Plants population

A risk equation for nuclear power may be derived by imagining a world with a very large nuclear power plant population. All plants are identical with the same demography and meteorology. The plants are separated such that one does not affect the other. Each year, n, plants fail in the ith failure mode, causing a population dose tf,. If the effects are additive, the population dose (other risk measures could be used) is linearly proportional to the number failing (Equation 1.4-4), where ( is... 

Various forms have been developed to collect plant data. Figures 6.1 and 6.2 are generic forms published in EuReDatA Project No. 3. The Specimen Inventory form, Figure 6.1, is designed to collect data needed to establish the equipment description and total equipment population. Many maintenance systems offer some of these data, but usually not in a useful format or to the extent desired. The Specimen Event or Failure Report form, Figure 6.2, is used to capture failure event data that, when summed, will allow determination of the failure rate numerator—the number of failures within a unique plant population. 

A quite different approach to the study of plant responses to stress has been explored by those ecologists who have followed the example of Harper (1977) in applying to plants techniques originally deployed in investigations of animal populations. Here the methodology has been demographic and the resulting data have allowed responses to stress to be analysed in terms of fluctuations in the rates of mortality and recruitment of either plant populations or plant parts (e.g. leaves, inflorescences). 

This clearly overstates the potential of demographic study to provide a mechanistic understanding of plant responses to environments and, if implemented, would lead to unnecessary delay in the development of generalising principles. The remainder of this chapter is founded on the assumption that the most direct route to a coherent predictive theory of plant responses to stress is likely to involve a synthesis of insights derived from plant population biology, ecophysiology, and many other fields of botanical endeavour. 

Hamrick, J. L. and Godt, M. J. W. 1989. Allozyme diversity in plant species. Pages 43-63 in A. H. D. Brown, M. T. Clegg, A. L. Kahler and B. S. Weir (eds.) Plant Population Genetics, Breeding and Germplasm Resources. Sinauer, Sunderland, MA. 

In ponds where there are viable fish and plant populations, algae are seldom seen. Explain why this might happen. 

Pesticides may not only change the genetic structure of a plant population, but also cause damage, sterility, and malformed outgrowths (morphoses) of the autonomic and reproductive organs. For example, up to 70% of barley plants treated with pesticides were observed to have ear malformation. Using 2,4-D and foxim on barley increased the number of plants with morphoses by a factor of 18-24 [3]. 

The two most critical factors in terms of air quality standards are duration of exposure and concentration. These two factors determine the exposure dose for a plant. In determining the response of vegetation, concentration is more important than time. A given dose presented to a plant in a short period has a greater effect than the same dose applied over a longer period. This suggests a threshold effect for plant populations and is probably related to the repair mechanisms inherent in bio-... 

A much larger cohort of 8854 men, 2293 of whom were exposed to acrylamide, from 1925 to 1983 was examined for mortality. This cohort consisted of four chemical plant populations. No statistically significant excess of all-cause or cause-specific mortality was found among acrylamide workers. Analysis by acrylamide exposure levels showed no trend of increased risk of mortality from several cancer sites. Although the authors concluded that the results do not support the hypothesis that aery-... 

A retrospective study of 136 BCME workers employed at least 5 years revealed 5 cases of lung cancer, which represented a ninefold increase in lung cancer risks 0.54 cases would have been expected to occur in the plant population. The predominant histologic type of carcinoma was small cell undifferentiated. Exposure ranged from 7.5 to 14 years, and the mean induction period was 15 years. In addition, abnormal sputum cytology was observed in 34% of 115 current workers with exposure to BCME for 5 or more years, as contrasted with 11 % in a control group. 

There was no evidence that MOCA was tumorigenic in a study of 31 active workers exposed from 6 months to 16 years. Quantitative analysis of the workers urine confirmed exposure to the chemical. In addition, the records were reviewed for 178 employees who at one time had worked with MOCA but who thereafter had had no further exposure for at least 10 years. The general health of exposed workers with respect to illness, absenteeism, and medical history was similar to that of the total plant population. Two deaths in this group due to malignancy had been diagnosed before any work with or exposure to MOCA. For the plant population in general, there were 115 cancer deaths/100,000 over a 15-year period... 

Better understanding of allelochemicals in plant population dynamics in ecosystems will provide a basis for improved management decisions for managers of rangelands and forests. This will be especially significant for ecosystems undergoing drastic changes such as a forest that has burned or has been harvested. 

Table 28 Quinolizidine alkaloid frequencies in plant populations of Fabaceae in the boreal zone during 1999-2003...

Shiojiri, K., Takabayashi, J., Yano, S. and Takafuji, A. (2001). Infochemically mediated tritrophic interaction webs on cabbage plants. Population Ecology 43 23-29. 

In the plant pathology literature, only systemic fungicides with kick-back action are considered curative, but here, we include any pesticides that limit further spread of pests and diseases in the plant population. Provided no petroleum-based synergists or carriers are used. 

A key characteristic of natural plant populations is their genetic and phenotypic heterogeneity. 

By observing human, animal, or plant populations exposed to a chemical (epidemiology)... 

Willey, R.W. and S.B. Heath. 1964. The Quantitative Relationship between Plant Population and Yield. Adv. Agron. 21 281-320. 

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