Long-term variation in brown trout, Salmo trutta L., stocking success in a large lake: interplay between availability of suitable prey and size at release     

P. Hyvärinen  A. Huusko 《Ecology of Freshwater Fish》2005,14(4):303-310

Abstract –  Factors affecting long-term variation in brown trout, Salmo trutta L., stocking success were examined in a large lake, Lake Oulujärvi, in central Finland. Brown trout were stocked in spring (late May to early June) in 1974–1991 and in summer (late June to early July) in 1992–2001. The biomass of the vendace, Coregonus albula (L.), population (prey) at release time had the largest positive effect on stocking success within both periods: biomass of adult vendace in spring and both 0+ and adult vendace in summer. Increasing the size of stocked fish had a positive effect if the vendace available at release were only adults. The increasing trend of predator-catch-per-unit-effort (CPUE) [combined CPUE of northern pike Esox lucius L., burbot Lota lota (L.), and pike-perch Stizostedion lucioperca (L.)] through the study period and its negative effect on trout stocking success suggested an increasing effect of predation within the entire time series.  相似文献   

Effects of low and high calcium intake prepartum on calcium mobilization rate around parturition in dairy cows     

A E van de Braak  A T van 't Klooster  A Malestein  J A Faber 《The Veterinary quarterly》1986,8(1):12-23

Forty-one dairy cows were fed a low (LCa-13 g/d) and a high (HCa-83.5 g/d) calcium ration in the 8 weeks prior to parturition and the effect on the Ca mobilization rate around parturition was studied. Plasma Ca values were stable in the LCa group around parturition. In the older cows of the HCa group a very slight decrease in the mean plasma Ca was observed: 2.58 mmol/l at 12-36 h ante partum decreased to 2.38 mmol/l at parturition. Hypocalcaemia, which commonly occurs around parturition, did not occur in 40 of the cows. A subclinical hypocalcaemia (1.8 mmol/l) occurred in one cow (parity 10) from the HCa group. To assess the efficiency of Ca mobilization, a severe hypocalcaemia (1.0 mmol/l) with clinical signs was induced by means of Na2EDTA infusion (0.90 mmol/min), starting at 10 h post-partum. The older cows in the LCa group required more Na2EDTA than those in the HCa group. Higher urinary hydroxyproline excretion in the week before parturition in the LCa than in the HCa group suggested a higher bone turnover. Plasma PTH levels around parturition were not significantly different between the groups. The amount of colostrum milked out in the first 10 h post-partum did not influence Ca homeostasis around parturition. The results contradict those of many other experiments in which hypocalcaemia was observed in cows ingesting high levels of Ca. It is concluded that the restricted feed intake prepartum possibly had a favourable effect on Ca homeostasis.  相似文献   

Effects of pesticides and fertilizer on invertebrate populations of grass and wheat plots in Kent in relation to productivity and yield     

BRIGITTE S. LINZELL  D. S. MADGE 《Grass and Forage Science》1986,41(2):159-174

At a site in Kent, perennial ryegrass (Lolium perenne) variety S24 and Italian ryegrass (L. multiflorum) variety RVP, wheat varieties Armada and Norman, and the original mixed grass ley were grown in small plots during 1982–84. Two toxic pesticides (phorate and aldicarb) were applied to half the total number of plots three times each year to eliminate soil invertebrate populations. Fertilizer was also applied to most plots. The yields of the crops, grown with and without pesticide, and the effects of the fertilizer were compared. Grass herbage yield was measured on three occasions during the summers of 1983 and 1984. Wheat grain yields were also determined in 1983. During the first year significant differences were not apparent in grass dry matter yield between pesticide-treated and non-treated plots, but significant differences were found in the second year. The perennial ryegrass was more susceptible to pest damage than the Italian ryegrass or the grass ley. Grass yields varied between cuts and in relation to variety and pesticide treatment, yields tending to be greater in untreated plots. Fertilizer treatment greatly increased grass dry matter yields, particularly with the Italian ryegrass. The effects of pesticide treatment on both wheat varieties varied although some yield enhancement was evident. Invertebrate animal populations in pesticide and fertilizer-treated plots were also assessed in autumn 1982, spring and autumn 1983 and spring 1984. In contrast to pesticide treatment, fertilizer treatment had little effect on soil invertebrate populations. Nematode populations were reduced at each sampling occasion by the pesticide treatment. Slug populations were initially unaffected but were subsequently reduced. Leatherjackets, by far the most abundant pest in both grass and wheat plots, were markedly affected by pesticides on all sampling occasions. Generally, fewer soil-dwelling dipterous larvae were recovered in spring than in autumn. Stem-boring dipterous larvae were virtually absent.  相似文献   

Der Wert forstgeschichtlicher Forschung für die waldbauliche Wissenschaft und Praxis     

Dr. H. Frhr v. Pechmann 《European Journal of Forest Research》1938,60(14):433-443

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Bücheranzeigen     

Köftler  Dr. Rohmeder 《European Journal of Forest Research》1938,60(10):322-325

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Neuzeitliche Geräte und Arbeitsverfahren bei der Prüfung des Forstsaatgutes     

Regierungsforstrat Dr. habil. E. Rohmeder 《European Journal of Forest Research》1938,60(7):218-231

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The relations of Didymodus,or Diplodus     

Gill T 《Science (New York, N.Y.)》1884,3(62):429-430

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Qntgegnung auf die im Abgeordnetenhaufe zu Berlin in der Sisung vom 3. Decbr. 1867 gegen das hannover’fche Forftmefen gefallenen Aeuserungen. Qin Schreiben des Forftdirectors Burdhardt an bie Mitglieder bes Landtags aus der Brobing Hannober. 14 Seiten in 4°. Hannober. Q. Rümpler 1868. Breis 18 fr     

F. Baur 《European Journal of Forest Research》1868,12(1):113-120

Ohne Zusammenfassung  相似文献   

Ueber die praktifche Berwendung der vom Forftmeifter Alers zu Helmftädt erfundenen Flügelfäge     

Herzogl Braunfchm. 《European Journal of Forest Research》1869,13(1):301-304

Ohne Zusammenfassung  相似文献   

Ueber das Rlopfen und Beregnen der Eichenglanzrinbe; ein Beitrag zur Schälwaldftatif     

J. E. Reubranb 《European Journal of Forest Research》1870,14(1):137-139

Ohne Zusammenfassung  相似文献