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331.
332.
Strange E Galbraith H Bickel S Mills D Beltman D Lipton J 《Environmental management》2002,29(2):290-300
The amount of ecological restoration required to mitigate or compensate for environmental injury or habitat loss is often
based on the goal of achieving ecological equivalence. However, few tools are available for estimating the extent of restoration
required to achieve habitat services equivalent to those that were lost. This paper describes habitat equivalency analysis
(HEA), a habitat-based “service-to-service” approach for determining the amount of restoration needed to compensate for natural
resource losses, and examines issues in its application in the case of salt marsh restoration. The scientific literature indicates
that although structural attributes such as vegetation may recover within a few years, there is often a significant lag in
the development of ecological processes such as nutrient cycling that are necessary for a fully functioning salt marsh. Moreover,
natural variation can make recovery trajectories difficult to define and predict for many habitat services. HEA is an excellent
tool for scaling restoration actions because it reflects this ecological variability and complexity. At the same time, practitioners
must recognize that conclusions about the amount of restoration needed to provide ecological services equivalent to those
that are lost will depend critically on the ecological data and assumptions that are used in the HEA calculation. 相似文献
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This second part of the study concerned the plant cover, gas contents, and soil properties of the side slope area of the landfill, which is not protected against gas infiltration. Five different sites on the slope and a control site outside the landfill were chosen, and pipes were installed in the region. Gas contents were tested, and plant cover recorded by quadrat analysis Over 20 species of grasses, herbs, and vines were present on the slope The relative adaptabilities of the species were ranked according to the abundance of the plants Plant cover was found to be negatively correlated with landfill gas contents. The landfill soil had elevated contents of nitrogen, organic carbon, and extractable metals Total nitrogen, ammonia nitrogen, and extractable lead were further identified to be negatively correlated while available phosphate was positively correlated with plant cover 相似文献
336.
Fred R. Kuss 《Environmental management》1986,10(5):637-650
This article reviews some of the more important factors found to influence the susceptibility of plants to trampling impacts associated with recreational use of natural areas. A three-way interaction mediates plant responses to impacts: plant x environment x stress level(s). Plant responses vary in part according to the genetic constitution of the plant, life and growth form, the adaptive flexibility of the plant, and anatomical differences inherent to growth habit and morphology. Other factors that influence plant sensitivities to impacts are the habitat environments in which plants grow, since a number of conditions such as moisture excesses or deficiencies, nitrogen or oxygen starvation, late frosts, etc., cause physiological injury and may increase plant sensitivity to impacts. Among the environmental factors that may increase or lessen plant sensitivities to impacts are soil moisture levels, canopy density, elevation, aspect, microclimate, soil drainage, texture, fertility and productivity. Seasonal influences also bear consideration since environmental changes and phonological and physiological events are mediated by time of year. Stresses are caused by both direct and indirect forms of impact and vary according to season of use, frequency and amount of use, and the type of activity. These interactions are further complicated by evidence that inter- and intraspecific competition, antagonism, and commensalism may influence differences in the sensitivity of plant communities to impacts. 相似文献
337.
Daniel Leblanc Pierre Ouellette 《Journal of the American Water Resources Association》1988,24(2):341-345
ABSTRACT: Various techniques, one of which is zoning, are used to control the extent of flood damage. The benefit-cost analysis of zoning programs must take into account the random nature of flooding. This paper outlines a method for determining not only the expected value of the benefit-cost ratio, but also the probability of such a zoning program being profitable. It also presents an application of the method to the assessment of the Outaouais Regional Community zoning program. 相似文献
338.
ABSTRACT The flooding conditions in the basin of the Red River of the North are reviewed in terms of the accuracy of the flood forecasts and the response of both the floodplain occupants and government agencies to these forecasts. The flood prediction methods in Canada and the United States are compared. The accuracy of these prediction measures for the major floods in recent history is reviewed. The differences between the way in which the American and Canadian authorities approach the flood emergencies are outlined. The accuracy of the forecasts are plotted against a number of parameters which reflect the efficiency of the flood fighting measures initiated by those flood forecasts. The significant features of these plots are discussed. 相似文献
339.
Nicolotti G Rettori A Paoletti E Gullino ML 《Environmental monitoring and assessment》2005,105(1-3):175-191
This paper reports morphological and physiological damage caused by polluted seaspray to coastal pine forests in Liguria (Northern Italy) and suggests the most reliable parameters for surfactant-pollution biomonitoring. Concentrations of surfactants in surface seawater, seaspray, and that deposited on Pinus halepensis and Pinus pinea needles were determined in samples from five sites. Decline of the pines in the Western part of Liguria was greater than in the East, and was associated with higher surfactant levels deposited on the crowns. Chloride content of needles was higher in damaged pines, even if it did not reach toxic levels. Stomata micromorphologies did not differ between species in the crown parts facing the sea, while differences were significant in the back crown parts that were not directly exposed to polluted sea breezes. Water content and noon water potential indicated interference in water relations of damaged trees. In conclusion, none of the investigated parameters was by itself a comprehensive index of surfactant damage. A simultaneous survey of several parameters is suggested to investigate the impact of surfactants on coastal vegetation. The most useful parameters were: directionality of crown damage, surfactant depositions on the needles, chloride accumulation in the needles, structural injury to epistomatal chambers, needle water content and potential. 相似文献
340.