scholarly journals Modelling and  assessing driving factors of the spatial and temporal dynamics of the sand  dunes in the district of Errachidia, Morocco

2021 ◽  
Author(s):  
Tudal SINSIN ◽  
Fouad MOUNIR ◽  
Ahmed El ABOUDI
Keyword(s):  
Sand Dune ◽  
Temporal Dynamics ◽  
Moving Average ◽  
Sand Dunes ◽  
Ecological Factors ◽  
Temperature And Precipitation ◽  
Spatial And Temporal Dynamics ◽  
Combined Action ◽  
Landsat Satellite ◽  
Dune Dynamics

The desertification affects more than 250,000 ha in the district of Errachidia and results in the expansion of desert landscapes such as the Regs, Hamadas and the Dunes. The latter is a big concern in the district since it is the source of siltation, which threatens dwellings, cultivated lands and water bodies. It is of paramount importance to understand the causes and consequences of silting to develop strategies to combat it. Thus, first, we analysed the spatial and temporal dynamics of sand dunes until 2069 by applying the Seasonal Autoregressive Integrated Moving-Average (SARIMA) model on a time series of sand dune areas. These areas were calculated annually from 1987 to 2019 by computing the sand cover index (SCI) on Landsat satellite images. Furthermore, we evaluated the influence of different natural and human factors such as temperature, precipitation, wind, vegetation, and population growth, on sand dune dynamics using Spearman’s correlation test. The results indicated that the area of sand dunes will increase by 1.7% per year between 2019 and 2069 in the district of Errachidia. This increase would be mainly caused by the combined action of ecological factors, which vary from year to year. In general, temperature and precipitation act indirectly on wind and vegetation to influence the dynamics of sand dunes in hyper-arid areas where the soil is bare or poorly covered with vegetation, where precipitation is low and where temperature is high.

scholarly journals Effect of ecological factors on the zonation of wetland vegetation

2011 ◽  
Vol 74 (1) ◽  
pp. 73-81 ◽  
Author(s):  
Richard Hrivnák
Keyword(s):  
Water Table ◽  
Aquatic Macrophytes ◽  
Temporal Dynamics ◽  
Typha Latifolia ◽  
Ground Surface ◽  
Ecological Factors ◽  
Marsh Vegetation ◽  
Spatial And Temporal Dynamics ◽  
Belt Transect

The influence of some ecological factors to aquatic and marsh vegetation was studied during 1998-2000. Three basic vegetation units (<em>Caricetum buekii</em>, <em>Typhetum latifoliae</em> and <em>Ceratophylletum submersi</em>) and three transitional communities were defined in the belt transect, which was established along the moisture gradient. The content of available soil nutrients in individual vegetation types differed only in case of the <em>Ceratophyllum submersum</em> community, where a higher magnesium and nitrogen content accumulated due to specific environmental conditions. Water and marsh vegetation is usually characterised by a pronounced spatial and temporal dynamics. In the studied area, its zonation was dependent from the terrain morphology, and both depth and duration of floods. The fluctuation of ground and surface water table during a three-year period caused changes in the occurrence and cover of several species (e.g. <em>Carex buekii</em>, <em>Typha latifolia</em>, aquatic macrophytes). Pronounced changes in the cover of some species occurred even within a single vegetation season due to the long-term sink of water table below the ground surface.

scholarly journals Possible ecology and epidemiology of medically important mosquito-borne arboviruses in Great Britain

2006 ◽  
Vol 135 (3) ◽  
pp. 466-482 ◽  
Author(s):  
J. M. MEDLOCK ◽  
K. R. SNOW ◽  
S. LEACH
Keyword(s):  
Great Britain ◽  
Disease Ecology ◽  
Temporal Dynamics ◽  
Ecological Factors ◽  
Human Infection ◽  
Mosquito Vectors ◽  
West Nile ◽  
Spatial And Temporal Dynamics ◽  
Reservoir Hosts ◽  
Ecological Differences

Nine different arboviruses are known to be transmitted by, or associated with, mosquitoes in Europe, and several (West Nile, Sindbis and Tahyna viruses) are reported to cause outbreaks of human disease. Although there have been no reported human cases in Great Britain (GB), there have been no published in-depth serological surveys for evidence of human infection. This paper investigates the ecological and entomological factors that could influence or restrict transmission of these viruses in GB, suggesting that in addition to West Nile virus, Sindbis and Tahyna viruses could exist in enzootic cycles, and that certain ecological factors could facilitate transmission to humans. However, the level of transmission is likely to be lower than in endemic foci elsewhere in Europe due to key ecological differences related to spatial and temporal dynamics of putative mosquito vectors and presence of key reservoir hosts. Knowledge of the potential GB-specific disease ecology can aid assessments of risk from mosquito-borne arboviruses.

COMPUTATIONAL MODELS FOR SAND RIPPLE AND SAND DUNE FORMATION

1993 ◽  
Vol 07 (09n10) ◽  
pp. 2025-2034 ◽  
Author(s):  
HIRAKU NISHIMORI ◽  
NORIYUKI OUCHI
Keyword(s):  
Sand Dune ◽  
Computational Models ◽  
Sand Dunes ◽  
Simple Analysis ◽  
Sand Ripple ◽  
Rich Variety ◽  
Ripple Formation ◽  
The Rich ◽  
Dune Dynamics ◽  
Quantitative Explanation

Computational models for sand ripple and sand dune dynamics are proposed. From the results of the simulations, with the simple analysis of these models, we give the quantitative explanation for sand ripple formation and that for the origin of the rich variety of sand dunes’ shape.

scholarly journals Spatial dynamics of land cover in the Sdamas region (Tiaret, Algeria)

2018 ◽  
Vol 27 (1) ◽  
pp. 12-19
Author(s):  
Mohamed Azzaoui ◽  
Benchohra Maamar ◽  
Leila Soudani ◽  
Belgacem Nouar ◽  
Mohamed Berreyah ◽  
...  
Keyword(s):  
Land Cover ◽  
Temporal Dynamics ◽  
Spatial Dynamics ◽  
Ground Level ◽  
Human Action ◽  
Mineral Surfaces ◽  
Factors Affecting ◽  
Spatial And Temporal Dynamics ◽  
Landsat Satellite ◽  
Bare Soils

The Sdamas massif to which our contribution relates is located in West Algeria, it is an integral part of the Tiaret mountains. The aim of our study is to analyze the land cover of the Sdamas region over a 43-year interval grouped into 9 thematic classes: mineral surfaces (urban planning), wetland, vegetation, bare soils and fallow etc. The spatial and temporal dynamics of land use require regular monitoring of vegetation cover from remote sensing imagery. It is for this reason that we relied on field data to perform the diachronic analysis with three well-defined scenes 1972, 1998 and 2015, using Landsat satellite images (MSS, TM and ETM +). The analysis of these maps covering the same region shows the different changes that have taken place at ground level. We found that our natural plant space has undergone a strong degradation, disruption and regression because of different human activities, namely: overgrazing, clearing, fires, urbanization, (there has been a remarkable increase in the population of the communes of the study area). Inadequate and ineffective forestry interventionsand work, and lack of sustained protection are reasons of these processes. Factors affecting the forest ecosystem are bioclimate and human action. Indeed, the bioclimate, through atmospheric drought, is the main factor governing the diversity of these formations of the Sdamas mountains.

Spatial and temporal dynamics of lexico-semantic processing in American Sign Language

2011 ◽  
Author(s):  
M. Leonard ◽  
N. Ferjan Ramirez ◽  
C. Torres ◽  
M. Hatrak ◽  
R. Mayberry ◽  
...  
Keyword(s):  
American Sign Language ◽  
Sign Language ◽  
Semantic Processing ◽  
Temporal Dynamics ◽  
American Sign ◽  
Spatial And Temporal Dynamics

Spatial and temporal dynamics of Pacific capelin Mallotus catervarius in the Gulf of Alaska: implications for ecosystem-based fisheries management

2020 ◽  
Vol 637 ◽  
pp. 117-140 ◽  
Author(s):  
DW McGowan ◽  
ED Goldstein ◽  
ML Arimitsu ◽  
AL Deary ◽  
O Ormseth ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Marine Ecosystem ◽  
Gulf Of Alaska ◽  
Data Series ◽  
Limited Information ◽  
Important Species ◽  
Multiple Data ◽  
Spatial And Temporal Dynamics ◽  
Spawning Areas ◽  
Spatio Temporal

Pacific capelin Mallotus catervarius are planktivorous small pelagic fish that serve an intermediate trophic role in marine food webs. Due to the lack of a directed fishery or monitoring of capelin in the Northeast Pacific, limited information is available on their distribution and abundance, and how spatio-temporal fluctuations in capelin density affect their availability as prey. To provide information on life history, spatial patterns, and population dynamics of capelin in the Gulf of Alaska (GOA), we modeled distributions of spawning habitat and larval dispersal, and synthesized spatially indexed data from multiple independent sources from 1996 to 2016. Potential capelin spawning areas were broadly distributed across the GOA. Models of larval drift show the GOA’s advective circulation patterns disperse capelin larvae over the continental shelf and upper slope, indicating potential connections between spawning areas and observed offshore distributions that are influenced by the location and timing of spawning. Spatial overlap in composite distributions of larval and age-1+ fish was used to identify core areas where capelin consistently occur and concentrate. Capelin primarily occupy shelf waters near the Kodiak Archipelago, and are patchily distributed across the GOA shelf and inshore waters. Interannual variations in abundance along with spatio-temporal differences in density indicate that the availability of capelin to predators and monitoring surveys is highly variable in the GOA. We demonstrate that the limitations of individual data series can be compensated for by integrating multiple data sources to monitor fluctuations in distributions and abundance trends of an ecologically important species across a large marine ecosystem.

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