed taphonomies, and stratigraphic and paleogeographic setting suggest that the lingulids occupied a hiatal concentration that had previously been reworked, but not significantly transported, by tropical storms. The final burial event was a storm that exhumed …

How Many Track Horizons Are Exposed At Dinosaur Valley State Park? Stratigraphy Of The Cretaceous Glen Rose Formation Track Sites Of The Paluxy River, Glen Rose, Texas, Benjamin Dattilo, Sadye Howald, James Farlow, Anthony Martin

Benjamin F. Dattilo

The dinosaur tracks of the Glen Rose Formation in the Paluxy River at Dinosaur Valley State Park are among the best preserved and most abundant in the world. While many track sites are easily correlated to the Main Tracksite, others, especially those at the extreme ends of the park, are differently preserved and not obviously correlated. To count track horizons, several stratigraphic sections were measured along the river from upstream at the McFall Ledge Site to 7.6 km downstream at the County Road 1001 crossing (3.1 km linear distance). These reveal 6 meters of strata separating two track-bearing horizons exposed …

Mass And Nutrient Loss In Decaying Hardwood Boles At Hubbard Brook, Chris E. Johnson

Chris E Johnson

No abstract provided.

Will Hubbard Brook Soils Be A Source Or Sink Of Carbon In A Changing Climate?, Chris E. Johnson

Chris E Johnson

No abstract provided.

The World’S Deepest Subterranean Community - Krubera-Voronja Cave (Western Caucasus), Alberto Sendra, Ana Sofia P.S. Reboleira

Ana Sofia P.S. Reboleira

Subsurface biota extends over a wide variety of habitats that can be spatially interconnected. The largest communities of this subsurface biota inhabit cavities and are well known mainly in caves where biologists are able to have access. Data about deep subterranean communities and arthropods living under one thousand meters was unknown. An expedition to world’s deepest cave, Krubera-Voronja in Western Caucasus, revealed an interesting subterranean community, living below 2000 meters and represented by more than 12 species of arthropods, including several new species for science. This deep cave biota is composed of troglobionts and also epigean species, that can penetrate …

The Contribution Of Fe (Iii) And Humic Acid Reduction To Ecosystem Respiration In Drained Thaw Lake Basins Of The Arctic Coastal Plain, David A. Lipson, Ted K. Raab, Dominic Goria, Jaime Zlamal

Ted K. Raab

Previous research showed that anaerobic respiration using iron (Fe) oxides as terminal electron acceptor contributed substantially to ecosystem respiration (ER) in a drained thaw lake basin (DTLB) on the Arctic coastal plain. As DTLB age, the surface organic layer thickens, progressively burying the Fe-rich mineral layers. We therefore hypothesized that Fe (III) availability and Fe reduction would decline with basin age. We studied four DTLB across an age gradient, comparing seasonal changes in the oxidation state of dissolved and extractable Fe pools and the estimated contribution of Fe reduction to ER. The organic layer thickness did not strictly increase with …

Classification Of The Alterations Of Beaver Dams To Headwater Streams In Northeastern Connecticut, U.S.A., Denise Burchsted, Melinda D. Daniels

Denise Burchsted

Of the many types of barriers to water flow, beaver dams are among the smallest, typically lasting less than a decade and rarely exceeding 1.5 m in height. They are also among the most frequent and common obstructions in rivers, with a density often exceeding ten dams per km, a frequency of construction within a given network on a time scale of years, and a historic extent covering most of North America. Past quantification of the geomorphologic impact of beaver dams has primarily been limited to local impacts within individual impoundments and is of limited geographic scope. To assess the …

Evidence That Glucose Is The Major Transferred Metabolite In Dinoflagellate–Cnidarian Symbiosis, Matthew S. Burriesci, Ted K. Raab, John R. Pringle

Ted K. Raab

Reef-building corals and many other cnidarians are symbiotic with dinoflagellates of the genus Symbiodinium. It has long been known that the endosymbiotic algae transfer much of their photosynthetically fixed carbon to the host and that this can provide much of the hostʼs total energy. However, it has remained unclear which metabolite(s) are directly translocated from the algae into the host tissue. We reexamined this question in the small sea anemone Aiptasia using labeling of intact animals in the light with 13C-bicarbonate, rapid homogenization and separation of animal and algal fractions, and analysis of metabolite labeling by gas chromatography-mass spectrometry. We …

Water Table Height And Microtopography Control Biogeochemical Cycling In An Arctic Coastal Tundra Ecosystem, David A. Lipson, Donatella Zona, Ted K. Raab, Francis Bozzolo, Marguerite Mauritz, Walter C. Oechel

Ted K. Raab

Drained thaw lake basins (DTLB’s) are the dominant land form of the Arctic Coastal Plain in northern Alaska. The presence of continuous permafrost prevents drainage and so water tables generally remain close to the soil surface, creating saturated, suboxic soil conditions. However, ice wedge polygons produce microtopographic variation in these landscapes, with raised areas such as polygon rims creating more oxic microenvironments. The peat soils in this ecosystem store large amounts of organic carbon which is vulnerable to loss as arctic regions continue to rapidly warm, and so there is great motivation to understand the controls over microbial activity in …

Reduction Of Iron (Iii) And Humic Substances Plays A Major Role In Anaerobic Respiration In An Arctic Peat Soil, David A. Lipson, Mony Jha, Ted K. Raab, Walter C. Oechel

Ted K. Raab

Arctic peat soils contain vast reserves of organic C and are largely anaerobic. However, anaerobic respiration, particularly the role of Fe(III) and humic substances as electron acceptors, is not well understood in such ecosystems. We investigated these processes in a drained thaw lake basin on the Arctic coastal plain near Barrow, Alaska. We measured concentrations of soluble Fe and other potential electron acceptors, described the microbial community, and performed experiments in the laboratory and field to measure net rates of Fe(III) reduction and the relationship of this process to C cycling. In most areas within the basin, aerobic conditions existed …

Background Fluorescence In Groundwater From A Tropical Karst Island Aquifer, Michelle Hoffman

Michelle Hoffman

Background levels of four fluorescent compounds were monitored biweekly at thirteen sampling sites on Guam, consisting of subtidal and intertidal springs, dissolution fractures, and internal upland contact spring discharge, over a 13-month period from 2006 to 2007. Samples were compared to local precipitation and to seawater samples from four nearby reef flats. The data revealed that the concentrations of optical brighteners were consistently two orders of magnitude greater than either sodium fluorescein or rhodamine WT, while Eosine Y was rarely detected. Background levels in seawater, by comparison, accounted for 25% or more of the fluorescent compounds detected at the thirteen …

Reproducibility Of Soil Moisture Ensembles When Representing Soil Parameter Uncertainty Using A Latin Hypercube–Based Approach With Correlation Control, Alejandro N. Flores, Dara Entekhabi, Rafael L. Bras

Alejandro N. Flores

Representation of model input uncertainty is critical in ensemble-based data assimilation. Monte Carlo sampling of model inputs produces uncertainty in the hydrologic state through the model dynamics. Small Monte Carlo ensemble sizes are desirable because of model complexity and dimensionality but potentially lead to sampling errors and correspondingly poor representation of probabilistic structure of the hydrologic state. We compare two techniques to sample soil hydraulic and thermal properties (SHTPs): (1) Latin Hypercube (LH) based sampling with correlation control and (2) random sampling from SHTP marginal distributions. A hydrology model is used to project SHTP uncertainty onto the soil moisture state …

Model Estimates Of Net Primary Productivity, Evapotranspiration, And Water Use Efficiency In The Terrestrial Ecosystems Of The Southern United States During 1895–2007, Hanqin Tian, Guangsheng Chen, Mingliang Liu, Chi Zhang, Ge Sun, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Shufen Pan, Arthur Chappelka

Chaoqun (Crystal) Lu

The effects of global change on ecosystem productivity and water resources in the southern United States (SUS), a traditionally ‘water-rich’ region and the ‘timber basket’ of the country, are not well quantified. We carried out several simulation experiments to quantify ecosystem net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) (i.e., NPP/ET) in the SUS by employing an integrated process-based ecosystem model (Dynamic Land Ecosystem Model, DLEM). The results indicated that the average ET in the SUS was 710 mm during 1895–2007. As a whole, the annual ET increased and decreased slightly during the first and second half …

The Coconut Palm, Cocos Nucifera, Impacts Forest Composition And Soil Characteristics At Palmyra Atoll, Central Pacific, Hillary S. Young, Ted K. Raab, Douglas J. Mccauley, Amy A. Briggs, Rodolfo Dirzo

Ted K. Raab

Cocos nucifera, the coconut palm, has a pantropical distribution and reaches near monodominance in many atolls, low lying islands and coastal regions. This paper examines the ecological correlation between C. nucifera abundance and changes in forest structure, floristic diversity and forest soil characteristics. Cumulatively, these data show that C. nucifera has important impacts on floristic, structural and soil characteristics of forests where it becomes dominant. Given the high proportion of tropical coastal areas in which C. nucifera is now naturalized and abundant, this likely has important implications for coastal forest diversity and structure.

Meta-Analysis Of Fertilization Experiments Indicates Multiple Limiting Nutrients In Northeastern Deciduous Forests, Matthew A. Vadeboncoeur

Matthew A Vadeboncoeur

It is widely accepted that N limits primary production in temperate forests, although colimitation by N and P has also been suggested, and on some soils, Ca and base cations are in short supply. I conducted a meta-analysis to assess the strength of existing experimental evidence for limitation of primary production by N, P, and Ca in hardwood forests of the northeastern United States and southeastern Canada using data from 35 fertilization experiments in deciduous forests on glaciated soils across the region.

There is strong evidence for N limitation (formal meta-analysis weighted mean response ratio = 1.51, p < 0.01; simple mean = 1.42, p < 0.001). Forest productivity also tended to increase with additions of P (simple mean = 1.15, p = 0.05) and Ca (simple mean = 1.36, p < 0.001). Across all treatments, 85% of response ratios were positive. Multiple-element additions had larger effects than single elements, but factorial experiments showed little evidence of synergistic effects between nutrient additions. Production responses correlated positively with the rate of N fertilization, but this effect was reduced at high rates of ambient N deposition.

Management Strategies To Improve Yield And Nitrogen Use Of Spring Wheat And Field Pea In The Semi-Arid Northern Great Plains Usa, Andrew W. Lenssen, Brett Allen, Upendra Sainju, Thecan Caesar, Robert Lartey, Robert Evans

Andrew W. Lenssen

Available water and N fertility are primary constraints to crop production in the northern Great Plains of the USA. A field trial was initiated in 2004 to compare four crop rotations in a complete factorial of two tillage and two management systems. Rotations were continuous spring wheat (SW), pea-SW, barley hay-pea-SW, and barley hay-corn-pea-SW. Tillage systems were no till and field cultivator tillage, while management systems were conventional and ecological. Conventional management included broadcast nitrogen fertilizer, standard seeding rates, and short stubble height. Ecological management practices varied by crop, and included banded nitrogen fertilizer for cereals, increased seeding rate, delayed …

In The Heat Of The Law, It's Not Just Steam: Geothermal Resources And The Impact On Thermophile Biodiversity, Donald J. Kochan, Tiffany Grant

Donald J. Kochan

Significant research has been conducted into the utilization of geothermal resources as a ‘green’ energy source. However, minimal research has been conducted into geothermal resource utilization and depletion impacts on thermophile biodiversity. Thermophiles are organisms which have adapted over millions of year to extreme temperature and chemical compositions and exist in hot springs and other geothermal resources. Their ability to withstand high temperatures makes them invaluable to scientific and medical research. Current federal and California case law classify geothermal resources as a mineral, not a water resource. Acquisition of rights to develop a geothermal resource owned or reserved by the …

Channel-Reach Morphology Dependence On Energy, Scale, And Hydroclimatic Processes With Implications For Prediction Using Geospatial Data, Alejandro N. Flores, Brian P. Bledsoe, Christopher O. Cuhaciyan, Ellen E. Wohl

Alejandro N. Flores

Channel types found in mountain drainages occupy characteristic but intergrading ranges of bed slope that reflect a dynamic balance between erosive energy and channel boundary resistance. Using a classification and regression tree (CART) modeling approach, we demonstrate that drainage area scaling of channel slopes provides better discrimination of these forms than slope alone among supply- and capacity-limited sites. Analysis of 270 stream reaches in the western United States exhibiting four common mountain channel types reveals that these types exist within relatively discrete ranges of an index of specific stream power. We also demonstrate associations among regional interannual precipitation variability, discharge …

Pmr6, A Pectate Lyase–Like Gene Required For Powdery Mildew Susceptibility In Arabidopsis, John P. Vogel, Ted K. Raab, Celine Schiff, Shauna C. Somerville

Ted K. Raab

The plant genes required for the growth and reproduction of plant pathogens are largely unknown. In an effort to identify these genes, we isolated Arabidopsis mutants that do not support the normal growth of the powdery mildew pathogen Erysiphe cichoracearum. Here, we report on the cloning and characterization of one of these genes, PMR6. PMR6 encodes a pectate lyase-like protein with a novel C-terminal domain. Consistent with its predicted gene function, mutations in PMR6 alter the composition of the plant cell wall, as shown by Fourier transform infrared spectroscopy. pmr6-mediated resistance requires neither salicylic acid nor the ability to perceive …

Visualizing Rhizosphere Chemistry Of Legumes With Mid-Infrared Synchrotron Radiation, Ted K. Raab, Michael C. Martin

Ted K. Raab

A bright synchrotron light source operated by the Lawrence Berkeley National Laboratory served as an external source for infrared (IR) microscopy of plant root microcosms. Mid-IR light from synchrotrons is 2-3 orders of magnitude brighter than conventional sources, providing contrast based on the chemical information in the reflected signal at a spatial resolution near the diffraction-limit of 3-10 microns. In an experiment using plant root microcosms fitted with zinc selenide IR-transmissive windows (50 mm x 20 mm x 1 mm), we describe chemical differences and similarities within the root zone of mung bean (Vigna radiata L.), grown with or without …

An Empirical Model Of Amino Acid Transformations In An Alpine Soil, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson

Ted K. Raab

Amino acids are potentially important nitrogen (N) sources for plants in many ecosystems. However, a quantitative understanding of organic N availability is lacking for most ecosystems. This study estimates seasonal amino acid fluxes in an alpine tundra soil using three independent data sets. In previous work in an alpine dry meadow ecosystem in the Front Range of the Colorado Rocky Mountains, we measured signifcant rates of amino acid production from soil peptides during the plant growing season. This suggested that proteolysis of native soil peptides could serve as a measure of amino acid availability to plants. Here we use a …

Soil Amino Acid Utilization Among Species Of The Cyperaceae: Plant And Soil Processes, Ted K. Raab, David A. Lipson, Steven K. Scmidt, Russ K. Monson

Ted K. Raab

Amino acids are released during the decomposition of soil organic matter and have been shown to be utilized as a nitrogen source by some non-mycorrhizal species in the family Cyperaceae (the sedge family). Twelve out of 13 Cyperaceae species examined in the current study were capable of absorbing soil amino acids in the non-mycorrhizal state. With two exceptions (two species in the genus Kobresia), species from subalpine or alpine habitats exhibited lower rates of total nitrogen uptake compared to species from more temperate habitats, which is possibly explained by lower growth rates in the alpine and subalpine species and a …