Search results for "Dry season"
showing 10 items of 25 documents
Seasonal and habitat effects on the nutritional properties of savanna vegetation: Potential implications for early hominin dietary ecology.
2019
The African savannas that many early hominins occupied likely experienced stark seasonality and contained mosaic habitats (i.e., combinations of woodlands, wetlands, grasslands, etc.). Most would agree that the bulk of dietary calories obtained by taxa such as Australopithecus and Paranthropus came from the consumption of vegetation growing across these landscapes. It is also likely that many early hominins were selective feeders that consumed particular plants/plant parts (e.g., leaves, fruit, storage organs) depending on the habitat and season within which they were foraging. Thus, improving our understanding of how the nutritional properties of potential hominin plant foods growing in mo…
Seasonal variations in schistosoma haematobium egg excretion in school-age girls in rural Kwazulu-Natal province, South Africa
2018
Background. A predominant feature of Schistosoma haematobium infection is urinary egg excretion, and microscopic egg detection remains the accepted standard field diagnostic tool. Praziquantel is the drug of choice for schistosomiasis, and the World Health Organization recommends that it should be administered to all children >4 years of age living in schistosomiasis-endemic areas. The frequency of mass drug administration depends on the prevalence rate in the community. Urinary schistosome egg output has a day-to-day and hour-to-hour intrasubject variation. Therefore, it is important to assess possible seasonal variations in egg excretion to improve the planning of drug treatment. Objectiv…
Animal Perception of Seasonal Thresholds: Changes in Elephant Movement in Relation to Rainfall Patterns
2012
Background The identification of temporal thresholds or shifts in animal movement informs ecologists of changes in an animal’s behaviour, which contributes to an understanding of species’ responses in different environments. In African savannas, rainfall, temperature and primary productivity influence the movements of large herbivores and drive changes at different scales. Here, we developed a novel approach to define seasonal shifts in movement behaviour by examining the movements of a highly mobile herbivore (elephant; Loxodonta africana), in relation to local and regional rainfall patterns. Methodology/Principal Findings We used speed to determine movement changes of between 8 and 14 GPS…
Black and brown carbon over central Amazonia: long-term aerosol measurements at the ATTO site
2018
The Amazon rainforest is a sensitive ecosystem experiencing the combined pressures of progressing deforestation and climate change. Its atmospheric conditions oscillate between biogenic and biomass burning (BB) dominated states. The Amazon further represents one of the few remaining continental places where the atmosphere approaches pristine conditions during occasional wet season episodes. The Amazon Tall Tower Observatory (ATTO) has been established in central Amazonia to investigate the complex interactions between the rainforest ecosystem and the atmosphere. Physical and chemical aerosol properties have been analyzed continuously since 2012. This paper provides an in-depth analysis of t…
Assessments for the impact of mineral dust on the meningitis incidence in West Africa.
2013
9 pages; International audience; Recently, mineral dust has been suspected to be one of the important environmental risk factor for meningitis epidemics in West Africa. The current study is one of the first which relies on long-term robust aerosol measurements in the Sahel region to investigate the possible impact of mineral dust on meningitis cases (incidence). Sunphotometer measurements, which allow to derive aerosol and humidity parameters, i.e., aerosol optical thickness, Angström coefficient, and precipitable water, are combined with quantitative epidemiological data in Niger and Mali over the 2004-2009 AMMA (African Monsoon Multidisciplinary Analysis) program period. We analyse how th…
Dynamics and Predictability of a Heavy Dry-Season Precipitation Event over West Africa—Sensitivity Experiments with a Global Model
2009
Abstract In January 2002 the Cape Verde region in tropical West Africa was hit by an exceptionally heavy precipitation event. Rain rates of up to 116 mm (48 h)−1 caused harmful impacts on the local population. The rainfall was triggered by a series of two upper-level disturbances penetrating from the extratropics to the West African coast. This study investigates the dynamics and predictability of this event on the basis of simulations with the global model Global Model Europe (GME) of the German Weather Service [i.e., Deutscher Wetterdienst (DWD)] initialized by the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis data. Free forecasts satisfactorily reproduce the upper-l…
Dry-Season Precipitation in Tropical West Africa and Its Relation to Forcing from the Extratropics
2008
Abstract Precipitation is a major socioeconomic factor in the Guineo-Soudanian zone of tropical West Africa with its distinct summer rainy season from May to October. Albeit rare, precipitation during the dry season can have substantial impacts on the local hydrology and human activities reaching from the rotting of harvests to improved grazing conditions. This study provides an observationally based synoptic and dynamical analysis of an abundant rainfall event during the dry season of 2003/04 that affected the countries of Nigeria, Benin, Togo, and Ghana. The results point to a forcing of the rainfalls from the extratropics in the following ways: 1) Upper-level clouds and moisture to the e…
Monsoon and land use in Sri Lanka
1979
Agricultural land use in Sri Lanka roughly shows a division of the island in two major parts, according to the climatic division into the Wet and Dry Zones. Therefore, it is the ultimate, most important question for agricultural land use in Sri Lanka whether the seasonal occurrence of a distinct dry season, which is characteristic of the Dry Zone, is also the most delimiting factor for land use or not. It seems true, in fact, that the long SW monsoonal dry season in the Dry Zone is the major fact for a large-scale division of Sri Lanka according to the crops under cultivation and the cropping systems. Paddy (rice) and tea are the leading crops in the Dry as well as Wet Zone. They are at the…
Start of the dry season as a main determinant of inter-annual Mediterranean forest production variations
2014
Abstract Recent investigations have highlighted the dependence of Mediterranean forest production on spring rainfall. The current work introduces the concept of the start of the dry season (SDS) and performs a three-step analysis to determine the effect of SDS on Mediterranean forest production. Seven forest zones of Tuscany (Central Italy), which present differently pronounced Mediterranean features, are considered. First, a statistical analysis investigates the influence of spring water budget on forest Normalized Difference Vegetation Index (NDVI) inter-annual variations during July–August. The analysis is then extended to assess the impact of inter-annual SDS variability on forest gross…
Feeding and management techniques to favour summer sheep milk and cheese production in the Mediterranean environment
2015
Sheep milk production in summer can lead to a diversification of milk products and to a more regular product distribution in the market throughout the year. However, in Mediterranean countries small ruminant production cycles are subjected to seasonal variations in forage resources. During summer, a key period for out of season production systems, nutrition plays a fundamental role in regulating the quantity and quality of milk production. In this review, feeding strategies and techniques that could be applied for out of season production in dairy ewes under different Mediterranean conditions are described for intensive, pasture-based and mixed systems. The most common feeding strategies us…