Reconstruction of Tertiary Metasequoia forests. I. Test of a method for biomass determination based on stem dimensions

Accurate reconstruction of the biomass, structure, and productivity of ancient forests from their fossilized remnants remains an interesting challenge in paleoecology. In well-preserved Tertiary fossil Metasequoia forests of Canada's Arctic, in situ stumps and fragments of stems, treetops, and branches contain substantial information about tree dimensions that can be used to determine tree height, stand biomass, and other characteristics such as canopy depth and structure, and the history of stand development. To validate a method for reconstructing the biomass of the Eocene floodplain Metasequoia forests of Axel Heiberg Island, we measured stump diameters and spacing, and stem, branch, and treetop characteristics in living Metasequoia glyptostroboides and Chamaecyparis thyoides stands in ways that simulate the limited measurements that can be made in well-preserved fossil forests in Canada and probably elsewhere. We used those limited measurements to estimate tree height and volume, branch and foliar dry weights, and tree biomass. The estimates derived from the limited data set are usually within 15% of the estimates derived from the methods currently used in forest ecology for determining those metrics in modern forests. Under appropriate conditions, the biomass of ancient forests can be estimated with reasonable confidence.

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Allometry and size structure of trees in two ancient snow forests in coastal British Columbia

Canadian Journal of Forest Research ◽

10.1139/x07-172 ◽

2008 ◽

Vol 38 (2) ◽

pp. 278-288 ◽

Cited By ~ 8

Author(s):

Roberta Parish ◽

Gordon D. Nigh ◽

Joseph A. Antos

Keyword(s):

Size Structure ◽

Model Development ◽

Tree Height ◽

Tsuga Heterophylla ◽

Diameter Ratio ◽

Data Set ◽

Crown Length ◽

Shade Tolerant Species ◽

Height Change ◽

Ancient Forests

Shade-tolerant trees that start in the understory but ultimately reach the canopy persist through different microhabitat conditions during their ontogeny. We evaluate how the height to diameter ratio and the crown ratio (crown length/tree height) change during development and differ among four coniferous species ( Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes, Chamaecyparis nootkatensis (D. Don) Spach, Tsuga mertensiana (Bong.) Carrière, and Tsuga heterophylla (Ref.) Sarg.) in ancient forests. At two sites, we measured diameter, height, and height to the base of live crown for trees ≥4.0 cm diameter at breast height in four 0.25 ha plots. For each species, we constructed models of height based on diameter and crown length using part of the data for model development and part as the test data set. Models predicting tree height were effective for all species, and adding crown length considerably improved the prediction over diameter alone. The height to diameter ratio increased until the subcanopy and then decreased for two shade-tolerant species (A. amabilis and T. heterophylla) but decreased linearly throughout ontogeny for C. nootkatensis. Crown ratio increased as trees became larger except for C. nootkatensis, where the reverse occurred. Differences in allometric relationship among species reflect patterns of crown development and also suggest different approaches to a common structural constraint in these forests: heavy snow loads.

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ARCCAD AS A GIS PLATFORM FOR UNDERSTANDING THE VEGETATION OF STEPHEN F. AUSTIN STATE UNIVERSITY

HortScience ◽

10.21273/hortsci.29.7.729c ◽

1994 ◽

Vol 29 (7) ◽

pp. 729c-729

Author(s):

Susan Lindley ◽

D. L. Creech

Keyword(s):

Tree Height ◽

Current Status ◽

State University ◽

Data Set ◽

Tree Health ◽

History Of ◽

History Of The University ◽

The University ◽

Analytical Tools ◽

The Impact

Stephen F. Austin State University is known as the ``University Among the Pines.” The campus is located along the banks of LnNana creek in the center of Nacogdocha, the oldest town in Texas. Rich with history, the community and the university are now recognizing that cultural. historical and landscape treasure deserve greater protection and conservation. This project involves: 1) collecting a data set of each tree on campus including quadrant identifier, plant ID #, species, dbh, tree health, location, crow diameter, tree height and tree value, 2) placing all trees on a campus map in ArcCAD®, a Geographic Information System (GIS) developed for the PC, 3) linking map entities (trees, polygons, themes) with specific rows in a database, and 4) developing a query strategy to ask questions of the landscape. Database queries are powerful analytical tools which can generate resultant maps that answer specific landscape questions. These maps can then be queried again for further analysis. Examples of typical queries might include: 1) illustrate only those pines with a dbh greater than 24″, 2) identify all oak trees within thirty feet of a building, or 3) illustrate all trees over sixty feet with poor tree health. ArcCAD® links the easy drafting capabilities of AutoCAD® with much of the functionality of a true GIS workstation. Map files can be linked to a database(s), text, and visual images (TIF files). We have scanned and are currently archiving old photographs of the campus for future linkages. By understanding the history of the university landscape and documenting the current status of campus vegetation, decision-makers can have at strategies that lessen the impact of development.

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Cataloging accreted stars within Gaia DR2 using deep learning

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936866 ◽

2020 ◽

Vol 636 ◽

pp. A75 ◽

Cited By ~ 3

Author(s):

B. Ostdiek ◽

L. Necib ◽

T. Cohen ◽

M. Freytsis ◽

M. Lisanti ◽

...

Keyword(s):

Milky Way ◽

Simulated Data ◽

Selection Methods ◽

Matter Distribution ◽

Data Set ◽

Hydrodynamic Simulations ◽

History Of ◽

Dark Matter Distribution ◽

Gaia Dr2

Aims. The goal of this study is to present the development of a machine learning based approach that utilizes phase space alone to separate the Gaia DR2 stars into two categories: those accreted onto the Milky Way from those that are in situ. Traditional selection methods that have been used to identify accreted stars typically rely on full 3D velocity, metallicity information, or both, which significantly reduces the number of classifiable stars. The approach advocated here is applicable to a much larger portion of Gaia DR2. Methods. A method known as “transfer learning” is shown to be effective through extensive testing on a set of mock Gaia catalogs that are based on the FIRE cosmological zoom-in hydrodynamic simulations of Milky Way-mass galaxies. The machine is first trained on simulated data using only 5D kinematics as inputs and is then further trained on a cross-matched Gaia/RAVE data set, which improves sensitivity to properties of the real Milky Way. Results. The result is a catalog that identifies ∼767 000 accreted stars within Gaia DR2. This catalog can yield empirical insights into the merger history of the Milky Way and could be used to infer properties of the dark matter distribution.

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Eocene origin, Miocene diversification and intercontinental dispersal of the genus Drosera (Droseraceae)

10.1101/2020.08.06.240234 ◽

2020 ◽

Author(s):

Sandeep Sen ◽

Neha Tiwari ◽

R Ganesan

Keyword(s):

Dna Sequences ◽

Evolutionary Biology ◽

Charles Darwin ◽

Long Distance ◽

Data Set ◽

Origin And Evolution ◽

Fossil Calibration ◽

History Of ◽

Nuclear Its

AbstractResolving the evolutionary history of plant carnivory is of great interest to biologists throughout the world. Among the carnivorous plants, Genus Drosera (Droseraceae) is highly diverse with a wide pantropical distribution. Despite being a group of interest for evolutionary biology studies since the time of Charles Darwin, the historical biogeography of this group remains poorly understood. In this study, with an improved species sampling from Genbank, we present a reanalyzed phylogenetic hypothesis of the genus Drosera. We developed a dated molecular phylogeny of Drosera from DNA sequences of nuclear ITS and chloroplast rbcL genes. Divergence times were estimated on the combined dataset using an uncorrelated lognormal relaxed clock model and a known fossil calibration implemented in BEAST. The maximum clade credibility tree was then used for ancestral range estimations using DEC+J model implemented in BioGeoBEARS. Our analysis suggests that Drosera evolved during the Mid Eocene 36 Ma [95% HPD: 49.5-26] and have diversified and dispersed from the late Miocene onwards. Ancestral areas estimated using the DEC+J models suggest an African origin followed major radiation within Australia. Diversification in Drosera is temporally congruent with the prevailing drier conditions during the Miocene. From Miocene, grasslands and open habitats dominated across continents and might have provided ecological opportunities for their dispersal and diversification. Several long-distance dispersals and range extensions and in situ radiations coinciding with the evolution of drier conditions can explain their extant distribution across continents. Overall our data set provides fresh insights into the biogeographic factors that shaped the origin and evolution of the genus Drosera.

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North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

Scientific Reports ◽

10.1038/s41598-021-83329-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. Alexis P. Rodriguez ◽

Kenneth L. Tanaka ◽

Ali M. Bramson ◽

Gregory J. Leonard ◽

Victor R. Baker ◽

...

Keyword(s):

Katabatic Wind ◽

Spiral Pattern ◽

Near Surface ◽

Valuable Source ◽

History Of ◽

North Polar ◽

Human Exploration ◽

Erosional Event

AbstractThe clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

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Development of a Field Deployable Firebrand Flux and Condition Measurement System

Fire Technology ◽

10.1007/s10694-020-01074-x ◽

2020 ◽

Author(s):

Simone Zen ◽

Jan C. Thomas ◽

Eric V. Mueller ◽

Bhisham Dhurandher ◽

Michael Gallagher ◽

...

Keyword(s):

Imaging Techniques ◽

Time History ◽

Infrared Camera ◽

Thermal Conditions ◽

Particle Characterization ◽

Fire Dynamics ◽

Rate Of Spread ◽

New Instrument ◽

History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

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In Situ exploration of the giant planets

Experimental Astronomy ◽

10.1007/s10686-021-09775-z ◽

2021 ◽

Author(s):

O. Mousis ◽

D. H. Atkinson ◽

R. Ambrosi ◽

S. Atreya ◽

D. Banfield ◽

...

Keyword(s):

Solar System ◽

Giant Planets ◽

Atmospheric Composition ◽

Formation History ◽

History Of ◽

Composition Structure ◽

Galileo Probe ◽

Probe Measurements

AbstractRemote sensing observations suffer significant limitations when used to study the bulk atmospheric composition of the giant planets of our Solar System. This impacts our knowledge of the formation of these planets and the physics of their atmospheres. A remarkable example of the superiority of in situ probe measurements was illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases’ abundances and the precise measurement of the helium mixing ratio were only made available through in situ measurements by the Galileo probe. Here we describe the main scientific goals to be addressed by the future in situ exploration of Saturn, Uranus, and Neptune, placing the Galileo probe exploration of Jupiter in a broader context. An atmospheric entry probe targeting the 10-bar level would yield insight into two broad themes: i) the formation history of the giant planets and that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. An atmospheric probe could represent a significant ESA contribution to a future NASA New Frontiers or flagship mission to be launched toward Saturn, Uranus, and/or Neptune.

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Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317006159 ◽

2017 ◽

Vol 12 (S330) ◽

pp. 148-151 ◽

Cited By ~ 1

Author(s):

Edouard J. Bernard

Keyword(s):

Star Formation ◽

Star Formation History ◽

Solar Neighbourhood ◽

The Sun ◽

Thick Disc ◽

Formation History ◽

Magnitude Diagram ◽

History Of

AbstractWe took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

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The merger-driven evolution of massive early-type galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002434 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 62-66

Author(s):

Carlo Cannarozzo ◽

Carlo Nipoti ◽

Alessandro Sonnenfeld ◽

Alexie Leauthaud ◽

Song Huang ◽

...

Keyword(s):

Mass Velocity ◽

Selection Criteria ◽

Velocity Dispersion ◽

Ex Situ ◽

Scaling Relations ◽

Early Type ◽

History Of ◽

Kinematic Properties ◽

Shed Light

AbstractThe evolution of the structural and kinematic properties of early-type galaxies (ETGs), their scaling relations, as well as their stellar metallicity and age contain precious information on the assembly history of these systems. We present results on the evolution of the stellar mass-velocity dispersion relation of ETGs, focusing in particular on the effects of some selection criteria used to define ETGs. We also try to shed light on the role that in-situ and ex-situ stellar populations have in massive ETGs, providing a possible explanation of the observed metallicity distributions.

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Economics of respiratory disease in dairy replacement heifers

Animal Health Research Reviews ◽

10.1017/s1466252320000250 ◽

2020 ◽

Vol 21 (2) ◽

pp. 143-148

Author(s):

Michael W. Overton

Keyword(s):

Respiratory Disease ◽

Milk Production ◽

Incident Case ◽

Data Set ◽

Dairy Heifers ◽

The Usa ◽

History Of ◽

On Farm ◽

The Impact ◽

Selective Culling

AbstractBovine respiratory disease (BRD) is a frequent disease concern in dairy cattle and is most commonly diagnosed in young dairy heifers. The impact of BRD is highly variable, depending on the accuracy and completeness of detection, effectiveness of treatment, and on-farm culling practices. Consequences include decreased rate of weight gain, a higher culling risk either as heifers or as cows, delayed age at first service, delayed age at first calving, and in some cases, lower future milk production. In this data set of 104,100 dairy replacement heifers from across the USA, 36.6% had one or more cases diagnosed within the first 120 days of age with the highest risk of new cases occurring prior to weaning. Comparison of the raising cost for heifers with BRD and those without a recorded history of BRD resulted in an estimated cost per incident case occurring in the first 120 days of age of $252 or $282, depending upon whether anticipated future milk production differences were considered or not. Current market conditions contributed to a cost estimate that is significantly higher than previously published estimates, driven in part by the losses associated with selective culling of a subset of heifers that experienced BRD.

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