Edge Of Patch Research Articles

Study on the Impact of Spatial Resolution on Fractional Vegetation Cover Extraction with Single-Scene and Time-Series Remote Sensing Data

The spatial resolution of remote sensing images directly affects the accuracy, efficiency, and computational cost of extracting the fractional vegetation cover (FVC). Taking the Liyang woodland region, Jiangsu Province, as the study area, FVCs with varying spatial resolutions were extracted separately from Sentinel-2, Landsat-8, MOD13Q1, and MOD13A1. The variations in FVCs extracted from remote sensing images with varying spatial resolutions were analyzed at one specific time and time series within a year. The results show that (i) the overall mean FVC values of the four spatial resolution images did not differ substantially; however, FVCs with varying spatial resolutions present with a regular pattern of overestimation or underestimation at different vegetation levels. (ii) Taking the 10 m spatial resolution FVC as the reference, the accuracy values of FVC extraction at 30 m, 250 m, and 500 m resolutions were 91.0%, 76.3%, and 76.7%, respectively. The differences in the spatial distribution of FVCs are the most obvious at water–land interfaces and at the edge of each woodland patch. (iii) The highest accuracy of time-series FVC extraction from lower-resolution images is in the range of 0.6~0.7 for FVC. The degree of variation in FVC of time series varying spatial resolutions depends on the season and vegetation cover conditions. In summary, there are considerable differences in the need to monitor high-resolution images depending on the FVC level of the land surface. This study provides a reference for selection and accuracy research of remote sensing images for FVC extraction.

Location matters: survival of artificial nests is higher in small grassland patches and near the patch edge

Nest survival is an important part of breeding success in grassland ecosystems, and the location of nests can determine vulnerability to different predators. We conducted an experiment with artificial nests to evaluate jointly the predation rate on nests at different spatial scales (landscape, patch and tussock) and the relative abundance of potential nest predators (small mammals and birds) in a temperate grassland area. In November 2014 and 2016, we installed 288 artificial nests in Common Pampas Grass Cortaderia selloana grasslands in the southeastern Pampas region, Argentina. The nests were placed in two 10‐ha plots in a continuous grassland patch (c. 900 ha) within a reserve and in two small grassland patches (1.5 and 1.8 ha) in an agricultural matrix (landscape‐scale), at the patch edge and inside the patches (patch‐scale), and at two heights within the tussock grass (tussock‐scale). In 2016, we also conducted live trapping of small mammals and surveyed birds along strip transects at the sampling sites. Nests located in patches within an agricultural matrix and near the edge had greater relative survival than those set in the reserve and inside the patches, respectively. This might be explained by the lower relative abundance of small mammals that we found outside the reserve. Artificial nest survival values recorded at the landscape‐scale contrasted with those previously observed for natural nests. Our results could be partly explained by differences in nest density between agro‐patches and those within the reserve. Future studies could also evaluate the role of parental nest defence on nest survival.

Impacts of Transportation Networks on the Landscape Patterns—A Case Study of Shanghai

During 1995–2010, a comparison of the comprehensive effects of four different types of urban roads on landscape diversity in Shanghai was performed. Remote sensing images from 1995, 2000, 2005, and 2010 and the transfer matrix mathematical model were used to conduct the research, which focused on studying the rule of land use change in the study area over the past 15 years. Seven different landscape indices (SHDI, SHEI, ED, NP, TE, AWMSI, and MSI) were also selected to analyze the landscape pattern of Shanghai in three different periods and to explore the regularity of its dynamic changes and influential factors. Buffer analysis and statistical analyses were applied to represent the relationship between the distance from different roads quantitatively (e.g., railway, highway, national highway, and provincial highway) and a series of landscape pattern metrics (e.g., SHDI, PD, ED, and IJI) thus exploring the influence of transportation routes on the surrounding ecological environment. The results showed that (1) each type of landscape in the study area changed considerably during the research periods, a great amount of cultivated land was transformed into construction land, and the water area largely decreased. (2) The transportation routes exerted different impacts on the road landscape during different periods, and the effects were more obvious at the early stage of road construction. (3) The national way and the highway influenced the patch density (PD) index and edge density (ED) index more clearly, while the national way and the railway had greater effects on the landscape diversity indices. This study presents an approach that can be applied to quantitatively describe the impacts of transportation routes on landscape patterns and has the potential to facilitate route network planning.

Filtering ground noise from LiDAR returns produces inferior models of forest aboveground biomass in heterogenous landscapes

ABSTRACT Airborne LiDAR has become an essential data source for large-scale, high-resolution modeling of forest aboveground biomass and carbon stocks, enabling predictions with much higher resolution and accuracy than can be achieved using optical imagery alone. Ground noise filtering – that is, excluding returns from LiDAR point clouds based on simple height thresholds – is a common practice meant to improve the `signal’ content of LiDAR returns by preventing ground returns from masking useful information about tree size and condition contained within canopy returns. However, ground returns may be helpful for making accurate aboveground biomass predictions in heterogeneous landscapes that include a patchy mosaic of vegetation heights and land cover types. In this paper, we applied several ground noise filtering thresholds while mapping forest AGB across New York State (USA), a heterogenous landscape composed of both contiguously forested and highly fragmented areas with mixed land cover types. We fit random forest models to predictor sets derived from each filtering intensity threshold and compared model accuracies, paying attention to how changes in accuracy correlated with landscape structure. We observed that removing ground noise via any height threshold systematically biases many of the LiDAR-derived variables used in AGB modeling, with mean correlation (Spearman’s ) between variables increasing from 0.183 to 0.266. We found that that ground noise filtering yields models of forest AGB with lower accuracy than models trained using predictors derived from unfiltered point clouds, with RMSE increasing by up to 2.2 Mg ha-1 statewide. Although we only modeled AGB for forest cover types, models fit to predictors derived from filtered point clouds performed worse as landscape heterogeneity (as measured by patch density and edge density) increased, suggesting ground returns are particularly useful when modeling edge forests. Our results suggest that ground filtering should be a carefully considered decision when mapping forest AGB, particularly when mapping heterogeneous and highly fragmented landscapes, as ground returns are more likely to represent useful `signal’ than extraneous `noise’ in these cases.

Widespread bird species show idiosyncratic responses in residual body mass to selective logging and edge effects in the Colombian Western Andes

Abstract Forest fragmentation is a major driver of tropical bird endangerment, yet the mechanisms underlying species losses in fragmented landscapes remain poorly known. Loss of foraging microhabitats and food diversity in fragmented landscapes are potential mechanisms explaining fragmentation sensitivity. We, therefore, measured the body condition (i.e., body mass adjusted for individual size) of 20 tropical understory birds as a proxy for food availability across gradients of fragment patch size and silvicultural histories in the Western Andes of Colombia. Specifically, we asked (1) if body condition correlates with patch size, edge effects, or selective logging disturbance; and (2) if species responses were driven by the same explanatory variables or varied idiosyncratically. We documented significant variation in body condition with covariates in 11 of 20 (55%) understory bird species, and 55% of significant correlations were with fragmentation and selective-logging associated variables. Species responses were idiosyncratic and contrasting, with at least 1 significant response to each fragmentation-related covariate. Most effects, however, were driven by logging-induced changes to vegetation structure including loss of large-diameter trees, reduction in foliage height diversity and canopy cover, and loss of understory vegetation. The body condition of frugivores and nectarivores increased with logging-induced shifts in vegetation structure, with canopy gaps potentially favoring early-successional fruiting and flowering plants. By contrast, some insectivores suffered lower body condition with loss of vegetation structure (reduced foliage height diversity). Overall, our data support the hypothesis that fragmentation and selective logging change food resources available to birds and that some widespread nectarivores, frugivores, and omnivores may benefit from increasing edge density and logging-driven vegetation disturbance. We also documented significant positive effects of breeding condition on body condition, however, highlighting the need to control for this factor. Body condition may therefore be a useful index of habitat suitability when paired with analyses of abundance and demographic changes.

New locality record of crab-eating mongoose Herpestes urva (Hodgson, 1836) from Parbat District of Nepal

Crab-eating mongoose Herpestes urva is one of the least studied small mammal species of Nepal with very few confirmed locality records. This paper presents the new location of crab-eating mongoose from agricultural land adjacent to the Schima-Castanopsis-dominated forest habitat of Parbat District in Gandaki Province, Nepal. Three individuals of crab-eating mongoose were sighted and photographed at an altitude of 1,515 m on swampy agricultural land at the edge of a fragmented forest patch of Schima-Castanopsis-dominated forest in Arthar Village of Kushma Municipality.

A Novel Differentially Fed Dual-Polarized Filtering Magneto-Electric Dipole Antenna for 5G Base Station Applications

In this article, a compact differentially fed ±45° dual-polarized filtering magneto-electric (ME) dipole antenna with improved harmonic suppression is proposed and analyzed. First, the fusion of loop-slot dipole and half-wave vibrator is calculated and mentioned to furnish theoretical guidance. Then, by reasonably placing two pairs of second-order step impedance feedlines and a loop-slot patch, a corresponding two-mode loop-vibrator combination filtering antenna with an upper radiation null is naturally constructed. Moreover, simply by loading four open-circuit stubs at the center of octagonal slot patch edge, another extra resonance mode and radiation null in the upper band can be simultaneously obtained. Later, through hiring the reconstructed third-order stub-loaded-resonator (SLR) feedlines, wideband harmonic suppression along with a third radiation null is unaffectedly achieved. Finally, the optimized antenna is fabricated and tested. The measured results reveal it realizes a wideband impedance bandwidth of 42.0% (2.78–4.26 GHz) and a high port isolation of 35 dB. Also, the length of its harmonic suppression is measured from 4.56 to 7 GHz, while the depth reaches more than 20 dB. In addition, the measured gain and radiation efficiency curves in the operating band are relatively stable and both are at a high average value (8.2 dBi, 85%).

A Compact High-Gain Microstrip Patch Antenna with Improved Bandwidth for 5G Applications

This paper presents a High Gain, enhanced Bandwidth Patch antenna for 5G operations. The dual-band is achieved using an inset-fed feeding technique for the microstrip patch antenna, which operates at the 28/38GHz millimeter-wave band. The high gain of the patch is achieved by inserting two rectangular slots on the radiating element of the patch. The designed antenna Bandwidth is improved by incorporating three steps at the edge of the rectangular patch. The substrate used for the format is Rogers RT Duroid 5880, with a thickness of 0.508mm, loss tangent of 0.0009, and a relative permittivity constant of 2.2. Ansys HFSS software is used for the simulation. The design attained a maximum gain of 8.2dB and 7.8dB at 27.84GHz and 39.32GHz. The impedance bandwidth response of 1.46 and 4.27GHz at the respective resonating frequencies below the -10dB line of the parameters are achieved. A compact antenna is proposed with a size of 3.2x4.9x0.508 and has a high Gain with a wide Bandwidth at both bands. The proposed antenna has achieved a good performance within the operating bands, making it suitable for 5G applications.

Broadband circularly polarized 2 × 2 MIMO array for midband 5G wireless applications

Abstract The novel compact size orthogonally fed 2 x 2 Multiple Input and Multiple Output (MIMO) array antenna for mid-band Fifth Generation (5G) wireless application is presented. The antenna configuration consists of diamond-shaped patches employed at the top of substrate. The V-shaped common ground slot structure is employed at the bottom of substrate. A broadband circular polarization is achieved by simply combining two circular polarization modes obtained from ground V slot and top patch feed structure. Mainly, the impedance bandwidth (IBW) and gain are enhanced by protruding slots on ground and cutting edges of patches. The measured result shows that 1.70 – 8.00 GHz (6.30 GHz) of IBW, 8.8 dBic of peak gain, and 3 dB axial ratio bandwidth from 1.81 – 3.87 GHz (2.06 GHz) are obtained. The proposed antenna performances are experimentally validated by fabricating and testing it for measured result analysis without using power divider.

A compact TM03 mode penta‐polarization agile MSA for interference mitigation in 5G ultra‐dense point to point environment

Signal interference in the recent 5G ultra-dense environment is becoming severe due to the co-existence of large RF nodes operating in the constrained spectrum. In this article, a polarization agile approach for the designing of an RF system is studied to mitigate interference issues besides the communication and signal processing approach. A compact single-fed single layer penta-polarization agile higher-order microstrip patch is analyzed probably for the first time in the literature. The proposed antenna possesses a very low profile of less than 0.01 λ (λ free-space wavelength). Reconfigurable orthogonal feeding with switches is connected with the horizontal and vertical patch edges. Subsequently, these are excited separately and simultaneously using switchable PIN diodes and appropriate bias networks to realize horizontal, vertical, and 45° slant polarization states. Successively, diagonal patch corners are truncated to initiate right and left-hand circular polarizations. Slots are etched on specific orientation of currents on the patch surface to improve side-lobe levels. A prototype is analyzed, simulated, and fabricated at TM03 mode and operating at 5.8 GHz band with penta-polarization agility. A consistent 11 dBi realized broadside gain is measured covering the 10 dB reflection loss and 3 dB axial ratio bandwidth in both the principal planes.

Coupling effects of strain rate and fatigue damage on wheel-rail rolling contact behaviour: a dynamic finite element simulation

ABSTRACT A comprehensive 3-D explicit finite element (FE) model was established to investigate the frictional wheel-rail rolling contact responses in this study, in which the strain rate effect and initial fatigue damage of wheel/rail materials were taken into account via inputting relevant stress-strain response curves. Four friction exploitation levels were included to examine the dynamic contact responses in terms of contact load, contact patch area, creep characteristic, and stress/strain state. It is found that the nodal velocities on the rail surface at the trailing and leading edges of the contact patch are in opposite directions once the slip occurs. The strain rate hardening effect will significantly increase the Mises stress and suppress the plastic deformation of the wheel and rail at high creep levels, while the Mises stress will decrease with the increase of fatigue damage but the plastic strain will increase correspondingly.

Characteristics of Day-Roosts Used by Northern Long-Eared Bats (Myotis septentrionalis) in Coastal New York

In North America, Myotis septentrionalis (Northern Long-eared Bat) has experienced precipitous declines from white-nose syndrome. As these bats become rare and difficult to capture, additional day-roost assessments to inform management may fill gaps in our understanding, particularly in habitats and regions where such roosts have never been surveyed. Over 2 summers, we radio-tracked 16 individuals from a maternity colony on Long Island, NY, in a small forested patch surrounded by development and ocean. These bats disproportionately selected small, suppressed Robinia pseudoacacia (Black Locust) trees or snags for roosting. Generally, roosts occurred within the interior or edges of this forest patch, rather than surrounding suburbia, reinforcing the hypothesis that Northern Long-eared Bats are forest adapted. Our study shows even small tracts of forest in coastal, urban areas may have conservation value in providing day-roost and foraging habitat.

Bandwidth improvement of patch antenna and array with out‐of‐band rejection based on SISL platform for 5G applications

AbstractA low‐profile patch antenna is designed for bandwidth enhancement based on a substrate‐integrated suspended line (SISL) platform using low‐cost FR‐4 substrates. Two identical slots are cut at the patch edges for antenna miniaturization and controlling the first resonance. To achieve the bandwidth enhancement and ensure the uniformity of radiation patterns of the proposed design, two pairs of symmetrical slots are etched out on a rectangular patch. Thus, the second resonance is introduced, leading to significant bandwidth enhancement from 5% to 10%. Besides, two radiation nulls are generated. Based on the proposed design above, the antenna array comprising two identical radiating elements for gain enhancement and out‐of‐band rejection improvement is proposed, which provides another method for further improving the filtering response. The antenna element operates from 4.69 to 5.17 GHz with a measured gain of 8.9 dBi at the broadside direction, while the array achieves a high gain of 11.3 dBi.

Effects of Vegetation Patch Patterns on Channel Morphology: A Numerical Study

AbstractThis study investigates the effects of vegetation patch patterns on the morphological evolution of alluvial river channels at the reach‐scale. For this, a new two‐dimensional numerical biomorphodynamic model has been developed using the Telemac‐Mascaret system. Considering the newest development in the topic, the effects of vegetation on bedload transport are included by extending Einstein's parameters for the sediment transport formula. The model was subsequently validated by published laboratory experiments reproducing alternate bar dynamics with different vegetation establishment scenarios. The validated model was then used to study the influence of vegetation patch patterns on the channel morphological evolution considering the two most observed ones: (a) the filled pattern with plants well distributed within the patch, and (b) the stripe pattern with plants established only along the patch edges. 14 scenarios were simulated in total, including sensitivity analyses on the coefficients of vegetation characteristics. The results indicate that the morphological responses of an alternate bar system to the stripe pattern consist of channel widening, steeper slope and reduced water depth, with increased sediment transport rates. The effects of the filled pattern are similar but weaker. The results also show that with the stripe pattern, the alternate bars tend to migrate toward the centerline forming center bars. Besides, the scroll bars forming downstream are shorter, corresponding to less visible chute channels, compared to the filled pattern. Despite much less vegetation coverage, the stripe pattern decreases the bar elongation rates in a way similar to the filled pattern.

Kelp habitat fragmentation reduces resistance to overgrazing, invasion and collapse to turf dominance

Abstract Across many temperate coastlines worldwide, kelp habitat has degraded to be replaced by alternative reef‐states with consequences to ecosystem functioning. Identifying both causes of decline and mechanisms of resilience of remnant kelp habitat is critical for managing and restoring these ecosystems. We use a combination of aerial imagery and field experiments to reveal dynamics of kelp habitat fragmentation during phase‐shift from kelp Ecklonia radiata to overgrazed sea urchin barrens Heliocidaris erythrogramma in Port Phillip bay (Australia). Analysis of aerial images spanning 6 years (2009–2014) revealed fragmentation of kelp patches to result in increase in perimeter‐to‐area ratio during phase‐shift. Sea urchin foraging behaviour also changed from the edge to interior of kelp patches, with destructive grazing at the patch edge. Multiple modes of grazing were observed, with greatest rates of kelp bed decline occurring when urchins simultaneously grazed from the ‘outside‐in’ and ‘inside‐out’ of kelp patches. Overgrazing also triggered establishment of invasive kelp Undaria pinnatifida and proliferation of turf algae. Overgrazing reinforced native kelp decline, with overgrazing exacerbated by reduced provision of drift‐kelp. Synthesis and applications. Perimeter–area ratio of kelp patches can predict phase‐shift, with patch extinction occurring when ratios exceeded a critical ratio of ~0.7. Monitoring dynamics of this critical ratio using aerial imagery provides a novel and cost‐effective indicator of kelp ecosystem resilience for preventing further losses. Targeted culling/harvesting of overgrazing sea urchins along patch edges will enhance native kelp survival and decrease perimeter‐to‐area ratio of remnant kelp patches; reducing risk of phase‐shift to sediment‐trapping turfs and invasive kelp, dually promoting recovery of kelp ecosystems.

Comparative Study of Lipid- and Polymer-Supported Membranes Obtained by Vesicle Fusion

We compare the fusion of giant lipid and block-copolymer vesicles on glass and poly(dimethylsiloxane) substrates. Both types of vesicles are similar in their ability to fuse to hydrophilic substrates and form patches with distinct heart or circular shapes. We use epifluorescence/confocal microscopy and atomic force microscopy on membrane patches to (i) characterize bilayer fluidity and patch-edge stability and (ii) follow the intermediate stages in the formation of continuous supported bilayers. Polymer membranes show much lower membrane fluidity and, unlike lipids, an inability of adjacent patches to fuse spontaneously into continuous membranes. We ascribe this effect to hydration repulsion forces acting between the patch edges, which can be diminished by increasing the sample temperature. We show that large areas of supported polymer membranes can be created by fusing giant vesicles on glass or poly(dimethylsiloxane) substrates and annealing their edges.

Assessment of the impact of anthropogenic stress on wetlands of the upper Ganga Delta, India: a multi criteria decision making approach

This study attempts to measure wetland degradation in the upper part of the Ganga Delta between 1991 and 2021, using multi-criteria based anthropogenic stress assessment. The degree of anthropogenic stress is assessed using the Analytical Hierarchy Process (AHP) and optimized AHP scheme using the Partial Least Square regression (PLS) based Variable Importance Projection methods (VIP). This multi criteria decision making (MCDM) has stressed the closeness to the urban areas, transport arteries, occupancy of the settlements and cultivated areas, and demographic changes. Results showed a concerning level of wetland area loss (2.009 sq. km/year) along with an increasing number of wetlands by 26.91%. Estimated Perimeter Area Ratio (PARA), Largest Patch Index (LPI) and Edge Density (ED) have showcased a significant change in their shape and size. An absolute figure of 28.11% and 30.14% of wetland area has been lost within the highest anthropogenic stress zone computed using AHP-VIP and AHP respectively.

A Single-Layer Dual-Band Dual-Sense Circularly Polarized Patch Antenna Array With Small Frequency Ratio

A planar dual-band dual-sense circularly polarized (CP) microstrip array is proposed. This array is implemented on a single-layer substrate and easily extended to the design of a larger array. A new antenna element is exploited by symmetrically placing the nonradiative resonators on four side edges of a square patch. A quantitative design method is proposed based on the equivalent circuit model of the antenna element. For given two operating frequencies, the required design parameters of the patch and nonradiative resonators can be calculated. Theoretical magnitude ratio and phase difference responses of two far-field components, as well as axial ratio responses under different parameters, are presented to reveal the characteristics of the antenna element. Full-wave simulation results are found to agree well with the theoretical ones. To further validate the effectiveness, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> element dual-band dual-sense CP array operating at 2.40 and 2.68 GHz is designed, fabricated, and measured, where a small frequency ratio of 1.117 is achieved. The measured realized gains in the low and high bands are 11.7 and 11.8 dBi, respectively, which are approximately equal.

A low profile single feed compact dual-band penta-polarization agile microstrip antenna for interference mitigation in point to point link in Ultra-Dense environment

This study takes an antenna perspective approach to mitigate signal interference issues in ultra-dense environment along with communication and signal processing domain. A compact single layered dual-band penta-polarization agile microstrip patch antenna (MSA) using single feed is studied and proposed. Each band switches between five distinct polarization states. Additionally, the proposed antenna possesses a very low profile of less than 0.01λ (λ free-space wavelength). A square patch is enclosed by a square ring to attain two distinct reconfigurable frequency bands by using switching diodes and biasing networks. Orthogonal microstrip lines connected with a single coax feed are selectively chosen by biasing network to excite the adjacent patch edges to achieve dual linear polarization (LP). Circular polarization (CP) with dual sense of rotation at each band is attained by switchable diagonal-truncated corners of outer ring. Subsequently, 45° slant polarization is achieved by simultaneous activation of the orthogonal feed lines with equal phases and amplitude. A penta-polarized antenna prototype is designed and fabricated to operate at 5.2 GHz and 5.8 GHz bands respectively. Simulation results of all ten reconfigurable states are found to be consistent with the measurement.

Effects of local climate and habitat heterogeneity on breeding-bird assemblages of semi-natural grasslands

The intensification of agricultural land-use, abandonment and afforestation have caused severe loss and degradation of nutrient-poor, semi-natural grasslands across Europe. Calcareous grasslands have an outstanding value for nature conservation due to their highly diverse flora and fauna, including birds. However, knowledge of environmental factors driving the composition of bird communities in calcareous grasslands is still scarce. The aim of our study was to compare the breeding-bird assemblages of calcareous grasslands and the second most common semi-natural grassland type in the study area (Diemel Valley, Central Germany), mesic grasslands, along an elevation (climate) gradient. For each grassland type, we randomly selected 27 square-shaped plots with a size of 5 ha each and a cover of the focal grassland type of at least 50% within the plot. Our study revealed that both the number and density of threatened species of breeding birds were higher in plots of calcareous grasslands than in those of mesic grasslands. Based on multivariable generalised linear mixed-effects models, the most important predictors of overall species richness and density of breeding birds in plots of calcareous grasslands were the area of juniper-rich calcareous grassland and Shannon habitat diversity. By contrast, the number and density of threatened species were in both grassland types mainly driven by breeding-season temperature. Heterogeneous, juniper-rich calcareous grasslands seem to be a key habitat for bird assemblages with high species richness and density. These grasslands usually consisted of small-scale habitat mosaics providing suitable nesting sites and foraging grounds in close proximity. By contrast, mesic grasslands had rather homogeneous swards and shrubs or trees were normally restricted to the edges of the grassland patches. Based on our study, increasing habitat heterogeneity at the landscape scale and within grasslands is the key to enhancing species richness and density of breeding birds.