Small-scale Disturbances Research Articles

Estimating disturbance in a tropical forested habitat using a modified ecological disturbance index with rank-order weights of criteria

Anthropogenic plot-level disturbances may influence insect communities in an ecosystem. Documenting these small-scale disturbances through remote sensing in forested habitats of the developing world can be expensive. Disturbance indices can also be computed using visible signs of disturbance documented through ground-level surveys. In this study, we use a previously reported disturbance index to document the level of anthropogenic disturbances in two forested habitats in West Bengal, India, in the context of exploring plot-level habitat disturbances likely to influence the resident bee (Hymenoptera: Apoidae) fauna of the study sites. We introduce modifications to the established index by using rank-order weights of each identified criterion, instead of perceived weights. Using rank-order weights of criteria is considered suitable for removing evaluator bias when working with human-assigned weights. It is also thought that it is easier for expert as well as non-expert decision makers to arrive at a consensus when evaluating the ranks of criteria, instead of weights. This approach may be considered for calculating other ecological indices that involve multiple criteria with human-assigned weights. In addition, we report the results of our investigation into the relation between bee abundance and disturbance at each study site based on monthly surveys.

Towards a sustainable nature reserve management: Using Bayesian network to quantify the threat of disturbance to ecosystem services

Ecosystem services (ESs) of mountain areas may be impacted by cumulative and interactive effects of multiple disturbances including insect infestations, wildfires, timber harvesting, and building construction. However, the impacts of natural and human disturbances on ESs and the trade-offs/synergies among ESs are poorly known, particularly in mountain ecosystems with diverse landscapes. Here, we used the Qilian Nature Reserve in northwestern China as a case study, for which we quantified mountain disturbances with a BEAST algorithm and three critical ESs (carbon sequestration, water yield, and habitat quality) with the CASA and InVEST models. We then simulated ESs using the BN model, and estimated the impacts of disturbances on ESs and their trade-offs in different environment conditions through multi-scenario analysis. Our results suggested that BEAST could effectively capture the patterns and dynamics of small-scale disturbances, which were previously difficult to predict with normal land use/cover products. The established BN model could simulate the spatio-temporal dynamics of carbon sequestration, water yield, and habitat quality with an average classification error of 17.8, 12.7 and 4.5% for each ES, respectively. Significant synergy existed between carbon sequestration and habitat quality at the regional scale, while trade-off existed between water yield and the other two ESs. Specifically, these trade-offs/synergies among ESs tended to be weak at medium value of ESs, but stronger at higher and lower states. Thus, significant differences existed in the “win-lose” solutions between water yield and the other two ESs, further resulting the limited space to simultaneously improve three ESs. Disturbances at medium frequency and low-medium intensity were beneficial for the maintenance and improvement of three ESs. The BN model is a promising decision support tool to integrate small-scale disturbances into ES evaluation and identify the most suitable management solutions for mountain ecosystems; this could provide critical information for decision-makers and guidance for sustainable development.

Bird response to forest disturbance size in mountain spruce forests in Central Europe

Although natural disturbances are likely to occur more frequently and be more severe in future as a result of climate change, we have little evidence concerning the effect of disturbance size and severity on species diversity. We aimed to compare effects of varying size and severity of natural disturbances on bird species composition in the non-intervention area of Šumava National Park, Czech Republic. For this purpose, we surveyed bird communities in 1) small- and 2) large-scale disturbance, 3) enclaves of live trees in large-scale disturbance areas, and 4) non-disturbed forests. Furthermore, we used habitat characteristics to identify structural factors affecting species composition of bird communities. Birds were sampled by the point count method during the 2021 breeding season and analysed using linear models. Additionally, we use principal component analysis (PCA) to characterize four defined disturbance classes using habitat characteristics. The most important habitat characteristics for bird communities are structural complexity, live tree density, and understorey cover. Small-scale disturbances increased structural complexity of a forest and had a generally positive effect on birds. Both small- and large-scale disturbances supported species nesting on the ground and shrub layer. In contrast, large-scale disturbances negatively affected canopy nesting and specialist species. This likely was due to a reduction of small-scale habitat heterogeneity with increasing disturbance severity. High-severity disturbance changes structurally rich forests to rather uniform, open-canopy habitats that are temporally unsuitable for closed-canopy birds. On the other hand, low-severity disturbance enhances large-scale habitat heterogeneity and maintains suitable habitat for species of closed-canopy forest, including some specialist species.

Slope stability analysis of deep-seated landslides using limit equilibrium and finite element methods in Debre Sina area, Ethiopia

Slope failure is a recurring natural hazard in the western margin of the Main Ethiopian Rift and especially around the Debre Sina area. To minimize the damage caused by failure events, a detailed investigation of landslide-prone areas identified using numerical modelling plays a crucial role. The main aim of this study is to assess the stability of slopes and to evaluate and compare safety factors calculated by the different available numerical methods. Stability analyses of slopes prone to different types of failures were performed with different techniques. The stability was assessed for slopes of complex geometry composed of aphanitic basalt, porphyritic basalt, tuff, and colluvium (poorly sorted clayey sand to silty sand) using the limit equilibrium method and the shear strength reduction method based on finite elements. Furthermore, numerical analysis was done under static and pseudo-static loading using the horizontal seismic coefficient to model their stability during a seismic event. Satellite images were used to select failure-prone slopes based on slope properties and identified past landslides, as well as to derive structural and geological information for the numerical models. The slope stability analysis indicates that the studied slopes are unstable, and any small-scale disturbance will further reduce the factor of safety and cause failure. The slope stability of landslide prone hills in the study area strongly depends on the saturation conditions and the seismic load.

Large-scale influence of numerical noises as artificial stochastic disturbances on a sustained turbulence

We investigate the large-scale influence of numerical noises as tiny artificial stochastic disturbances on a sustained turbulence. Using two-dimensional (2-D) turbulent Rayleigh–Bénard convection (RBC) as an example, we solve numerically the Navier–Stokes equations, separately, by means of a traditional algorithm with double precision (denoted RKwD) and the so-called clean numerical simulation (CNS). The numerical simulation given by RKwD is a mixture of the ‘true’ physical solution and the ‘false’ numerical noises that are random and can be regarded as a kind of artificial stochastic disturbances; unfortunately, the ‘true’ physical solution is mostly at the same level as the ‘false’ numerical noises. By contrast, the CNS can greatly reduce the background numerical noise to any a required level so that the ‘false’ numerical noises are negligible compared with the ‘true’ physical solution, thus the CNS solution can be used as a ‘clean’ benchmark solution for comparison. It is found that the numerical noises as tiny artificial stochastic disturbances could indeed lead to large-scale deviations of simulations not only in spatio-temporal trajectories but also even in statistics. In particular, these numerical noises (as artificial stochastic disturbances) even lead to different types of flows. The shearing convection occurs for the RKwD simulations, and its corresponding flow field turns to a kind of zonal flow thereafter; however, the CNS benchmark solution always sustains the non-shearing vortical/roll-like convection during the whole process of simulation. Thus we provide rigorous evidence that numerical noises as a kind of small-scale artificial stochastic disturbances have quantitatively and qualitatively large-scale influences on a sustained turbulence, i.e. the 2-D turbulent RBC considered in this paper.

Detection of Vertical Changes in the Ionospheric Electron Density Structures by the Radio Occultation Technique Onboard the FORMOSAT-7/COSMIC2 Mission over the Eruption of the Tonga Underwater Volcano on 15 January 2022

A large near-surface perturbation such as the eruption of the Tonga underwater volcano on 15 January 2022 can generate disturbances in the Earth’s atmosphere and ionosphere. It is quite challenging to detect and investigate the disturbances in the vertical direction due to the lack of ground-based instruments, especially in the ocean area. To examine the vertical disturbances due to the Tonga eruption, this study utilizes the radio occultation (RO) technique onboard the satellites of the FORMOSAT-7/COSMIC2 (F7/C2) mission to sound the ionospheric electron density (Ne) profiles in the Central Pacific Ocean area around the eruption. The ionospheric Ne profiles show that the eruption almost annihilated the typical Chapman-layer structure over the eruption in the nighttime on 15 January. The Hilbert–Huang transform was applied to expose the vertical changes in the Ne structures as functions of wavelength and altitude. The analysis shows not only the occurrence of the small-scale disturbances with a wavelength of ~20 km from 100 km to 500 km altitudes, but also the significant attenuation of the structures with a wavelength >50 km, which has never been reported before. The time series of the total electron content from the ground-based Global Navigation Satellite System receiver near the eruption also verifies the significant long-lasting disturbances due to the eruption.

Experiment investigation on the effect of inlet circumferential non-uniformity on the stall behaviours in a transonic axial compressor with axisymmetric stall precursor

The circumferential non-uniformity is becoming a high risk for jet engines in the future with cutting-edge intake design and undesirable inflow, like crosswind and highly turbulence. This leads to the requirement of a well-designed non-uniformity-tolerant compressor. In those research, the test rigs are mainly low-speed compressors whose stalls are triggered by small length scale disturbance of several blade pitches. The load achieves its maximum value at the trailing edge of the distortion, and spikes tend to emerge from this region. Thus, the circumferential non-uniformity usually deteriorates the stall margin. Unlike the spike, the partial surge shows axisymmetric features in both phase and amplitude since the embryonic period. It is interesting to find out the influence of circumferential uniformity of local disturbance at the hub on the propagation of partial surge. Thus, this paper implemented an experimental method on a transonic axial compressor with an axisymmetric stall precursor originating from the hub, partial surge. The non-uniformity patterns are varied by adjusting the distortion sector with different angles. The stall margin decreased with the sector angle of 90 degrees. In contrast, an unexpected result indicated that the stall margin increased with the sector angle of 120 degrees and 180 degrees, which were affected by two mechanisms, i.e., partial-surge-suppression and embryo-stall-cells-motivation. First, when the sector angle was 90 degrees and 120 degrees, the non-uniformity suppressed the partial surge and the formation of embryo rotating stall cells in the distorted region. With the development of partial surge, the embryo rotating stall cells in the undistorted region grew larger than those in the uniform case. Secondly, the partial surge inception disappeared when the sector angle was further enlarged to 180 degrees. The embryo rotating stall cells at the rotor tip emerged from the distorted region and died out in the undistorted region.

Spatial and temporal distribution dataset of benthic macroalgae during the 2015-2016 tropical monsoonal cycle in Malaysia.

The effects of small-scale disturbances, such as monsoon, are understudied in tropical regions. The storms associated with monsoon events not only modify the local macroalgal community structure, but also reveal the continuation of short-term recolonisation. Thus, this study aims to determine the variation in species, assemblage and cover of macroalgae during the monsoonal cycle from 2015 to 2016. This paper presents data on the spatial and temporal distribution of benthic macroalgae along the coastline of Johor, Malaysia. The information is presented as raw and partially-processed data, which summarises the cover and frequency of macroalgae at the respective study sites. This paper describes an important set of data that can be used further for in-situ experiments on the effects of environmental disturbances towards pioneer and climax species in tropical areas. This study provides a description of the east coast shore of Peninsular Malaysia, specifically in Johor coast in 2015-2016. The spatial and temporal distribution and abundance of a total of 41 taxa were assessed at four monsoon-exposed locations. These data provide a comprehensive baseline against disturbance and recolonisation of macroalgal community can be effectively and objectively evaluated.

Fast Detection of SSR for Wind Parks Connected to Series-Compensated Transmission Systems

The interactions between wind parks and the series-compensated transmission lines can bring about sub- or super-synchronous resonance (SSR) incidents which jeopardize the safe operation of the entire network. In practice, such incidents may emerge under various conditions as different types of wind turbines with various parameters can be deployed at several locations in the network. Hence, it is crucial to efficiently identify the conditions that lead to adverse interactions and their subsequent SSR incidents. This paper proposes a simulation-based method, namely disturb and scan (DaS), for fast and automated detection of SSR. The proposed technique uses small-scale disturbances in time-domain electromagnetic transient (EMT) simulations to perform spectral analysis along with positive-sequence impedance scans. Numerical results are presented and validated for benchmark systems that utilize type-III and type-IV wind turbines. The system operators can adopt the developed methodology to quickly assess the risks of SSR, evaluate conditions of instability, and improve their network protection and control schemes.

Small-scale spontaneous dynamics in temperate beech stands as an importance driver for beetle species richness

Natural dynamics in forests play an important role in the lives of many species. In the landscape of managed forests, natural disturbances are reduced by management activities. This usually has a significant effect on insect diversity. The effect of small-scale natural dynamics of protected beech stands on the richness of saproxylic and non-saproxylic beetles was investigated. Sampling was carried out by using flight interception traps in the framework of comparing different developmental stages: optimum, disintegration, and growing up, each utilizing 10 samples. We recorded 290 species in total, of which 61% were saproxylic. The results showed that the highest species richness and thus abundance was in the disintegration stage. In each developmental stage, species variation was explained differently depending on the variable. Deadwood, microhabitats, and canopy openness were the main attributes in the later stages of development for saproxylic beetles. For non-saproxylics, variability was mostly explained by plant cover and canopy openness. Small-scale disturbances, undiminished by management activities, are an important element for biodiversity. They create more structurally diverse stands with a high supply of feeding and living habitats. In forestry practice, these conclusions can be imitated to the creation of small-scale silvicultural systems with active creation or retention of high stumps or lying logs.

Features of Winter Stratosphere Small-Scale Disturbance during Sudden Stratospheric Warmings

We analyzed the characteristics of small-scale wave disturbances emerging during the evolution and transformation of the jet stream (JS) in the winter stratosphere and the lower mesosphere of the northern hemisphere, including the periods of sudden stratospheric warming (SSW) events. Continuous generation of small-scale wave disturbances is shown to occur over quiet geomagnetic winter periods in the region of a steady jet stream in the strato–mesosphere. We studied spatial spectra for the vertical velocity variations, determined by the parameters of emerging wave disturbances. The greatest intensities of disturbances are recorded in the regions corresponding to the high velocities of the JS (from 100 m/s and higher). In the northern hemisphere, those latitudes encompass ~40–60° N. When a steady jet stream forms, the horizontal length and periods of the most intensive wavelike disturbances are shown to vary within 300–1000 km and 50–150 min correspondingly (which match the characteristic scales of internal gravity waves, or IGWs). During the SSW prewarming stage, the JS transforms substantially. Over the same periods, a disturbance intensification is recorded, as well as the emergence of larger-scale disturbances with 3000–5000-km horizontal wavelengths, and even higher. After the SSW peak and during the stratosphere circulation recovery, the velocity in the JS substantially decreases and an essential reduction in wave-disturbance generation occurs. There are decreases in the average amplitude values (by factors of 1.8–6.7). The strongest amplitude drop was observed for short waves (zonal wavelength λU = 300 km). The maximum attenuation for all wavelengths was observed for the strongest 2008/2009 winter SSW. For the analyzed events, such attenuation was observed for up to about a month after the SSW peak. Thus, JS disruption during major SSWs leads to deactivating the source for generating small-scale wave disturbances in the stratosphere. This may affect disturbances in higher atmospheric layers. The results obtained are the experimental evidence that JS itself is the primary source for the generation of IGWs in the stratosphere–lower mesosphere.

Investigation on the Contribution of Large-Scale Fluctuation and Small-Scale Disturbance of Coolant to Heat Transfer Enhancement in a Rectangular Channel With Pin Fins

Abstract The flow field in a channel with staggered pin-fin array was measured using time-resolved Particle Imaging Velocimetry (PIV). The distributions of flow field statistics were compared with those of Nusselt number on the endwall measured by thermochromic liquid crystal (TLC) of the same geometry. Lower-order large-scale fluctuation and higher order small-scale disturbances were examined separately using Proper Orthogonal Decomposition (POD) to study the flow field characteristics and their individual effect on the heat transfer enhancement. Pin fins with circular and square cross-section geometries were studied at Reynolds numbers of 10,000 and 20,000. Results indicate that for circular pin fins, the distribution of lateral/transverse velocity fluctuations or turbulent kinetic energy from large-scale vortex shedding resembles that of local Nu, and the heat transfer augmentation downstream of the recirculation zone is dominant, while the heat transfer enhancement is limited in the shear layer on both sides of recirculation where disturbances are small scale. However, for square pin fins, heat transfer augmentation in the shear layer is as strong as that downstream of recirculation, while large-scale fluctuations downstream is much weaker than small scale disturbances in the shear layer. Compared to small-scale disturbances, large-scale fluctuations are found to contribute more efficiently to endwall heat transfer enhancement both for circular and for square pin fins. Large-scale fluctuation, as well as heat transfer enhancement, weakens with the increase in Reynolds number, while smaller-scale disturbance grows stronger at the same time.

Vegetation Change in a Sand Prairie over Ten Years Following a Gas Pipeline Installation

Sand prairies experience relatively high rates of small-scale disturbance, feature a high complement of annual plant species, and are fairly dynamic in terms of year-to-year micro-scale species composition. In summer 2011, an underground natural gas pipeline was installed across Sand Prairie Natural History Reservation 19 km west of North Newton, KS. The resulting excavation left a strip 560 m long and 24 m wide devoid of aboveground vegetation. From August 2012 to 2021, I monitored vegetation composition in 60 0.75 × 0.75 m2 quadrats along six parallel transect lines: three lines along the center of the excavated area and three placed 20 m away in prairie unaffected by earth-moving vehicles. Quadrat species richness was higher in the undisturbed reference area in the first year, but higher in the pipeline area in four later years. There were no consistent area differences in species evenness. Annual species richness was higher within the pipeline area every year. In contrast, perennial species richness was higher in the reference area during the first seven years. Coverage by annuals was higher every year within the pipeline area, whereas coverage by perennials was consistently higher in the reference area. Bray-Curtis Similarity for the two areas ranged from 29.2 to 55.8% across years, but was not trending upward with time. Twenty-one species were restricted to the pipeline area; several other species were beginning to move from the reference area to the pipeline area. Both Floristic Quality Index and modified FQI were consistently higher for the reference area than for the pipeline area. It is too early to project the time frame for the pipeline area to recover a species composition indistinguishable from the undisturbed reference site, but clearly a period longer than ten years will be required.

An update on the 4D-LETKF data assimilation system for the whole neutral atmosphere

Abstract. The four-dimensional local ensemble transform Kalman filter (4D-LETKF) data assimilation system for the whole neutral atmosphere is updated to better represent disturbances with wave periods shorter than 1 d in the mesosphere and lower thermosphere (MLT) region. First, incremental analysis update (IAU) filtering is introduced to reduce the generation of spurious waves arising from the insertion of the analysis updates. The IAU is better than other filtering methods, and also is commonly used for middle atmospheric data assimilation. Second, the order of horizontal diffusion in the forecast model is changed to reproduce the more realistic tidal amplitudes that were observed by satellites. Third, the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) and Special Sensor Microwave Imager/Sounder (SSMIS) observations in the stratosphere and mesosphere also are assimilated. The performance of the resultant analyses is evaluated by comparing them with the mesospheric winds from meteor radars, which are not assimilated. The representation of assimilation products is greatly improved not only for the zonal mean field but also for short-period and/or horizontally small-scale disturbances.

The Small-Scale Instability of the Air–Water Interface Responsible for the Bag-Breakup Fragmentation

Abstract The “bag breakup” fragmentation is the dominant mechanism for spume droplet production in high winds, which substantially affects the ocean–atmosphere exchange processes. The amount of droplets ejected from the surface, as well as their typical sizes, is prescribed by the surface wind velocity and fetch. The corresponding empirical correlations were obtained only for the limited parameters of the laboratory environment. The applicability range can be extended through the construction of a theoretical model that describes the initiation of the bag-breakup fragmentation, estimates the fragmenting liquid volume prescribing the droplet sizes, and determines the dependence on the wind parameters. This paper presents such a model. First, we conducted linear stability analysis of small-scale disturbances at the water surface under a high wind; this showed that the small-scale ripples (about 1 cm) propagating against the wind in the surface wind drift following the reference frame grew fast due to the Kelvin–Helmholtz instability, when the wind friction velocity exceeded the threshold of about 1 m s−1. Given the weak dispersion, the nonlinear stage of evolution was addressed using the Riemann simple wave equation modified to describe the increasing disturbances. The analytical solution for the equation suggested the scaling of the volume of liquid undergoing the bag-breakup fragmentation and its dependence on in agreement with the laboratory data. Using the scaling, we calculated the statistics of the bag-breakup fragmentation based on the lognormal size distribution of the fragmenting objects. Significance Statement The “bag breakup” fragmentation is the dominant mechanism for generating spray in hurricane winds. The parameters of spray droplets substantially affect the exchange processes between the ocean and the atmosphere and, thereby, the development of sea storms. The rapid process of spray generation can only be studied in laboratory environments using sophisticated experimental techniques. To apply the laboratory data to field conditions, we need a theoretical model that describes the threshold for fragmentation initiation, the fragmenting liquid volume, which scales the size and number of spray droplets, their dependence on wind parameters, etc. In the present work, we suggest a simple analytical model of the bag-breakup initiation, verify it in the laboratory experiment, and suggest the statistical description of the fragmentation events.

Long-Term Recovery of Selected Indicator Species Following Soil Disturbance and Compaction in an Old-Growth Longleaf Pine (Pinus palustris) Woodland

Reference sites with relatively unaltered plant communities are used regularly to establish targets for ecological restoration, yet few are free from anthropogenic disturbances. In this study, we sought to understand the capacity for native community indicators and other plant species to recover from abandoned woods roads and tilled soils within reference sites. We mapped disturbances in a 34 ha portion of the Wade Tract, an old-growth longleaf pine-wiregrass (Pinus palustris-Aristida stricta) woodland using GPS and LiDAR and counted stems of 25 native species (20 woody and 5 herbaceous) in plots within disturbances (n = 32; disturbed), 3 m adjacent to disturbances (n = 32; adjacent), and >5 m from any disturbance (n = 30; reference). Ten species were considered indicator species of intact longleaf pine woodlands. We also quantified soil conditions within the disturbed, adjacent, and reference sites. Disturbed sites had more compacted surface soils than adjacent or reference sites and, in a subset of the sites, soil bulk density and soil strength were greater in disturbed than in adjacent. Indicator species were less frequent in disturbed sites than in adjacent or reference sites (except for Quercus pumila). Three oaks (Q. incana, Q. margaretta, and Q. laevis) and 3 other woody species (Rhus copallinum, Sassafras albidum, and Morella cerifera) were significantly less common in the disturbed sites than in adjacent or reference sites. The near absence of some oaks and other woody species on disturbed sites warrants including these species as indicators of intact regional ground cover for longleaf pine woodlands. Legacies of small-scale soil disturbances in relatively undisturbed perennial-dominated ground cover flora reveals the potential for cumulative degradation over decades and underscores the need to avoid such disturbances in remnant longleaf pine woodlands.

Scale Sensitivity of the Gill Circulation. Part I: Equatorial Case

Abstract We investigate the steady dynamical response of the atmosphere on the equatorial β plane to a steady, localized, midtropospheric heating source at the equator. Expanding Gill’s seminal work, we vary the latitudinal and longitudinal scales of the diabatic heating pattern while keeping its total amount fixed. We focus on characteristics of the response that would be particularly important if the circulation interacted with the hydrologic and energy cycles: the overturning circulation and the low-level wind. In the limit of very small scale in either the longitudinal or latitudinal direction, the vertical energy transport balances the diabatic heating and this sets the intensity of the overturning circulation. In this limit, a fast low-level westerly jet is located around the center of diabatic heating. With increasing longitudinal or latitudinal scale of the diabatic heating, the intensity of the overturning circulation decreases and the low-level westerly jet decreases in maximum velocity and spatial extent relative to the spatial extent of this heating. The associated low-level eastward mass transport decreases only with increasing longitudinal scale. These results suggest that moisture-convergence feedbacks will favor small-scale equatorial convective disturbances while surface-heat-flux feedbacks would favor small-scale disturbances in mean westerlies and large-scale disturbances in mean easterlies. Part II investigates the case of off-equatorial heating.

АНАЛІЗ ОСНОВНИХ ПАРАМЕТІВ МАЛОАМПЛІТУДНИХ РОЗРИВНИХ ПОРУШЕНЬ ВУГІЛЬНИХ ПЛАСТІВ ТА ПРОСТОРОВЕ ЗОБРАЖЕННЯ ПОВЕРХНІ ЗМІЩУВАЧА

Purpose. Carrying out a statistical analysis of the main parameters of low-amplitude discontinuous disturbances in a coal seam and restoring a spatial image of the disjunctive mixer surface. Methodology. Based on the results of a statistical sampling of data on small-scale disturbances of the coal seam, obtained directly from the field diary of the chief geologist of the mining enterprise, a classification of discontinuous disturbances of the coal seam by types, angle, dip azimuth and amplitude was made. A comparison was made of the recorded faults in the layers located at a small distance from each other, which made it possible to reproduce the spatial position of the fault and build the surface of its displacement. Results. Statistical data processing has shown that the majority of all faults are normal faults, and the dip angles of their faults range from 55 to 75º, while the dip azimuth of almost half of fault fault faults lies in the range of 0 – 100º. It can be seen from the distribution of the amplitude of disturbances that its indicator in the vast majority of tectonic discontinuities does not exceed 2 meters and, according to the conditions for the possibility of crossing discontinuities by clearing operations, such discontinuities pass with undercutting of side rocks by combines, which reduces the rate of feat and increases equipment wear. Originality. Comparison of faults recorded in formations located at a small distance from each other showed that their main parameters are very different at different horizons, due to which the spatial arrangement and the surface of the disjunctive mixer has a very complex shape, which does not allow predicting the location of the fault by simple geometric transfer from one layer to another. Practical value. The results obtained allow us to establish that the most common amplitude of tectonic faults is in the range from 0 to 2 m, the parameters of the same faults can change at different horizons, and the surface of the fault mixer is a complex geometric shape, which makes it impossible to simple transfer of the fault line from the upper to the lower layer, but requires the use of more efficient methods for predicting faults.

Monitoring of small rock pools reveals differential effects of chronic anthropogenic disturbance on birds and mammals in the Calakmul region, southern Mexico

AbstractGreat attention has been drawn to the impacts of habitat deforestation and fragmentation on wildlife species richness. In contrast, much less attention has been paid to assessing the impacts of chronic anthropogenic disturbance on wildlife species composition and behaviour. We focused on natural small rock pools (sartenejas), which concentrate vertebrate activity due to habitat’s water limitation, to assess the impact of chronic anthropogenic disturbance on the species richness, diversity, composition, and behaviour of medium and large-sized birds and mammals in the highly biodiverse forests of Calakmul, southern Mexico. Camera trapping records of fauna using sartenejas within and outside the Calakmul Biosphere Reserve (CBR) showed that there were no effects on species richness, but contrasts emerged when comparing species diversity, composition, and behaviour. These effects differed between birds and mammals and between species: (1) bird diversity was greater outside the CBR, but mammal diversity was greater within and (2) the daily activity patterns of birds differed slightly within and outside the CBR but strongly contrasted in mammals. Our study highlights that even in areas supporting extensive forest cover, small-scale chronic anthropogenic disturbances can have pervasive negative effects on wildlife and that these effects contrast between animal groups.

Intra-Annual Variation in Mesophotic Benthic Assemblages on the Insular Slope of Southwest Puerto Rico as a Function of Depth and Geomorphology

There is limited information on the intra-annual variability of mesophotic coral ecosystems (MCEs), worldwide. The benthic communities, measured as % cover, of two geomorphologically different mesophotic sites (El Hoyo and Hole-in-the-Wall) were examined during 2009–2010 in southwest Puerto Rico. Depths sampled were 50 and 70 m. At each site/depth combination, two permanent transects, measuring 10-m long by 40-cm wide, were surveyed by successive photoquadrants, 0.24 m2 in area. Scleractinian corals, octocorals, macroalgae, crustose coralline algae (CCA), sponges and unconsolidated sediment were the main components along the transects. Significant community differences were observed both among sites and among depths. Differences among sites were greater at 50 m than at 70 m. The El Hoyo site at 50 m was the most divergent, and this was due to a lower coral and sponge cover and a higher algal cover (Amphiroa spp., Peyssonnelia iridescens, turf) relative to the other site/depth combinations. As a consequence, the differences in community structure with depth were larger at El Hoyo than at Hole-in-the-Wall. The communities at 70 m were distinguished from those at 50 m by the greater proportion of the corals Agaricia undata, Madracis pharensis and CCA, and a reduced cover of the cyanobacterium Schizothrix. Temporal variation in the benthic assemblages was documented throughout the year. For both mesophotic sites, the magnitude of change at 50 m was significantly greater than at 70 m. For both depths, the magnitude of change at El Hoyo was significantly greater than at Hole-in-the-Wall. All assemblages experienced almost the same temporal patterns, despite the differences in species composition across sites and depths. Changes in temporal patterns are driven by an increase in the percent cover of the macroalgae Dictyota spp., and a decrease in the percent cover of non-colonized substrata (sand, pavement or rubble). Relatively rapid, intra-annual changes are dictated by the negative correlation between cyclic Dictyota spp. cover and open substrata cover. Other observed mechanisms for rapid community changes in the photoquadrants were diseases and collapses of substrata along with their associated fauna indicating that small-scale disturbance processes may play an important role within MCEs.