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391.
Carbon sequestration in terrestrialecosystems and geologic formations providesa significant opportunity for California toaddress global climate change. The physicalsize of its resources (e.g., forests,agriculture, soils, rangeland, and geologicformations) and the expertise in Californiaprovides a substantial foundation fordeveloping carbon sequestration activities.Furthermore, the co-benefits of carbonsequestration – such as improved soil andwater quality, restoration of degradedecosystems, increased plant and cropproductivity, and enhanced oil recovery – are significant. In fact, carbonsequestration often represents a `noregrets' strategy – implementing carbonsequestration provides multiple benefits,even without the advent of global climatechange.Nevertheless, researchers need to addressseveral issues to determine more accuratelythe potential, benefits, and costs ofsequestering carbon in California'sterrestrial ecosystems and geologicformations, as well as to identify the mostpromising sequestration methods and theiroptimal implementation. One key issue isthe type of regulatory constraints facingdevelopers of carbon sequestrationprojects: what permits are needed fordeveloping these projects? The permittingprocess may impede the penetration ofsequestration technologies into the marketif the costs (including transaction costs)of obtaining the permits are too burdensomeand costly. For example, at least ninefederal regulations and seven stateregulations will potentially influencecarbon sequestration projects inCalifornia. This paper also provides anexample of the types of permits needed fordeveloping a carbon sequestration project,using California as an example. It ispossible that a carbon sequestrationproject may have to obtain a total of 15permits (3 federal, 6 state, 6 local),before it even starts to operate. In theconcluding section, we offer some suggestedareas for research and activities forpolicy makers. 相似文献
392.
We examined the physiological and morphological response patterns of plains cottonwood [Populus deltoides subsp. monilifera (Aiton) Eck.] to acute water stress imposed by groundwater pumping. Between 3 and 27 July 1996, four large pumps were used
to withdraw alluvial groundwater from a cottonwood forest along the South Platte River, near Denver, Colorado, USA. The study
was designed as a stand-level, split-plot experiment with factorial treatments including two soil types (a gravel soil and
a loam topsoil over gravel), two water table drawdown depths (∼0.5 m and >1.0 m), and one water table control (no drawdown)
per soil type. Measurements of water table depth, soil water potential (Ψs), predawn and midday shoot water potential (Ψpd and Ψmd), and D/H (deuterium/hydrogen) ratios of different water sources were made in each of six 600-m2 plots prior to, during, and immediately following pumping. Two additional plots were established and measured to examine
the extent to which surface irrigation could be used to mitigate the effects of deep drawdown on P. deltoides for each soil type. Recovery of tree water status following pumping was evaluated by measuring stomatal conductance (g
s
) and xylem water potential (Ψxp) on approximately hourly time steps from before dawn to mid-afternoon on 11 August 1996 in watered and unwatered, deep-drawdown
plots on gravel soils. P. deltoides responded to abrupt alluvial water table decline with decreased shoot water potential followed by leaf mortality. Ψpd and percent leaf loss were significantly related to the magnitude of water table declines. The onset and course of these
responses were influenced by short-term variability in surface and ground water levels, acting in concert with physiological
and morphological adjustments. Decreases in Ψpd corresponded with increases in Ψmd, suggesting shoot water status improved in response to stomatal closure and crown dieback. Crown dieback caused by xylem
cavitation likely occurred when Ψpd reached −0.4 to −0.8 MPa. The application of surface irrigation allowed trees to maintain favorable water status with little
or no apparent cavitation, even in deep-drawdown plots. Two weeks after the partial canopy dieback and cessation of pumping,
g
s
and Ψxp measurements indicated that water stress persisted in unwatered P. deltoides in deep-drawdown plots. 相似文献
393.
Experimental ecotoxicological studies on the norm of reaction to anthropogenic acidification were performed with representative hydrobionts from aquatic ecosystems of the northern taiga zone. Interspecific, interpopulation, and age-related differences in tolerance to acidity and the significant dependence of this parameter on water pH in natural habitats of corresponding populations were revealed. 相似文献
394.
Species composition, abundance, and some ecological features of pollinating insects have been studied in urbanized landscapes. Changes in the composition of bumblebees (Hymenoptera) and butterflies (Lepidoptera, Rhopalocera) and their adaptive potential in urban environments are considered.__________Translated from Ekologiya, No. 4, 2005, pp. 286–293.Original Russian Text Copyright © 2005 by Eremeeva, Sushchev. 相似文献
395.
R. S. STENECK T. P. HUGHES J. E. CINNER W. N. ADGER S. N. ARNOLD F. BERKES S. A. BOUDREAU K. BROWN C. FOLKE L. GUNDERSON P. OLSSON M. SCHEFFER E. STEPHENSON B. WALKER J. WILSON B. WORM 《Conservation biology》2011,25(5):904-912
Abstract: Unsustainable fishing simplifies food chains and, as with aquaculture, can result in reliance on a few economically valuable species. This lack of diversity may increase risks of ecological and economic disruptions. Centuries of intense fishing have extirpated most apex predators in the Gulf of Maine (United States and Canada), effectively creating an American lobster (Homarus americanus) monoculture. Over the past 20 years, the economic diversity of marine resources harvested in Maine has declined by almost 70%. Today, over 80% of the value of Maine's fish and seafood landings is from highly abundant lobsters. Inflation‐corrected income from lobsters in Maine has steadily increased by nearly 400% since 1985. Fisheries managers, policy makers, and fishers view this as a success. However, such lucrative monocultures increase the social and ecological consequences of future declines in lobsters. In southern New England, disease and stresses related to increases in ocean temperature resulted in more than a 70% decline in lobster abundance, prompting managers to propose closing that fishery. A similar collapse in Maine could fundamentally disrupt the social and economic foundation of its coast. We suggest the current success of Maine's lobster fishery is a gilded trap. Gilded traps are a type of social trap in which collective actions resulting from economically attractive opportunities outweigh concerns over associated social and ecological risks or consequences. Large financial gain creates a strong reinforcing feedback that deepens the trap. Avoiding or escaping gilded traps requires managing for increased biological and economic diversity. This is difficult to do prior to a crisis while financial incentives for maintaining the status quo are large. The long‐term challenge is to shift fisheries management away from single species toward integrated social‐ecological approaches that diversify local ecosystems, societies, and economies. 相似文献
396.
Abstract A dynamic model based on the linear systems theory is developed in designing a highly cybernetic farming strategy to efficiently manage residuals generated in farm ecosystems. A linear cybernetic model would be used to describe the dynamic behavior of resource flow in the farm ecosystem in which the state variables are resource quantities, and the control variables are residual quantities. The controlled process is defined as the controlled management strategy change. Cybernetic mechanism shows the application of residuals as control measures have determinate effects on the controlled process as along as the farming system is observable and controllable in the control sense. To illustrate the model algorithm the idea is applied to simulate the dynamic response of residual phosphorus concentrations in an integrated pig/corn farming system located in the south Taiwan region. General results show that the residual phosphorous concentration is influenced by farming activities which are controlled by a system of gross input and net output parameters. This paper demonstrates using input‐output analysis technique that residuals generated in the farming system is the most important cybernetic variable, so that the proper management of residuals alone has the potential to maintain future productivity and sustainability. 相似文献
397.
Abstract: Globally, ecosystems are under increasing anthropogenic pressure; thus, many are at risk of elimination. This situation has led the International Union for Conservation of Nature (IUCN) to propose a quantitative approach to ecosystem‐risk assessment. However, there is a need for their proposed criteria to be evaluated through practical examples spanning a diverse range of ecosystems and scales. We applied the IUCN's ecosystem red‐list criteria, which are based on changes in extent of ecosystems and reductions in ecosystem processes, to New Zealand's 72 naturally uncommon ecosystems. We aimed to test the applicability of the proposed criteria to ecosystems that are naturally uncommon (i.e., those that would naturally occur over a small area in the absence of human activity) and to provide information on the probability of ecosystem elimination so that conservation priorities might be set. We also tested the hypothesis that naturally uncommon ecosystems classified as threatened on the basis of IUCN Red List criteria contain more threatened plant species than those classified as nonthreatened. We identified 18 critically endangered, 17 endangered, and 10 vulnerable ecosystems. We estimated that naturally uncommon ecosystems contained 145 (85%) of mainland New Zealand's taxonomically distinct nationally critical, nationally endangered, and nationally vulnerable plant species, 66 (46%) of which were endemic to naturally uncommon ecosystems. We estimated there was a greater number of threatened plant species (per unit area) in critically endangered ecosystems than in ecosystems classified as nonthreatened. With their high levels of endemism and rapid and relatively well‐documented history of anthropogenic change, New Zealand's naturally uncommon ecosystems provide an excellent case‐study for the ongoing development of international criteria for threatened ecosystems. We suggest that interactions and synergies among decline in area, decline in function, and the scale of application of the criteria be used to improve the IUCN criteria for threatened ecosystems. 相似文献
398.
Chantal Gascuel-Odoux Florence Massa Patrick Durand Philippe Merot Olivier Troccaz Jacques Baudry Claudine Thenail 《Environmental management》2009,43(5):921-935
While many scientific studies show the influence of agricultural landscape patterns on water cycle and water quality, only
a few of these have proposed scientifically based and operational methods to improve water management. Territ’eau is a framework
developed to adapt agricultural landscapes to water quality protection, using components such as farmers’ fields, seminatural
areas, and human infrastructures, which can act as sources, sinks, or buffers on water quality. This framework allows us to
delimit active areas contributing to water quality, defined by the following three characteristics: (i) the dominant hydrological
processes and their flow pathways, (ii) the characteristics of each considered pollutant, and (iii) the main landscape features.
These areas are delineated by analyzing the flow connectivity from the stream to the croplands, by assessing the buffer functions
of seminatural areas according to their flow pathways. Hence, this framework allows us to identify functional seminatural
areas in terms of water quality and assess their limits and functions; it helps in proposing different approaches for changing
agricultural landscape, acting on agricultural practices or systems, and/or conserving or rebuilding seminatural areas in
controversial landscapes. Finally, it allows us to objectivize the functions of the landscape components, for adapting these
components to new environmental constraints. 相似文献
399.
We present here a terrestrial carbon cycle model based on a scheme of the phytomass change, which is continuous in time. The experimental information about net primary production, living and dead phytomass, and soil organic matter for various ecosystems is used for calibration of the model. The suggested model enables to characterize terrestrial ecosystems as carbon sources or carbon sinks and to evaluate intensity of these sources and sinks. The model is applied for the European territory of Russia as a case study. Intensity of the total exchange carbon flux for this territory is evaluated. The obtained results allow to conclude that the given territory is the sink of carbon. 相似文献
400.
This is a study of the scientific component of an effort to restore an urban river by removing a low-head dam. The Secor Dam
is owned by a local government entity near Toledo, Ohio. The proposed removal of the last structure impeding flow on the Ottawa
River has broad appeal, but the owner is concerned about liability issues, particularly potential changes to the flood regime,
the presence of contaminated sediments behind the dam, and possible downstream transport of reservoir sediments. Assessing
sediment contamination involved sediment sampling and analysis of trace metals and organic contaminants. Forecasting sediment
transport involved field methods to determine the volume and textural properties of reservoir and upstream sediment and calculations
to determine the fate of reservoir sediments. Forecasting changes in the flood regime involved HEC-RAS hydrological models
to determine before and after dam removal flood scenarios using LiDAR data imported into an ArcGIS database. The resulting
assessment found potential sediment contamination to be minor, and modeling showed that the removal of the dam would have
minimal impacts on sediment transport and flood hazards. Based on the assessment, the removal of the dam has been approved
by its owners. 相似文献