Suchergebnisse

AbstractThis study investigated rainfall variabilities in Kilembe. Secondary (monthly rainfall) data for the study were obtained from the Uganda National Meteorological Authority in Kampala, Uganda, for the period 1986–2016. To determine the temporal variation of rainfall, a Mann–Kendall method and Sen's slope estimator test were used. The results showed that March, April, May, October, and November represented the smallest coefficient of variation indicating modest variability of rainfall in these months, whereas June and July had the largest coefficient of variation. The month of July recorded an overall lowest average rainfall and a decreasing trend in rainfall. The study further revealed a historical general upward trend in rainfall between 1986 and 2016 in Kilembe. The trend in the monthly and annual rainfall is partly attributed to the Intertropical Convergence Zone, influx of moisture from Congo Forest, and climate change. The area recorded also two peaks of rainfall in the year, one in April and another in September, revealing a bimodal pattern of rainfall. The findings indicate that the government should adopt policy measures in the form of an adaptive strategy in order to save the people in the impacted areas.

In many rural regions of developing countries, natural resource dependency means changes in climate patterns hold tremendous potential to impact livelihoods. When environmentally-based livelihood options are constrained, migration can become an important adaptive strategy. Using data from the Mexican Migration Project, we model U.S. emigration from rural communities as related to community, household and climate factors. The results suggest that households subjected to very recent drought conditions are less likely to send a U.S. migrant, but in communities with drought two years prior and with strong migration histories, emigration is much more likely. In regions lacking such social networks, rainfall deficits actually reduce migration propensities, perhaps reflecting constraints in the ability to engage in migration as a coping strategy. Policy implications emphasize diversification of rural Mexican livelihoods in the face of contemporary climate change.

Abstract
Rural farmers in Mozambique rely on rain-fed agriculture for food and income, yet they experience high rainfall variability ranging from extreme drought to flooding rainfall from tropical cyclone systems. To explore linkages between rainfall and agriculture, the authors regress changes in annual household per capita agricultural income on reliance on staple food crops, agricultural and demographic characteristics, and rainfall patterns using longitudinal data for rural households for 2002 and 2005. They characterize rainfall patterns by defining nine rainfall zones using the percent of normal rainfall received in each month of three agricultural growing seasons and rainfall from two tropical cyclones that occurred during the study period. Results show that in a period where monthly rainfall seldom occurred in normal amounts, most households experienced decreases in agricultural income. Even after controlling for rainfall patterns, they find that greater household dependency on staple crop agriculture is associated with declining annual agricultural income. They also find that areas affected by both wet and dry rainfall extremes in the first year of the study had decreases in the well-being of rural households when measured two years later. Taken together, their findings suggest that antipoverty policies focused on increasing agricultural income seem likely to fail in countries characterized by highly variable rainfall and exposure to extreme events, particularly when coupled with high levels of poverty and widespread dependence on rain-fed agriculture.

Soil and water losses caused by water erosion represent a risk of environmental damage and loss of soil productivity, with economic, social and environmental consequences. Plant cover is an important ally against water erosion, together with the knowledge of rainfall characteristics. Thus, this study aimed to evaluate the soil and water losses and to determine rainfall patterns in two homogeneous eucalyptus plantations; one in Yellow Argisol, located in Teixeira de Freitas, and another in Humiluvic Spodosol, located in Caravelas, both in the Extreme South of the state of Bahia. Erosion plots were installed, and consisted of three treatments: bare soil, eucalyptus, and native forest. Rainfall data was obtained from an automatic gauging station, with 10 minute registration interval for erosivity (erosivity index EI30) and rainfall pattern analyses. Higher soil losses were observed in Yellow Argisol, and the advanced rainfall pattern was predominant. Eucalyptus minimum tillage was efficient in reducing soil and water losses by water erosion.

We would like to thank Angel Caravantes Mart ınez for his help in the field and the laboratory, and Karin Djendouci for her assistance in glucosinolate extraction and identification. The authors thank Mark Lineham for revising the English ; Evidence is accumulating of the disruptive effects of climate change on species interactions. However, little is known about how changes in climate patterns, such as temporal shifts in rainfall events, will affect multitrophic interactions. Here, we investigated the effects of changes in rainfall patterns on the interactions between root herbivores, a plant, and its associated aboveground insects in a semiarid region by experimentally manipulating in the field rainfall intensity and frequency. We found that a shift in rainfall severely constrained biomass acquisition and flowering of the plant Moricandia moricandioides, resulting in fitness reduction. Importantly, enhanced rainfall affected the interactions between below- and some aboveground herbivores, disrupting the positive effects of root herbivores on chewing insects. The shifts in precipitation had also plant-mediated consequences for planthoppers, the dominant sapsuckers in our study system. A combination of mechanisms involving biomass acquisition and plant defenses seemed to be responsible for the different responses of insects and their interactions with the plant. This study provides evidence that altered rainfall patterns due to climate change affect not only trophic groups differentially but also their interactions. ; Spanish Government CGL2011-24840 CGL2015-71634-P BBVA-P17_ECO_0021 BES-2012-059576

The extent and intensity of parasitism is known to be affected by climatic conditions. Climate changes among other factors have been confirmed to exert more influence on helminths and thus, on the diseases caused by helminths. Freshwater snails serve as specific intermediate hosts for trematodes of medical and veterinary importance and snail ecology is important in the transmission of the parasites. Snail-borne trematodiasis are heavily dependent on the environment for dissemination and are greatly affected by climate. Correlating rainfall patterns, snail abundance and trematode infection have been known to aid in the design of control models for snail-borne diseases. Freshwater snail samples were collected from August to December in years 2012 and 2014 to determine abundance and prevalence of trematode infection. Rainfall data for the study period was obtained from the Department of Geography, University of Ibadan. A total of 550 freshwater snails samples were collected in 2012 and 480 in 2014. The snails identified were Physa, Lymnaea, Bulinus and Melanoides species. Examination for trematodes cercariae was carried out using the crushing method. In 2012, 18 snails out of 550, (3.3%) were infected with trematode species with evidence of cercariae release while 0% was recorded in 2014. The total recorded rainfall for the study period in 2012 and 2014 was 35.20mm and 303.40mm respectively. This result showed that rainfall has an effect on the survivability and availability of freshwater snails and thus could be a factor in determining the prevalence of snail-borne infections.

AbstractSand dune systems in the arid region of north‐western China are maintained by sand‐stabilizing vegetation, which provides critical ecosystem services. Limited knowledge of soil moisture recharge in these systems hinders sand stabilization efforts. To increase the understanding of soil moisture response to rainfall, we analysed soil water transport in the desert vadose zone of sand dunes and dune slacks following four natural rainfall events during the growing season of 2017. Rainfall was dominated by small rain events (<5.0 mm), accounting for 58% of total rainfall events. Soil moisture at 5–25 cm depth in dune slacks was significantly higher and more variable to 60 cm depth than in sand dunes. Soil moisture at 5 cm depth was replenished with rainfall amounts of <5 mm in dune slacks, but not in sand dunes. When rainfall amount reached 20 mm, soil moisture in dune slack and in sand dune increased, but was much higher in dune slack than in sand dune at depth of 5 cm; after the rain, soil moisture remained at a relatively high level in dune slack but not in sand dune. This was possible because dune slacks had higher silt contents and root biomass, which played a key role in improving soil water holding capacity or accelerating rainfall infiltration at 0–25 cm depth. Overall, the rainfall‐driven hydrological regime coupled with soil physical factors regulated spatial and temporal variability of soil moisture in a sand dune system.

Small reservoirs (SRs) are important infrastructures for providing water for a wide range of activities in Burkina Faso and other semiarid environments. In recent years, SRs have become even more important, considering the effects of climate change and variability such as erratic rainfall patterns, recurrent droughts and floods, delays in the onset of the rains (Laux et al. 2008), increased incidence of in-season dry spells (Lacombe et al. 2012), and high evapotranspiration rates. SRs provide vulnerable rural communities with water for multiple purposes, including domestic and agricultural uses (McCartney et al. 2012; Venot et al. 2012). However, a number of external factors are negatively influencing the sustainable uses of SRs. Rapid population growth (Zuberi and Thomas 2012) and its attendant human-induced activities are a threat to the quality of water in SRs, as are agricultural extensification and intensification around SRs, including the increased use of inorganic fertilizers. ; European Union ; International Fund for Agricultural Development ; Internal Review

"February 1974." ; Title from cover. ; Mode of access: Internet.