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Historical Impacts (historical + impact)
Selected Abstracts6.,No More Hiroshimas and Sharp WeaponsAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 1 2009Keping Wang When it comes to rethinking the Hiroshima A-bombing and its historical impact, there arise a number of approaches to be exercised from different perspectives related to the human condition and the current situation today. This essay presents two of them: a poetical reflection and a philosophical pondering that are characterized by either factual inquiry or empirical wisdom. The former is deplorably sentimental and unforgettable with regard to the deadliest mode of warfare that has ever occurred in human history. The philosophical pondering from a Taoist viewpoint is thought-provoking and instructive with ongoing relevance to the problematic globe. Hence when the poet calls out "No More Hiroshimas," we shall go ahead and appeal for "No More Wars,""No More Sharp Weapons," or "No More Excessive Forces." However, what haunts the world all the time is constant warfare at varied scales here and there; and what worries us right now is the hard fact that some nations are presumably taking the risk of developing nuclear weapons on a starvation budget, for they think that they are under the threat and pressure of other countries armed with plenty of such mass-destructive devices. They all seem to have neglected or obliterated the historical memory of Hiroshima as a symbol of the worst violence ever known to humankind. [source] Estimating the human impact on populations of the endangered noble crayfish (Astacus astacus L.) in north-western PolandAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2006Holger K. Schulz Abstract 1.The Pomorskie Lakeland close to the town of Miastko shows the highest density of stocks of the noble crayfish Astacus astacus (L.) in the lowlands of north-western Poland. In summer 2002, the present status of this highly threatened species was analysed by means of mark and recapture trapping. 2.Nine lakes with known occurrence of A. astacus were investigated. Each lake was surveyed with regard to the crayfish population density, water quality and potential recent and historical impact of fisheries and recreation. The estimated population density was evaluated statistically with respect to a set of potential environmental variables. 3.The estimated densities of A. astacus populations varied from very abundant (6.6 adult individuals per trap per night) to absent. Two lakes were found to contain the non-indigenous crayfish Orconectes limosus (Raf.). The population density was not correlated with conductivity, pH, transparency, alkalinity, the concentration of ammonium, calcium, chloride, nitrate, nitrite, total nitrogen, total phosphorus, or with the trophic status of the lakes. A. astacus occurred in lakes ranging from mesotrophic to eutrophic. 4.The results suggest that both occurrence and density of A. astacus populations depended on criteria associated with human activities that have altered the aquatic environment. Abundance of A. astacus was negatively correlated with eel (Anguilla anguilla) stocking intensity (r = ,0.88; p < 0.01) and number of yearly net catches (r = ,0.66; p < 0.05) and positively correlated with distance to nearest town (r = 0.72; p < 0.05). 5.It is concluded that the introduction of O. limosus most likely resulted from fishery activities, emphasizing the need for regulations to reduce the negative impact of lake fisheries on native crayfish stocks. Copyright © 2005 John Wiley & Sons, Ltd. [source] Compensating for wetland losses in the United StatesIBIS, Issue 2004Joy B. Zedler Impacts of climate change on US wetlands will add to those of historical impacts due to other causes. In the US, wetland losses and degradation result from drainage for agriculture, filling for urbanization and road construction. States that rely heavily on agriculture (California, Iowa, Illinois, Missouri, Ohio, Indiana) have lost over 80% of their historical area of wetlands, and large cities, such as Los Angeles and New York City, have retained only tiny remnants of wetlands, all of which are highly disturbed. The cumulative effects of historical and future degradation will be difficult to abate. A recent review of mitigation efforts in the US shows a net loss of wetland area and function, even though ,no net loss' is the national policy and compensatory measures are mandatory. US policy does not include mitigation of losses due to climate change. Extrapolating from the regulatory experience, one can expect additional losses in wetland areas and in highly valued functions. Coastal wetlands will be hardest hit due to sea-level rise. As wetlands are increasingly inundated, both quantity and quality will decline. Recognition of historical, current and future losses of wetland invokes the precautionary principal: avoid all deliberate loss of coastal wetland area in order to reduce overall net loss. Failing that, our ability to restore and sustain wetlands must be improved substantially. [source] Contemporary and historical impacts of megaherbivores on the population structure of tree euphorbias in South African subtropical thicketAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010Richard M. Cowling Abstract African elephant and black rhinoceros , both megaherbivores , impact negatively on the abundance of succulent plants, including tree succulents, in South Africa's subtropical thicket. We sampled 35 sites in subtropical thicket to assess historical and contemporary impacts of African elephant and black rhinoceros on the population structure of three species of succulent tree euphorbia. Population age structures were highly variable and showed no species-specific effects. Almost half the sites had growing populations dominated by young individuals. Sites having contemporary impacts had significantly fewer individuals in the 30,75 years age range, but this effect declined with increasing terrain slope. Eighty-one percent of sites assumed to have been impacted by megaherbivores historically had individuals that predated rhino and elephant extirpation in the region. This and other population age structure data indicate that megaherbivores and tree euphorbias coexisted historically on terrain of low relief. However, in areas not subject to contemporary impacts, euphorbia populations are likely to be much higher now than historically, owing to population relaxation after the extirpation of megaherbivores in the mid 1800s. Given the sensitivity of tree euphorbias to megaherbivore impacts, managers should consider monitoring the population structure of these species in order to identify thresholds of potential concern regarding megaherbivore impacts. Résumé L'éléphant et le rhinocéros africains , deux méga-herbivores , ont un impact négatif sur l'abondance de plantes succulentes, y compris des arbres succulents, dans les fourrés subtropicaux d'Afrique du Sud. Nous avons prélevé des échantillons dans 35 fourrés subtropicaux afin d'évaluer les impacts anciens et actuels des éléphants et des rhinos noirs africains sur la structure de la population de trois espèces d'euphorbes arborescentes succulentes. Les structures d'âges des populations étaient très variables et ne présentaient aucun effet spécifique des espèces. Près de la moitié des sites contenaient des populations en croissance dominées par de jeunes individus. Les sites qui présentaient des impacts actuels comptaient significativement moins d'individus de la classe d'âge comprise entre 30 et 75 ans, mais cet effet diminuait lorsque la pente du terrain s'accentuait. Quatre-vingt-un pour cent des sites supposés avoir subi jadis l'impact des méga-herbivores contenaient des individus qui dataient d'avant l'élimination des rhinos et des éléphants. Ceci, tout comme d'autres données sur la structure d'âge des populations, indique que les méga-herbivores et les euphorbes arborescentes ont longtemps coexisté sur les terrains de faible relief. Cependant, dans les zones qui ne subissent aucun impact actuel, les populations d'euphorbes sont susceptibles d'être beaucoup plus hautes aujourd'hui que jadis, en raison de la libération induite par l'élimination des méga-herbivores au milieu des années 1800. Etant donné la sensibilité des euphorbes arborescentes face aux impacts des méga-herbivores, les gestionnaires devraient envisager le suivi continu de la structure de la population de ces espèces afin de déterminer les seuils d'alerte potentiels en ce qui concerne les impacts des méga-herbivores. [source] 55 Ice age kelp forests: climate-driven changes in kelp forest distribution since the last glacial maximumJOURNAL OF PHYCOLOGY, Issue 2003M. H. Graham Kelp forest distributions are constrained by the availability of rocky substrate within the depth range tolerable for growth and reproduction, which can vary over relatively short geological timescales (millennia) due to interactions between coastal bathymetry and climate-driven changes in eustatic sea level. Using GIS, a digital bathymetric map, sea level curves, and published kelp depth tolerances, I reconstructed changes in the size and distribution of giant kelp (Macrocystis pyrifera) forests in the Southern California Bight since the last glacial maximum. Reconstructions predicted that the total area of available kelp forest habitat for the California Channel Islands during the last glacial maximum (18.5 kyr BP; 628 square km) was greater than at present (382 square km) but less than at 16.5 kyr BP (1130 square km). Available kelp forest habitat along the southern California mainland also increased rapidly from 18.5 to 16.5 kyr BP but continued to increase with sea level rise. Differences in the effects of sea level rise on coastal geomorphology between the islands and mainland further constrained the extent of rocky substrate available to kelps. Given biomass and productivity estimates from present-day kelp forests, these reconstructions suggest more productive and spatially extensive island kelp forests near the last glacial maximum than at present, but the opposite pattern for the mainland. These climate-driven changes in kelp forest distribution and productivity likely had important historical impacts on the ecology and evolution of the present-day kelp ecosystem including kelp forest exploitation by early human inhabitants of southern California. [source] | ||||||||||