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681.
Abstract: We examined cougar ( Puma concolor ) dispersal, emigration, and immigration in the San Andres Mountains, New Mexico, from 1985 to 1995 to quantify the effects of dispersal on the local population and surrounding subpopulations. We captured, tagged, and radio-collared animals to detect the arrival of new immigrants and dispersal characteristics of progeny. We found that cougars in southern New Mexico exhibited a metapopulation structure in which cougar subpopulations were separated by expanses of noncougar habitat and linked by dispersers. Of 43 progeny (n = 20 males , 23 females ) studied after independence, only 13 females exhibited philopatric behavior. Males dispersed significantly farther than females, were more likely to traverse large expanses of noncougar habitat, and were probably most responsible for nuclear gene flow between habitat patches. We estimated that an average of 8.5 progeny (i.e., cougars born in the study area) successfully emigrated from and 4.3 cougars successfully immigrated to the San Andres Mountains each year. Concurrently, an average of 4.1 progeny were recruited into the San Andres cougar population. Protected cougar subpopulations can contribute to metapopulation persistence by supplying immigrants to surrounding subpopulations that are affected by fragmentation or offtake by humans. Cougar population dynamics and dispersal behavior dictate that cougar management and conservation should be considered on a regional scale. 相似文献
682.
Uncertainty plays a major role in Integrated Coastal Zone Management (ICZM). A large part of this uncertainty is connected
to our lack of knowledge of the integrated functioning of the coastal system and to the increasing need to act in a pro-active
way. Increasingly, coastal managers are forced to take decisions based on information which is surrounded by uncertainties.
Different types of uncertainty can be identified and the role of uncertainty in decision making, scientific uncertainty and
model uncertainty in ICZM is discussed. The issue of spatial variability, which is believed to be extremely important in ICZM
and represents a primary source of complexity and uncertainty, is also briefly introduced. Some principles for complex model
building are described as an approach to handle, in a balanced way, the available data, information, knowledge and experience.
The practical method of sensitivity analysis is then introduced as a method for a posterior evaluation of uncertainty in simulation
models. We conclude by emphasising the need for the definition of an analysis plan in order to handle model uncertainty in
a balanced way during the decision making process. 相似文献
683.
684.
685.
M. Tufail Sikander M. Mirza Arif Mahmood A. A. Qureshi Yasir Arfat H. A. Khan 《Journal of environmental radioactivity》2000,50(3):283
Using the closed-can technique, radon exhalation rate measurements have been carried out for shale and coal samples collected from various mines located in the Chakwal and Makarwal areas of Pakistan. For the two areas, the measured average values of the exhalation rates from shale are 1.45±0.13 and 0.67±0.25 Bq m−2 h−1 and for coal are 1.0±0.03 and 0.65±0.32 Bq m−2 h−1, respectively. These values are much lower than the measured exhalation rates from alum-shale-based Nordic concrete which has values in the 50–200 Bq m−2 h−1 range. The lower values of the measured exhalation rates from the shale and coal deposits in the Chakwal and Makarwal areas are indicative of their lower uranium contents and mine workers in these areas do not face any abnormal health hazard due to radon since the exhalation rates have been found to be on the low side. 相似文献
686.
687.
Climatic characteristics of the northern Moscow region and the periodicity of seedage in Norway spruce were analyzed retrospectively.
The relationship between the intensity of seedage and weather conditions in the period before seedage was revealed. 相似文献
688.
The interactions of zebra mussels, invertebrates, fish, and microorganisms were studied experimentally. Trends in the distribution
of total bacterial biomass, the abundance of heterotrophic organisms, and their functional activities in water and grounds
were analyzed. The most favorable conditions for development of bacteria developed in June, in the presence of fish and without
zebra mussels. In experimental ecosystems with zebra mussels, a decrease in the abundance and activity of microorganisms and
a change of dominant yeast forms were observed. 相似文献
689.
690.
The index of cenotic significance and other indices calculated on its basis were used for revealing specific structural features of zooplanktonic communities in lakes differing in productivity. The results showed that new indices (complexity coefficient, index of cenotic significance of dominant species, and integrated cenotic significance of the zooplankton) strongly correlate with the trophic status of the water body and are more responsive to changes in the structure of the community than the Shannon–Weaver index of species diversity. The results confirm the hypothesis that the structure of zooplankton is simplified in the course of lake eutrophication. 相似文献