Spatial distribution of Serengeti wildebeest in relation to resources

1999 ◽  
Vol 77 (8) ◽  
pp. 1223-1232 ◽  
Author(s):  
John F Wilmshurst ◽  
John M Fryxell ◽  
Brian P Farm ◽  
ARE Sinclair ◽  
Chris P Henschel
Keyword(s):  
Spatial Distribution ◽  
Energy Intake ◽  
Large Scale ◽  
Spatial Scales ◽  
Mechanistic Model ◽  
Large Herbivores ◽  
Serengeti Ecosystem ◽  
Dry Seasons ◽  
Behavioural Factors ◽  
Wet And Dry Seasons

We investigated the spatial distribution of radio-marked wildebeest (Connochaetes taurinus) in the Serengeti ecosystem in relation to the distribution of their food resources, comparing patterns in the wet and dry seasons and at local and landscape spatial scales. A mechanistic model of ruminant energy optimization predicted that wildebeest should maximize energy intake on swards 3 cm high and maintain energy balance on swards between 3 and 10 cm high. At the ecosystem scale, wildebeest preferred short and intermediate-height grass of moderate greenness during both the wet and dry seasons. This was consistent with the model prediction which suggests that large-scale movements by wildebeest are motivated, at least partially, by an energy-maximizing strategy. At the local scale, however, wildebeest showed spatial selectivity only on the basis of grass greenness, not on grass height. This differed from model expectations and may have resulted from wildebeest exploiting ephemeral green flushes of grass caused by localized rainfall in their movement radius. According to these results, the influence of other nutritional or behavioural factors on wildebeest distributions is not rejected, yet they suggest the potentially important role of an energy intake maximizing strategy on movement patterns. Our findings show that wildebeest movements are broadly similar to those of other large herbivores that migrate in response to resource gradients.

scholarly journals A BRIEF OBSERVATION OF THE FORMATION OF COHERENT STRUCTURES AND TURBULENCE OVER A RAIN FOREST AREA IN CENTRAL AMAZÔNIA: THE ATTO-CLAIRE/IOP – 1/2012 EXPERIMENT

2017 ◽  
Vol 35 (3) ◽  
Author(s):  
Newton Silva de Lima ◽  
Julio Tota da Silva ◽  
Maurício José Alves Bolzam ◽  
Alan Dos Santos Ferreira ◽  
Matheus Da Rocha Pietzsch
Keyword(s):  
Coherent Structures ◽  
Large Scale ◽  
Inflection Point ◽  
Terra Firme ◽  
Central Amazonia ◽  
Intensive Observation ◽  
Dry Seasons ◽  
Box Plot ◽  
Observation Period ◽  
Wet And Dry Seasons

ABSTRACT. This work used micrometeorological measurements of temperature and wind in order to characterize the turbulence due to wind in a terra firme forest in central Amazonia as part of the ATTO-CLAIRE / IOP-1 (2012) (Amazon Tall Tower Observatory – Cooperative LBA Airborne Regional Experiment / Intensive Observation Period – 2012 / LBA – Large Scale Biosphere-Atmosphere Experiment in the Amazon). This research was conducted at the Uatumã ATTO Sustainable Development Reserve in the State of Amazonas, Brazil, from February to September, 2012, and used data from February 26 to September 07, 2012, dates that partially encompass the wet and dry seasons, respectively. The ATTO site has 5 towers: one that is 320m, and four that are 80 m in height, and this research was conducted on an 80 m triangular tower. A total of ten 3D and 2D ultrasonic anemometers were installed on the tower, and the importance of these instruments used for flux measurements is also evident when taking into account the fact that the dissemination and diffusion of seeds and chemical composts in the forest happens through the action of turbulent fluxes. In order to understand the wind profile, the inflection point of the wind velocity, and coherent structures (ECs) and local turbulence, box-plot diagrams, quadrant analyses, wavelet potential spectrum, and energy potential analyses were conducted. The turbulence characterized at the ATTO had a roll or ramp structure during the study period, which represents favorable conditions for the maintenance of the forest during the wet and dry seasons in the Central Amazon. Keywords: inflection point, ramp, wavelet, turbulence. RESUMO. Este trabalho faz uso de medidas micrometeorológicas de temperatura e vento, com finalidade de caracterizar a turbulência aerotransportada em uma floresta de terra firme na Amazônia Central, realizadas no experimento ATTO-CLAIRE / IOP-1 (2012) (Amazon Tall Tower Observatory – Cooperative LBA Airborne Regional Experiment / Intensive Observation Period – 2012 / LBA – Large Scale Biosphere-Atmosphere Experiment in Amazônia), no sítio do ATTO, na Reserva de Desenvolvimento Sustentável do Uatumã – AM (Brasil) nos meses de fevereiro a setembro de 2012, com dados analisados a partir do dia 26 de fevereiro de 2012 até o dia 7 de setembro de 2012, entre as estações úmida e seca na Amazônia Central, no complexo de torres altas composta de 5 (cinco) torres; uma de 320 m e 4 (quatro) de 80 m. Este trabalho foi realizado na torre triangular (80 m). Foram instalados 10 (dez) anemômetros ultrassônicos de 3D e 2D. Equipamentos necessários em método de fluxos, visto que, a disseminação e difusão de sementes e compostos químicos da floresta, faz-se também por fluxos turbulentos. Para compreensão do perfil de vento, ponto de inflexão do perfil da velocidade do vento, estruturas coerentes e a turbulência local, para tal desenvolveu-se a partir dos dados processados, diagrama de caixa (box-plot ), análise de quadrantes, espectro de potência em ondeletas, espectro de energia. A turbulência caracterizada no ATTO, foi de estruturas do tipo “rolo” ou rampa, para o período estudado, condições favoráveis para manutenção da floresta em período úmido-seco na Amazônia Central.Palavras-chave: ponto de inflexão, rampa, ondeleta, turbulência.

scholarly journals Influence of the spatial distribution of gravity wave activity on the middle atmospheric circulation and transport

2016 ◽  
Author(s):  
Petr Šácha ◽  
Friederike Lilienthal ◽  
Christoph Jacobi ◽  
Petr Pišoft
Keyword(s):  
Spatial Distribution ◽  
Gravity Wave ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Mechanistic Model ◽  
Polar Vortex ◽  
Wave Activity ◽  
Residual Circulation ◽  
Density Profiles ◽  
Longitudinal Variability

Abstract. Analyzing GPS radio occultation density profiles, we have recently pointed out a localized area of enhanced gravity wave (GW) activity and breaking in the lower stratosphere of the Eastern Asia/North-western Pacific (EA/NP) region. With a mechanistic model for the middle and upper atmosphere (MUAM), experiments are performed to study a possible effect of such a localized IGW breaking region on the large-scale circulation and transport and also more generally, possible influence of spatial distribution of gravity wave activity on the middle atmospheric circulation and transport. The results indicate an important role of the spatial distribution of GW activity for the polar vortex stability, formation of planetary waves (PW) and for the strength and structure of the zonal mean residual circulation. Also, a possible effect of a zonally asymmetric GW breaking in the longitudinal variability of Brewer–Dobson circulation is analyzed. Finally, consequences of our results for a variety of research topics (Sudden Stratospheric Warmings, atmospheric blocking, teleconnections and a compensation mechanism between resolved and unresolved drag) are discussed.

scholarly journals Cloud characteristics, thermodynamic controls and radiative impacts during the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) experiment

2017 ◽  
Vol 17 (23) ◽  
pp. 14519-14541 ◽  
Author(s):  
Scott E. Giangrande ◽  
Zhe Feng ◽  
Michael P. Jensen ◽  
Jennifer M. Comstock ◽  
Karen L. Johnson ◽  
...  
Keyword(s):  
Large Scale ◽  
Amazon Basin ◽  
Department Of Energy ◽  
Cloud Characteristics ◽  
Radiative Impacts ◽  
Atmospheric Radiation Measurement ◽  
Dry Seasons ◽  
Basin Region ◽  
Cloud Regimes ◽  
Wet And Dry Seasons

Abstract. Routine cloud, precipitation and thermodynamic observations collected by the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) and Aerial Facility (AAF) during the 2-year US Department of Energy (DOE) ARM Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign are summarized. These observations quantify the diurnal to large-scale thermodynamic regime controls on the clouds and precipitation over the undersampled, climatically important Amazon basin region. The extended ground deployment of cloud-profiling instrumentation enabled a unique look at multiple cloud regimes at high temporal and vertical resolution. This longer-term ground deployment, coupled with two short-term aircraft intensive observing periods, allowed new opportunities to better characterize cloud and thermodynamic observational constraints as well as cloud radiative impacts for modeling efforts within typical Amazon wet and dry seasons.

scholarly journals Linking spatial patterns of terrestrial herbivore community structure to trophic interactions

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jakub Witold Bubnicki ◽  
Marcin Churski ◽  
Krzysztof Schmidt ◽  
Tom A Diserens ◽  
Dries PJ Kuijper
Keyword(s):  
Spatial Distribution ◽  
Community Structure ◽  
Spatial Variation ◽  
Spatial Scales ◽  
Landscape Scale ◽  
Top Down ◽  
Large Herbivores ◽  
Bottom Up ◽  
Vegetation Heterogeneity ◽  
Herbivore Community

Large herbivores influence ecosystem functioning via their effects on vegetation at different spatial scales. It is often overlooked that the spatial distribution of large herbivores results from their responses to interacting top-down and bottom-up ecological gradients that create landscape-scale variation in the structure of the entire community. We studied the complexity of these cascading interactions using high-resolution camera trapping and remote sensing data in the best-preserved European lowland forest, Białowieża Forest, Poland. We showed that the variation in spatial distribution of an entire community of large herbivores is explained by species-specific responses to both environmental bottom-up and biotic top-down factors in combination with human-induced (cascading) effects. We decomposed the spatial variation in herbivore community structure and identified functionally distinct landscape-scale herbivory regimes (‘herbiscapes’), which are predicted to occur in a variety of ecosystems and could be an important mechanism creating spatial variation in herbivory maintaining vegetation heterogeneity.

scholarly journals Large-Scale Spatial Distribution of Virioplankton in the Adriatic Sea: Testing the Trophic State Control Hypothesis

2003 ◽  
Vol 69 (5) ◽  
pp. 2664-2673 ◽  
Author(s):  
C. Corinaldesi ◽  
E. Crevatin ◽  
P. Del Negro ◽  
M. Marini ◽  
A. Russo ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Large Scale ◽  
Trophic State ◽  
Spatial Scales ◽  
Environmental Parameters ◽  
Viral Abundance ◽  
Trophic Conditions ◽  
Additional Information ◽  
Autotrophic Biomass ◽  
Viral Distribution

ABSTRACT Little is known concerning environmental factors that may control the distribution of virioplankton on large spatial scales. In previous studies workers reported high viral levels in eutrophic systems and suggested that the trophic state is a possible driving force controlling the spatial distribution of viruses. In order to test this hypothesis, we determined the distribution of viral abundance and bacterial abundance and the virus-to-bacterium ratio in a wide area covering the entire Adriatic basin (Mediterranean Sea). To gather additional information on factors controlling viral distribution on a large scale, functional microbial parameters (exoenzymatic activities, bacterial production and turnover) were related to trophic gradients. At large spatial scales, viral distribution was independent of autotrophic biomass and all other environmental parameters. We concluded that in contrast to what was previously hypothesized, changing trophic conditions do not directly affect virioplankton distribution. Since virus distribution was coupled with bacterial turnover times, our results suggest that viral abundance depends on bacterial activity and on host cell abundance.

scholarly journals Human Cortical Thickness Organized into Genetically-determined Communities across Spatial Resolutions

2017 ◽  
Vol 29 (1) ◽  
pp. 106-118 ◽  
Author(s):  
Aaron F Alexander-Bloch ◽  
Samuel R Mathias ◽  
Peter T Fox ◽  
Rene L Olvera ◽  
Harold H H Göring ◽  
...  
Keyword(s):  
Cortical Thickness ◽  
Large Scale ◽  
Computational Models ◽  
Spatial Scales ◽  
Mechanistic Model ◽  
Expression Patterns ◽  
Genetic Correlations ◽  
Brain Anatomy ◽  
Extended Pedigrees ◽  
Organizational Principles

Abstract The cerebral cortex may be organized into anatomical genetic modules, communities of brain regions with shared genetic influences via pleiotropy. Such modules could represent novel phenotypes amenable to large-scale gene discovery. This modular structure was investigated with network analysis of in vivo MRI of extended pedigrees, revealing a “multiscale” structure where smaller and larger modules exist simultaneously and in partially overlapping fashion across spatial scales, in contrast to prior work suggesting a specific number of cortical thickness modules. Inter-regional genetic correlations, gene co-expression patterns and computational models indicate that two simple organizational principles account for a large proportion of the apparent complexity in the network of genetic correlations. First, regions are strongly genetically correlated with their homologs in the opposite cerebral hemisphere. Second, regions are strongly genetically correlated with nearby regions in the same hemisphere, with an initial steep decrease in genetic correlation with anatomical distance, followed by a more gradual decline. Understanding underlying organizational principles of genetic influence is a critical step towards a mechanistic model of how specific genes influence brain anatomy and mediate neuropsychiatric risk.

scholarly journals Cloud Characteristics, Thermodynamic Controls and Radiative Impacts During the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment

2017 ◽  
Author(s):  
Scott E. Giangrande ◽  
Zhe Feng ◽  
Michael P. Jensen ◽  
Jennifer Comstock ◽  
Karen L. Johnson ◽  
...  
Keyword(s):  
Large Scale ◽  
Amazon Basin ◽  
Short Term ◽  
Cloud Characteristics ◽  
Cloud Regime ◽  
Radiative Impacts ◽  
Dry Seasons ◽  
Thermodynamic Regime ◽  
Basin Region ◽  
Wet And Dry Seasons

Abstract. Routine cloud, precipitation and thermodynamic observations collected by the ARM Mobile Facility (AMF) and Aerial Facility (AAF) during the two-year DOE ARM Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign are summarized. These observations quantify the diurnal to large-scale thermodynamic regime controls on the clouds and precipitation over the undersampled, climatically important, Amazon basin region. The extended ground deployment of cloud-profiling instrumentation enabled a unique look at multiple cloud regime controls at high temporal and vertical resolution. This longer-term ground deployment coupled with two short-term aircraft intensive observing periods allowed new opportunities to better characterize cloud and thermodynamic observational constraints as well as cloud radiative impacts for modeling efforts within typical Amazon ‘wet’ and ‘dry’ seasons.

scholarly journals DISTRIBUCIÓN ESPACIAL, ABUNDANCIA Y RELACIÓN CON CARACTERÍSTICAS DEL HÁBITAT DEL CARACOL PALA EUSTROMBUS GIGAS (LINNAEUS) (MOLLUSCA: STROMBIDAE) EN EL ARCHIPIÉLAGO NUESTRA SEÑORA DEL ROSARIO, CARIBE COLOMBIANO

2016 ◽  
Vol 39 (1) ◽  
Author(s):  
Kelly Gómez Campo ◽  
Mario Rueda ◽  
Carolina García Valencia
Keyword(s):  
Spatial Distribution ◽  
Population Density ◽  
Reproductive Activity ◽  
Average Density ◽  
Distribution Analysis ◽  
Wet Season ◽  
Spawning Stock ◽  
Dry Seasons ◽  
The Caribbean ◽  
Wet And Dry Seasons

Population density and spatial distribution of the Caribbean conch, Eustrombus gigas (Linnaeus), as well as its association to different habitats were evaluated at 184 stations sampled systematically in two seasons (wet and dry) in Nuestra Señora del Rosario archipelago. Each individual was counted and measured in a circular area of 1256.6 m2 (sampling unit) by SCUBA diving and in situ observations on the types of habitats were made. The average density (± SD) of the species was low compared with other regions in the Caribbean, 4.0 ind/ha ± 10.8 and 3.7 ind/ha ± 9.3, for the wet and dry seasons, respectively. Adults represented 89 and 64 % of the population surveyed for each season, and were specifically located at Bajo Tortugas and Isla Tesoro. Although reproductive activity was observed during the wet season, population density was below critical levels to guarantee the population´s reproductive success. The spatial distribution analysis showed that the abundance of adults was spatially structured in both seasons, with important aggregations at Bajo Tortugas and Isla Tesoro. Juveniles did not show spatial structure for neither season due to the low observed abundance. Multiple regression models explained 48 and 14 % of the total variance in the abundance of adults during the wet and dry seasons, respectively; with depth, mean grain size, and percentage of mixed coral as predictor variables. It is recommended to establish Bajo Tortugas and Isla Tesoro as special protected areas in order to maintain the adult spawning stock, while the same conservation measure should be implemented at Isla Arena in order to protect juveniles on seagrass beds.

scholarly journals Influence of the spatial distribution of gravity wave activity on the middle atmospheric dynamics

2016 ◽  
Vol 16 (24) ◽  
pp. 15755-15775 ◽  
Author(s):  
Petr Šácha ◽  
Friederike Lilienthal ◽  
Christoph Jacobi ◽  
Petr Pišoft
Keyword(s):  
Spatial Distribution ◽  
Gravity Wave ◽  
Large Scale ◽  
Mechanistic Model ◽  
Polar Vortex ◽  
Wave Activity ◽  
Northwestern Pacific ◽  
Residual Circulation ◽  
Teleconnection Patterns ◽  
Longitudinal Variability

Abstract. Analysing GPS radio occultation density profiles, we have recently pointed out a localised area of enhanced gravity wave (GW) activity and breaking in the lower stratosphere of the east Asian–northwestern Pacific (EA/NP) region. With a mechanistic model of the middle and upper atmosphere, experiments are performed to study the possible effect of such a localised GW breaking region on large-scale circulation and transport and, more generally, a possible influence of the spatial distribution of gravity wave activity on middle atmospheric dynamics.The results indicate the important role of the spatial distribution of GW activity for polar vortex stability, formation of planetary waves and for the strength and structure of zonal-mean residual circulation. Furthermore, a possible effect of a zonally asymmetric GW breaking in the longitudinal variability of the Brewer–Dobson circulation is analysed. Finally, consequences of our results for a variety of research topics (e.g. sudden stratospheric warming, atmospheric blocking, teleconnection patterns and a compensation mechanism between resolved and unresolved drag) are discussed.

scholarly journals Impacts of Emerging Agricultural Practices on Groundwater Quality in Kahe Catchment, Tanzania

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2263 ◽  
Author(s):  
Lwimbo ◽  
Komakech ◽  
Muzuka
Keyword(s):  
Groundwater Quality ◽  
Large Scale ◽  
Agricultural Practices ◽  
Pesticides Residues ◽  
Average Value ◽  
Intensive Use ◽  
Shallow Wells ◽  
Dry Seasons ◽  
Deep Boreholes ◽  
Wet And Dry Seasons

This paper assesses the impacts of farmers’ intensive use of agrochemicals (fertilizers and pesticides) on groundwater quality in the Kahe catchment. Samples were collected during the wet and dry seasons of the year 2018 and analyzed for the presence of agrochemicals in the water. Groundwater chemistry was dominated by magnesium-sodium-bicarbonate (Mg-Na-HCO3−). The cations levels were in the trend of Mg2+ >Na+ > Ca2+ > K+, whereas anions were HCO3− > Cl− > SO42− for both seasons. The NO3− had an average value of about 18.40 ± 4.04 and 7.6 ± 1.7 mg/L in the wet and dry season, respectively. Elevated levels of nitrate, sulfate, phosphate, and ammonium were found in water samples collected near the large-scale sugarcane plantation in the catchment. For both seasons, Pb, Cd, Fe, Mn, Zn and Cu concentrations averaged approximately 0.08 ± 0.03, 0.11 ± 0.03, 0.16 ± 0.02, 0.11 ± 0.01, 0.46 ± 0.05, and 0.55 ± 0.02 mg/L, respectively. On the other hand, the concentrations were higher in shallow wells than in the deep boreholes. Pesticides’ residues were below the detection limit in all sampled groundwater. The findings from this study provide important information for intervention in groundwater quality management in Kahe Catchment, Tanzania.

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