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441.
Ronald C. Griffin 《Journal of the American Water Resources Association》1990,26(2):219-225
ABSTRACT: Municipalities typically seek additional water supplies whenever prospective population and economic growth suggests the inadequacy of currently available water supply. The benefit of supply enhancement is usually construed as avoiding debilitating water scarcity. A more effective approach to planning is to compare the benefits and costs of supply augmentation. The net present value of benefits for a supply increase in a representative Texas community is calculated for alternative scenarios relating to population growth, rate growth, and the temporal distribution of the increased supply. Consumer surplus measures are sensitive to all three of these factors and vary from $0 to over $4000 per acre-foot. A notable finding is that the added supply may offer zero values in cases where real water prices increase at an annualized rate of 4 percent (or greater) which is half the rate occurring in Texas from 1981–1985. 相似文献
442.
Eric Griffin 《Natural resources forum》1996,20(2):153-161
The following article is an attempt to reconcile the opinions of various activist-oriented non-governmental organizations (NGOs) on the use of gender analysis as a policy tool in the field of international development and macroeconomic policy. Of special concern to the author is the evolving relationship between international financial institutions (IFIs) and grassroots environmental NGOs seeking reform in macroeconomic policy initiation, implementation and evaluation. The ideas presented below are those of the author alone, and are solely intended to facilitate dialogue between the aforementioned parties as an alternative to the characteristic set of untenable demands and concomitant uncompromising resistance. Thus stated, the reader is challenged to remove his/her professional hat to accept or reject the validity of the propositions with an equal proportion of reason and intuition. 相似文献
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Understanding the demography and function of biotope-forming seaweed species is of great importance for the conservation of
the target species itself, as well as its associated organisms. The brown seaweed Ascophyllum nodosum is fundamental for the functioning of coastal marine ecosystems in the North Atlantic. In this study, we use a data-based
size-classified matrix model to investigate the temporal and spatial variability in demography, and the environment-specific
stochastic sensitivity and elasticity, of two A. nodosum populations, one in western Sweden and one on the Isle of Man in the Irish Sea. A significant difference between the two
populations was that the Swedish population had comparably low and more variable stochastic population growth rate (λ
s). This pattern was partly explained by the relatively high and varying mortality rates during extreme ice-years in Sweden,
and by the lower survival of small individuals during all years. There were also fewer large individuals in Sweden due to
lower transitions to the larger size-classes and higher probability of shrinkage. Sensitivities were analogous in the two
populations, and showed a high selection pressure for increased individual growth. Elasticities were also similar, with the
exception that survival of the smallest individuals (i.e., transition a
1,1), had a higher elasticity on the Isle of Man. Overall, the stochastic growth rate (λ
s) was most sensitive to proportional changes in loop- (i.e., survival within size-class) and, to some extent, growth-transitions
in both study areas. These results show that structurally and demographically diverging A. nodosum populations may be similarly sensitive to changes in vital rates. This, in turn, indicates a plastic life history of A. nodosum that may cope with large environmental variability. The results further suggest that environmental change affecting the survival
or growth of the larger, reproductive A. nodosum individuals could have severe and regional effects on the abundance and biomass of this species, with potential negative
effects on the biodiversity of the associated communities. 相似文献