875 resultados para seedling establishment
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This paper employs establishment level data from the annual respondents database to consider technological differences between establishments operating in the UK. We adopt very precise measures of technology, arguably much more detailed than have hitherto been employed to address the key question of whether use of technology differs by nationality. After numerous controls we find that typically North American establishments have a higher probability of being more technologically intensive than their UK counterparts. This result also stands up in panel analysis. © Scottish Economic Society 2005, Published by Blackwell Publishing.
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A sample of run-off water from a vertical, slate rock surface in Wales, U.K. contained abundant fragments of the lichen Parmelia glabratula ssp. fuliginosa from about 0.6 to 8.0 mm in diameter, a few fragments of Parmelia conspersa from 0.6 to 4.0 mm in diameter and a large number of unidentified propagules from 0.2 to 0.5 mm in diameter. The colonization of permanent plots on the rock surface was studied over six years. At the end of the experiment relatively few thalli of Parmelia conspersa, Parmelia glabratula ssp. fuliginosa and Buellia aethalea had established in plots on undisturbed and newly-exposed slate. Fragments (2 mm in diameter) of Parmelia conspersa placed on horizontal pieces of slate survived up to 120 days in cracks, 20 days on a thin smear of bird droppings but only 2-3 days on smooth slate, against small joints in the rock or in small holes. Isidia of Parmelia conspersa placed on horizontal pieces of slate established equally in plots on smooth undisturbed slate and in plots on the surface exposed after the removal of large Parmelia conspersa thalli, but less well on newly-exposed slate. These results suggest that lichen propagules are abundant in run-off water but establishment is a hazardous process. This may be attributable to a shortage of suitable sites on the substratum for attachment of propagules.
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Dispersal, establishment and survival were studied in a population of Hypogymnia physodes (L.) Nyl. growing on an isolated tree (Prunus blireiana L.) at a site in North Seattle, U.S.A. Lichen propagules were trapped daily on adhesive strips pinned to various sites on the tree over a period of 36 days. Both soredia and fragments were deposited on the strips, particularly on the upper branches of the tree, with soredia being considerably more numerous than fragments. Daily variation in total soredia deposited did not correlate with 10 climatic variables including wind speed, relative humidity and average temperature. Establishment and survival of propagules were studied by introducing soredia and fragments into various sites on the bark and by observing the distribution of small thalli in different microsites. Microtopography of bark significantly influenced establishment and survival. Survival was poor on smooth bark compared with survival on algal or lichen crusts and on rough bark. Survival of soredia did not vary significantly at different locations on the tree. It is likely that colonization of the tree by H. physodes occurs largely by soredia. Colonization appears to be limited more by the range of dispersal over the tree than by differential survival over different parts of the tree.
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In the early 1990's, outline designs for two wetland nature reserves were being prepared: the Teeside International Nature Reserve (TINR) and the Cardiff Bay Barrage Environmental Compensation Measures at Redwick, Gwent. The initial design for both proposals identified reedbed as a desirable habitat for establishment. The initial design works identified the importance of reedbed evapotranspiration [ET(Reed)] within the water budget, however, literature searches identified a paucity of information on this parameter. Field experiments for the measurement of ET(Reed) from Phragmites australis are described for three sites distributed across England and Wales. Reference Crop Evapotranspiration (ETo) was calculated using techniques recommended by the Food and Agriculture Organisation. A technique for the calculation of a reedbed crop coefficient [Kc(Reed)[, from ET(Reed) and ETo data is discussed. Kc(Reed) values produced in the project were found to be similar to those developed previously in continental Europe. Mean monthly and crop development stage Kc(Reed) values are presented which are applicable in the UK and possibly worldwide. A conceptual hydrological model of surface water fed reedbed systems is developed, and used to calculate the hydrological sustainability of reedbed creation areas in the UK. Finally, the water budget model is verified using data from a small clay catchment located on the TINR. In addition, a methodology is developed for the hydrological design of surface water fed reedbed systems, and recommendations required for the feasibility, design and establishment stage of reedbed creation sites. Further research needs are also identified.
Some obstacles to the establishment of a universal method of education for parenthood by the P.N.E.U
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Iridescent blue leaf coloration in four Malaysian rain forest understory plants, Diplazium tomentosum Bl. (Athyriaceae), Lindsaea lucida Bi. (Lindsaeaceae), Begonia pavonina Ridl. (Begoniaceae), and Phyllagathis rotundifolia Bl. (Melastoma- taceae) is caused by a physical effect, constructive interference of reflected blue light. The ultrastructural basis for this in D. tomentosum and L. lucida is multiple layers of cellulose microfibrils in the uppermost cell walls of the adaxial epidermis. The helicoidal arrangement of these fibrils is analogous to that which produces a similar color in arthropods. In B. pavonina and P. rotundifolia the blue-green coloration is caused by parallel lamellae in specialized plastids adjacent to the abaxial wall of the adaxial epidermis. The selective advantage of this color production, if any, is unknown.
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Seedlings of the red mangrove, Rhizophora mangle L., were grown under light conditions differing in both photosynthetic photon flux density (PPFD) and spectral quality (red:far-red ratio, R:FR). During the first 8 mo of development, parameters of stem, leaf, and root growth were affected by PPFD. Significant responses to lowered R:FR, however, were limited to internode extension. The results are moderately indicative of a strategy to persist in shade, but illustrate the complexity of light responses and suggest that precise categorization as shade-tolerant or -intolerant may be unbefitting for this species at this particular stage of development.
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The purpose of this study was to establish a polymerase chain reaction (PCR)-restriction enzyme assay for detecting the hereditary hemochromatosis (HHC) mutation, C282Y, in gestational and gestational diabetic subjects in South Florida. DNA samples from 43 gestational subjects were amplified by PCR, digested with RsaI, and analyzed by electrophoresis. An allelic frequency of 2.33%, or 4.65% heterozygosity, was observed. The assay is successful and applicable to future studies on HHC and gestational diabetes. ^
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The Balmis expedition, sent to America by the Spanish monarch Charles IV in 1803, was a watershed in the history of Medicine as it made smallpox vaccination available for the first time, effectively prevented the disease from spreading, and saved thousands of lives. Immunization required complex administrative measures and political decisions including the creation of Vaccination Boards, all of which involved different sectors of Spanish American society. This dissertation argues that at the beginning of the nineteenth century the Spanish American colonial state had reached some level of maturity and cohesion that made it capable of executing this complex project in public health. The significance of this mobilization and the every-day experience in implementing this new public health measure is the center of this work. It is situated geographically in Venezuela and Cuba, entities which took different evolutionary paths in the nineteenth century. The organization and functioning of Vaccination Boards in these two areas are used to illustrate the state formation process, and sharp political differences in this critical period.
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This study examined whether high nutrient concentrations associated with leaf-cutting ant nests influence plant growth and plant water relations in Amazon rain forests. Three nests of Atta cephalotes were selected along with 31 Amaioua guianensis and Protium sp. trees that were grouped into trees near and distant (>10 m) from nests. A 15N leaf-labelling experiment confirmed that trees located near nests accessed nutrients from nests. Trees near nests exhibited higher relative growth rates (based on stem diameter increases) on average compared with trees further away; however this was significant for A. guianensis (near nest 0.224 y−1 and far from nest 0.036 y−1) but not so for Protium sp. (0.146 y−1 and 0.114 y−1 respectively). Water relations were similarly species-specific; for A. guianensis, near-nest individuals showed significantly higher sap flow rates (16 vs. 5 cm h−1), higher predawn/midday water potentials (−0.66 vs. −0.98 MPa) and lower foliar δ13C than trees further away indicating greater water uptake in proximity to the nests while the Protium sp. showed no significant difference except for carbon isotopes. This study thus shows that plant response to high nutrient concentrations in an oligotrophic ecosystem varies with species. Lower seedling abundance and species richness on nests as compared with further away suggests that while adult plants access subterranean nutrient pools, the nest surfaces themselves do not encourage plant establishment and growth.
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The hydrodynamics of tree islands during the growth of newly planted trees has been found to be influenced by both vegetation biomass and geologic conditions. From July 2007 through June 2009, groundwater and surface-water levels were monitored on eight recently planted tree islands at the Loxahatchee Impoundment Landscape Assessment (LILA) facility in Boynton Beach, Florida, USA. Over the 2-year study, stand development coincided with the development of a water-table depression in the center of each of the islands that was bounded by a hydraulic divide along the edges. The water-table depression was greater in islands composed of limestone as compared to those composed of peat. The findings of this study suggest that groundwater evapotranspiration by trees on tree islands creates complex hydrologic interactions between the shallow groundwater in tree islands and the surrounding surface water and groundwater bodies.
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Within the main elements of economic sustainability, socio-cultural sustainability, and environmental sustainability, the criteria of 'carrying capacity’ have ben emphasized through residents’ perception analysis to explore practical methods towards the application and implementation of such criteria. As data analysis revealed, the main tourist resources in the case of North Cyprus –the coast and the beach- have a certain capacity to sustain the impact and pressure of tourism. Despite the significance of the indigenous environment and with respect to the residents’ perception of optimum carrying capacity levels, this issue has not been given a due consideration. This has resulted in a process of coastal development which bypasses any measure ore application of a standard to harmonize the degree of physical development and the capacity of the beach. The main objective of this paper is to establish the concept of ‘carrying capacity’ as the means to achieve the reconciliation of environmental impacts with tourism development. The study concludes that, if carrying capacity measurement and its implementation are not incorporated into the planning decision as a clear policy, there will be grave negative consequences for those resources attracting visitors.
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1. Area of Investigation The relative need of higher standards in healthcare foodservice facilities. Individual opinions of foodservice directors. 2. Materials and Methods Used Existing text, trade publications, interviews with industry leaders, conferences with estemmed professors and the author's own experience were used for research and evaluation. An important method used to evaluate the need for higher standards was a descriptive survey and the analysis thereof. 3. Major Findings A. The survey showed, with a 42 percent response, that the overwhelming majority of the respondents have problems within their department. B. It is presumed that these problems are caused by a lack of standards and/or a failure to meet existing standards. 4. Results and Conclusions A. The objectives of the majority of health-care facilities is to provide the best possible care at lowest possible price. The objectives of the foodservice department is to provide the best possible food at the most reasonable cost. B. Continuous education of foodservice directors in all facets of the industry are necessary so that each foodservice director has the capacity to establish and maintain, and in some cases surpass his or her own standards. C. Where no standards exist minimum requirements should be set to satisfy the objectives and goals of both the facility and foodservice department.
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Between May 1920 and March 1923, there were seventy-three houses belonging to the County Cork establishment burnt down by IRA and anti-treaty forces. More houses were destroyed by this method in Cork than in any other Irish county in the same timeframe. The establishment were targeted by the IRA for their political, military and social persuasions that were essentially in opposition to the nationalist movement. The motivations behind these burnings is examined, the main reasons being reprisals for actions taken by Crown forces, military reasons, loyalty of house owners to the British government and agrarianism. The geographical distribution of these burnings is also provided to reveal how active individual IRA brigades were that operated within the county. Though there were few areas of the county left unaffected by the occurrence of arson attacks, there were higher concentrations of burnings in some areas. The house burnings in County Cork did not conform to the national pattern of house burnings and the reasons for this are explored. This study argues that the presence of Crown forces in Cork and their implementation of an official reprisal policy in January 1921 escalated military conflict, and arson attacks became a key tactic utilised by IRA forces in response to this policy. The aftermath of house burnings for members of the establishment is revealed through the various compensation committees that were formed after both the War of Independence and Civil War. Key sources for this study included personal papers of both the establishment and military figures, IRA witness statements, local and national newspapers, the 1901 and 1911 Irish Censuses, Colonial Office Papers, compensation claims filed with the British government and Irish Free State, and others from archives throughout Ireland and the United Kingdom.