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D Moulton-Barrett 《CMAJ》1985,132(3):279-280
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Hierochloë odorata (L.) Beauv. is restricted to the upper zone of salt marshes and rarely becomes dominant.
In the field, the species was found not to have strict N, P, K requirements. It grew in a range of pH values from 4.3 to 7.9, tolerated salinities up to 500 mhos and favoured soils with a moisture content from 25 to 30%. It grew in situations with a mean water table between 14 and 28 cm below the surface. Natural shading in the field was found to increase the heights of plants by about 30%. The application of fertilizer in the field increased the height of sweet grass but also stimulated the growth of associated species. In the greenhouse, the effects of different soils and fertilizers on plant growth were assessed. Inorganic fertilizer (12:18:12) application produced more leaves and tillers than organic fertilizer (6:2:0).
Sweet grass grows in a zone of reduced competition between the dune species and the salt-marsh species. Near the salt-marsh, the species may be limited by high salt concentration. The low levels of competition offered by cultivation and the responsiveness of the species to fertilizer suggests that cultivation of Hierochloë odorata may be successful. 相似文献
In the field, the species was found not to have strict N, P, K requirements. It grew in a range of pH values from 4.3 to 7.9, tolerated salinities up to 500 mhos and favoured soils with a moisture content from 25 to 30%. It grew in situations with a mean water table between 14 and 28 cm below the surface. Natural shading in the field was found to increase the heights of plants by about 30%. The application of fertilizer in the field increased the height of sweet grass but also stimulated the growth of associated species. In the greenhouse, the effects of different soils and fertilizers on plant growth were assessed. Inorganic fertilizer (12:18:12) application produced more leaves and tillers than organic fertilizer (6:2:0).
Sweet grass grows in a zone of reduced competition between the dune species and the salt-marsh species. Near the salt-marsh, the species may be limited by high salt concentration. The low levels of competition offered by cultivation and the responsiveness of the species to fertilizer suggests that cultivation of Hierochloë odorata may be successful. 相似文献
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Fifteen species of planktonic copepods are recorded from Bras d'Or Lakes, Nova Scotia, Canada. Pseudocalanus minutus, Oithona similis, Temora longiremis, and Tortanus discaudatus are the dominant species. The distribution of planktonic copepods in Bras d'Or Lakes as well as in the adjacent Gulf of St. Lawrence is discussed. 相似文献
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J. O. Godden 《CMAJ》1963,89(10):525-526
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R. E. Scheibling 《Helgoland Marine Research》1984,37(1-4):233-242
Mass mortalities ofStrongylocentrotus droebachiensis, attributed to disease, have occurred along the Atlantic coast of Nova Scotia from 1980 to 1982. An amoeboid protist has been tentatively identified as the pathogenic agent. Temperature appears to play an important role in triggering epizootics and determining the extent of mortality. Epizootics have occurred in the autumn of each year during months of record high temperatures. The virtual elimination of echinoids over a large area of coast has enabled regeneration of kelp beds. Disease may play a key role in determining the structure and stability of benthic communities off Nova Scotia and elsewhere by controlling echinoid abundance. 相似文献
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I O Okraku 《Social biology》1975,22(4):326-337
The relationship between fertility and occupation is compared for: 1) deep-sea fishermen who are away from home as long as 21 days at a time with short rests between; 2) in-shore fishermen who are away at sea most nights; and 3) plant workers in the locality, used as controls. Particular attention was given to the families of fishermen who had done the same job since marriage. The population was old, relatively speaking, due to outmigration of younger people. 73% of the wives were over 30 years of age. Deep-sea fishermen are younger and have higher incomes than in-shore men (42.1 years vs 49.7 and $3544 vs $2900). Among women 15-44 years of age mean number of children for deep-sea fishermen was 3.35; in-shore, 3.60; plant workers, 3.62. Among those whose husbands had held the same job since marriage the variation was greater: deep-sea, 2.54; in-shore, 3.46; plant workers, 3.35. Among women over 45-years-old whose husbands had held the same job since marriage the number of children was 2.61, 3.94, and 4.27, respectively. 33% of plant workers had more children than desired and 66.7% said they had as many as desired. However, 25.9% of in-shore fishermen and 50% of deep-sea fishermen had fewer than desired. Interval between births was similar for all occupational groups (23.5-26.7 months) but the wives of deep-sea fishermen terminated childbearing earlier. Contraception was used only by the younger women, usually coitus interruptus or rhythm. Sterilization may have been important but it was hard to find out whether the 15% of wives who reported operations which made further childbearing impossible intended sterilization. 35.7% of deep-sea fishermens' wives reported such operations, generally women with larger families. 相似文献