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961.
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964.
To participate in the potential market for carbon credits based on changes in the use and management of the land, one needs to identify opportunities and implement land-use based emissions reductions or sequestration projects. A key requirement of land-based carbon (C) projects is that any activity developed for generating C benefits must be additional to business-as-usual. A rule-based model was developed and used that estimates changes in land-use and subsequent carbon emissions over the next twenty years using the Eastern Panama Canal Watershed (EPCW) as a case study. These projections of changes in C stocks serve as a baseline to identify where opportunities exist for implementing projects to generate potential C credits and to position Panama to be able to participate in the emerging C market by developing a baseline under scenarios of business-as-usual and new-road development. The projections show that the highest percent change in land use for the new-road scenario compared to the business-as-usual scenario is for urban areas, and the greatest cause of C emission is from deforestation. Thus, the most effective way to reduce C emissions to the atmosphere in the EPCW is by reducing deforestation. In addition to affecting C emissions, reducing deforestation would also protect the soil and water resources of the EPCW. Yet, under the current framework of the Clean Development Mechanism (CDM), only credits arising from reforestation are allowed, which after 20 years of plantation establishment are not enough to offset the C emissions from the ongoing, albeit small, rate of deforestation in the EPCW. The study demonstrates the value of spatial regional projections of changes in land cover and C stocks: The approach helps a country identify its potential greenhouse gas (GHG) emission liabilities into the future and provides opportunity for the country to plan alternative development pathways. It could be used by potential project developers to identify which types of projects will generate the largest C benefits and provide the needed baseline against which a project is then evaluated. Spatial baselines, such as those presented here, can be used by governments to help identify development goals. The development of such a baseline, and its expansion to other vulnerable areas, well positions Panama to respond to the future market demand for C offsets. It is useful to compare the projected change in land cover under the business-as-usual scenario to the goals set by Law 21 for the year 2020. Suggested next steps for analysis includeusing the modeling approach to exploreland-use, C dynamics and management ofsecondary forests and plantations, soilC gains or losses, sources ofvariability in the land use and Cstock projections, and other ecologicalimplications and feedbacks resulting fromprojected changes in land cover.  相似文献   
965.
本文概述了引起萨尔瓦多红树林退化的各种因素,并分析了拟议中的红树林产权变化对贫困的海岸带社区红树林的意义.目前萨尔瓦多红树林生态系统的采伐和转化模式可通过补贴权利的透镜来观察,这种补助就是为特定用途向一些参与者授予财产权(而不授权给别人).遗憾的是,对红树林资源的使用进行管理的现有法律法规体系是相互矛盾和含混不清的.一些现行的法律对生态系统的使用和转变问题做出了完全相反的规定.如果不对各项补贴权利重新定义,就不能确保对红树林进行合理、持续的管理.但这种权利的重新定义应考虑其生活与生态系统的健康状况密切相关的那些群体的需要.  相似文献   
966.
Oil spills caused by maritime transport of petroleum products are still an important source of ocean pollution, especially in main production areas and along major transport routes. We here provide a historical and geographic analysis of the major oil spills (>700 t) since 1960. Spills were recorded from several key marine ecosystems and marine biodiversity hotspots. The past four decades have been characterized by an overall decrease in the number of accidents and tonnes of oil spilled in the sea, but this trend was less distinct in the European Atlantic area. Recent black tides from the Erika and Prestige vessels provided new evidence for the high risk of accidents with serious ecological impact in this area, which according to our analysis is historically the most important oil spill hotspot worldwide. The English Channel and waters around Galicia in Spain were the areas with most accidents. Maritime transport in European Atlantic waters has been predicted to continue increasing. Together with our own results this suggests that, in addition to measures for increased traffic safety, deployment of emergency capacities in the spill hotspot areas may be crucial for a sustainable conservation of sea resources and ecosystems.Electronic Supplementary Material  Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.  相似文献   
967.
In this paper we report the fetal loss rate in relation to both maternal and gestational age in 1764 pregnant women who underwent transabdominal chorionic villus sampling (TA-CVS) between January 1986 and August 1990. The fetal loss rate, considered as a proportion of continuing pregnancies, decreased with advancing gestational age at sampling from 4.3 per cent before 9 weeks to 0.4 per cent at or after 13 weeks, the difference being statistically significant (p <0.025). The fetal loss rate increased from 1.6 per cent in women under 30 to 2.4 per cent in women of 40 years or over, but the difference was not statistically significant. Considering that the total fetal loss rate before 28 weeks' gestation was on average 1.91 percent (1.3 per cent under 35 years and 2.8 per cent in women of 35 or over), we believe that TA-CVS is a safe and effective technique for prenatal diagnosis of genetic diseases.  相似文献   
968.
An anticyclonic slope water oceanic eddy (SWODDY), named AE6, was sampled in the southern Bay of Biscay from 12 to 31 August 1998 to assess changes in the abundance and composition of phytoplankton assemblages related to the mesoscale feature. SWODDY AE6 showed characteristic biological signatures. A twofold increase in chlorophyll a concentration was found at the eddy centre relative to surrounding waters. Picoplankton cells accounted for a lower fraction of total chlorophyll a values at the eddy centre (44–50%) than outside the eddy (54–61%). Microscopic cell counts and HPLC pigment analysis showed that diatoms were almost entirely confined to the eddy centre, but both techniques yielded different results when studying other phytoplankton groups. Microscopic cell counts indicated that the spatial distribution of diatoms, dinoflagellates and unidentified flagellates was significantly influenced by SWODDY AE6, showing maximum abundance inside the mesoscale feature. HPLC pigment analysis provided more detailed information about the composition of pico–nanoplanktonic organisms. Pigment data processed by means of the CHEMTAX program showed "chlorophytes", "haptophytes" and "dinoflagellates II" (having haptophyte-like pigments and gyroxanthin-diester) as the more abundant "pigment classes" at the eddy centre, whereas dominance of "chlorophytes" and higher contribution of "cyanobacteria" (type Synechococcus) were estimated in the surrounding waters.Communicated by S.A. Poulet, Roscoff  相似文献   
969.
Nest concealment varies strongly within populations of many species. Although some studies have revealed the beneficial effects of concealment in mitigating predation pressure on nests, other studies were unable to find similar effects. One potential reason for the mixed results is that parental behaviour may compensate for the effects of nest cover, and specifically designed experimental studies are needed to reveal this compensation. I studied the effects of concealment on the probability of nest survival in the blackcap (Sylvia atricapilla), by experimentally manipulating the degree of nest-foliage cover. There was a significant effect of the treatment depending on nest type and the phase of nesting. Whereas there was no effect of concealment on nest survival in natural nests, there was a positive effect in real nests baited with plasticine clutches (i.e. without parental activity). Parents probably behaviourally compensated for poor concealment in natural nests (nest guarding, defence). In line with this, there was no effect of concealment on nest survival during incubation, whereas there was probably a positive effect in the nestling phase. Parents spent more time on the nest during incubation (80%) than during the care of nestlings (40%) and, consequently, had more opportunities to compensate for poor cover. In general, we cannot use single measures of behaviours or states (nest concealment) as an indication of predation risk because of the capacity for compensation in other behaviours.Communicated by C. Brown  相似文献   
970.
Nirchio  M.  Fenocchio  A. S.  Swarça  A. C.  Pérez  J. E. 《Marine Biology》2004,146(1):161-165
This paper reports the results of cytogenetic analyses carried out on Porichthys plectrodon using conventional Giemsa staining, C-banding and silver staining techniques. A diploid chromosome count of 2n=44 was observed, consisting of 8 metacentric, 10 submetacentric, 6 subtelocentric and 20 acrocentric chromosomes. Differences in length made it possible to identify homologous chromosomes within the metacentric group. Constitutive heterochromatin was distributed as large pericentromeric blocks in pairs 1 and 2, while the rest of the chromosomes were marked in centromeric regions, some more conspicuously than others. One pair of small-sized acrocentric NOR-bearing chromosomes (21) was identified by the nucleolar regions located terminally on their short arms.Communicated by P.W. Sammarco, Chauvin  相似文献   
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