Flat Areas Research Articles

Response of macrobenthic communities to a Spartina alterniflora management project on tidal flats in Hangzhou Bay, China

Spartina alterniflora is one of the most invasive plants on Chinese tidal flats. To explore the responses of macrobenthic communities to the removal of S. alterniflora and the restoration of tidal flats, a survey of macrobenthic and sediment environmental factors was carried out in June 2022 in the mudflat recovery area (MRA) of tidal flats on the south bank of Hangzhou Bay, China. A proximate natural mudflat area (NMA), S. alterniflora area (SAA) and Scirpus mariqueter area (SMA) were selected for comparison with the MRA. A total of 48 macrobenthic species were identified, with 13, 28, 22 and 21species in the MRA, NMA, SAA and SMA, respectively. Cluster, multidimensional scaling (MDS) and SIMPER analysis suggested that the similarity between macrobenthic communities in the MRA and the NMA was high, whereas the similarity between macrobenthic communities in the MRA and SAA and the MRA and SMA was very low. The similarity between macrobenthic communities in the SAA and the SMA was high. ANOSIM analysis suggested that the differences between regions were greater than those within regions (R = 0.881). The sediment factors in the MRA were substantially different from those in the other three habitats, while the sediment factors in the SMA and the SAA were the most similar. Macrobenthos were mainly affected by the mean diameter of the sediment particles. After 1 year of natural recovery in the MRA, the macrobenthos approached the pre-project levels, but to ensure the effectiveness of the treatment project and prevent the recurrence of S. alterniflora, continuous monitoring should be carried out.

Unforeseen cascading effects of an inlet opening

The opening of the Cacela Inlet (southern Portugal) in 2010 led to unforeseen effects observed after 2017, including an extreme acceleration of the retreat of the inland lagoon margin from about 0.2 to 2 m/year. This was a consequence of the development of a large flood delta in an area of limited accommodation space, forcing the main tidal channel to move inland. The coastal retreat currently affects a flat sandy area that separates the old and inactive Cacela cliff from the lagoon. Between 2035 and 2040, the currently inactive Cacela cliff is likely to become active again, posing a potential risk of damage to a medieval fortress and the existing settlement of Cacela Velha, an unforeseen cascading effect of the opening of the inlet. In order to prevent instability and damage to this legally protected area of national and public interest, several coastal management measures will be required.

Analysis of spatiotemporal land use change characteristics in the upper watershed area of the Qingshui River basin from 1990 to 2020

Introduction: Land use land cover (LULC) change is an important factor driving global change, influenced by the interaction between human activities and natural ecosystems. The upper watershed of the Qingshui River is adversely affected due to anthropogenic activities. Therefore, analyzing the driving factors of land use changes in this area is crucial for ecological protection and sustainable development.Methods: Based on the long-term Landsat image data from 1990–2020, the spatiotemporal change characteristics of the LULC rate and its driving factors in the upper watershed of the Qingshui River basin were analyzed using the land use transfer matrix and dynamic degree of land use processes. The redundancy analysis was performed to investigate the links between LULC changes, socio-economic and climatic variables.Results: From 1990–2020, the area under waters and woodland decreased by −2.94 km2 and −451.44 km2, respectively. Meanwhile, grassland, arable land, construction land, and unused land area increased by 278.71 km2, 115.72 km2, 46.48 km2 and 13.49 km2. In terms of the proportion area to the total land (2334.10 km2), woodland accounted for 63.43–44.09% of the total land and was mainly distributed in the east; arable land was 17.00–21.96% and was largely distributed on both sides of the middle and lower parts of the basin; construction land comprised 1.03–3.02% and was generally found in flat areas near the downstream and water area was only 0.1–0.01% which primarily covered the Qingshui River and its tributaries from 1990–2020. Construction and unused lands showed the fastest rate of change, followed by water area and grasslands. Accelerated urbanization, rapid socio-economic development, and the farmland-to-forest policy were the main driving forces behind the change in LULC in the upper reaches of the Qingshui River.Discussion: The findings of this study can assist in planning strong management strategies for ecological protection and socio-economic sustainable development in the study area.

Tracking dynamics characteristics of tidal flats using landsat time series and Google Earth Engine cloud platform

Tidal flats serve as vital spatial resources within coastal wetlands and play crucial roles in biological habitat preservation, environmental conservation, and human development. However, accurately delineating their extent from instantaneous remote sensing images poses challenges, owing to the dynamic interplay between seawater and land. Therefore, this study utilized the consistency of remote sensing satellites and developed a multi-feature decision approach based on the long-term remote sensing datasets and the Google Earth Engine (GEE) cloud platform for determining the spatial extent, classifying types, and mapping the spatial-temporal distribution of the tidal flats. Initially, a multi-temporal image stack was compiled from the filtered remote sensing images. Subsequently, the modified normalized difference water index (MNDWI) and automated water extraction index (AWEI) were calculated to establish the maximum and minimum water surfaces using the extreme value composite algorithm (EVCA). The Otsu algorithm and spatial overlay analysis method were then utilized to accurately delineate the spatial extent of the tidal flats. Additionally, the Normalized Difference Vegetation Index (NDVI) was utilized to accurately identify tidal flat types. Post-processing involves elevation data and mathematical morphological methods to mitigate the impact of permanent water bodies. Finally, the accuracy of the extracted spatial extent and types of tidal flats was evaluated. The efficacy and practicality of the proposed method were validated using the Zhoushan Archipelago and Landsat time series in China. The results revealed the following: (1) the acquired tidal flat information exhibited evident boundaries and accurate types, achieving an overall accuracy (OA) of 94.80 % and a Kappa coefficient of 0.89; (2) the area of tidal flats in the Zhoushan Archipelago increased from 2,182.19 ha in 1985 to 3,761.21 ha in 2020, with an average annual increase of 45.12 ha and an average annual increase rate of 1.57 %; and (3) over 35 periods, the area transformed from other land types to tidal flats amounted to 2,895.74 ha, while the area converted from tidal flats to other land types totaled 1,651.90 ha. The three islands with the most rapid growth in tidal flat area were Liuheng Island, Dachangtu Island, and Daishan Island, with changes of 675.68 ha, 380.47 ha, and 362.63 ha, respectively. This method can offer an automated, swift, and accurate approach for tidal flat extraction, demonstrating high precision and practical effectiveness, thereby providing robust technical support for coastal resource surveys.

Cap-assisted snare capture technique for resection of fibrotic large polyps

Background and AimsEndoscopic mucosal resection (EMR) of non-lifting or fibrotic polyps may pose challenges, especially when the snare fails to capture flat or depressed fibrotic areas. We present “cap-assisted snare capture” technique using the distal attachment clear cap as an adjunct to EMR for the resection of residual fibrotic tissue. MethodsThree consecutive patients referred for EMR of colonic laterally spreading tumors were included in this case series. Prior to EMR referral, biopsy or attempt for resection of these lesions was not performed. The fibrotic residual tissue after EMR was resected using distal attachment clear cap at tip of adult colonoscope, by placing a soft braided hot snare around the fibrotic tissue and suctioning of tissue into the distal attachment cap while simultaneously closing snare. The suction was released and snare capture of targeted tissue was confirmed prior to snare resection of tissue. The resected site was evaluated for perforation and bleeding prior to closure with clips. ResultsThree presented cases demonstrate the effectiveness of the “cap-assisted snare capture” technique in resecting residual fibrotic tissue and highlights the safety and efficacy of this technique in challenging EMR scenarios (video). There was no perforation, significant bleeding or major adverse events. Conclusions“Cap-assisted snare capture” is a simple technique to assist with resecting fibrotic adenomatous tissue that cannot be captured with conventional snare closure. Its simplicity, use of standard equipment, and effectiveness makes it a valuable adjunct technique in difficult EMR procedures. Larger cohort studies are needed to validate the safety and efficacy of this technique.

Application of accuracy improvement algorithms for extraction of topographic information and drainage network from DEM using GIS

The extraction of drainage network and watershed information is prerequisite for the study of watershed characteristics like morphometric analysis, which provides a basis for hydrological planning and modeling. The advanced tools of algorithms, Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) data and Geographical Information System (GIS) software are used to extract drainage networks and their watershed boundaries. These tools are complicated to use or produce more errors in the extraction of elevation and drainage networks when applied to flat areas. For removal of errors and to improve the accuracy in preparation of DEM and extraction of drainage network, Burada Kalava River Basin, Andhra Pradesh, India has been taken for application of accuracy improvement algorithms. An automatic generation of drainage network and watershed using digital elevation model results in positional errors due to variations in slope and topography. This study aimed to generate a catchment area and stream network that closely represent the natural stream network and the streams’ real positions. The step-by-step methodology using GRASS-interfaced Quantum GIS algorithms are given for pre-processing of DEM data to improve the positional accuracy before automatic extraction of the stream network and catchment area to resemble the real situation of the watershed. Secondly, efforts are made to analyze the DEM during automatic generation of the stream network and catchment area by assigning various area threshold values, including the application of pour point coordinates in improving the stream network and watershed characteristics. The results are verified and validated with the field information in order to improve the accuracy levels of DEM quality in generation of drainage network and catchment area.

Genetic relationships and introgression events between wild and cultivated grapevines (Vitis vinifera L.): focus on Italian Lambruscos

Research efforts on genomic structure and ecology of wild populations of Vitis vinifera L. offer insights on grape domestication processes and on the assortment evolution of the cultivated forms. Attention is also paid to the origin of traditional, long-cultivated varieties, often producing renowned and valuable wines. The genetic relationships between 283 Vitis vinifera cultivated varieties (subsp. sativa) and 65 individuals from 9 populations of the sylvestris subspecies mainly from northern Italy were explored by means of molecular markers (27 nuclear and 4 chloroplastic microsatellites). Several episodes of contamination of the wild germplasm by the pollen of specific grape cultivars were detected, implying concern for maintaining the purity of the wild form. At the same time, events of introgression from the wild subspecies resulted playing a crucial role in the emergence of several cultivated varieties with a clear admixed genome ancestry sativa-sylvestris. These included Lambruscos originated from the flat areas crossed by the Po and Adige rivers in northern Italy, while other cultivars still called Lambrusco but typical of hilly areas did not show the same admixed genome. Historical and ecological evidences suggesting an adaptative recent post-domestication process in the origin of several Italian Lambruscos are discussed.

Small-scale hydrological patterns in a Siberian permafrost ecosystem affected by drainage

Abstract. Climate warming and associated accelerated permafrost thaw in the Arctic lead to a shift in landscape patterns, hydrologic conditions, and release of carbon. In this context, the lateral transport of carbon and shifts therein following thaw remain poorly understood. Crucial hydrologic factors affecting the lateral distribution of carbon include the depth of the saturated zone above the permafrost table with respect to changes in water table and thaw depth and the connectivity of water-saturated zones. Landscape conditions are expected to change in the future due to rising temperatures and polygonal or flat floodplain Arctic tundra areas in various states of degradation; hydrologic conditions will also change. This study is focused on an experimental site near Chersky, northeast Siberia, where a drainage ditch was constructed in 2004 to simulate landscape degradation features that result in drier soil conditions and channeled water flow. We compared water levels and thaw depths in the drained area (dry soil conditions) with those in an adjacent control area (wet soil conditions). We also identified the sources of water at the site via stable water isotope analysis. We found substantial spatiotemporal changes in the water conditions at the drained site: (i) lower water tables resulting in drier soil conditions, (ii) quicker water flow through drier areas, (iii) larger saturation zones in wetter areas, and (iv) a higher proportion of permafrost meltwater in the liquid phase towards the end of the growing season. These findings suggest decreased lateral connectivity throughout the drained area. Shifts in hydraulic connectivity in combination with a shift in vegetation abundance and water sources may impact carbon sources and sinks as well as transport pathways. Identifying lateral transport patterns in areas with degrading permafrost is therefore crucial.

Use of GIS tools, enhanced by FFT filtering methods, to detect blurred craters in Synthetic Digital Elevation Models, to improve their location and morphological characterisation

Filtered Geomorphic Reference Models (FGRMs), extracted from High-Pass Filters based on the Fast Fourier Transform (HPF-FFT), provide a semi-automated and objective detection of a wide range of geoforms and geomorphic situations (flat areas, slopes, depressions, or valley bottoms). The method is sensitive enough to reveal numerous inflection points that enable the identification of subtle changes in relief polarity, resulting in accurate representations of real land depressions. The effectiveness of this method has been demonstrated in lunar landscapes, utilizing altimetry extracted from high-precision Planetary Digital Elevation Models (PDEMs) to construct crater inventories with well-defined FGRMs. However, when analysing lunar environments with closely-spaced geomorphic features, the FGRMs display blurring and generalization effects, reducing their capability to identify all existing crater depressions. This limitation controls the ability of FGRMs, to generate reliable crater inventories. This study examines such effects in three experiments. Using Synthetic Digital Relief Models (SDRMs) constructed by means of a MATLAB script two experiments are performed. In Experiment_1 different scenarios of proximity between aligned craters are analysed. The marks, or footprints, formed by craters of identical size and shape (i.e., circular bowl-shaped depressions with central peaks) are considered, resulting in simplified PDEMs. Various scenarios of crater centre separation (proximity) and the presence of internal features within craters are also analysed. Experiment_2 validates the method with different proximities, locations and crater sizes. Experiment_3 validates the approach in a sampled area of LRO lunar PDEM corresponding to Zelinskiy crater (Mare Ingenii area). To address these blurring effects, a hybrid methodology is employed, generating FGRMs extracted from HPF-FFT, in conjunction with other GIS and remote sensing tools, such as singular point zoning, aspect-slope zoning, and edge-limits zoning. As a result, the correspondence between the FGRMs and the synthetic forms is examined, aiding the comprehension of the graphical response provided by filtering in these cratered areas. The methodology demonstrates that FGRMs derived from HPF-FFT are sensitive to capturing connections between shapes as soon as the crater features start to merge, while blurring becomes evident when the craters are located at a proximity of <20 model units. Additionally, the results highlight the method's utility in accurately locating crater footprints and morphologically characterizing inner crater features, even when crater centres are closely spaced. This approach effectively mitigates blurring effects and enables the precise localization of crater marks and their internal features. The validations carried out in complex relief and high precise DEMs provide a use in real situation.

Microtopography effects on pedogenesis in the mudstone-derived soils of the hilly mountainous regions

Topography is a critical factor that determines the characteristics of regional soil formation. Small-scale topographic changes are referred to microtopographies. In hilly mountainous regions, the redistribution of water and soil materials caused by microtopography is the main factor affecting the spatial heterogeneity of soil and the utilization of land resources. In this study, the influence of microtopography on pedogenesis was investigated using soil samples formed from mudstones with lacustrine facies deposition in the middle of the Sichuan Basin. Soil profiles were sampled along the slopes at the summit, shoulder, backslope, footslope, and toeslope positions. The morphological, physicochemical, and geochemical attributes of profiles were analyzed. The results showed that from the summit to the toeslope, soil thickness increased significantly and profile configuration changed from A–C to A–B–C. The total contents of Ca and Na decreased at the summit, backslope, and footslope, while the total contents of Al, Fe and Mg showed an opposite trend. On the summit and shoulder of the hillslope, weathered materials were transported away by gravity and surface erosion, exposing new rocks. As a result, soil development in these areas was relatively weak. In flat areas such as the footslope and toeslope with sufficient water conditions, the addition of weathered components and the prolonged contact between water, soil, and sediment led to further chemical weathering, resulting in highly developed characteristics. Microtopography may influence physicochemical properties, chemical weathering, and redistribution of water and materials, causing variations in pedogenic characteristics at different slope positions.

Spatiotemporal Evolution and Future of Carbon Storage in Resource-Based Chinese Province: A Case Study from Shanxi Using PLUS–InVEST Model Prediction

Resource exploitation markedly alters land use and ecological carbon storage, posing risks to carbon sinks and food security. This study analyzes land-use change from 1990 to 2020 in the resource-based province of Shanxi, China. By introducing a mineral resource driver, the PLUS model was used to predict four scenarios: natural development (ND), cropland protection (CP), ecological protection (EP), and dual protection of ecology and cropland (DP). The spatial and temporal evolutions of carbon storage were then analyzed using the InVEST model. Forests were predominantly distributed in mountainous areas, with croplands in southerly and central flat areas, construction lands in and around cities, and mining lands sporadically distributed across Shanxi. From 1990 to 2020, croplands and grasslands decreased, while forest, construction, and mining lands increased. Carbon storage decreased continuously, with a total loss of 15.1 × 106 t. High-value carbon storage areas were in the Lüliang, Taihang, and Taiyue Mountains, and low-value areas were in the more populous central and southern regions. Carbon storage was predicted to decline by 2035 under the ND and CP scenarios and to exceed that of 2020 under the EP and DP scenarios. The DP scenario projected an increase of 4.93 × 106 t in carbon storage by 2035. The DP scenario realizes the protection of carbon sinks in resource-based areas and maintains food security, providing a theoretical reference for achieving carbon neutrality and high-quality sustainable development in Shanxi Province.

GeoSparseNet: A Multi-Source Geometry-Aware CNN for Urban Scene Analysis

The convolutional neural networks (CNNs) functioning on geometric learning for the urban large-scale 3D meshes are indispensable because of their substantial, complex, and deformed shape constitutions. To address this issue, we proposed a novel Geometry-Aware Multi-Source Sparse-Attention CNN (GeoSparseNet) for the urban large-scale triangular mesh classification task. GeoSparseNet leverages the non-uniformity of 3D meshes to depict both broad flat areas and finely detailed features by adopting the multi-scale convolutional kernels. By operating on the mesh edges to prepare for subsequent convolutions, our method exploits the inherent geodesic connections by utilizing the Large Kernel Attention (LKA) based Pooling and Unpooling layers to maintain the shape topology for accurate classification predictions. Learning which edges in a mesh face to collapse, GeoSparseNet establishes a task-oriented process where the network highlights and enhances crucial features while eliminating unnecessary ones. Compared to previous methods, our innovative approach outperforms them significantly by directly processing extensive 3D mesh data, resulting in more discerning feature maps. We achieved an accuracy rate of 87.5% when testing on an urban large-scale model dataset of the Australian city of Adelaide.

The elevated low-relief landscapes of the Eastern Alps

The morphology of the Eastern European Alps is characterized by a bimodal slope distribution with relatively flat surface areas located at both high and low elevations. While low-slope regions in valley floors are easily explained by base-level erosion or sediment fill, low-slope surfaces at summit levels are unusual and have both been interpreted to (a) have formed by glacial erosion or (b) reflect remnants of old base levels that survived uplift and subsequent erosion. In order to contribute to this debate, we present a map of these surfaces on the scale of the Eastern Alps (mapped at roughly 1:300,000 scale). Importantly, our mapping covers both areas glaciated in the Pleistocene and areas that have remained unglaciated.Mapping results show that elevated low relief surfaces occur at roughly equal proportions in formerly glaciated and unglaciated regions, thus giving strong support to the notion that they are relicts of paleosurfaces formed at base level. As karst caves often form near the phreatic-vadose transition also at base level, we support our interpretation with a statistic analysis of passage lengths of some 13,000 karst caves in the region. Hypsometric analysis shows that the distribution of low-relief surfaces differs between formerly ice-covered and ice-free regions. We explain this by glacial overprinting of the surfaces during the Pleistocene. Based on the hypsometric analysis a correlation of the low-relief surface and caves across the Eastern Alps remains unclear, most likely because uplift varies across the region. However, plotting the elevation of the paleosurfaces relative to an arbitrary base level of the nearest 300 km2 catchment provides distinct peaks in hypsometric analysis suggesting a somewhat clearer correlation of levels between different regions.Because many of these surfaces are known to have formed at base level in the Pliocene, we therefore suggest that Pliocene surface-uplift in much of the Eastern Alps is of long wavelength. Topographic differences between major valleys and basins surrounding the Alps were created due to erodibility contrasts between Miocene sediments and basement. Tectonic dissection of the Eastern Alps causing variable uplift rates of different blocks appears to have been minor in the last 5 my of the uplift history.

Improvement of Direct Learning Model Using Calculator on Mathematics Learning Achievement of Roving Material and Flat Area in Grade IV Elementary School

This study aims to determine whether the results of learning achievement of students who apply to learning using a direct learning model using a calculator obtain better results than classes that apply to learning using conventional models. This research is quasi-experimental research using a pretest-posttest control group design. The population in this study was the fourth grade of SD UMP, Kembar sub-district, Banyumas Regency, in 2020, which amounted to 59 students. The sample in this study is class IV A, totalling 29 students, and class IV B, totalling 30 students. Class IV A is an experimental class using the application of learning with direct learning models. Class IV B is a control class using the application of direct learning models without a calculator. The sampling technique used is cluster random sampling. The data collection technique in this study was a test in the form of a description, namely pretest and posttest. The results of nonparametric test calculations in u-test Ho are rejected, and Ha is accepted. The results of calculations using SPSS obtained sig &lt; 0.05 or sig 0.001 &lt; 0.05, so there was a significant difference between the experimental class and the control class. Based on the results obtained from the data, it can be concluded that the direct learning model uses a calculator to measure mathematics learning achievement in the material of circumference and area of flat shapes in grade IV elementary school.

Source Analysis and Bioavailability of Soil Cadmium in Poyang Lake Plain of China Based on Principal Component Analysis and Positive Definite Matrix Factor

In order to identify the source and bioavailability of soil Cd in the alluvial geological high background area, 3799 topsoil samples and 140 root soil samples were collected from the Jiulong area on the south bank of Poyang Lake, Jiangxi Province. The results confidently indicate that the range of topsoil Cd content is 0.02~8.12 ppm, with an exceedance rate of 14.6%. It is noteworthy that exceedance points were mostly distributed in quaternary sediments. The geostatistical analysis clearly shows that the spatial distribution characteristic of topsoil Cd is higher in the north and lower in the south. The area with extremely high values (&gt;90% quantile) is predominantly located in the tidal flat and low-lying areas of the mainstream of the Xinjiang River. The PCA analysis confirms that the main source of topsoil Cd is man-made activities related to industry and mining. Soil Cd is primarily derived from upstream industrial and mining discharge (58.5%), as revealed by the PMF model analysis. The active Cd content in root soil is 77 ppb, with higher levels observed in the north and lower levels in the south. These findings suggest a significant risk of Cd diffusion along the upstream stream and deposition in the low-lying parts of the north. It is worth noting that Cd’s bioavailability and active forms in paddy fields are the highest, which can have a detrimental effect on food security. The correlation analysis suggests that genetic sources primarily control the bioavailability of soil Cd, followed by soil physicochemical properties such as SOC, Fe-Al oxides, and soil texture. Preventing source pollution and cutting off water system transmission are effective methods for preventing and controlling soil Cd pollution. These methods ensure the safety of cultivated land in the lakeside area of Poyang Lake Plain.

Structural architecture of the Mapimí Biosphere Reserve and its surroundings, north-central Mexico: New insights from U–Pb geochronology and interpreted structural data

The Mapimí Biosphere Reserve is in northeastern México, near the boundary between the Mesozoic Coahuila platform and the Mexican central basin. A large portion of the Reserve is a broad bolson where isolated mountains are surrounded by flat terrain. Two slightly elevated areas (benches) are subtle topographic features in the Reserve. There, in rolling hills occur folded, Upper Cretaceous – Paleogene, poorly-lithified and -exposed transitional and continental sediments and tilted Paleogene volcanic and subvolcanic rocks. Each bench occupies a band that is ∼75 × 20 km. A land strip where playa lakes and salt-flats occur separates the benches. Deformation style within the benches differ from those in regions where platform carbonates or Mexican central basin rocks dominate. Structures within the benches are gentle, open folds and medium sized (15 - 3 km in diameter) structural domes and basins. Furthermore, orientation of the fold axes shows a wide scatter. There is at least one folded structure in the Reserve that displays an interference pattern that indicates refolding. Post-Oligocene normal faults bound the benches and overprinted on the folded structures. However, the most important normal fault, which cuts in half two domes and one structural basin, lacks a clear topographic scarp. The occurrence of broad exposures of the Upper Cretaceous Indidura Formation in flat areas, interpreted as the footwall block of a major normal fault, is consistent with the interpretation that the benches are rocky pediments partially covered by alluvium and/or eolian sediments. Thus, it appears that Cenozoic extension has been inactive for a long period of time in this portion of the Mexican Basin and Range province. The best evidence of NNW, down to the SW normal faults within the Reserve is in the Sierra de Mohóvano. There, an array of domino-style normal faults cut Oligocene volcanic rocks and gravel deposits. The master fault of the domino array is adjacent and parallel to a fold in Mesozoic marine rocks.We attribute the unusual characteristic of the folds in the Reserve to 1) the region is near the boundary among the large calcareous platform and the basin, and the boundary had a significant curvature, concave toward the W. This geometry caused complex deformation during crustal shortening, as tectonic transport associated with the Mexican orogen is toward the NE, 2) a significant difference in competence between the poorly consolidated transitional and continental deposits and the more competent rocks in the carbonate platform also played a role in the formation of the structures, as folds in the benches formed during the waning stage of the Mexican orogen, as suggested by the detrital zircon U–Pb ages, which are as young as ∼30 Ma, 3) Oligocene magmatic activity caused the emplacement of laccoliths, which locally modified older folds forming domes, 4) finally, Basin and Range extension (<27 Ma) cut across the folded sediments and overlying volcanic rocks. Evidence of extension in the Reserve is subtle as normal faults have remained inactive for a long time, while isostatic uplift and erosion developed the pediment, effectively masked most fault scarps.

Geomorphological Evolution in the Tidal Flat of a Macro-Tidal Muddy Estuary, Hangzhou Bay, China, over the Past 30 Years

Tidal flat plays an important role in coastal development because of its ecological and spatial resources. We take the southern tidal flat in the macro-tidal turbid Hangzhou Bay as an example to study the long-term (1990–2020) evolution of the muddy tidal flat, using remote sensing data and field observational data. The detailed bathymetric elevation of the tidal flat is obtained, using remote sensing images of Landsat and Sentinel-2, combined with the real-time kinematic (RTK) data. The correlation coefficient between the remote sensing data and the RTK data is 0.73. The tidal flat and vegetation areas are affected by reclamation. The total tidal flat area decreased by 467.78 km2. The vegetation area declined from 64.98 km2 in 2000 to 13.41 km2 in 2015 and recovered to 41.62 km2 in 2020. The largest change in tidal flat slope occurs in the eastern and western sides of the tidal flat, compared with the wide middle part. The total length of tidal creeks decreased to 45.95 km in 2005 and then increased to 105.83 km in 2020. The middle- and low-grade tidal creeks accounted for 91.4%, with a curvature slightly larger than 1 in 2020. High-grade tidal creeks occur inside the vegetation areas, with less bending and fewer branch points. Vegetation promotes the development of tidal creeks but limits the lateral swing and bifurcation. These results provide a basis for the management of global tidal flat resources and ecosystems.

The Cambrian (Paibian–Jiangshanian; Steptoean) dokimocephalid trilobite Deckera Frederickson, 1949 in Laurentian North America

Abstract The Cambrian dokimocephalid trilobite genus Deckera Frederickson, 1949 is a minor component of Steptoean (Jiangshanian) faunas of Laurentian North America. The original diagnosis emphasized strongly inflated palpebral areas of fixed cheeks and elevated palpebral lobes as important and novel characters. An appraisal of archival and new specimens from Oklahoma, Missouri, Pennsylvania, Nevada, Utah, and Newfoundland show that the genus is geographically widespread and likely represented by as many as nine species, although only two of them are named formally. Deckera cf. D. aldenensis Frederickson, 1949 from Nevada extends the stratigraphic range of Deckera down to the base of the Jiangshanian Stage, and new species from Nevada and Newfoundland take the genus down farther, into upper Paibian strata. Paibian species show that some basal members of the genus have weakly inflated, nearly flat palpebral areas with palpebral lobes that sit well below the crest of the glabella. A revised diagnosis of Deckera focuses on the broad cranidium with width across the palpebral lobes much greater than the sagittal length. Pygidia are known for a few species and all of them have an unusual flexure of the posterior margin and border. Lectotype and paralectotype specimens are designated for Deckera completa.

Archaeobotanical data from the Sabor Valley reveal shifting moments in landscape and agriculture in NW Iberia during the Holocene

NW Iberia is dominated by Atlantic climate areas that favour pollen preservation, useful for palaeoecological studies. However, the region also includes Mediterranean sectors in which preservation of such palaeoenvironmental evidence is more difficult. To overcome these constraints, archaeological plant macroremains can be used to help characterize flora and vegetation dynamics at a local and regional level. To fill the gap in knowledge in an understudied Mediterranean region, a large archaeobotanical study was conducted at the river Sabor valley, NE Portugal. With 13 archaeological sites sampled for charcoal, fruits and seeds, it allowed the study of vegetation throughout the Holocene, starting in the Mesolithic up to Modern times, with some chronological gaps. Tree taxa dominates the older period and an expansion of shrubby taxa since Bronze age was observed. Diversification of plants used during the Iron Age and Roman period suggests an intensification of resources exploitation and deforestation. These trends seem to be related with changes in human settlements and productive strategies. During Prehistory, agricultural fields were established in flat and wide areas, and, during Iron Age, fortified granaries were used to store large amounts of grains, particularly free-threshing wheat. Drastic changes in settlement during Roman times and the establishment of small farms producing wine and/or olive oil were testified by the occurrence of Olea and Vitis in both anthracological and carpological datasets. Data from more recent periods is scarce. Results highlight that the combination of several proxies and integration of archaeological evidence helps to understand ecological dynamics in areas without pollen data and contributes to the characterization of heterogeneous areas under diverse climatic conditions and with a variety of social trends.

Representational drift as a result of implicit regularization

Recent studies show that, even in constant environments, the tuning of single neurons changes over time in a variety of brain regions. This representational drift has been suggested to be a consequence of continuous learning under noise, but its properties are still not fully understood. To investigate the underlying mechanism, we trained an artificial network on a simplified navigational task. The network quickly reached a state of high performance, and many units exhibited spatial tuning. We then continued training the network and noticed that the activity became sparser with time. Initial learning was orders of magnitude faster than ensuing sparsification. This sparsification is consistent with recent results in machine learning, in which networks slowly move within their solution space until they reach a flat area of the loss function. We analyzed four datasets from different labs, all demonstrating that CA1 neurons become sparser and more spatially informative with exposure to the same environment. We conclude that learning is divided into three overlapping phases: (i) Fast familiarity with the environment; (ii) slow implicit regularization; and (iii) a steady state of null drift. The variability in drift dynamics opens the possibility of inferring learning algorithms from observations of drift statistics.