Effect Of Different Seasons Research Articles

Streambank erosion in two watersheds of the Central Claypan Region of Missouri, United States

This study was undertaken to assess the importance of streambank erosion to the total in-stream sediment of two agricultural watersheds within the Central Claypan Areas. The objective of this research was to determine the effect of stream order, adjacent land use, and season on streambank erosion rates. Thirty-four study sites were established in 2007 and 2008 within Crooked and Otter Creek watersheds, two claypan watersheds located in northeastern Missouri. At each site, field assessments of severely to very severely eroding bank length were determined along 300 to 400 m (984 to 1,312 ft) stream reaches. A factorial experimental design was implemented with four land uses (crop, forest, pasture, and riparian forest), three seasons, and three stream orders (1st, 2nd, and 3rd). Each treatment was replicated three times for each stream order, except for the cropped 3rd order treatment as only one suitable treatment site could be found. Streambank erosion was measured using erosion pins, which were installed in randomly assigned plots that included at least 20% of the eroded bank length within each site. The effect of different seasons was assessed by measuring the length of the exposed pins three times per year (March, July, and November). The bulk density and carbon and nitrogen content of bank material were also determined. Sediment loss rates showed that season and the three-way interaction between season, land use, and stream order were highly significant. Erosion rates were consistently higher in the winter months than spring/summer and fall seasons; however, the significant three-way interaction precluded a simple interpretation of the seasonal effect. Soil nutrient concentration data showed that forest sites had significantly lower C and N concentrations than other land uses. At the watershed scale, bank sediment accounted for 79% to 96% of the total in-stream sediment and 21% to 24% of the total N exported from the study area. These results indicate that streambanks are the dominant source of sediment and a significant source of N in these streams. Therefore, improved management of riparian areas to decrease streambank erosion would result in significant water quality improvement in streams of the Central Claypan Areas in northeastern Missouri.

Seasonal and interannual validation of satellite-measured reservoir levels at the Kainji dam

Although several studies have demonstrated the potential for inland water monitoring using satellite radar altimeters, the technology still carries with it certain limitations. Therefore, the direct application of altimetry data to reservoir management is often preceded by validation of satellite altimetry data with reliable ground-measured data. Kainji reservoir in Nigeria was selected for this study due to its remote geographical location, hydrological behavior, operational requirements, and morphometry. Validation of Kainji reservoir altimetric levels would highlight the applicability of the technology for monitoring one of Africa’s largest reservoirs with a surface area of 1270 km2. We performed and improved the validation exercise by separating each lake level dataset into two separate seasons: dry and wet, to investigate the effect of different seasons on the relationship between ground-measured and satellite-measured data sets. Lake level data from Topex/Poseidon and ERS/ENVISAT satellite altimeters were compared with gage data from 1992 to 2002. The results suggested a significantly higher relationship between gage and satellite data for the wet season (R2=0.93) than for the dry season (R2=0.77). For interannual validation, the trend was the same for both satellite altimeters but the relationship was generally higher for the T/P altimeter (R2=0.95). Root-mean-square errors in water levels ranged between 0.50 to 0.83 m for both altimeters and seasons, agreeing with values expected for lakes of identical physical characteristics. Key words: Satellite altimetry, remote sensing water, reservoir level variation, Kainji dam, African lakes.

Daily rhythms of native Brazilians in summer and winter

Access to electricity, granting relative independence of human activity on the dark phase of the day, has been pointed out as an important cause for the absence of seasonal changes in the daily rhythms of humans living in urban areas. Featuring a population of adult Guarani natives living without access to electricity, the present naturalistic study was designed to explore possible effects of different natural photoperiods and temperature on human circadian rhythms. We compared time series of wrist temperature (WT) and motor activity in winter and summer, respectively, of 24 individuals aged 18 to 80. Twenty-four-hour rhythms of WT showed lower amplitudes and higher mean levels in summer, with no significant seasonal differences in acrophase. In contrast, rest-activity (RA) rhythms exhibited a significantly later rest on- and offset in summer, but no seasonal changes in duration, amplitude and mean level. We furthermore identified a phase advance of both the WT acrophase and rest onset with increasing age of the individuals. We concluded that in our study the effect of different seasons was reflected in the amplitude and mean level of the WT rhythm, as well the onset of nighttime rest, which was delayed in summer.

Effect of Season and Gender on the Physical and Chemical Composition of Black Wildebeest (Connochaetus gnou) Meat

The aim of this study was to investigate the effect of different seasons and gender on the physical and chemical composition of black wildebeest (Connochaetus gnou) meat. Twenty-six black wildebeest were harvested at Maria Moroka Nature Reserve, in the Free State Province, South Africa, during winter, spring and autumn. Mean body and carcass weight did not differ (P > 0.05) between either seasons or genders. However, dressing percentage was higher (P 0.05) between seasons, whereas differences (P < 0.05) in temperature of carcasses measured 24 h post-mortem could be ascribed to differences in ambient temperature. Meat from animals harvested during spring (5.52 and 39.63%) had a higher (P ≤ 0.05) drip and cooking loss compared to those harvested in winter (2.27 and 34.59%) and autumn (3.61 and 33.88%). Meat was the most (P < 0.05) tender during autumn (2.27 kg/1.27 cm dia...

Calculation of Channel Capacity Considering the Effect of Different Seasons for Higher Altitude Platform System

This paper presents effect of the weather impairments on a high altitude platform (HAP) broadband wireless communication system. It is shown that attenuation due to oxygen, water vapor, fog, cloud, and rain has significant effect on a radio link which is operating in a millimeter frequency range. Channel capacity is calculated for different seasons using Shannon's channel capacity theorem. The location of HAP is taken to be Delhi (India). Further, it is considered that a user and the HAP platform are stationary.

RETRACTED: Contrasting pattern of methanotrophs in dry tropical forest soils: Effect of soil nitrogen, carbon and moisture

Population dynamics of methane-oxidizing bacteria (MOB) was measured for 2 consecutive years for four forest and one savanna sites in seasonally dry tropical regions of India. The soils were nutrient-poor and well drained. These sites differed in vegetational cover and physico-chemical features of soils. There were significant differences in MOB population size during the 2 years (mean 0.40 and 0.48 x 10(5) cells g(-1) dry soil), and at different sites (mean 0.38-0.59 x 10(5) cells g(-1) dry soil). The mean population size of MOB was higher (P<0.05) in dry seasons than in the rainy season at all the sites. There was a significant season and site interaction, indicating that the effect of different seasons differed across the sites. There was a positive relation between soil moisture and MOB population size during summer (the driest period) and a negative relation during the rest of the year. The number of MOB was consistently higher for the Kotwa hill base site than rest of the sites having higher soil organic C and total N. The results suggested that in seasonally dry tropical forests the moisture, C and N status of the soil regulates the population size of MOB (methanotrophs) in the long term.

Effects of timing of prescribed fire on the demography of an invasive plant, spotted knapweed Centaurea maculosa

Summary Prescribed burning is a key tool used in prairie and savanna restoration projects. The timing and frequency of prescribed fires are important variables to consider because they can differentially affect the survival of individual plant species, including noxious exotic species. We used annual censuses and population matrix analysis to evaluate the demographic consequences of burning on populations of the invasive species spotted knapweed Centaurea maculosa in a Michigan, USA, prairie restoration experiment. We compared spring, summer and autumn burns at two frequencies: annually (2000–03) and in alternate years (2001, 2003). We examined the effects of different seasons and frequencies of prescribed fire on the survival, growth and reproduction of C. maculosa populations, and used life‐table response experiments and elasticity analyses to determine how season of fire affects population growth rates. We found that annual summer burning was the only treatment that significantly reduced overall population growth rates. The life‐table response experiment analysis indicated which life stages contributed the most to changes in population growth rates under the different treatments. The summer burn treatments reduced population growth by reducing reproduction. The different burn treatments altered the elasticity structure of populations, but in general reproduction of adults as well as survival of non‐reproductive adults and juveniles remained important in all treatments. This indicates that future attempts to control C. maculosa should focus on combinations of treatments targeting these life stages. Synthesis and applications. Management decisions regarding prescribed burning in grassland restoration projects should consider the responses of individual species already present in the system. In particular, it is important to consider the effects of burning on noxious invasive species that may or may not have different life histories and responses to fire compared with native species. Population matrix modelling provides a more complete picture of the effects of management on population responses compared with other measures based only on community composition and relative abundance. Depending on the goals of a restoration, non‐traditional management options, such as summer burning in mid‐west USA prairies, may be effective management tools for the control of invasive species.

Riparian vegetation response to different intensities and seasons of grazing

Sustainable management of riparian ecosystems depends on our understanding of these complex systems. Thus far, the scientific literature has not adequately addressed the effects of livestock grazing on riparian areas in the American southwest. Most available information is observational, anecdotal, based on unreplicated experiments, or compares heavily grazed areas to areas from which livestock have been completely excluded. This study, in the Black Range of western New Mexico, compared effects of different seasons of use (cool season, warm season, and dormant season) and grazing intensities (light, moderate, and none) of cattle on young narrowleaf cottonwood (Populus angustifolia James) populations, and herbaceous vegetation in 2 adjacent southwestern riparian areas. Cottonwoods in lightly grazed and moderately grazed plots received significantly greater use than cottonwoods in ungrazed plots which experienced negligible grazing pressure. Increased grazing pressure did not have significant impacts on cottonwood populations. Effects of season of use were significant on both herbaceous species richness and diversity. We conclude that no single riparian area management approach is best in all situations, but the grazing treatments used in this study appear to have been successful at maintaining riparian communities.

Riparian vegetation response to different intensities and seasons of grazing

Sustainable management of riparian ecosystems depends on our understanding of these complex systems. Thus far, the scientific literature has not adequately addressed the effects of livestock grazing on riparian areas in the American southwest. Most available information is observational, anecdotal, based on unreplicated experiments, or compares heavily grazed areas to areas from which livestock have been completely excluded. This study, in the Black Range of western New Mexico, compared effects of different seasons of use (cool season, warm season, and dormant season) and grazing intensities (light, moderate, and none) of cattle on young narrowleaf cottonwood (Populus angustifolia James) populations, and herbaceous vegetation in 2 adjacent southwestern riparian areas. Cottonwoods in lightly grazed and moderately grazed plots received significantly greater use than cottonwoods in ungrazed plots which experienced negligible grazing pressure. Increased grazing pressure did not have significant impacts on cottonwood populations. Effects of season of use were significant on both herbaceous species richness and diversity. We conclude that no single riparian area management approach is best in all situations, but the grazing treatments used in this study appear to have been successful at maintaining riparian communities.

Riparian vegetation response to different intensities and seasons of grazing

Sustainable management of riparian ecosystems depends on our understanding of these complex systems. Thus far, the scientific literature has not adequately addressed the effects of livestock grazing on riparian areas in the American southwest. Most available information is observational, anecdotal, based on unreplicated experiments, or compares heavily grazed areas to areas from which livestock have been completely excluded. This study, in the Black Range of western New Mexico, compared effects of different seasons of use (cool season, warm season, and dormant season) and grazing intensities (light, moderate, and none) of cattle on young narrowleaf cottonwood (Populus angustifolia James) populations, and herbaceous vegetation in 2 adjacent southwestern riparian areas. Cottonwoods in lightly grazed and moderately grazed plots received significantly greater use than cottonwoods in ungrazed plots which experienced negligible grazing pressure. Increased grazing pressure did not have significant impacts on cottonwood populations. Effects of season of use were significant on both herbaceous species richness and diversity. We conclude that no single riparian area management approach is best in all situations, but the grazing treatments used in this study appear to have been successful at maintaining riparian communities.

Effect of Different Seasons on Cross-Bred Cow Milk Composition and Paneer Yield in Sub-Himalayan Region

The study was designed to evaluate the seasonal influences on cross-bred cow milk composition and paneer yield in Dhauladhar mountain range of sub-himalayan region. Fifty samples from each season were collected from a herd of Jersey×Red Sindhi ×Local cross-bred cows during summer (April-June), rainy (July-September) and winter (November-February) and analyzed for fat, total solids (TS) and solids not fat (SNF). Paneer was prepared by curdling milk at 85±2°C with 2.5 per cent citric acid solution. Overall mean for fat, TS and SNF content of milk and paneer yield were 4.528, 13.310, 8.754 and 15.218 per cent respectively. SNF and TS content varied among seasons being highest in winter (8.983% and 13.639%) followed by summer (8.835% and 13.403%) and lowest in rainy season (8.444% and 12.888%). Paneer yield was lowest (14.792%) in rainy season and highest (15.501%) in winter season. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 4 : 528-530)

Effect of Different Seasons on the Performance of Grey Giant Rabbits under Sub-Temperate Himalayan Conditions

An experiment was conducted on 190 progeny (winter -74; summer -59; rainy -57) of 12 Grey Giant rabbits (10 female +2 males), to assess the effect of different seasons in a year, on their reproductive, growth and productive performances along with feed efficiency, under sub-temperate Himalayan conditions. The daily meteorological attributes recorded during winter (October to March), summer (April to June) and rainy (July to September) seasons, and analysed were minimum and maximum temperature, relative humidity and rainfall. Various biological parameters recorded were doe weights at mating and kindling, litter size at birth, litter weight at birth, kit mortality, litter size at weaning, litter weight at weaning, weekly body weight up to 98 d and weaner mortality. Individual weight gains, dressing percentages, meat weights, liver weights, raw-pelt weights, processed pelt weights and processed pelt areas at slaughter on d 84 and 98, respectively were also recorded. The feed and fodder compositions and their nutritive values during different seasons were also analysed. Average ambient temperature during winter, summer and rainy seasons were 13.2±2.8, 22.4±3.7 and 24.8±2.3°C, respectively. The average relative humidity and total rainfall for winter, summer and rainy seasons were 68.9±1.5% and 48±26.6mm, 66.3±4.8% and 125.6±56.8 mm, and 77.3±1.3% and 116.3±90.4 mm, respectively. The weight of doe at mating and kindling, litter size at birth, litter weight at birth and litter size at weaning were comparatively higher whereas litter weight at weaning was significantly (p<0.05) higher during winter as compared to summer and rainy seasons. The kit mortality was significantly (p<0.05) higher during winter while the weaner mortality was significantly (p<0.05) higher during rainy season. At 84 d, the live weight per doe, slaughter weight, dressing percentage and liver weight were significantly (p<0.05) higher during winter than summer and rainy. Similarly, the gain in weight and meat weight at 84 and 98 d were significantly (p<0.05) higher during winter. The weight of raw pelt and processed pelt were recorded significantly (p<0.05) higher during winter while no difference in the area of processed pelts during different seasons could be observed. No difference in the biological performance could be observed between sexes in any of the seasons. Roughage analysis revealed comparatively higher crude protein percent and lower crude fibre percent during summer and rainy seasons than in winter. The roughage dry matter intake was comparatively higher during summer and rainy seasons vis-a-vis constant amount of concentrate supplied during all the three seasons. The digestibilities of dry matter was significantly (p<0.05) lower, whereas that of crude fiber, acid detergent fibre and cellulose were negative during winter. Interestingly, the feed:gain was exceedingly well during winter than in other seasons and it is concluded that it was the best season for production of rabbits under sub-temperate Himalayan conditions. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 6 : 812-820)

Effect of soil nitrogen, carbon and moisture on methane uptake by dry tropical forest soils

Methane uptake was measured for two consecutive years for four forest and one savanna sites in a seasonally dry tropical region of India. The soils were nutrient-poor and well drained. These sites differed in vegetational cover and physico-chemical features of the soil. There were significant differences in CH4 consumption rates during the two years (mean 0.43 and 0.49 mg m-2 h-1), and at different sites (mean 0.36 to 0.57 mg m-2 h-1). The mean uptake rate was higher (P < 0.05) in dry seasons than in the rainy season at all the sites. There was a significant season and site interaction, indicating that the effect of different seasons differed across the sites. There was a positive relation between soil moisture and CH4 uptake rates during summer (the driest period) and a negative relation during the rest of the year. The results suggested that seasonally dry tropical forests are a strong sink for CH4, and C and N status of soils regulates the strength of the sink in the long term.

Economic impact analysis of load forecasting

This paper examines the economic impact of inaccurate load forecasts. Monte Carlo simulations are used to study the effect of different load forecasting accuracy. Investigations into the effect of improving the daily peak load forecasts, effect of different seasons of the year and effect of utilization factors are also presented.

Effect of different seasons on concentration of plasma luteinizing hormone and seminal quality vis-�-vis freezability of buffalo bulls (Bubalus bubalis)

Seasonal variations in semen quality, freezability and plasma luteinizing hormone (LH) levels were studied between summer and spring. Semen volume, density and initial sperm motility did not differ significantly between different seasons. Plasma LH decreased between summer and spring but the differences were, however, not significant. Pre-freezing motility did not differ significantly but post-freezing motility varied significantly (P less than 0.01) between seasons. Post-freezing motility was lowest during summer and highest during winter. It can be concluded that summer spermatozoa may be fragile and cannot withstand freezing stress. To increase reproductive efficiency in buffalo during summer, semen should be frozen during winter and spring and used during hot weather conditions. Seasonal variations in plasma LH levels were insignificant.

Performance of S1 Progenies from a Sorghum Random‐Mating Population Sampled in Different Years1

Samples of 200 S1's each taken from the same random‐mating sorghum [Sorghum bicolor (L.) Moench] population in 3 different years were evaluated as S1 progenies for agronomic and grain protein traits for 2 years in a blocks‐in‐repllcatlons design to determine the effect of different seasons and different personnel on sampling. Means, family and family ✕ year variances, heritabilities, predicted gains from selection, and genetic correlations were determined from the three samples. The results were related to expected plant breeding progress, particularly recurrent selection. Significant differences were obtained among the three sample means for each of seven traits, except tillerlng. The ranges of differences between sample means were small, however, and of little plant breeding importance. Family variance components differed little among the three samples for all traits except hcight and tillering. These two traits also had relatively large family ― year variance components compared to their respective family variance components. Variability in height was attributed to drought that suppressed height during years of sampling but which was expressed during more favorable years of evaluation. Genetic correlations among the same pair of traits tended to be similar in the three samples, but there were four nonhomogeneous sets. Broad‐sense heritabilities, calculated from plot means, and predicted gains from selection for each trait were similar in each of the three samples and indicated that S1's sampled any year from the same base population could be used for family recurrent sclectlon with expectation of essentially the same progress.