7141 research outputs found
Sort by
Responses of Nutrient Resorption to Human Disturbances in Phoebe bournei Forests
Get PDFNutrient resorption plays an important role in the nutrient conservation of plants and ecosystem nutrient cycling. Although community succession and nutrient addition could regulate plant nutrient resorption, how resorptions of foliar nutrients vary with human disturbances remains unclear. With the economic development, Phoebe bournei forests (PF) have suffered varying degrees of human disturbances in China. In this study, the leaf nutrient resorption efficiency (RE) of the PF under two disturbances (i.e., severe and mild disturbances) were investigated. Results showed that the phosphorus (P) contents of green leaf, senesced leaf, and soil were low under both disturbances, reflecting that the PF had a potential P limitation. Phosphorus and potassium (K) REs were higher under the severe disturbance than those under the mild disturbance. The potassium resorption efficiency was the highest among the three REs under both disturbances. In addition, nutrient resorption efficiencies increased with green leaf nutrient contents under both disturbances. However, there were negative significant relationships of specific leaf area and leaf dry matter content with nutrient resorption under both disturbances. These findings provide a new perspective of nutrient resorption and revealed the potential impact of human disturbances on the nutrient cycle in forest ecosystems
Assessing the contribution of immigrants to Canada\u27s nursing and health care support occupations: a multi-scalar analysis
Get PDFBackground
The World Health Organization adopted the Global Strategy on Human Resources for Health Workforce 2030 in May 2016. It sets specific milestones for improving health workforce planning in member countries, such as developing a health workforce registry by 2020 and ensuring workforce self-sufficiency by halving dependency on foreign-trained health professionals. Canada falls short in achieving these milestones due to the absence of such a registry and a poor understanding of immigrants in the health workforce, particularly nursing and healthcare support occupations. This paper provides a multiscale (Canada, Ontario, and Ontario’s Local Health Integration Networks) overview of immigrant participation in nursing and health care support occupations, discusses associated enumeration challenges, and the implications for health workforce planning focusing on immigrants. Methods
Descriptive data analysis was performed on Canadian Institute for Health Information dataset for 2010 to 2020, and 2016 Canadian Census and other relevant data sources. Results
The distribution of nurses in Canada, Ontario, and Ontario’s Local Health Integration Networks reveal a growth in Nurse Practitioners and Registered/Licensed Practical Nurses, and contraction in the share of Registered Nurses. Immigrant entry into the profession was primarily through the practical nurse cadre. Mid-sized communities registered the highest growth in the share of internationally educated nurses. Data also pointed towards the underutilization of immigrants in regulated nursing and health occupations. Conclusion
Immigrants comprise an important share of Canada’s nursing and health care support workforce. Immigrant pathways for entering nursing occupations are complex and difficult to accurately enumerate. This paper recommends the creation of an integrated health workforce dataset, including information about immigrant health workers, for both effective national workforce planning and for assessing Canada’s role in global health workforce distribution and utilization
Examining the Integration of Landsat Operational Land Imager with Sentinel-1 and Vegetation Indices in Mapping Southern Yellow Pines (Loblolly, Shortleaf, and Virginia Pines)
Get PDFThe mapping of southern yellow pines (loblolly, shortleaf, and Virginia pines) is important to supporting forest inventory and the management of forest resources. The overall aim of this study was to examine the integration of Landsat Operational Land Imager (OLI ) optical data with Sentinel-1 microwave C-band satellite data and vegetation indices in mapping the canopy cover of southern yellow pines. Specifically, this study assessed the overall mapping accuracies of the canopy cover classification of southern yellow pines derived using four data-integration scenarios: Landsat OLI alone; Landsat OLI and Sentinel-1; Landsat OLI with vegetation indices derived from satellite data—normalized difference vegetation index, soil-adjusted vegetation index, modified soil-adjusted vegetation index, transformed soil-adjusted vegetation index, and infrared percentage vegetation index; and 4) Landsat OLI with Sentinel-1 and vegetation indices. The results showed that the integration of Landsat OLI reflectance bands with Sentinel-1 backscattering coefficients and vegetation indices yielded the best overall classification accuracy, about 77%, and standalone Landsat OLI the weakest accuracy, approximately 67%. The findings in this study demonstrate that the addition of backscattering coefficients from Sentinel-1 and vegetation indices positively contributed to the mapping of southern yellow pines
Effects of Color Attributes on Trap Capture Rates of Chrysobothris femorata (Coleoptera: Buprestidae) and Related Species
Get PDFChrysobothris spp. (Coleoptera: Buprestidae) and other closely related buprestids are common pests of fruit, shade, and nut trees in the United States. Many Chrysobothris spp., including Chrysobothris femorata, are polyphagous herbivores. Their wide host range leads to the destruction of numerous tree species in nurseries and orchards. Although problems caused by Chrysobothris are well known, there are no reliable monitoring methods to estimate local populations before substantial damage occurs. Other buprestid populations have been effectively estimated using colored sticky traps to capture beetles. However, the attraction of Chrysobothris to specific color attributes has not been directly assessed. A multi-color trapping system was utilized to determine color attraction of Chrysobothris spp. Specific color attributes (lightness [L*], red to green [a*], blue to yellow [b*], chroma [C*], hue [h*], and peak reflectance [PR]) were then evaluated to determine beetle responses. In initial experiments with mostly primary colors, Chrysobothris were most attracted to traps with red coloration. Thus, additional experiments were performed using a range of trap colors with red reflectance values. Among these red reflectance colors, it was determined that the violet range of the electromagnetic spectrum had greater attractance to Chrysobothris. Additionally, Chrysobothris attraction correlated with hue and b*, suggesting a preference for traps with hues between red to blue. However, males and females of some Chrysobothris species showed differentiated responses. These findings provide information on visual stimulants that can be used in Chrysobothris trapping and management. Furthermore, this information can be used in conjunction with ecological theory to understand host-location methods of Chrysobothris
Effect of Mulch Type and Depth on Rooting of Stem Cuttings and Weed Control in Containers
Get PDFWeeds are a major problem in cutting propagation and compete with the main crop for water, sunlight, and nutrients, thus reducing growth and marketable quality of rooted cuttings. Due to the high labor cost of hand weeding, mulches can be an alternative method for weed control in the propagation environment. The objective of this research was to determine the effect of mulches (coarse vermiculite, rice hulls, paper pellets, and pine pellets) on rooting of stem cuttings and weed control when applied at 0.5- and 1-inch depths. Cuttings of three plant species [‘Nanho Blue’ butterfly bush (Buddleja davidii), ‘Catawba’ crape myrtle (Lagerstroemia indica), ‘Phantom’ hydrangea (Hydrangea paniculata)] were stuck in 2.5-inch-diameter containers filled with pine bark substrate and treated with mulch. In a separate study, seeds of four weed species [creeping woodsorrel (Oxalis corniculata), hairy bittercress (Cardamine hirsuta), large crabgrass (Digitaria sanguinalis), mulberry weed (Fatoua villosa)] were sown onto the mulch surface. Rooting percentage was unaffected by mulch type or depth for any of the three crop species (‘Nanho Blue’ butterfly bush, ‘Catawba’ crape myrtle, ‘Phantom’ hydrangea). Pine pellets did not affect root dry weight of any crop species, but root length and volume of ‘Catawba’ crape myrtle was reduced by pine pellets at 1-inch depth. Rice hulls slightly reduced the root length and volume of ‘Catawba’ crape myrtle, but the reduction was less than 50%. Pine pellets and paper pellets (both depths) reduced growth of all four weed species. Even though weed seeds germinated in pine and paper pellets, seedlings did not grow large enough to potentially affect crop rooting. In conclusion, pine pellets and paper pellets at 0.5-inch depth can be effective in suppressing weed populations with minimal effect on rooting
Teachers’ Reported Use of Phenomenon-Based Learning in Secondary STEM Classrooms
No full textEven though phenomena, observations or experiences that appear in our lives daily, areparticularly important in STEM, historically they have been a missing component inscience education, which frequently focused on general content knowledge.Concentrating primarily on content knowledge does not always give students the tools toapply knowledge to real-world situations. Initiating learning through the lens of a real-world phenomenon encourages students to build STEM knowledge. Rather than having adisconnected learning experience, with phenomenon-based learning, students are moreequipped to make sense of the world around them, design solutions, and problems solve.The purpose of this qualitative study was to explore how STEM educators implementphenomenon-based learning and what techniques they use to increase STEM literacy intheir classrooms. The participants in this study included STEM educators in an urbanMiddle Tennessee school district. Data sources included demographic surveys, interviewswith each of the participants, and curricular artifacts. The research question that guidedthis study was “How are STEM educators implementing phenomenon-based learning?”Insight into the teachers’ motivational, planning and implementation process wasrevealed. Several conclusions were drawn based on this study of teachers’ reported useof phenomenon-based learning including 1) teachers chose activities primarily basedupon administrative support, the more resources, the more rigorous the activity; 2)teachers select activities that will gain attention and interest of their students based uponacademy, hobbies, and culture; and 3) STEM literacy is promoted primarily with the useof journal articles while alternative options are available
Stepwise and Varying Warming Impacts on Heterotrophic Respiration and Microbial Functions in Carbon Poor and Rich Switchgrass Soils
No full textLaboratory soil incubations are used to examine soil responses to changing environment in well-controlled conditions. Stepwise warming (SW) scenario adopted in incubations compares microbial responses at two constant temperatures to simulate warming effects. However, implementing temperature fluctuations in soil-incubations (varying warming (VW) scenario) can mimic in-situ conditions. We investigate SW and VW effects on heterotrophic respiration and underlying microbial mechanisms on two switchgrass (Panicum virgatum L.) soils with contrasting soil organic carbon (SOC) content, one in middle Tennessee with low-SOC (2.05%), another in Texas with high-SOC (8.48%). Soils were incubated for 90 days under SW and VW scenarios with 10 collections. Soil heterotrophic respiration (Rs), cumulative respiration (Rc), microbial biomass carbon & nitrogen (MBC, MBN), biomass-specific heterotrophic respiration (Rss), and extracellular enzyme activities were quantified per collection. Three-way repeated measure ANOVA was conducted for each soil to test main and interactive effects of temperature (warming), warming scenario, and collection on respiration and microbial relevant variables. Results showed warming significantly increased Rs and Rc, reduced enzyme activities associated with nitrogen (N) or phosphorus (P) acquisitions in both soils but significantly increased MBC and Rss in Texas soils. Second, SW resulted in greater respiratory loss than VW in both soils. Last, warming at least doubled Rc under VW but little or no change was observed in SW. Despite positive warming effects on respiration in both soils, this study suggested contrasting warming effects of different temperature change scenarios on soil respiration likely driven by divergent responses in microbial community, enzymatic and physiological features
