End Of Dry Period Research Articles

Methane and carbon dioxide emissions from different ecosystems at the end of dry period in South Vietnam

The carbon cycle includes important fluxes of methane (CH4) and carbon dioxide (CO2) between the ecosystem and the atmosphere. The fluxes may acquire either positive (release) or negative values (consumption). We calculated these fluxes based on short-campaign in situ chamber measurements from four ecosystems of South Vietnam: intact mountain rain forest, rice field, Melaleuca forest and mangroves (different sites with Avicennia or Rhizophora and a typhoon-disturbed gap). Soil measurements were supplemented by chamber measurements of gas fluxes from the tree stems. Measuring CH4 and CO2 together facilitates the assessment of the ratio between these two gases in connection with current conditions and specificity of individual ecosystems. The highest fluxes of CH4 were recorded in the Melaleuca forest, being within the range from 356.7 to 784.2 mg CH4–C m−2 day−1 accompanied by higher fluxes of CH4 release from Melaleuca tree stems (8.0–262.1 mg CH4–C m−2 day−1). Significant negative soil fluxes of CH4 were recorded in the mountain rain forest, within the range from − 0.3 to − 0.8 mg CH4–C m−2 day−1. Fluxes of CO2 indicate prevailing aerobic activity in the soils of the ecosystems investigated. Quite a large variability of CO2 fluxes was recorded in the soil of the Avicennia mangroves. The in situ measurements of different ecosystems are fundamental for follow-up measurements at different levels such as aerial and satellite gas fluxes observations.

CLIMATIC INFLUENCES ON LEAF FALL SEASONALITY IN THE ATLANTIC FOREST (SERRA DOS ÓRGÃOS NATIONAL PARK – RJ- BRAZIL)

We compare temporal variations in leaf fall among three sites of evergreen Atlantic Forest and analyze how climatic variables influence it. Sites were located at Serra dos Orgaos National Park at different altitudes. Litter was collected monthly, from September 1997 to September 2005. Leaves were separated from other litter elements, oven-dried and weighted. Differences in leaf fall mass among grids and how they correlated with temporal variations were analyzed. Climatic variables were obtained from a nearby station and deviations from climatological normals were analyzed. We grouped climatic variables using Principal Component Analyses (PCA) and the highest scores of the two main factors were selected to construct regression models for different time lags. Leaf fall represented 50.5-70 percent of the total litter fall and mean leaf fall differed significantly among grids. However, leaf fall seasonality in the three areas were correlated. Leaf fall increased at the end of dry periods, when temperature and precipitation started to increase. Climatic variables were classified into two groups: seasonal and anomaly. Models constructed with lag variation from 0 and 6 months show that leaf fall was best explained by an anomaly in the maximum mean temperature, with lag 0, and by precipitation, with a six-month lag. We conclude that plant species respond immediately to drastic deviations from climatic factors, while regular climatic conditions are responsible for the seasonality of leaf fall, most likely as a late response to water shortage at the end of the dry season. .

Use of Herbal Preparations in Dry Cow Management against Sub Clinical Mastitis - An Alternative Approach

Sub clinical mastitis is the most prevalent disease in the dairy cows due to managemental problem which causes huge economic losses to the farmers. Animals are susceptible to new intramammary infections both at the beginning and end of dry period. Dry cow management is an important tool to control sub clinical mastitis. Managing dry cows by use of an antibiotics causes a detrimental effect on both human and animal health. So, at present herbs are gaining importance for treating the cow against mastitis. Use of herbal preparations by intramammary route, teat sealants either internally or externally or combination therapy can help in the reduction of new intramammary infections as well as cure existing infection from the udder of cow. Hence, use of herbal preparations to control sub clinical mastitis in dairy cow can be an innovative and alternative approach in cattle health care practices.

Drying and Rainfall Shape the Structure and Functioning of Nitrifying Microbial Communities in Riverbed Sediments.

Non-flow periods in fluvial ecosystems are a global phenomenon. Streambed drying and rewetting by sporadic rainfalls could drive considerable changes in the microbial communities that govern stream nitrogen (N) availability at different temporal and spatial scales. We performed a microcosm-based experiment to investigate how dry period duration (DPD) (0, 3, 6, and 9 weeks) and magnitude of sporadic rewetting by rainfall (0, 4, and 21 mm applied at end of dry period) affected stocks of N in riverbed sediments, ammonia-oxidizing bacteria (AOB) and archaea (AOA) and rates of ammonia oxidation (AO), and emissions of nitrous oxide (N2O) to the atmosphere. While ammonium (NH4+) pool size decreased, nitrate (NO3−) pool size increased in sediments with progressive drying. Concomitantly, the relative and absolute abundance of AOB and, especially, AOA (assessed by 16S rRNA gene sequencing and quantitative PCR of ammonia monooxygenase genes) increased, despite an apparent decrease of AO rates with drying. An increase of N2O emissions occurred at early drying before substantially dropping until the end of the experiment. Strong rainfall of 21 mm increased AO rates and NH4+ in sediments, whereas modest rainfall of 4 mm triggered a notable increase of N2O fluxes. Interestingly, such responses were detected only after 6 and 9 weeks of drying. Our results demonstrate that progressive drying drives considerable changes in in-stream N cycling and the associated nitrifying microbial communities, and that sporadic rainfall can modulate these effects. Our findings are particularly relevant for N processing and transport in rivers with alternating dry and wet phases – a hydrological scenario expected to become more important in the future.

Analysis of the reproductive stage and ovarian histomorphometry of Dermanura cinerea (Chiroptera: Phyllostomidae) in an Atlantic Forest fragment of Pernambuco, northeastern Brazil

ABSTRACT: This study aimed to analyze the reproductive stage, histology and morphometry of the ovary of Dermanura cinerea in an Atlantic Forest fragments in the Biological Reserve of Saltinho, Pernambuco, Brazil. Adult females were captured monthly by mist net, during two consecutive nights from June/2014 to November/2015. The meteorological data were provided by the National Institute of Meteorology and grouped together with the reproductive data, in six periods: period I (June to August/2014), period II (September to November/2014), period III (December/2014 to February/2015), period IV (March to May/2015), period V (June to August/2015) and period VI (September to November/2015). The females were classified according to their reproductive stages in: Inactive, pregnant, lactating and postlactating. Among the 25 females caught, 10 inactive females were selected for the histomorphometric analysis of the ovaries and then they were euthanized. After that, the specimens had their ovaries removed, fixed, processed and included in Paraplast. The organs were cut and stained by Hematoxylin - Eosin and the histological slides produced were submitted to the appropriate optical microscope analysis. Each type of ovarian follicle was estimated according to the histological characteristics evidenced for other mammals. In the morphometric analysis, it was considered: The area of the ovary (measured in square millimeter), Quantification of different types of ovarian follicles (unilaminar and multilaminar primary follicles, antral and matures) and corpus luteum, as well as the area of each by those different follicles (measured in square micrometer) The results indicated that 16 females were inactive, 5 were lactating, 4 were pregnant and no post-lactating. The histological analysis revealed that the ovaries of D. cinerea exhibit characteristics, structures and cellular types similar to other mammals. The morphometric data of the study area were statistically evaluated using the Student’s t-test. Therefore, ovarian histomorphometric analysis are very important to infer with greater certainty about the reproduction of a species. Thus, it was observed that females of D. cinerea exhibit two reproductive peaks, that is, they can give birth either at the end of dry periods or from the beginning to the middle of the rainy season. The main feature observed in the ovary of this species, found in the Atlantic Forest area of the state of Pernambuco, is the preparation of the ovarian cortex to ovulate in months of high rainfall throughout the year. Therefore, this species tries to adjust its reproductive period with the variations of the environmental conditions, so that the reproduction might occur during the period more favorable for the maintenance of their offspring.

Long-term monitoring and evaluating biological activity of in situ anaerobic reductive dechlorination at a highly recharged and TCE-contaminated aquifer

AbstractFew studies have evaluated how rainfall recharges affect biological dechlorination of trichloroethene (TCE). In this study, a sequence of three well-to-well tests (Phases I, II, and III) were performed for 100 d to investigate the variation of biological dechlorination of TCE at a highly recharged and TCE-contaminated aquifer. Test solutions containing different nutrients were delivered into the aquifer through a nitrogen gas spray. In Phase I, where only formate was supplied, the degradation of TCE to cis-dichloroethene (cis-DCE) was negligible. However, when sulfate as well as formate was introduced during Phase II, the reductive dechlorination of TCE occurred. During Phase III, fumarate was also provided as an alternative electron donor. High cis-DCE production rates were observed with complete degradation of formate and sulfate at 65th day monitoring, the end of dry period in Phase III. Since then, there were heavy rainfalls that accounted for approximately 36% of total annual precipitation in...

Controlling Subclinical Mastitis by Antibiotic Application during Dry Period of Dairy Cow

Prevention of mastitis is essential, as one of the efforts to control disease in dairy cow. Dry period has implications to understand the mastitis and its control strategies. The udder is very susceptible to be infected both at the beginning and towards the end of dry period. This is linked to physiological changes in udder. Treatment with antibiotics during the dry period can reduce new infection about 82% and has several advantages. The success rate of subclinical mastitis treatment is much higher (80-90%) compared to the treatment during lactation (30-40%); the doses of antibiotic can be higher and safer, due to its retention time in udder becomes longer; the risk of antibiotic contamination in milk can be avoided because the udder is not milked. Antibiotic application during dry period is the best way to treat subclinical and chronic mastitis. Treatment during dry period is a specific mastitis control for intramammary infection to avoid economic losses. Key words: Antibiotic, dry period, subclinical mastitis

Chuva de sementes em uma floresta de galeria no Parque do Bacaba, em Nova Xavantina, Mato Grosso, Brasil

O estudo foi realizado na floresta de galeria do Córrego Bacaba, no Parque Municipal do Bacaba (14º43'12,2S e 52º21'36,7"W), em Nova Xavantina, MT. A dispersão de sementes foi analisada e comparada entre três porções da floresta (alto, meio e baixo), distantes cerca de 200 m entre si, em um gradiente topográfico. Foram distribuídos, aleatoriamente, 20 coletores circulares de 0,3 m² em cada porção de floresta, sendo as coletas de sementes realizadas quinzenalmente, entre junho de 2007 e maio de 2008. O material foi submetido à secagem em estufa até peso constante e as sementes, separadas em duas categorias, baseando-se na presença de estruturas de voo (V) e na ausência dessas estruturas (NV). O número de morfoespécies e de sementes e a biomassa foram comparados entre as porções de floresta e entre os períodos seco e chuvoso. Coletaram-se 20.965 sementes em 24 quinzenas, sendo 777 do tipo V e 20.188 do tipo NV. Na porção do alto ocorreram 52 morfoespécies de sementes, no meio 55 e no baixo 49. A diversidade de morfoespécies de sementes foi inferior à diversidade de espécies de plantas lenhosas na mesma área. Considerando o padrão sazonal de dispersão de sementes, tanto para as V (número, morfoespécies e biomassa) quanto para as NV (biomassa), recomenda-se um controle no fluxo de visitantes no Parque do Bacaba, especialmente nos meses de pico de dispersão de sementes, no final do período seco e início do chuvoso (setembro-dezembro). Medidas de excursionismo de mínimo impacto poderão trazer benefícios para o estabelecimento de sementes e plântulas e garantir a sustentabilidade da floresta.

Growth and photosynthetic activity of micropropagated strawberry plants inoculated with endomycorrhizal fungi (AMF) and growing under drought stress

The plants produced by in vitro methods are free of any microflora contrary to natural systems where plants are colonized by symbiotic fungi. The present paper reports the experiments carried out to evaluate the role of arbuscular endomycorrhizal fungi in development of micropropagated strawberries and their photosynthetic activity (measured by chlorophyll fluorescence) under drought conditions. Mycorrhization strongly affected growth and tolerance to water deficiency of the plants cultivated in greenhouse. Wilting of not-mycorrhized plants was accompanied by drastic increase of Fo and Tfm and decrease of Fm. At the same time, the value of these parameters for mycorrhized plants did not change. Drastic decrease in the value of parameters Fv/Fm, Fv/Fo and Fo/Fm for plants without AMF appeared at the end of dry period. Rise of Fs and decrease Rfd was noted only for not-mycorrhized plants. The plants colonized by fungi, fully recovered their photosynthetic activity when watering was restored.

Effects of age and state of incisor dentition on the chemical composition of the skeleton of sheep grazing hill pastures

SUMMARYThe chemical composition of the skeleton, mandible and 4th lumbar vertebra of 59 Scottish Blackface female sheep from a ‘broken mouth’ farm was determined. There were 27 6½-year-old sheep (11 with sound mouths, 16 with broken mouths), 16 5½-year old sheep (with loose incisor teeth which at the outset of the experiment were clipped to gum level) and 16 2½-year-old sheep. Sheep from each group were slaughtered at the beginning of pregnancy and in mid-lactation and from those with broken mouths and from the 5½-year-old and 2½-year-old groups at the end of the subsequent dry period. The sheep grazed hill pastures and received an energy supplement during late pregnancy and early lactation.There were no differences between the 6½-year-old sheep with broken mouths and those with sound mouths in total skeletal mineral content or in the density of ash (ash: volume ratio) or organic matrix (organic matter: volume ratio) in the mandible and lumbar vertebra at the beginning of pregnancy or in mid-lactation. Nor were there differences in the density of ash or organic matrix between any groups, although the skeletons of the 6½-year-old sheep were larger. The lumbar vertebra, which is rich in cancellous bone, had a lower ash and organic matrix density in the 5½- and 2½-year-old sheep. It is suggested that bone mineralization may proceed slowly on such hill pastures.The rates of repletion of the skeleton during the dry period, 0·35, 0·47 and 0·66 g Ca/day, respectively, in the 6½-year-old sheep with broken mouths, 5½-year-old and 2½-year-old sheep were much slower than rates given in the literature for sheep under controlled conditions. It is suggested that factors other than the major nutrients, protein, Ca and P, may be limiting repletion of the skeleton.Recovery of the ash density of the vertebra was not complete at the end of the dry period. This was especially so in the sheep with broken mouths and resulted mainly from a failure to replace bone organic matrix.The implications for the development of broken mouth of cyclical changes in the density of cancellous bone and of evidence that the ability to maintain and to remineralize the skeleton deteriorates with increasing age, are discussed.