摘要:

The satyrine butterfly Erebia epipsodea shows a population structure unlike that of any other butterfly studied in detail. Rather than being divided into numerous small populations which only rarely exchange individuals, E. epipsodea occurs in vast, effectively panmictic populations which may cover hundreds of square kilometers. There is a great deal of individual movement, and the butterflies are able to recognize and leave ecologically unsuitable areas. Such areas do not, however, seem to pose substantial barriers to their movement.

ISSN:0012-9658    

DOI:10.2307/1933605

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

The selection scheme employed a two—vial apparatus in which beetles (Tribolium castaneum (CS) and T. confusum (CF)) could move in one direction between vials. One inactive line and one active line were selected for five generations in both species. A second active line in which selection for activity was more intense was selected for three generations in both species. In CS, both active lines differed significantly from the controls. The inactive line approached a significant difference. In CF, only the second active line attained a significant difference from control level. The responses developed by this selection procedure apparently were not due to reactivity to conditioned medium.

ISSN:0012-9658    

DOI:10.2307/1933606

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Hoop pine (Araucaria cunninghamii Ait.), a nitrogen—sensitive rain—forest species can be grown without fertilizers as an underplanting to established stands of Pinus, on soils which will not support open plantings of pure hoop pine without fertilizing with nitrogen at the rate of 112 kg/ha per year. Stem volume growth rates of 6.6 m3/ha per year representing 28% of total stand increment have been obtained in 15—year—old underplantings. Removal of the Pinuscomponent from mixed stands of Pinus and Araucaria led to chlorosis of the remaining hoop pine but no significant decline in foliar nitrogen levels nor loss in growth over the ensuing 3 years. In contrast, 2—year—old transplants of Araucaria established on a site from which mature Pinus had been clear felled exhibited extremely slow growth and chlorosis, which could be overcome either by shading or applying nitrogen fertilizers. Underplants responded only slightly to added nitrogen compared to open plantings. Nitrogen requirements of fertilized open plants and unfertilized underplants were similar, however, being approximately 0.005 g nitrogen/g dry matter produced. The rate of immobilization of nitrogen by 8—year—old underplants established at 1,160 trees/ha was only 3.4 kg/ha per year. The source of nitrogen for underplantings is discussed, and nitrogen requirements of hoop pine are considered in relation to light intensity. It is concluded that the success of underplanting is due to a multiplicity of factors,including (1) the role of nitrogen fixation in conjunction with Pinus and Araucaria; (2) the increased availability of nitrogen as a consequence of changes in the soil—nitrogen cycle; and (3) the effect of reduced light intensity on improving the carbohydrate/nitrogen balance in Araucaria under conditions of low soil—nitrogen availability.

ISSN:0012-9658    

DOI:10.2307/1933607

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

With appropriate modifications, Lettau's climatonomical theory (quantitative climatic description) may be applied to the characterization of vegetative influences on microclimate. The theory was tested on a sumac canopy which was alternately shaded and unshaded by the drift of cumulus cloud shadows. Results showed that the canopy layer had a relatively low thermal admittance, but the geometry of the canopy elements had a profound influence on the thermal properties of the layer. The observed thermal responses for the given meteorological conditions represent a single spectral distribution, characteristic of this particular canopy.

ISSN:0012-9658    

DOI:10.2307/1933608

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Optimum germination of Iva annua seeds occur at 15° C. Temperature and salinity interact in their effect on germination. Increases in osmotic concentration of media cause a gradual decrease in germination percentages at optimal temperatures. Sodium chloride, the most common salt in saline areas occupied by I. annua, has an osmotic rather than a toxic effect on germination.

ISSN:0012-9658    

DOI:10.2307/1933609

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

The advantages of the electrical conductivity procedure proposed for the measurement of microbially evolved CO2, previously absorbed in alkali, are that it is rapid and the exposure time to atmospheric CO2is only a few seconds. It is as accurate as other accepted techniques.

ISSN:0012-9658    

DOI:10.2307/1933610

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Growth of Eucalyptus gummifera and E. maculata seedlings is statistically correlated with the concentrations of a number of soil nutrients. Step—wise multiple linear regression models of seedling growth are presented with soil nitrogen, phosphorus, calcium, and aluminum as independent variables. Regression models with soil calcium and phosphorus as independent variables give the best estimates of seedling growth.

ISSN:0012-9658    

DOI:10.2307/1933611

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

ISSN:0012-9658    

DOI:10.2307/1933612

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

ISSN:0012-9658    

DOI:10.2307/1933613

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

ISSN:0012-9658    

DOI:10.2307/1933614

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY