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Regional economic impact assessment (REIA) and social impact assessment (SIA) are methodologically close, since REIA provides predictions of change in employment both directly and indirectly resulting from a project, thereby giving some indication of future population changes, derived demand for social services and infrastructure, and the likely regional social mix. There are, however, a number of theoretical difficulties with conventional REIAs. As extrapolations they normally avoid discussion of processes of structural change, which could result in substantial changes within the time horizon of a project. Another issue is the justification for including secondary project impacts in assessing a project's worth....
Interspecific interactions of herbivores sharing a host plant may be important in structuring herbivore communities. We investigated host plant-mediated interactions of root (Hylobius transversovittatus) and leaf herbivores (Galerucella calmariensis), released to control purple loosestrife (Lythrum salicaria) in North America, in field and potted plant experiments. In the potted plant experiments, leaf herbivory by G. calmariensis reduced H. transversovittatus larval survival (but not larval development) but did not affect oviposition preference. Root herbivory by H. transversovittatus did not affect either G. calmariensis fitness or oviposition preference. In field cage experiments, we found no evidence of interspecific...
The alien grass Bromus tectorum dominates stable annual-plant communities that have replaced native shrub-perennial grass communities over much of the semi-arid western United States. We conducted field competition experiments between B. tectorum and a native grass, Elymus elymoides, on two sites to determine the effects of B. tectorum competition on perennial grasses, and the role of B. tectorum competition in the stability of B. tectorum-dominated communities. B. tectorum competition acting on seedling-stage E. elymoides plants greatly reduced first-year relative growth rates and biomass which, in turn, reduced second-year survival, biomass, and flowering. However, B. tectorum competition acting on older E. elymoides...
• Theoretical and empirical research has supported the hypothesis that plant–plant interactions change from competition to facilitation with increasing abiotic stress. However, the consistency of such changes has been questioned in arid and semiarid ecosystems. • During a drought in the semiarid south-western USA, we used observations and a field experiment to examine the interactions between juveniles of a foundation tree (Pinyon pine, Pinus edulis ) and a common shrub (Apache plume, Fallugia paradoxa ) in replicated areas of high and low stress. • The presence of F. paradoxa reduced P. edulis performance at low-stress sites, but had the opposite effect at high-stress sites. However, the intensity of the...
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The relative competitive abilities of Agropyron desertorum and Agropyron spicatum under rangeland conditions were compared using Artemisia tridentata ssp. wyomingensis transplants as indicator plants. We found A. desertorum to have substantially greater competitive ability than A. spicatum as manifested by the responses of Artemisia shrubs that were transplanted into nearly monospecific stands of these grass species. The Artemisia indicator plants had lower survival, growth, reproduction, and late-season water potential in the neighborhoods dominated by A. desertorum than in those dominated by A. spicatum. In similar, essentially monospecific grass stands, neutron probe soil moisture measurements showed that stands...
Distributional patterns and species diversity of benthic insects in an alpine stream in Gunnison County, Colorado, USA were investigated on several levels of spatial scale, from faunal replacement over 1,000 vertical m to microdistribution within the stony substratum. Ecotones including zonation in terrestrial vegetation and in trout distribution did not appear to affect faunal replacement. Competition among congeners accounted for 7-30% of the cases, while in the majority of species, faunal replacement appeared to be associated with gradual changes in the physical gradient. Trout zonation may affect total numbers of insects, however, as the trout-free headwaters had two to six times higher insect densities. Microdistribution...
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A combination of altered fire regimes and pathogens has contributed towards densification and encroachment by shade-tolerant species into areas traditionally dominated by whitebark pine. As such, the CMP Hi5 Working Group technical team suggest canopy cover as a proxy for species encroachment. Stands with tree cover greater than 60% suggest successional species are outcompeting whitebark pine.
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Seedlings of the succulent crassulacean acid metabolism (CAM plant Agave deserti in the northwestern Sonoran Desert were found only in sheltered microhabitats, nearly all occurring under the canopy of a desert bunchgrass, Hilaria rigida. Apparently because soil surface temperatures can reach 71@?C in exposed areas, seedlings were generally located near the center or on the northern side of this nurse plant. Both species have shallow root systems, about half of the roots of H. rigida and all those for seedlings of A. deserti occurring above soil depths of 0.08 m. To examine competition for water between the nurse plant and an associated seedling, a three-dimensional model for root water uptake was developed. The...
I investigated the individual and joint effects of simulated herbivory and interspecific competition on survival of Coleogyne ramosissima Torr. (blackbrush) seedlings. Seeds of C. ramosissima and Bromus rubens L. (red brome grass) were collected at mid-elevations (1220 to 1770 m) of the Spring Mountains in southern Nevada. A pot trial experiment was conducted for six months (27 wk) in a controlled environmental greenhouse. This trial experiment, consisting of a 2 � 2 factorial design with simulated rodent herbivory and interspecific competition with B. rubens as the main effects, resulted in four treatments. Herbivory on C. ramosissima by heteromyid and non-heteromyid species of rodents was simulated by clipping...
Food demand influences agricultural production. Modern agricultural practices have resulted in polluted soil, air, and water; eroded soil; dependence on imported oil; and loss of biodiversity. The goal of this research was to compare the environmental effect of a vegetarian and nonvegetarian diet in California in terms of agricultural production inputs, including pesticides and fertilizers, water, and energy used to produce commodities. The working assumption was that a greater number and amount of inputs were associated with a greater environmental effect. The literature supported this notion. To accomplish this goal, dietary preferences were quantified with the Adventist Health Study, and California state agricultural...
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Extracting useful and accurate information from scanned geologic and other earth science maps is a time-consuming and laborious process involving manual human effort. To address this limitation, the USGS partnered with the Defense Advanced Research Projects Agency (DARPA) to run the AI for Critical Mineral Assessment Competition, soliciting innovative solutions for automatically georeferencing and extracting features from maps. The competition opened for registration in August 2022 and concluded in December 2022. Training and validation data from the map feature extraction challenge are provided here, as well as competition details and a baseline solution. The data were derived from published sources and are provided...
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Extracting useful and accurate information from scanned geologic and other earth science maps is a time-consuming and laborious process involving manual human effort. To address this limitation, the USGS partnered with the Defense Advanced Research Projects Agency (DARPA) to run the AI for Critical Mineral Assessment Competition, soliciting innovative solutions for automatically georeferencing and extracting features from maps. The competition opened for registration in August 2022 and concluded in December 2022. Training and validation data from the map georeferencing challenge are provided here, as well as competition details and a baseline solution. The data were derived from published sources and are provided...
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Extracting useful and accurate information from scanned geologic and other earth science maps is a time-consuming and laborious process involving manual human effort. To address this limitation, the USGS partnered with the Defense Advanced Research Projects Agency (DARPA) to run the AI for Critical Mineral Assessment Competition, soliciting innovative solutions for automatically georeferencing and extracting features from maps. The competition opened for registration in August 2022 and concluded in December 2022. Training and validation data from the competition are provided here, as well as competition details and baseline solutions. The data are derived from published sources and are provided to the public to...
Abstract (from http://www.tandfonline.com/doi/full/10.1080/02755947.2016.1146179): Over the last decade, the abundance of Largemouth Bass Micropterus salmoideshas increased in many northern Wisconsin lakes, causing concern among anglers and biologists regarding the potential for Largemouth Bass to negatively affect populations of Walleye Sander vitreus through predation or competition for prey. Our objectives were to determine whether (1) diet overlap and predation occurred between adult Walleyes and Largemouth Bass in four northern Wisconsin lakes and (2) the use of DNA barcoding to reduce unidentifiable fish in diet samples affected conclusions regarding diet overlap. A single occurrence of Walleye predation was...
Invasion of natural ecosystems by exotic plant species is a major threat to biodiversity. Disturbance to native plant communities, whether natural or management induced, is a primary factor contributing to successful invasion by exotic plant species. Herbivory by both wild and domestic ungulates exerts considerable impact on structure and composition of native plant communities. Intensive herbivory by ungulates can enhance exotic plant invasion, establishment, and spread for three reasons: (1) many exotic plants are adapted to ground disturbances such as those caused by ungulate feeding, trampling, and movements; (2) many exotic plants are adapted for easy transport from one area to another by ungulates via endozoochory...
The primary hypothesis for the astonishing success of many exotics as community invaders relative to their importance in their native communities is that they have escaped the natural enemies that control their population growth ? the `natural enemies hypothesis'. However, the frequent failure of introduced biocontrols, weak consumer effects on the growth and reproduction of some invaders, and the lack of consistent strong top-down regulation in many natural ecological systems indicate that other mechanisms must be involved in the success of some exotic plants. One mechanism may be the release by the invader of chemical compounds that have harmful effects on the members of the recipient plant community (i.e., allelopathy)....
A key selling point for the restructuring of electricity markets was the promise of lower prices. There is not much consensus in earlier studies on the effects of electricity deregulation in the U.S., particularly for residential customers. Part of the reason for not finding a consistent link with deregulation and lower prices was that the removal of transitional price caps led to higher prices. In addition, the timing of the removal of price caps coincided with rising fuel prices, which were passed on to consumers in a competitive market. Using a dynamic panel model, we analyze the effect of participation rates, fuel costs, market size, a rate cap and switch to competition for 16 states and the District of Columbia....
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These data were compiled in order to represent long-term (multi-decadal) forest growth across eight different experimental forests in the United States, each with replicated levels of density treatments, as well as an important drought index correlated to growth. Forests around the world are experiencing severe droughts and elevated competitive intensity due to increased tree density. These data can be utilized to not only examine differences in within-stand competition, as well the trends and impact of drought in different forests across a broad climatic gradient, but also the influence of interactions between drought and competition on forest growth. Growth is measured as a treatment level, annual basal area increment...
Categories: Data; Tags: Argonne Experimental Forest, Arizona, Bartlett Experimental Forest, Birch Lake Experiment, Black Hills Experimental Forest, All tags...
The demographic consequences of a severe drought year were examined for two experimental plantings of the herbaceous desert perennial Cryptantha flava(Boraginaceae) in northeastern Utah, United States. A total of 6680 nutlets were planted individually or in clusters of four both under shrubs and in open microhabitats within two natural populations. Survival, growth, and flowering as a function of density and microhabitat were followed for 7 years, including 1 year when precipitation just before and during the growing season was 74.5% below normal. The design permitted assessment of how intraspecific density and shrub cover affect demographic response to drought. Mortality increased and flowering decreased dramatically...
map background search result map search result map Competitive Ability Is Linked to Rates of Water Extraction. A Field Study of Two Aridland Tussock Grasses Interactions Between Seedlings of Agave Deserti and the Nurse Plant Hilaria Rigida Long-term Experimental Forest Growth and Drought Data USGS 1:24000-scale Quadrangle for Competition, MO 1987 Training and validation data from the AI for Critical Mineral Assessment Competition Map georeferencing challenge training and validation data Map feature extraction challenge training and validation data Whitebark Pine- Interspecific Competition USGS 1:24000-scale Quadrangle for Competition, MO 1987 Interactions Between Seedlings of Agave Deserti and the Nurse Plant Hilaria Rigida Competitive Ability Is Linked to Rates of Water Extraction. A Field Study of Two Aridland Tussock Grasses Whitebark Pine- Interspecific Competition Long-term Experimental Forest Growth and Drought Data Training and validation data from the AI for Critical Mineral Assessment Competition Map georeferencing challenge training and validation data Map feature extraction challenge training and validation data