scholarly journals Large-scale distribution patterns of carnivores in northern South Africa: implications for conservation and monitoring

Oryx ◽  
2011 ◽  
Vol 45 (4) ◽  
pp. 579-586 ◽  
Author(s):  
Michelle Thorn ◽  
Matthew Green ◽  
Mark Keith ◽  
Kelly Marnewick ◽  
Philip W. Bateman ◽  
...  
Keyword(s):  
South Africa ◽  
Large Scale ◽  
Extinction Risk ◽  
Spatial Scales ◽  
Rapid Assessment ◽  
Distribution Patterns ◽  
Distribution Data ◽  
Acinonyx Jubatus ◽  
Baseline Information ◽  
Local Range

AbstractAccurate assessment of carnivore population status is frequently hindered by insufficient distribution data. For northern South Africa we address this deficit by mapping new records from landscape-scale sign surveys, questionnaire interviews, problem animal records and camera trapping. The black-backed jackal Canis mesomelas and caracal Caracal caracal remain common and widespread. Ranges of the serval Leptailurus serval and brown hyaena Hyaena brunnea were much larger than previous estimates, reducing the risk of simultaneous extirpation across all occupied locations. The proportion of range area occupied was larger for several species, notably the leopard Panthera pardus, cheetah Acinonyx jubatus and serval. We conclude that the serval continues to recover from historical threats and is expanding into new areas. A larger brown hyaena range and less fragmented pattern of occurrence probably confers greater resilience to threats than was suggested by previous data. Reduced extinction risk arising from the increased area occupied by the cheetah and leopard is tempered by probable local range contraction. Our maps provide baseline information for monitoring the distribution of these six species, which is essential in managing ecological issues that have a spatial component such as responses to changing land use. Our results also demonstrate the utility of detection/non-detection surveys in rapid assessment of carnivore populations at large spatial scales.

scholarly journals Sedimentological evidence for seiching in a swell-dominated headland-bay system: Table Bay, Western Cape, South Africa

2021 ◽  
Vol 41 (4) ◽  
Author(s):  
Mike Woodborne ◽  
Burg Flemming
Keyword(s):  
South Africa ◽  
Standing Wave ◽  
Large Scale ◽  
Logarithmic Spiral ◽  
Distribution Patterns ◽  
Western Cape ◽  
Sediment Distribution ◽  
Maximum Period ◽  
Hydrodynamic Processes ◽  
Robben Island

AbstractTable Bay, South Africa, is a typical headland-bay system with a shoreline that can be described by a logarithmic spiral. A peculiarity and unique feature of Table Bay is the juxtaposition of Robben Island opposite its headland. As a consequence, the bathymetry defines an ellipsoidal basin which was postulated to potentially resonate in the form of long-period standing waves (seiches). One aim of this study, therefore, was to investigate whether any evidence for such resonant oscillations could be detected in the geomorphology and sediment distribution patterns. Indeed, the ellipsoidal shape of the basin can be framed by two converging log-spirals with their centres located opposite each other, one off Robben Island and the other on the Cape Town side of the bay. The so-called apex line, which divides the two spirals into equal parts is aligned SW–NE, i.e. more or less parallel to the direction of ocean wave propagation. The distribution patterns of all sedimentary parameters were found to be characterised by a strikingly similar trend to either side of the apex line. This supports the hypothesis that the basin of Table Bay appears to resonate in the form of a mode 1 standing wave, with the node positioned above the apex line in the centre of the bay. The maximum period of such a standing wave was calculated to be around 37 min. The study demonstrates that large-scale sediment distribution patterns can reveal the existence of specific hydrodynamic processes in coastal embayments. It is recommended that this phenomenon be investigated in greater detail aimed at verifying the existence of resonant oscillations in Table Bay and, in the event, at establishing its precise nature and trigger mechanism.

scholarly journals Unraveling the effects of environmental drivers and spatial structure on benthic species distribution patterns in Eurasian-Arctic seas (Barents, Kara and Laptev Seas)

Polar Biology ◽  
2020 ◽  
Vol 43 (11) ◽  
pp. 1693-1705
Author(s):  
Miriam L. S. Hansen ◽  
Dieter Piepenburg ◽  
Dmitrii Pantiukhin ◽  
Casper Kraan
Keyword(s):  
Environmental Factors ◽  
Spatial Structure ◽  
Large Scale ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Distribution Patterns ◽  
Environmental Drivers ◽  
Arctic Seas ◽  
Faunal Distribution ◽  
The Impact

Abstract In times of accelerating climate change, species are challenged to respond to rapidly shifting environmental settings. Yet, faunal distribution and composition are still scarcely known for remote and little explored seas, where observations are limited in number and mostly refer to local scales. Here, we present the first comprehensive study on Eurasian-Arctic macrobenthos that aims to unravel the relative influence of distinct spatial scales and environmental factors in determining their large-scale distribution and composition patterns. To consider the spatial structure of benthic distribution patterns in response to environmental forcing, we applied Moran’s eigenvector mapping (MEM) on a large dataset of 341 samples from the Barents, Kara and Laptev Seas taken between 1991 and 2014, with a total of 403 macrobenthic taxa (species or genera) that were present in ≥ 10 samples. MEM analysis revealed three spatial scales describing patterns within or beyond single seas (broad: ≥ 400 km, meso: 100–400 km, and small: ≤ 100 km). Each scale is associated with a characteristic benthic fauna and environmental drivers (broad: apparent oxygen utilization and phosphate, meso: distance-to-shoreline and temperature, small: organic carbon flux and distance-to-shoreline). Our results suggest that different environmental factors determine the variation of Eurasian-Arctic benthic community composition within the spatial scales considered and highlight the importance of considering the diverse spatial structure of species communities in marine ecosystems. This multiple-scale approach facilitates an enhanced understanding of the impact of climate-driven environmental changes that is necessary for developing appropriate management strategies for the conservation and sustainable utilization of Arctic marine systems.

scholarly journals Spatial Distribution of Reniform Nematode in Cotton as Influenced by Soil Texture and Crop Rotations

2015 ◽  
Vol 105 (5) ◽  
pp. 674-683 ◽  
Author(s):  
Claudia M. Holguin ◽  
Patrick Gerard ◽  
John D. Mueller ◽  
Ahmad Khalilian ◽  
Paula Agudelo
Keyword(s):  
South Carolina ◽  
Large Scale ◽  
Management Practices ◽  
Distribution Patterns ◽  
Sampling Scheme ◽  
Distribution Data ◽  
Sand Content ◽  
Cotton Production ◽  
Reniform Nematode ◽  
Neighborhood Structure

Reniform nematode (RN) is an important pest in cotton production. Knowledge of the distribution patterns of RN is essential for selecting sampling strategies and for site-specific management. A 3-year study was conducted in two fields in South Carolina with the purpose of characterizing the distribution of RN using a fine-scale sampling scheme in plots representing different soil textures (field 1), and using a large-scale arbitrary sampling scheme (field 2). Horizontal distribution data showed an aggregated pattern of RN densities at planting and after harvest in both fields each year, with patches ranging from 8 to 12 m. However, a significant neighborhood structure was only detected when suitable hosts (cotton and soybean) were planted. Correlations between RN densities and percent sand and silt were detected, showing nematode densities peaked when sand content was around 60% and declined when sand content increased above 60 to 65%. When fewer samples were taken in the field with more uniform sand content, percentage of sand was a less reliable predictor of RN densities. Vertical sampling showed the highest numbers of RN were found at 15 to 30 cm deep after cotton, but were deeper after a nonhost crop. Understanding distribution patterns of RN within a field may improve the effectiveness of management practices.

scholarly journals Colonization of macroalgal deposits by estuarine nematodes through air and potential for rafting inside algal structures

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0246723
Author(s):  
Bartelijntje Buys ◽  
Sofie Derycke ◽  
Nele De Meester ◽  
Tom Moens
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Distribution Patterns ◽  
Bedload Transport ◽  
Life History Trait ◽  
Small Scale ◽  
Marine Nematodes ◽  
Dispersal Capacity ◽  
Habitat Patches ◽  
Set Up

Dispersal is an important life-history trait. In marine meiofauna, and particularly in nematodes, dispersal is generally considered to be mainly passive, i.e. through transport with water currents and bedload transport. Because nematodes have no larval dispersal stage and have a poor swimming ability, their per capita dispersal capacity is expected to be limited. Nevertheless, many marine nematode genera and even species have near-cosmopolitan distributions, and at much smaller spatial scales, can rapidly colonise new habitat patches. Here we demonstrate that certain marine nematodes, like the morphospecies Litoditis marina, can live inside macroalgal structures such as receptacula and–to a lesser extent–floating bladders, which may allow them to raft over large distances with drifting macroalgae. We also demonstrate for the first time that these nematodes can colonize new habitat patches, such as newly deposited macroalgal wrack in the intertidal, not only through seawater but also through air. Our experimental set-up demonstrates that this aerial transport is probably the result of hitchhiking on vectors such as insects, which visit, and move between, the patches of deposited algae. Transport by wind, which has been observed for terrestrial nematodes and freshwater zooplankton, could not be demonstrated. These results can be important for our understanding of both large-scale geographic distribution patterns and of the small-scale colonization dynamics of habitat patches by marine nematodes.

Rapid Assessment Of Taal Volcano Protected Landscape (TVPL) Terrestrial Biodiversity

2017 ◽  
Vol 11 (1) ◽  
Keyword(s):  
Animal Species ◽  
Rapid Assessment ◽  
Ecological Status ◽  
Taal Volcano ◽  
Ecological Barriers ◽  
Floral Diversity ◽  
Forested Areas ◽  
Baseline Information ◽  
Study Sites ◽  
Terrestrial Biodiversity

With the exponential rise of human activities in the past decades, majority of studies conducted in Taal Volcano Protected Landscape (TVPL) are geared towards the conservation and preservation of Lake Taal’s remaining biodiversity. However, the current structure and assemblage of its terrestrial biotic communities remain relatively unstudied. In this study, we conducted biodiversity censuses in the four sites in TVPL to provide baseline information regarding the community structure of the selected study sites. Comparison of the plant diversity in Taal Volcano Crater Island and Romandan Falls within the forested areas of Mataas na Kahoy, Batangas reveal that both sites support remarkably different vegetation, with the former supporting a smaller floral diversity. The fairly small number of animal samples present difficulty in providing conclusive findings to the wildlife structure of the two study sites. However, the presence of 11 animal species exhibit valuable results in determining the ecological status of TVPL. It is deduced that several ecological barriers exist between the sites, which is attributed to their unique terrestrial biota.

Numerical Simulation of Hydrogen Transport at a Crack Tip in a Pipeline Steel

2006 ◽  
Author(s):  
Mohsen Dadfarnia ◽  
Petros Sofronis ◽  
Ian Robertson ◽  
Brian P. Somerday ◽  
Govindarajan Muralidharan ◽  
...  
Keyword(s):  
Distribution System ◽  
Large Scale ◽  
Pipeline Steel ◽  
Rapid Assessment ◽  
Crack Tip ◽  
Hydrogen Transport ◽  
Natural Gas Pipeline ◽  
Central Production ◽  
Materials Used ◽  
Pressure Hydrogen

The technology of large scale hydrogen transmission from central production facilities to refueling stations and stationary power sites is at present undeveloped. Among the problems which confront the implementation of this technology is the deleterious effect of hydrogen on structural material properties, in particular at gas pressure of 1000 psi which is the desirable transmission pressure suggested by economic studies for efficient transport. In this paper, a hydrogen transport methodology for the calculation of hydrogen accumulation ahead of a crack tip in a pipeline steel is outlined. The approach accounts for stress-driven transient diffusion of hydrogen and trapping at microstructural defects whose density may evolve dynamically with deformation. The results are used to discuss a lifetime prediction methodology for failure of materials used for pipelines and welds exposed to high-pressure hydrogen. Development of such predictive capability and strategies is of paramount importance to the rapid assessment of using the natural-gas pipeline distribution system for hydrogen transport and of the susceptibility of new alloys tailored for use in the new hydrogen economy.

scholarly journals Analysis of 220 Years of Floodplain Population Dynamics in the US at Different Spatial Scales

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 141
Author(s):  
Firoza Akhter ◽  
Maurizio Mazzoleni ◽  
Luigia Brandimarte
Keyword(s):  
Population Dynamics ◽  
Large Scale ◽  
Spatial Scales ◽  
National Level ◽  
State Level ◽  
Economic Activities ◽  
Protection Measures ◽  
Management Planning ◽  
The Us ◽  
Over Time

In this study, we explore the long-term trends of floodplain population dynamics at different spatial scales in the contiguous United States (U.S.). We exploit different types of datasets from 1790–2010—i.e., decadal spatial distribution for the population density in the US, global floodplains dataset, large-scale data of flood occurrence and damage, and structural and nonstructural flood protection measures for the US. At the national level, we found that the population initially settled down within the floodplains and then spread across its territory over time. At the state level, we observed that flood damages and national protection measures might have contributed to a learning effect, which in turn, shaped the floodplain population dynamics over time. Finally, at the county level, other socio-economic factors such as local flood insurances, economic activities, and socio-political context may predominantly influence the dynamics. Our study shows that different influencing factors affect floodplain population dynamics at different spatial scales. These facts are crucial for a reliable development and implementation of flood risk management planning.

scholarly journals Insectivorous songbirds as early indicators of future defoliation by spruce budworm

2021 ◽  
Author(s):  
Marion Germain ◽  
Daniel Kneeshaw ◽  
Louis De Grandpré ◽  
Mélanie Desrochers ◽  
Patrick M. A. James ◽  
...  
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Spruce Budworm ◽  
Detection Methods ◽  
Maximum Probability ◽  
Point Count ◽  
Probability Of Presence ◽  
Time Lagged ◽  
One Year ◽  
Local Sampling

Abstract Context Although the spatiotemporal dynamics of spruce budworm outbreaks have been intensively studied, forecasting outbreaks remains challenging. During outbreaks, budworm-linked warblers (Tennessee, Cape May, and bay-breasted warbler) show a strong positive response to increases in spruce budworm, but little is known about the relative timing of these responses. Objectives We hypothesized that these warblers could be used as sentinels of future defoliation of budworm host trees. We examined the timing and magnitude of the relationships between defoliation by spruce budworm and changes in the probability of presence of warblers to determine whether they responded to budworm infestation before local defoliation being observed by standard detection methods. Methods We modelled this relationship using large-scale point count surveys of songbirds and maps of cumulative time-lagged defoliation over multiple spatial scales (2–30 km radius around sampling points) in Quebec, Canada. Results All three warbler species responded positively to defoliation at each spatial scale considered, but the timing of their response differed. Maximum probability of presence of Tennessee and Cape May warbler coincided with observations of local defoliation, or provided a one year warning, making them of little use to guide early interventions. In contrast, the probability of presence of bay-breasted warbler consistently increased 3–4 years before defoliation was detectable. Conclusions Early detection is a critical step in the management of spruce budworm outbreaks and rapid increases in the probability of presence of bay-breasted warbler could be used to identify future epicenters and target ground-based local sampling of spruce budworm.

scholarly journals Modeling Spatiotemporal Population Changes by Integrating DMSP-OLS and NPP-VIIRS Nighttime Light Data in Chongqing, China

2021 ◽  
Vol 13 (2) ◽  
pp. 284
Author(s):  
Dan Lu ◽  
Yahui Wang ◽  
Qingyuan Yang ◽  
Kangchuan Su ◽  
Haozhe Zhang ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Relative Error ◽  
Urban Areas ◽  
Large Scale ◽  
Population Distribution ◽  
Spatial Optimization ◽  
Distribution Data ◽  
Mountainous Areas ◽  
Mean Relative Error ◽  
Nighttime Light

The sustained growth of non-farm wages has led to large-scale migration of rural population to cities in China, especially in mountainous areas. It is of great significance to study the spatial and temporal pattern of population migration mentioned above for guiding population spatial optimization and the effective supply of public services in the mountainous areas. Here, we determined the spatiotemporal evolution of population in the Chongqing municipality of China from 2000–2018 by employing multi-period spatial distribution data, including nighttime light (NTL) data from the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP-OLS) and the Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP-VIIRS). There was a power function relationship between the two datasets at the pixel scale, with a mean relative error of NTL integration of 8.19%, 4.78% less than achieved by a previous study at the provincial scale. The spatial simulations of population distribution achieved a mean relative error of 26.98%, improved the simulation accuracy for mountainous population by nearly 20% and confirmed the feasibility of this method in Chongqing. During the study period, the spatial distribution of Chongqing’s population has increased in the west and decreased in the east, while also increased in low-altitude areas and decreased in medium-high altitude areas. Population agglomeration was common in all of districts and counties and the population density of central urban areas and its surrounding areas significantly increased, while that of non-urban areas such as northeast Chongqing significantly decreased.

scholarly journals Mapping High Spatiotemporal-Resolution Soil Moisture by Upscaling Sparse Ground-Based Observations Using a Bayesian Linear Regression Method for Comparison with Microwave Remotely Sensed Soil Moisture Products

2021 ◽  
Vol 13 (2) ◽  
pp. 228
Author(s):  
Jian Kang ◽  
Rui Jin ◽  
Xin Li ◽  
Yang Zhang
Keyword(s):  
Soil Moisture ◽  
Large Scale ◽  
Spatial Scales ◽  
Microwave Remote Sensing ◽  
In Situ Measurements ◽  
Spatial Density ◽  
Linear Regression Method ◽  
Spatiotemporal Resolution ◽  
Pixel Scale

In recent decades, microwave remote sensing (RS) has been used to measure soil moisture (SM). Long-term and large-scale RS SM datasets derived from various microwave sensors have been used in environmental fields. Understanding the accuracies of RS SM products is essential for their proper applications. However, due to the mismatched spatial scale between the ground-based and RS observations, the truth at the pixel scale may not be accurately represented by ground-based observations, especially when the spatial density of in situ measurements is low. Because ground-based observations are often sparsely distributed, temporal upscaling was adopted to transform a few in situ measurements into SM values at a pixel scale of 1 km by introducing the temperature vegetation dryness index (TVDI) related to SM. The upscaled SM showed high consistency with in situ SM observations and could accurately capture rainfall events. The upscaled SM was considered as the reference data to evaluate RS SM products at different spatial scales. In regard to the validation results, in addition to the correlation coefficient (R) of the Soil Moisture Active Passive (SMAP) SM being slightly lower than that of the Climate Change Initiative (CCI) SM, SMAP had the best performance in terms of the root-mean-square error (RMSE), unbiased RMSE and bias, followed by the CCI. The Soil Moisture and Ocean Salinity (SMOS) products were in worse agreement with the upscaled SM and were inferior to the R value of the X-band SM of the Advanced Microwave Scanning Radiometer 2 (AMSR2). In conclusion, in the study area, the SMAP and CCI SM are more reliable, although both products were underestimated by 0.060 cm3 cm−3 and 0.077 cm3 cm−3, respectively. If the biases are corrected, then the improved SMAP with an RMSE of 0.043 cm3 cm−3 and the CCI with an RMSE of 0.039 cm3 cm−3 will hopefully reach the application requirement for an accuracy with an RMSE less than 0.040 cm3 cm−3.

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