摘要:

Techniques are described for quantitatively determining water movement and loss in pricklypear plants with tritiated water. Transpired vapor from plants which were injected with tritium was collected with a system that passed dry air over the pad surface and into collecting vials. Water was extracted from tissue samples by a modified freeze—drying technique. Combustion of tissue samples following extraction showed that the method was efficient for tritiated water recovery from the plant material when the extraction time was 8 hours and a warm—water bath temperature of 55°C was maintained.

ISSN:0012-9658    

DOI:10.2307/1935393

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Equations are derived which give the mean distance between small organisms randomly dispersed in three dimensions. Models based on binomial and Poisson distributions are developed and compared in terms of easily—measured field variables, and a quantitative criterion is given for choosing between them. The results are extended to mixed populations.

ISSN:0012-9658    

DOI:10.2307/1935394

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Regression equations are described which allow the calculation of the calories of energy consumed by a carnivore fed on whole laboratory mice (Mus musculus) given the individual weights of the mice eaten. The live—weight caloric density of mice weighing 4.8 g or less may be determined by the linear relationship: kcal/g live weight = 0.657 + 0.306 (g live body weight). Mice weighing more than 4.8 g may be considered to have a uniform live—weight caloric density of 2.14 ° 0.08 (SE) kcal/g. These conversion factors may be used for either frozen or freshly killed laboratory mice or laboratory raised Peromyscus polionotus. Fat indices (g fat/g lean dry weight) were not correlated with body weight. However, water indices (g water/g lean dry weight) decreased exponentially with increasing body weight. There was no change in the caloric value of the lean dry weight of the mice with increasing body weight.

ISSN:0012-9658    

DOI:10.2307/1935395

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Following preconditioning to three temperature regimes (5°—16°C, 21°—32°C, 32°—43°C), dark respiration was measured over a 35°C range in three geographically isolated populations of Atriplex polycarpa (Torr.) S. Wats. Intraspecific differences in carbon dioxide exchange were found which correlated with the climate of the area of origin of the population.

ISSN:0012-9658    

DOI:10.2307/1935396

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Measurements of dry—matter production in even—aged stands in northwestern New Brunswick show that the annual weight increment of mountain maple is constant while that of balsam fir increases. By age 25 the total production of balsam fir stands is 2.3 times, and the current production is 3.7 times, that of mountain maple.

ISSN:0012-9658    

DOI:10.2307/1935397

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Curvilinear ordinations similar to those of Swan (1970) are obtained by using principal component analysis on the same single—gradient models of vegetation. Any non—linear relationships between species will produce such a result.

ISSN:0012-9658    

DOI:10.2307/1935398

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

摘要:

Seeds of Melilotus alba and M. officinalis were sown in four different—sized openings in Canada bluegrass, a dominant of an old field. A relationship between seed germination and size of opening in the sod was not apparent but early seedling survival was correlated (P<.01) with size of opening, the larger openings yielding a greater number of viable seedlings. The areal extent of the dominant plant in the old field thus appears to regulate the number of sweetclover plants at an early stage of their life cycle.

ISSN:0012-9658    

DOI:10.2307/1935399

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

ISSN:0012-9658    

DOI:10.2307/1935400

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

ISSN:0012-9658    

DOI:10.2307/1935401

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY

ISSN:0012-9658    

DOI:10.2307/1935402

出版商:Ecological Society of America    

年代:1970

数据来源: WILEY