Cycling of aluminum and nutrients in litterfall of a red spruce (Picearubens Sarg.) stand in Maine

1989 ◽  
Vol 19 (1) ◽  
pp. 18-23 ◽  
Author(s):  
Lindsey E. Rustad ◽  
Christopher S. Cronan
Keyword(s):  
Elemental Composition ◽  
Seasonal Variations ◽  
Forest Floor ◽  
Red Spruce ◽  
Seasonal Differences ◽  
Annual Basis ◽  
Biological Cycling

Annual and seasonal variations in the concentration and total return of Al, Fe, Mn, Ca, Mg, K, Na, C, N, and P in litterfall were studied for a period of 2 years in a mature red spruce stand in central Maine. Seasonal differences in elemental composition were large. The greatest change occurred in the autumn, when the concentrations of Al, Fe, N, P, and K declined, while Ca and Mg concentrations peaked. On an annual basis, litterfall contributed 0.5, 0.5, 1.1, 13.8, 2.1, 5.3, 0.2, 17.6, and 1.3 kg •ha−1•year−1 of Al, Fe, Mn, Ca, Mg, K, Na, N, and P, respectively, to the forest floor. The input of Al in litterfall was 10 times as great as that in net canopy throughfall, indicating that the biological cycling of Al in litterfall was an important source of Al to the forest floor at this site.

Spatial and seasonal variations of elemental composition in Mt. Everest (Qomolangma) snow/firn

2007 ◽  
Vol 41 (34) ◽  
pp. 7208-7218 ◽  
Author(s):  
Shichang Kang ◽  
Qianggong Zhang ◽  
Susan Kaspari ◽  
Dahe Qin ◽  
Zhiyuan Cong ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Seasonal Variations

Variations in the fecundity of strongylid worms of the horse

Parasitology ◽  
1971 ◽  
Vol 63 (2) ◽  
pp. 289-298 ◽  
Author(s):  
C. P. Ogbourne
Keyword(s):  
Seasonal Variations ◽  
Adult Stage ◽  
Age Distribution ◽  
Horse Race ◽  
Seasonal Differences ◽  
Low Level ◽  
Infective Larvae ◽  
Laboratory Facilities ◽  
Strongylus Vulgaris ◽  
Faecal Egg Counts

SUMMARYA large proportion of Strongylus vulgaris, S. edentatus and Trichonema nassatum collected from the gut lumen of slaughtered horses during the winter did not contain eggs. The proportion of Trichonema catinatum without eggs declined to a low level during the winter and rose to relatively high levels during the summer, It has been concluded that worms without eggs are newly matured individuals and that seasonal variations in fecundity reflect similar fluctuations in the age distribution of the adult populations. These fluctuations are related to seasonal differences in the numbers of infective larvae ingested and to the length of parasitic development.Most Strongylus vulgaris, S. edentatus and Trichonema nassatum reach the adult stage during the winter and it has been suggested that an increase in worm numbers during this period is responsible for a rise in the faecal egg counts of horses in the spring. The observations on T. catinatum indicate that the level is maintained by the arrival of new individuals during the summer.I wish to thank Dr H. D. Crofton for his constant advice and encouragement during this work and Professor H. E. Hinton, F.R.S., for the provision of laboratory facilities. I am indebted to Mr L. J. Potter for allowing me to collect the parasites from his slaughterhouse at Bishop Sutton, near Bristol. This work was carried out during a research studentship funded by the Horse Race Betting Levy Board.

Seasonal variations of Italian Mediterranean Buffalo (Bubalus bubalis) Mozzarella cheese quality

2016 ◽  
Vol 83 (4) ◽  
pp. 476-478 ◽  
Author(s):  
David Ranucci ◽  
Angela Garofalo ◽  
Eleonora Urbani ◽  
Stefano Rea ◽  
Anna Rita Loschi ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Moisture Content ◽  
Milk Production ◽  
Seasonal Variations ◽  
Water Buffalo ◽  
Bubalus Bubalis ◽  
Quality Traits ◽  
Mozzarella Cheese ◽  
Seasonal Differences ◽  
Consumer Evaluation

Water buffalo Mozzarella cheese is more appreciated in the summer, but milk production is higher during wintertime, as water buffalo are seasonally polyoestrous animals. The aim of the study reported in this Research Communication was to evaluate the effect of the reversing of the calving period on Mozzarella cheese composition and quality traits. Ten batches of Mozzarella cheeses produced during the summer and winter periods were analysed for pH, colour, chemical composition. Seasonal differences were observed for cheese yield (26·66% in winter and 25·61% in summer), moisture content (66·54% in winter and 61·18% in summer) colour and consumer evaluation.

Seasonal variation in suicide rates by cause and sex

1986 ◽  
Vol 18 (4) ◽  
pp. 471-478 ◽  
Author(s):  
S. Araki ◽  
H. Aono ◽  
K. Murata ◽  
I. Shikata ◽  
Y. Mitsukuni
Keyword(s):  
Sex Differences ◽  
Seasonal Variation ◽  
Psychosocial Factors ◽  
Seasonal Variations ◽  
Profile Analysis ◽  
Age Difference ◽  
Seasonal Differences ◽  
Suicide Rates ◽  
Car Exhaust ◽  
Males And Females

SummarySeasonal variations in cause- and age-specific suicide rates in males and females were analysed in Osaka, Japan, for the years 1974–83, using profile analysis. Significant cause differences were found in males: (1) the rate for poisoning by domestic, car-exhaust or other gases was high in winter and spring and low in summer and autumn; (2) the rate for hanging, strangulation and suffocation was low in winter; (3) the rate for a variety of violent methods (chemicals, firearms, drowning, etc.) was high in summer. Similarly, there were sex differences in the variation for causes (2) and (3) and for ages 40–54. No significant age difference was found in either sex. Seasonal differences in the ease of suicidal methods and sex- and season-specific psychosocial factors were thought to be the major determinant of the seasonal variation.

scholarly journals Impacts of the photo-driven post-depositional processing on snow nitrate and its isotopes at Summit, Greenland: a model-based study

2021 ◽  
Author(s):  
Zhuang Jiang ◽  
Becky Alexander ◽  
Joel Savarino ◽  
Joseph Erbland ◽  
Lei Geng
Keyword(s):  
Seasonal Variations ◽  
Accumulation Rate ◽  
Ice Core ◽  
Snow Accumulation ◽  
Photic Zone ◽  
Seasonal Differences ◽  
Formation Pathway ◽  
Column Model ◽  
Annual Scale ◽  
Δ15n Variability

Abstract. Atmospheric information embedded in ice-core nitrate is disturbed by post-depositional processing. Here we used a layered snow photochemical column model to explicitly investigate the effects of post-depositional processing on snow nitrate and its isotopes (δ15N and Δ17O) at Summit, Greenland where post-depositional processing was thought to be minimal due to the high snow accumulation rate. We found significant redistribution of nitrate in the upper snowpack through photolysis and up to 21 % of nitrate was lost and/or redistributed after deposition. The model indicates post-depositional processing can reproduce much of the observed δ15N seasonality, while seasonal variations in δ15N of primary nitrate is needed to reconcile the timing of the lowest seasonal δ15N. In contrast, post-depositional processing can only induce less than 2.1 ‰ seasonal Δ17O change, much smaller than the observation (9 ‰) that is ultimately determined by seasonal differences in nitrate formation pathway. Despite significant redistribution of snow nitrate in the photic zone and the associated effects on δ15N seasonality, the net annual effect of post-depositional processing is relatively small, suggesting preservation of atmospheric signals at the annual scale under the present Summit conditions. But at longer timescales when large changes in snow accumulation rate occurs this post-depositional processing could become a major driver of the δ15N variability in ice core nitrate.

Seasonal Variability of Relationship between Main Ionospheric Characteristics and Solar/Geomagnetic Indices via Graphical Models of Conditional Independences

2021 ◽  
Author(s):  
Kateřina Podolská ◽  
Petra Koucká Knížová ◽  
Jaroslav Chum
Keyword(s):  
Time Series ◽  
Graphical Models ◽  
Seasonal Variations ◽  
Conditional Independence ◽  
Solar Cycles ◽  
Seasonal Differences ◽  
Ionospheric Response ◽  
Geomagnetic Indices ◽  
Before And After ◽  
Independence Graphs

<p>We investigated seasonal variations of relationships between main ionospheric characteristics and solar and geomagnetic indices in longitudinal perspective. We consider statistically significant differences in connections of ionospheric response to the F10.7cm, R, and Kp indices on seasonal time-scales during years 1975 – 2010 covering 21<sup>st</sup> – 23<sup>rd</sup> Solar Cycles. The periods of 21 days before and after Winter/Summer Solstices and Vernal/Autumnal Equinoces are considered as season. The foF2 time series in our analysis represent measurements of daily observational data which were obtained using mid-latitude (41.4°N – 54°N) ionosondes (Chilton, Slough RL052/SL051, Juliusruh/Rugen JR055, Boulder BC840). We used local time noon 5-hour foF2 averages. For the investigation, we used seasonal differences method of conditional independence graphs (CIG) models. Significant seasonal variations are visible during ascending and descending phases of Solar cycles.</p>

scholarly journals Decaying Logs as Germination Sites in Northern Hardwood Forests

1997 ◽  
Vol 14 (4) ◽  
pp. 178-182 ◽  
Author(s):  
Gregory G. McGee ◽  
John P. Birmingham
Keyword(s):  
New York ◽  
Forest Floor ◽  
Sugar Maple ◽  
Ground Cover ◽  
Tree Regeneration ◽  
Red Spruce ◽  
Yellow Birch ◽  
Northern Hardwood Forests ◽  
Northern Hardwood ◽  
Soil Scarification

Abstract While several authors have noted tree regeneration on decaying logs, the role that "nurse logs" play in maintaining tree diversity in eastern North American forests has remained unquantified. We sampled small seedling (≤ 5 cm high) densities of seven tree species on and directly adjacent to logs in two northern hardwood stands in the Adirondack mountains of New York. Polar ordination of 42 microsite plots revealed distinctly different small seedling communities on logs vs. forest floor. Yellow birch and red spruce densities were 24 times and 5 times greater on logs than forest floor, while those of sugar maple and striped maple were 8 times and 4 times greater on the forest floor. Maintaining a natural level (~5% ground cover) of well distributed logs can supplement site preparation techniques such as soil scarification to provide regeneration sites for yellow birch and red spruce, particularly in heavily stocked northern hardwood stands. North. J. Appl. For. 14(4):178-182.

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