Scale Of Meters Research Articles

Topographic Roughness as an Emergent Property of Geomorphic Processes and Events

AbstractEarth's terrestrial surfaces commonly exhibit topographic roughness at the scale of meters to tens of meters. In soil‐ and sediment‐mantled settings topographic roughness may be framed as a competition between roughening and smoothing processes. In many cases, roughening processes may be specific eco‐hydro‐geomorphic events like shrub deaths, tree uprooting, river avulsions, or impact craters. The smoothing processes are all geomorphic processes that operate at smaller scales and tend to drive a diffusive evolution of the surface. In this article, we present a generalized theory that explains topographic roughness as an emergent property of geomorphic systems (semi‐arid plains, forests, alluvial fans, heavily bombarded surfaces) that are periodically shocked by an addition of roughness which subsequently decays due to the action of all small scale, creep‐like processes. We demonstrate theory for the examples listed above, but also illustrate that there is a continuum of topographic forms that the roughening process may take on so that the theory is broadly applicable. Furthermore, we demonstrate how our theory applies to any geomorphic feature that can be described as a pit or mound, pit‐mound couplet, or mound‐pit‐mound complex.

Temperature stabilization of a lab space at 10 mK-level over a day.

Temperature fluctuations over long time scales (≳ 1h) are an insidious problem for precision measurements. In optical laboratories, the primary effect of temperature fluctuations is drifts in optical circuits over spatial scales of a few meters and temporal scales extending beyond a few minutes. We present a lab-scale environment temperature control system approaching 10mK-level temperature instability across a lab for integration times above an hour and extending to a day. This is achieved by passive isolation of the laboratory space from the building walls using a circulating air gap and an active control system feeding back to heating coils at the outlet of the laboratory's Heating-Ventilation-Air-Conditioning (HVAC) unit. These techniques together result in 20 dB suppression of the temperature power spectrum across the lab at 10-4Hz-approaching the limit set by statistical coherence of the temperature field-and 10mK Allan deviation around 15 °C after an hour of averaging, which is an order of magnitude better than any previous report for a full laboratory.

Reactive transport modeling of the Aquifer Thermal Energy Storage (ATES) system at Stockton University, New Jersey during seasonal operations

Hydrogeochemical processes associated with Aquifer Thermal Energy Storage (ATES) operations can often impact the system performance owing to mineral precipitation either at the wellbore or in the aquifer owing to changes in temperature and fluid disequilibria. Although failure of ATES systems due to mineral precipitation ("fouling") is common, predictive reactive-transport models have rarely been applied to plan their design and operation. The objective of this study is to develop a reactive-transport model by coupling thermal, hydrological, and chemical (THC) processes to evaluate effects of introduced atmospheric oxygen on water chemistry, mineral precipitation/dissolution, porosity, and permeability changes associated with an ATES system at Stockton University (New Jersey, USA). The THC model builds on a Thermal-Hydrological-Mechanical (THM) model of the site (Smith et al., 2021) that evaluated system failure owing to possible fracturing in the caprock or around the wellbore. The causes of the system failure are not known – potential causes include hydraulic fracturing owing to elevated pump pressures that took place, a flow pathway created by one of the boreholes, or a pre-existing natural hydrologic connection between the upper unconfined aquifer and the ATES aquifer, any of which could have led to oxygenated water entering the reservoir and causing the observed Fe-oxide fouling on well screens. The THC model is used to evaluate some of the hypotheses and observations regarding system failure owing to geochemical processes.The reactive-transport code TOUGHREACT V4 (Sonnenthal et al., 2021) was used to model the THC processes during seasonal heating and cooling operations at the Stockton ATES site over 6 years of operation. In the THC simulations, the primary effects on geochemistry were observed when the injection water is saturated with atmospheric oxygen. Simulations show greater precipitation of goethite near the cold wells as compared to the warm wells. Although volume fractions of Fe-hydroxides were relatively small, the model was aimed at processes in the aquifer at the scale of meters and larger rather than at the scale of mm or cm (i.e., a well screen). Kaolinite is the dominant precipitating phase, also around the cold wells. Illite dissolves near the cold wells and precipitates near the warm wells. There is a net decrease in the porosity near the cold wells and increase near the warm wells, although a slight amount of thermal contraction near the cold wells and expansion near the warm wells is responsible for a significant proportion of the porosity change. Owing to the coarse discretization of the numerical grid near the wells (compared to the screen thickness) the magnitude of permeability changes at the wellbore are likely underestimated. The reactive transport model in this study can be used for characterization of aquifers, optimizing the operational parameters (temperature, pressure, pH etc.), and planning of mitigation strategies for ATES systems.

Firmgrounds and hardgrounds in the Coniacian carbonate platform of the Iberian basin: Origin and model for development of omission surfaces in tidal environments

Distinctive erosional and omission surfaces occur at several stratigraphic levels in the tidal carbonates of the 3rd-order Coniacian sequence (Iberian Basin). They are ancient analogs of omission surfaces developed on lithified carbonates in subaerial and coastal settings. Omission surfaces consist of (i) firmground Glossifungites ichnofacies (Balanoglossites-Thalassinoides); and (ii) hardground Trypanites ichnofacies (scalloped and planar surfaces and Gastrochaenolites-Entobia surfaces). Firmgrounds are also related to erosion or ferruginous crusts. Hardground surfaces are related to bioerosion, dissolution and physical erosion. Grain size and textural features in Balanoglossites and Thalassinoides firmground surfaces are essentially the same, suggesting that even bathymetry could be similar. Several stages in hardgrounds consist of different, scalloped or planar surfaces related to bioerosion, dissolution and physical erosion. Gastrochaenolites-Entobia borers represent a major change in the trace fossil associations and imply different processes in their origin, being originated at slightly different depths with Gastrochaenolites representing shallower environments. The studied field sections display a cyclicity on the scale of meters that tentatively reflects the presence of 4th-order parasequence sets. Two kinds of sedimentary discontinuities have been used for correlation: omission surfaces and ferruginous crusts representing regional sea level falls and rises. Part of the described surfaces does not appear to have been previously recognized in older carbonate deposits. Their common presence of similar surfaces along modern coasts and in karst terrains, as well as their abundance in the Coniacian sequence, suggests that they might also be abundant in the geologic record in other sedimentary basins for defining palaeoshorelines.

The effect of terrain on the fine-scale genetic diversity of sub-Antarctic Collembola: A landscape genetics approach.

Biodiversity patterns are shaped by the interplay between geodiversity and organismal characteristics. Superimposing genetic structure onto landscape heterogeneity (i.e., landscape genetics) can help to disentangle their interactions and better understand population dynamics. Previous studies on the sub-Antarctic Prince Edward Islands (located midway between Antarctica and Africa) have highlighted the importance of landscape and climatic barriers in shaping spatial genetic patterns and have drawn attention to the value of these islands as natural laboratories for studying fundamental concepts in biology. Here, we assessed the fine-scale spatial genetic structure of the springtail, Cryptopygus antarcticus travei, which is endemic to Marion Island, in tandem with high-resolution geological data. Using a species-specific suite of microsatellite markers, a fine-scale sampling design incorporating landscape complexity and generalised linear models (GLMs), we examined genetic patterns overlaid onto high-resolution digital surface models and surface geology data across two 1-km sampling transects. The GLMs revealed that genetic patterns across the landscape closely track landscape resistance data in concert with landscape discontinuities and barriers to gene flow identified at a scale of a few metres. These results show that the island's geodiversity plays an important role in shaping biodiversity patterns and intraspecific genetic diversity. This study illustrates that fine-scale genetic patterns in soil arthropods are markedly more structured than anticipated, given that previous studies have reported high levels of genetic diversity and evidence of genetic structing linked to landscape changes for springtail species and considering the homogeneity of the vegetation complexes characteristic of the island at the scale of tens to hundreds of metres. By incorporating fine-scale and high-resolution landscape features into our study, we were able to explain much of the observed spatial genetic patterns. Our study highlights geodiversity as a driver of spatial complexity. More widely, it holds important implications for the conservation and management of the sub-Antarctic islands.

Does water transparency control the banding in shallow water iron formations?

Abstract Iron formations (IFs) are marine chemical sediments that are conined to the Precambrian rock record and provide unique insights into the co-evolution of the atmosphere-hydrosphere and biosphere through almost three billion years of Earth’s history. IFs commonly appear throughout the Archaean until the Palaeoproterozoic ca. 1.8 billion years ago and re-appear during the “Snowball Earth” epoch in the Neoproterozoic. The formation and deposition mechanism(s) of IFs are, however, still incompletely understood, hindering unique interpretations of palaeoenvironments. Many IFs are banded iron formations (BIFs) with layer thickness of alternating Fe- and Si-rich layers ranging over several orders of magnitude from the nanometre to the metre scale. A second textural type, so called granular iron formations (GIFs) that form above storm wave base become widespread in the Palaeoproterozoic. Understanding the fundamental mechanisms that are responsible for the textural types and the periodicity of banding in BIFs is crucial to link these features to the environmental and geochemical evolution of the Earth. We here provide a conceptual model that highlights the role of changing light conditions and water transparency for Iron Formation (IF) precipitation. We show that the model is particularly feasible for IFs deposited in shallow waters but may also be applicable for some IFs deposited in deeper water settings. The model builds on other primary Banded Iron Formation (BIF) precipitation models postulating that Fe(III)-(oxyhydr)oxide production can be dominated by anoxygenic photoautotrophic Fe2+-oxidising bacteria. These so called photoferrotrophs are adapted to very low light levels corresponding to about 1% of the light level required by oxygen-producing phototrophs allowing them to thrive deep down in the water column. The depth of Fe(III)-(oxyhydr)oxide production is mainly controlled by water turbidity which controls how deep photosynthetically available radiation (PAR) penetrates the water column. Eutrophic conditions result in relatively shallow Fe(III)-(oxyhydr)oxide production depth due to turbidity either induced by the biomass itself and/or by particles that are actively or passively produced by microorganisms (e.g., Fe(III) and Mn(IV)-(oxyhydr)oxides, sulphides), triggering the formation of Fe-rich bands. During oligotrophic stages, Fe(III)-(oxyhydr)oxides are only produced relatively deep down in the water column, so that only silica-rich bands form in the Fe(III)-(oxyhydr)oxide free upper water column. Reactive transport modelling adopted from Ozaki et al., (2019) shows that besides upwelling and nutrient supply, alternating Fe(III) production depth is mainly associated with changing light conditions as a result of water transparency. Periodicities reflected by alternating Fe- and Si-rich bands in IFs in our model can thus be associated with: (1) nutrient supply patterns; (2) additional sources of turbidity in the water column such as Fe(III) and Mn(IV) oxide particles, sulphides, and wind-blown silicate particles; or (3) formation and clearing of organic haze in the atmosphere. One or all of these reasons for low light conditions seem to become more important in the Palaeoproterozoic (<2.4 Ga) and could be partly responsible for the more widespread occurrences of shallow marine granular IFs relative to former epochs, which is often assigned to the gradual oxidation of the ocean. Our model shows that variable water transparency should be considered as additional factor for IF deposition especially for shallow marine settings. This model also reasonably explains the prominent layering in BIFs as syn-depositional feature.

A Highly Homogeneous Airborne Fungal Community around a Copper Open Pit Mine Reveals the Poor Contribution Made by the Local Aerosolization of Particles.

Fungi are ubiquitous and metabolically versatile. Their dispersion has important scientific, environmental, health, and economic implications. They can be dispersed through the air by the aerosolization of near surfaces or transported from distant sources. Here, we tested the contribution of local (scale of meters) versus regional (kilometers) sources by analyzing an airborne fungal community by ITS sequencing around a copper mine in the North of Chile. The mine was the regional source, whereas the soil and vegetal detritus were the local sources at each point. The airborne community was highly homogeneous at ca. 2000 km2, impeding the detection of regional or local contributions. Ascomycota was the dominant phylum in the three communities. Soil and vegetal detritus communities had lower alpha diversity, but some taxa had abundance patterns related to the distance from the mine and altitude. On the contrary, the air was compositionally even and unrelated to environmental or spatial factors, except for altitude. The presence of plant pathogens in the air suggests that other distant sources contribute to this region's airborne fungal community and reinforces the complexity of tracking the sources of air microbial communities in a real world where several natural and human activities coexist.

Distributed Optical Fibre Sensing for High Space‐Time Resolution Ocean Velocity Observations: A Case Study From a Macrotidal Channel

AbstractDespite significant recent technological advances, oceanographic observations on horizontal scales of meters to a few kilometres prove challenging. Exploiting legacy seafloor cables presents a disruptive prospect to address this gap, as it may provide low‐cost sustained observations with high space‐time resolution, enabled through novel opto‐electronic interrogation of optical fibers within the cables. Here, we demonstrate this approach in a renewable tidal energy cable embedded within a region with a strong barotropic tide. By making remote measurements continuously over 12 hr, we obtain the distributed differential strain experienced by 2 km of offshore cable from a diverse range of oceanic flow processes, with an along‐cable resolution of 2.04 m. We successfully identify: (a) nearshore wave breaking and its modulation by changes in water depth; (b) along‐cable tidal velocity, shown to be linearly related to the differential strain; and (c) high‐frequency motions consistent with 3‐dimensional turbulent processes, either of natural origin or from flow‐cable interaction. These inferences are supported by nearby conventional measurements of water depth and velocity.

Shape-from-shading Refinement of LOLA and LROC NAC Digital Elevation Models: Applications to Upcoming Human and Robotic Exploration of the Moon

The Lunar Reconnaissance Orbiter (LRO) has returned a wealth of remotely sensed data of the Moon over the past 15 years. As preparations are under way to return humans to the lunar surface with the Artemis campaign, LRO data have become a cornerstone for the characterization of potential sites of scientific and exploration interest on the Moon's surface. One critical aspect of landing site selection is knowledge of topography, slope, and surface hazards. Digital elevation models derived from the Lunar Orbiter Laser Altimeter (LOLA) and Lunar Reconnaissance Orbiter Camera (LROC) instruments can provide this information at scales of meters to decameters. Shape-from-shading (SfS), or photoclinometry, is a technique for independently deriving surface height information by correlating surface reflectance with incidence angle and can theoretically approach an effective resolution equivalent to the input images themselves, typically better than 1 m per pixel with the LROC Narrow Angle Camera (NAC). We present a high-level, semiautomated pipeline that utilizes preexisting Ames Stereo Pipeline tools along with image alignment and parallel processing routines to generate SfS-refined digital elevation models using LRO data. In addition to the present focus on the lunar south pole with Artemis, we also demonstrate the usefulness of SfS for characterizing meter-scale lunar topography at lower equatorial latitudes.

Unraveling microbial community structure–function relationships in the horizontal and vertical spatial dimensions in extreme environments

A fundamental challenge in soil macroecology is to understand how microbial community structure shapes ecosystem function along environmental gradients of the land surface at broad spatial scales (i.e. the horizontal dimension). However, little is known about microbial community structure–function relationships in extreme environments along environmental gradients of soil depth at finer spatial scales (i.e. the vertical dimension). Here, we propose a general spatial dimension partitioning approach for assessing the patterns and drivers of soil microbial community structure–function relationships across horizontal and vertical spatial gradients simultaneously. We leveraged a 200‐km desert soil salinity gradient created by a 12‐year saline‐water irrigation in the Tarim basin of Taklamakan Desert. Specifically, using a general linear model, hierarchical variance partitioning, and a path model, we assessed the patterns and key ecological processes controlling spatial turnover in microbial community structure (i.e. β‐diversity) and enzymatic activity relevant to carbon, nitrogen, and phosphorus cycling along soil salinity gradients across study sites (horizontal dimension) and soil depths (vertical dimension). We found a decoupled relationship between soil microbial β‐diversity and enzymatic activity. Differences in soil depth (on the scale of meters) were as important as geographic distance (on the scale of kilometers) in shaping bacterial and fungal β‐diversity. However, the vertical and horizontal turnover in enzymatic activity was largely attributed to an increase in the heterogeneity of soil properties, such as soil texture, water content, and pH. Our findings suggest that dispersal limitation controls microbial community β‐diversity and that environmental heterogeneity, rather than soil salinization, controls enzymatic activity. Taken together, this work highlights that in the face of ongoing environmental alterations, soil depth is an under‐explored spatial dimension that must be considered in soil conservation efforts as a critical factor in determining microbial community structure and function in extreme environments.

“Spiders” on the Moon: Morphological Evidence for Geologically Recent Regolith Drainage into Subsurface Voids

On the Moon, the surface morphology at the scale of meters and tens of meters is typically smooth and subdued due to regolith gardening. Sharp, “crisp,” meter-scale morphologic features are observed only where the regolith is either thin or recently disturbed. Such crisp morphologies are typically created by geologically recent meteoritic impacts of different scales. The prominent exception is so-called irregular mare patches (IMPs), rare small features of debated origin. We report here on the discovery of previously unknown crisp immature morphological features (named “spiders” due to their central circular region and radiating “legs”) not related to impacts and even more rare. The spiders are meters-deep depressions with near-radial chutes open toward the center which make an incipient dendritic pattern 50–80 m in diameter. All spiders found thus far occur in clusters in the same region in Mare Tranquillitatis in the immediate proximity to small IMPs. We interpret spiders as the result of an energetic granular flow of the regolith draining into shallow subsurface voids following the sudden collapse of the roofs of the voids. Regolith gardening destroys the spiders’ legs rapidly, on a timescale of a million years. If the entrance into the subsurface void remains unclogged, a spider appears to evolve into a pit; otherwise it evolves into a gentle depression and finally disappears. Our interpretation of spiders provides a consistent explanation of all of their features, occurrence settings, and associations.

Impact of Imperfect Kolsky Bar Experiments Across Different Scales Assessed Using Finite Elements

Abstract Typical Kolsky bars are 10–20 mm in diameter with lengths of each main bar being on the scale of meters. To push 104+ strain rates, smaller systems are needed. As the diameter and mass decrease, the precision of the alignment must increase to maintain the same relative tolerance, and the potential impacts of gravity and friction change. Finite element models are typically generated assuming a perfect experiment with exact alignment and no gravity. Additionally, these simulations tend to take advantage of the radial symmetry of an ideal experiment, which removes any potential for modeling nonsymmetric effects, but has the benefit of reducing computational load. In this work, we discuss results from these fast-running symmetry models to establish a baseline and demonstrate their first-order use case. We then take advantage of high-performance computing techniques to generate half symmetry simulations using Abaqus® to model gravity and misalignment. The imperfection is initially modeled using a static general step followed by a dynamic explicit step to simulate the impact events. This multistep simulation structure can properly investigate the impact of these real-world, nonaxis symmetric effects. These simulations explore the impacts of these experimental realities and are described in detail to allow other researchers to implement a similar finite element (FE) modeling structure to aid in experimentation and diagnostic efforts. It is shown that of the two sizes evaluated, the smaller 3.16-mm system is more sensitive than the larger 12.7 mm system to such imperfections.

High-resolution projections of outdoor thermal stress in the twenty-first century: a Tasmanian case study

To adapt to Earth’s rapidly changing climate, detailed modelling of thermal stress is needed. Dangerous stress levels are becoming more frequent, longer, and more severe. While traditional measurements of thermal stress have focused on air temperature and humidity, modern measures including radiation and wind speed are becoming widespread. However, projecting such indices has presented a challenging problem, due to the need for appropriate bias correction of multiple variables that vary on hourly timescales. In this paper, we aim to provide a detailed understanding of changing thermal stress patterns incorporating modern measurements, bias correction techniques, and hourly projections to assess the impact of climate change on thermal stress at human scales. To achieve these aims, we conduct a case study of projected thermal stress in central Hobart, Australia for 2040–2059, compared to the historical period 1990–2005. We present the first hourly metre-scale projections of thermal stress driven by multivariate bias-corrected data. We bias correct four variables from six dynamically downscaled General Circulation Models. These outputs drive the Solar and LongWave Environmental Irradiance Geometry model at metre scale, calculating mean radiant temperature and the Universal Thermal Climate Index. We demonstrate that multivariate bias correction can correct means on multiple time scales while accurately preserving mean seasonal trends. Changes in mean air temperature and UTCI by hour of the day and month of the year reveal diurnal and annual patterns in both temporal trends and model agreement. We present plots of future median stress values in the context of historical percentiles, revealing trends and patterns not evident in mean data. Our modelling illustrates a future Hobart that experiences higher and more consistent numbers of hours of heat stress arriving earlier in the year and extending further throughout the day.

Overview of the research work of Prof. Koyanagi and the composite materials laboratory

Materials at the quantum scale are highly unpredictable, making it impossible to predict certain measurements. There are also limitations to numerical simulations and modelling techniques for understanding advanced materials at the molecular scale. Professor Jun Koyanagi, Koyanagi Laboratory, Tokyo University of Science, Japan, is working to establish a quantitative link that connects the nanoscale simulations to the metre scale. This involves developing methods and techniques that accurately relate the behaviour observed at the molecular level to the macroscopic properties of the material. In order to do this, a comprehensive understanding of the underlying physics and mechanics at each scale is required. Koyanagiâ–™s team is hoping to apply multiscale numerical simulations that will help to ensure the long-term reliability of a range of advanced materials. A key focus of the research is carbon fibre reinforced plastic (CFRP) and Koyanagi wants to pave the way for the widespread use of CFRP in aerovehicles in the near future. The team will conduct multiscale numerical simulations and advanced material development to ensure the reliability and long-term durability of CFRP. This will allow them to confidently incorporate CFRP into the construction of aerovehicles and these will be more sustainable and environmentally friendly as the lightweight nature of CFRP will significantly contribute to enhancing fuel efficiency and reducing emissions. The researchers are using analytical and experimental methods to evaluate the thermal and mechanical properties of composite materials.

Deep learning to extract the meteorological by-catch of wildlife cameras.

Microclimate-proximal climatic variation at scales of metres and minutes-can exacerbate or mitigate the impacts of climate change on biodiversity. However, most microclimate studies are temperature centric, and do not consider meteorological factors such as sunshine, hail and snow. Meanwhile, remote cameras have become a primary tool to monitor wild plants and animals, even at micro-scales, and deep learning tools rapidly convert images into ecological data. However, deep learning applications for wildlife imagery have focused exclusively on living subjects. Here, we identify an overlooked opportunity to extract latent, ecologically relevant meteorological information. We produce an annotated image dataset of micrometeorological conditions across 49 wildlife cameras in South Africa's Maloti-Drakensberg and the Swiss Alps. We train ensemble deep learning models to classify conditions as overcast, sunshine, hail or snow. We achieve 91.7% accuracy on test cameras not seen during training. Furthermore, we show how effective accuracy is raised to 96% by disregarding 14.1% of classifications where ensemble member models did not reach a consensus. For two-class weather classification (overcast vs. sunshine) in a novel location in Svalbard, Norway, we achieve 79.3% accuracy (93.9% consensus accuracy), outperforming a benchmark model from the computer vision literature (75.5% accuracy). Our model rapidly classifies sunshine, snow and hail in almost 2 million unlabelled images. Resulting micrometeorological data illustrated common seasonal patterns of summer hailstorms and autumn snowfalls across mountains in the northern and southern hemispheres. However, daily patterns of sunshine and shade diverged between sites, impacting daily temperature cycles. Crucially, we leverage micrometeorological data to demonstrate that (1) experimental warming using open-top chambers shortens early snow events in autumn, and (2) image-derived sunshine marginally outperforms sensor-derived temperature when predicting bumblebee foraging. These methods generate novel micrometeorological variables in synchrony with biological recordings, enabling new insights from an increasingly global network of wildlife cameras.

Divergent community trajectories with climate change across a fine‐scale gradient in snow depth

Abstract Fine‐scale microclimate variation due to complex topography can shape both current vegetation distributional patterns and how vegetation responds to changing climate. Topographic heterogeneity in mountains is hypothesized to mediate responses to regional climate change at the scale of metres. For alpine vegetation especially, the interplay between changing temperatures and topographically mediated variation in snow accumulation will determine the overall impact of climate change on vegetation dynamics. We combined 30 years of co‐located measurements of temperature, snow and alpine plant community composition in Colorado, USA, to investigate vegetation community trajectories across a snow depth gradient. Our analysis of long‐term trends in plant community composition revealed notable directional change in the alpine vegetation with warming temperatures. Furthermore, community trajectories are divergent across the snow depth gradient, with exposed parts of the landscape that experience little snow accumulation shifting towards stress‐tolerant, cold‐ and drought‐adapted communities, while snowier areas shifted towards more warm‐adapted communities. Synthesis: Our findings demonstrate that fine‐scale topography can mediate both the magnitude and direction of vegetation responses to climate change. We documented notable shifts in plant community composition over a 30‐year period even though alpine vegetation is known for slow dynamics that often lag behind environmental change. These results suggest that the processes driving alpine plant population and community dynamics at this site are strong and highly heterogeneous across the complex topography that is characteristic of high‐elevation mountain systems.

Hydrogeological controls on formation of Patearoa saline site in Central Otago, New Zealand and definition of geoecological salt lines

ABSTRACT The Patearoa saline site in Maniototo basin has developed on variably clay-altered Otago Schist. Decomposition and sedimentary redistribution of schist outcrop components has led to formation of bare soil-free substrates (upper metre scale) with contrasting permeability to rain and shallow groundwater percolation. Relatively impermeable clay-rich substrates, with a surface crust (cm scale) of detrital clay and muscovite, are saline with electrical conductivity (EC) of 1–35 mS/cm and locally hyperalkaline (pH > 10), with evaporative mineral accumulations. These saline substrates are downslope of more permeable substrates consisting of coarse schist debris and fractured outcrops, which have lower salinity (EC < 1 mS/cm) and lower pH (<7). A salt line can be mapped at metre scale between these substrate types on hillsides. The geochemical contrasts across the salt line have strong effects on plant communities that are colonising bare ground. Initial colonisation of bare saline substrates by some plants changes the geochemical signatures of the surficial few centimetres to form proto-soil with lower EC and pH. Proto-soil development facilitates further colonisation by pasture grasses, but the underlying substrates remain saline and highly alkaline. Salt lines similar to the one at Patearoa are mappable elsewhere in the Otago area and constitute fundamental geoecological boundaries.

A new enigmatic lacustrine trackway in the upper Miocene of the Sierra de las Cabras (Jumilla, Murcia, Spain)

A new fossil trackway is described in the upper lacustrine Miocene in the Prebetic Zone of the Iberian Peninsula, in Jumilla town (Murcia region) called Aenigmatipodus jumillensis nov. ichnogen. nov. ichnosp. This trackway consists of a pattern made up of sets of three tracks or triads, which are subparallel to each other, arranged in alternate groups. Each track presents a depression formed by a central body that is three times as long as it is wide, with straight or slightly curved walls, with two shorter bodies placed at the ends, one of the ends being shorter and more pronounced than the opposite, which is longer and stretched. All the biomechanical possibilities compatible with an anatomical design that could leave the impression of three alternate triads of tracks are analysed. The supports are only from the extremities on one side of the organism (left or right), the displacement being by translation. It is concluded that it had to be a large arthropod (metre scale), with a hexapod or decapod (less probably octopod), which had to be dragged laterally by a current in a very shallow lake or wetland environment. To date, no fossil organism is known, nor its current equivalent, that corresponds to these characteristics.

Black-grass (Alopecurus myosuroides) in cereal multispectral detection by UAV

AbstractSite-specific weed management (on the scale of a few meters or less) has the potential to greatly reduce pesticide use and its associated environmental and economic costs. A prerequisite for site-specific weed management is the availability of accurate maps of the weed population that can be generated quickly and cheaply. Improvements and cost reductions in unmanned aerial vehicles (UAVs) and camera technology mean these tools are now readily available for agricultural use. We used UAVs to collect aerial images captured in both RGB and multispectral formats of 12 cereal fields (wheat [Triticum aestivumL.] and barley [Hordeum vulgareL.]) across eastern England. These data were used to train machine learning models to generate prediction maps of locations of black-grass (Alopecurus myosuroidesHuds.), a prolific weed in UK cereal fields. We tested machine learning and data set resampling methods to obtain the most accurate system for predicting the presence and absence of weeds in new out-of-sample fields. The accuracy of the system in predicting the absence ofA. myosuroidesis 69% and its presence above 5 g in weight with 77% accuracy in new out-of-sample fields. This system generates prediction maps that can be used by either agricultural machinery or autonomous robotic platforms for precision weed management. Improvements to the accuracy can be made by increasing the number of fields and samples in the data set and the length of time over which data are collected to gather data across the entire growing season.

Differential feeding habits of the shallow-water hydrothermal vent crab Xenograpsus testudinatus correlate with their resident vent types at a scale of meters

Abstract. The shallow-water hydrothermal vents (SVs) located off Kueishan (KS) Island, Taiwan, are one of the world's most intensively studied vent systems. It has long been known that white vents (WVs) and yellow vents (YVs) differ in the color and composition of the vent plumes. The endemic vent crabs (Xenograpsus testudinatus) are abundant in both vent types, and ovigerous females migrate to the vent periphery with a distance of 100–200 m to release their offspring. However, most research on the vent crabs was associated with WV or unspecified vent areas. To increase our knowledge of the crabs dwelling in other vent types, we compared the feeding habits of the vent crabs living in WV and YV with 2 sampling months. Specifically, we examined the benthic community of WV and YV, the isotopic niche width, and protein expression patterns of the crabs from the two vents at a distance of 100 m and sampled in July and August 2010. The coverage of sessile organisms and low-mobility fauna in WV was more abundant than in YV, based on the survey in August 2010. The δ13C and δ15N values of crabs differed spatially and temporally (multivariate analysis of variance test; p&lt;0.05). The niche width of the vent crabs from YV-August (0.88 ‰2) narrowed substantially compared to the rest, i.e., YV-July (2.94 ‰2), WV-July (2.88 ‰2), and WV-August (3.62 ‰2; p&lt;0.05), respectively. Based on the protein expression patterns, the vent crabs exhibited three groups, i.e., WV-July and YV-July, WV-August, and YV-August, respectively. Our results indicated that the dwelling crabs were associated with their living vent, and within-vent variability was more noticeable in YV compared to WV. We suggested that vent crabs inhabit their resident vent. Even at a scale of meters, trans-vent movement is probably rare as an adaptation to minimize predation risk.