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Double fertilization in Ephedra, a nonflowering seed plant: its bearing on the origin of angiosperms
Double fertilization and the associated formation of endosperm have long been considered unique and defining characters (autapomorphies) of the angiosperms. During normal fertilization in Ephedra nevadensis, a nonflowering seed plant, fusion of a second sperm nucleus with the ventral canal nucleus occurs regularly within the egg cytoplasm. The occurrence of double fertilization in Ephedra assumes added significance in light of its critical phylogenetic position as a basal member of the most closely related extant group of seed plants (Gnetales) to angiosperms. Thus, double fertilization in angiosperms and Ephedra may represent an evolutionary homology. Published in Science, volume 547, issue 4945, on pages 951 -...
We examined bird and bat mortality at a new 89-turbine windfarm constructed in an environmentally sensitive area in north-central Iowa. The windfarm became operational in November 2001. It is located in cropland between three Wildlife Management Areas (WMA's) with historically high bird use. In the past, migrant and resident waterfowl, shorebirds, raptors, and songbirds moved between the WMA's through the area now occupied by the windfarm. Studies of bird collision mortality in California and elsewhere raised concerns about the possibility of mortalities in this area. From April 15, 2003 and December 15, 2003 we searched for dead animals under 26 randomly selected turbines. Six 76.2 m by 3.0 m transects were maintained...
Lack of a 19th-century baseline temperature against which 20th-century warming can be referenced constitutes a deficiency in understanding recent climate change. Combination of borehole temperature profiles, which contain a memory of surface temperature changes in previous centuries, with the meteorological archive of surface air temperatures can provide a 19th-century baseline temperature tied to the current observational record. A test case in Utah, where boreholes are interspersed with meteorological stations belonging to the Historical Climatological Network, yields a noise reduction in estimates of 20th-century warming and a baseline temperature that is 0.6� +/- 6 0.1�C below the 1951 to 1970 mean temperature...
Some analysts think that biomass offers great potential as a renewable fiel for electricity generation. Biomass’ emissions of greenhouse gases, over its whole fiel cycle, are relatively insignificant when compared to even the “cleanest” of the fossil energy technologies — natural gas. Yet, the external costs (and benefits) of biomass fuel cycles, which stem from impacts other than those associated with greenhouse gases, are not necessarily trivial. Some of these impacts are similar to those that result from the combustion of fossil fbels. Other impacts are unique to biomass fiel cycles. This report describes methods to estimate many of the more important external costs (and benefits) of biomass fiel cycles.
This paper's objective is to apply Intervention Mapping, a planning process for the systematic development of theory- and evidence-based health promotion interventions, to the development of interventions to promote energy conservation behavior. Intervention Mapping (IM) consists of six steps: needs assessment, program objectives, methods and applications, program development, planning for program implementation, and planning for program evaluation. Examples from the energy conservation field are provided to illustrate the activities associated with these steps. It is concluded that applying IM in the energy conservation field may help the development of effective behavior change interventions, and thus develop...
Categories: Publication;
Types: Citation;
Tags: Changing,
attitudes,
public,
quality of life,
science
Offshore exploration and production of oil and gas have increased significantly in the last decade. Computer models are used in emergency response, contingency planning, and impact assessment to simulate the behavior of oil and gas if accidentally released from a well, pipeline, or ship. There are two types of models used for this purpose-models that have both plume dynamics stage and the advection diffusion stage and models that are of simplified nature that has only the advection diffusion stage. This paper compares both types of models and shows what information are similar and what are different and under what conditions. The paper also examines in detail about different criteria that can be used as the transition...
Categories: Publication;
Types: Citation;
Tags: balancing,
historical,
perspective,
protected,
role,
It is increasingly clear that a wide range of stakeholders should be included in the problem formulation phase of research aimed at solving environmental problems; indeed the inclusion of stakeholders at this stage has been formalized as an integral part of ecological risk assessment. In this paper, we advocate the additional inclusion of stakeholders in the refinement of research methods and protocols and in the execution of the research, rather than just at the final communication and reporting phase. We use a large study of potential radionuclide levels in marine biota around Amchitka Island as a case study. Amchitka Island, in the Aleutian Island Chain of Alaska, was the site of three underground nuclear tests...
Models project that land ecosystems may be able take up a considerable proportion of the carbon dioxide released by human activities, thereby counteracting the anthropogenic emissions. In their Perspective, Hungate et al. argue that these carbon uptake estimates are too high because the models do not take other nutrients such as nitrogen into account appropriately. The authors estimate that there will not be enough nitrogen available to sustain the high carbon uptake scenarios. Nutrients other than nitrogen may also affect carbon uptake in ways not captured by most models. Published in Science, volume 302, issue 5650, on pages 1512 - 3, in 2003.
Southwestern Fishes and the Enigma of "Endangered Species": Man's invasion of deserts creates problems for native animals, especially for freshwater fishes, credited to Deacon, James E, published in 1968. Published in Science, volume 159, issue 3822, on pages 1424 - 1432, in 1968.
How anthropogenic climate change will affect hydroclimate in the arid regions of southwestern North America has implications for the allocation of water resources and the course of regional development. Here we show that there is a broad consensus among climate models that this region will dry in the 21st century and that the transition to a more arid climate should already be under way. If these models are correct, the levels of aridity of the recent multiyear drought or the Dust Bowl and the 1950s droughts will become the new climatology of the American Southwest. Published in Science, volume 316, issue 5828, on pages 1181 - 1184, in 2007.
The Wyoming Landscape Conservation Initiative (WLCI) was launched in 2007 in response to concerns about threats to the State s world class wildlife resources, especially the threat posed by rapidly increasing energy development in southwest Wyoming. The overriding purpose of the WLCI is to assess and enhance aquatic and terrestrial habitats at a landscape scale, while facilitating responsible energy and other types of development. The WLCI includes partners from Federal, State, and local agencies, with participation from public and private entities, industry, and landowners. As a principal WLCI partner, the U.S. Geological Survey (USGS) provides multidisciplinary scientific and technical support to inform decisionmaking...
Categories: Publication;
Types: Citation;
Tags: Conservation,
Initiative,
Landscape,
U.S.,
U.S. Geological Survey,
Globalization may be the mantra of the new economy, but for the environment it may spell disaster, as international travel and trade are creating a tidal wave of exotic species that is transforming ecosystems worldwide. If ecologists could identify likely invaders, governments could simply restrict imports of those treacherous species, and managers could mercilessly weed them out or trap them. But the few predictive models are still hotly debated, and they apply to only a narrow range of organisms at best. Published in Science, volume 285, issue 5435, on pages 1834 - 1836, in 1999.
We examined bird and bat mortality at a new 89-turbine windfarm constructed in an environmentally sensitive area in north-central Iowa. The windfarm became operational in November 2001. It is located in cropland between three Wildlife Management Areas (WMA's) with historically high bird use. In the past, migrant and resident waterfowl, shorebirds, raptors, and songbirds moved between the WMA's through the area now occupied by the windfarm. Studies of bird collision mortality in California and elsewhere raised concerns about the possibility of mortalities in this area. From April 15, 2003 and December 15, 2003 we searched for dead animals under 26 randomly selected turbines. Six 76.2 m by 3.0 m transects were maintained...
This project was conducted to evaluate the feasibility of using geothermal effluents for developing and maintaining waterfowl wetlands. Information in the document pertains to a seven State area the West where geothermal resources have development potential. Information is included on physiochemical characteristics of geothermal effluents; known effects of constituents in the water on a wetland ecosystem and water quality criteria for maintaining a viable wetland; potential of sites for wetland development and disposal of effluent water from geothermal facilities; methods of ‘disposal of effluents, including advantages of each method and associated costs; legal and Institutional constraints which could affect geothermal...
Rising atmospheric carbon dioxide (Ca), a product of fossil fuel burning, land-use change, and cement manufacture, is expected to cause a large carbon sink in land ecosystems, partly mitigating human-driven climate change (1). Increasing biological nitrogen fixation with rising Ca has been invoked as a means to provide the N necessary to support C accumulation (2). As in many short-term experiments (3), we found that Ca enrichment increased N fixation during the first year of treatment in an oak woodland. However, the effect declined and disappeared by the third year. Ca enrichment consistently depressed N fixation during the 5th, 6th, and 7th years of treatment. Reduced availability of the micronutrient molybdenum,...
The U.S. Environmental Protection Agency (EPA, or the Agency) conducted a study that assesses the potential for contamination of underground sources of drinking water (USDWs) from the injection of hydraulic fracturing fluids into coalbed methane (CBM) wells. To increase the effectiveness and efficiency of the study, EPA has taken a phased approach. Apart from using real world observations and gathering empirical data, EPA also evaluated the theoretical potential for hydraulic fracturing to affect USDWs. Based on the information collected and reviewed, EPA has concluded that the injection of hydraulic fracturing fluids into CBM wells poses little or no threat to USDWs and does not justify additional study at this...
Categories: Publication;
Types: Citation;
Tags: Conservation,
Initiative,
Landscape,
U.S.,
U.S. Geological Survey,
The body temperature of desert iguanas implanted with miniature temperature-sensitive radio transmitters was continuously monitored in their natural habitat. Extensive thermoregulatory behavior occurred in retreat burrows prior to morning emergence. Such behavior permits the igluana to emerge from below ground at its preferred body temperature rather than suboptimal temperature at which activity in the burrow is initiated. Published in Science, volume 156, issue 3783, on pages 1757 - 1759, in 1967.
Evaporative water loss from the integument of the desert tortoise Gopherus agassizii constitutes a major proportion of the water loss, but is far less than in tortoises from wetter regions. Respiratory water loss also is less. Published in Science, volume 154, issue 3751, on pages 911 - 911, in 1966.
Globalization may be the mantra of the new economy, but for the environment it may spell disaster, as international travel and trade are creating a tidal wave of exotic species that is transforming ecosystems worldwide. If ecologists could identify likely invaders, governments could simply restrict imports of those treacherous species, and managers could mercilessly weed them out or trap them. But the few predictive models are still hotly debated, and they apply to only a narrow range of organisms at best. Published in Science, volume 285, issue 5435, on pages 1834 - 1836, in 1999.
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