Belowground Resource Exploitation in Semiarid Plants: A Comparative Study Using Two Tussock Grasses That Differ in Competitive Ability

The relative competitive abilities of Agropyron desertorum and Agropyron spicatum were compared using Artemisia tridentata transplants as indicator plants. Although these two tussock grasses have similar shoot growth forms and shoot physiological characteristics, they have substantial differences in their competitive abilities. Artemisia had lower survival, growth, reproduction, and water potential when transplanted into neighborhoods of A. desertorum than in neighborhoods of A. spicatum. Plant attributes associated with the differences in competitive ability were explored. Agropyron desertorum and~ spicatum have remarkably similar potential growth rates at warm soil temperatures. In a prolonged cold soil temperature treatment in the greenhouse, A. desertorum had a 66% greater aboveground relative growth rate than A. spicatum. These differences, however, were not apparent for early spring tiller growth rates in the field. Distinct differences in timing of root growth were found between the two tussock grasses. Aqropyron desertorum exhibited greater root growth during winter and early spring and invaded disturbed soil space more rapidly than A. spicatum, especially if the disturbance occurred soon after the snow had melted. Similarly, A. desertorum proliferated its roots in zones of nutrient enrichment created early in the spring sooner than A. spicatum. No differences in root growth were found between species in zones of nutrient enrichment that were created later in the growing season. Despite differences in early spring root growth, water extraction and radiophosphorus acquisition early in the spring were similar for the two grass species. Later in the spring, A. desertorum extracted more water and radiophosphorus than A. spicatum. Differences in resource extraction between the two species in a specific soil layer occurred weeks before A. spicatum, but not A. desertorurn, had obtained maximum root length. Early root growth probably provides A. desertorum an important head start over A. spicatum in soil exploration each growing season. Differences in resource extraction, however, do not become apparent between the two species of Agropyron until plant demand exceeds soil supply rate to the roots

Pantothenic Acid Status of Adolescents

Information on human needs for pantothenic acid is limited and no recommended daily allowance has been established; although a safe and adequate level of 4-7 mg/day has been suggested for adults and adolescents. The adolescent population is often at risk for nutritional problems because of unusual eating patterns and major physiological changes which occur at this time. Pantothenic acid levels in urine, whole-blood and erythrocytes were determined in a healthy adolescent population using radioimmunoassay techniques. Dietary intakes were calculated from 4 day diet records and evaluated using a computer data base developed at Utah State University in conjunction with USDA. Forty-nine percent of the females and 15 percent of the males consumed less than 4 mg/day; however average blood levels for both males and females were in a 11normal11 range relative to other populations {411.9 ± 102.8 ng/ml and 344.5 ± 113.6 ng/ml, respectively). Dietary intake was highly correlated to urinary excretion (p \u3c 0.001). Levels of pantothenic acid in erythrocytes correlated well to dietary intake and urinary excretion. A model was developed to predict circulating levels of pantothenic acid from dietary intake and urinary excretion

United We Stand: Narrative Study to Aid the Counseling Profession in Developing a Coherent Identity

The purpose of the study was to learn how non-counseling-related professions have navigated the developmental issues the counseling profession has been facing such as (1) strengthening identity, (2) presenting as one profession, (3) improving public perception and advocacy, and (4) creating licensure portability. The researchers provide the narratives of six people from three non-counseling-related professions who have been instrumental in the development of their respective professions. The overarching open-ended research question posed was, “What is the narrative history of your profession?” Follow-up questions were used to explore specific challenges within their respective professions that may have been similar to the developmental issues within the counseling profession. The narrative inquiry study results provided four emergent themes of how the participants navigated their developmental issues: Quality Accredited Education; Professional Identity; A Link between Accreditation, National Certification, a State License; and United Advocacy. © 2018: SunHee J. Eissenstat, Lynn Bohecker, and Nova Southeastern University

United We Stand: Narrative Study to Aid the Counseling Profession in Developing a Coherent Identity

The purpose of the study was to learn how non-counseling-related professions have navigated the developmental issues the counseling profession has been facing such as (1) strengthening identity, (2) presenting as one profession, (3) improving public perception and advocacy, and (4) creating licensure portability. The researchers provide the narratives of six people from three non-counseling-related professions who have been instrumental in the development of their respective professions. The overarching open-ended research question posed was, “What is the narrative history of your profession?” Follow-up questions were used to explore specific challenges within their respective professions that may have been similar to the developmental issues within the counseling profession. The narrative inquiry study results provided four emergent themes of how the participants navigated their developmental issues: Quality Accredited Education; Professional Identity; A Link between Accreditation, National Certification, a State License; and United Advocacy

Interactive effects of soil temperature and moisture on Concord grape root respiration

Root respiration has important implications for understanding plant growth as well as terrestrial carbon flux with a changing climate. Although soil temperature and soil moisture often interact, rarely have these interactions on root respiration been studied. This report is on the individual and combined effects of soil moisture and temperature on respiratory responses of single branch roots of 1-year-old Concord grape (Vitis labruscana Bailey) vines grown in a greenhouse. Under moist soil conditions, root respiration increased exponentially to short-term (1 h) increases in temperature between 10 °C and 33 °C. Negligible increases in root respiration occurred between 33 °C and 38 °C. By contrast to a slowly decreasing Q10 from short-term temperature increases, when roots were exposed to constant temperatures for 3 d, the respiratory Q10 between 10 °C and 30 °C diminished steeply with an increase in temperature. Above 30 °C, respiration declined with an increase in temperature. Membrane leakage was 89-98% higher and nitrogen concentration was about 18% lower for roots exposed to 35 °C for 3 d than for those exposed to 25 °C and 15 °C. There was a strong interaction of respiration with a combination of elevated temperature and soil drying. At low soil temperatures (10 °C), respiration was little influenced by soil drying, while at moderate to high temperatures (20 °C and 30 °C), respiration exhibited rapid declines with decreases in soil moisture. Roots exposed to drying soil also exhibited increased membrane leakage and reduced N. These findings of acclimation of root respiration are important to modelling respiration under different moisture and temperature regime

Phylogenetic Signal, Root Morphology, Mycorrhizal Type, and Macroinvertebrate Exclusion: Exploring Wood Decomposition in Soils Conditioned by 13 Temperate Tree Species

Woodlands are pivotal to carbon stocks, but the process of cycling C is slow and may be most effective in the biodiverse root zone. How the root zone impacts plants has been widely examined over the past few decades, but the role of the root zone in decomposition is understudied. Here, we examined how mycorrhizal association and macroinvertebrate activity influences wood decomposition across diverse tree species. Within the root zone of six predominantly arbuscular mycorrhizal (AM) (Acer negundo, Acer saccharum, Prunus serotina, Juglans nigra, Sassafras albidum, and Liriodendron tulipfera) and seven predominantly ectomycorrhizal (EM) tree species (Carya glabra, Quercus alba, Quercus rubra, Betula alleghaniensis, Picea rubens, Pinus virginiana, and Pinus strobus), woody litter was buried for 13 months. Macroinvertebrate access to woody substrate was either prevented or not using 0.22 mm mesh in a common garden site in central Pennsylvania. Decomposition was assessed as proportionate mass loss, as explained by root diameter, phylogenetic signal, mycorrhizal type, canopy tree trait, or macroinvertebrate exclusion. Macroinvertebrate exclusion significantly increased wood decomposition by 5.9%, while mycorrhizal type did not affect wood decomposition, nor did canopy traits (i.e., broad leaves versus pine needles). Interestingly, there was a phylogenetic signal for wood decomposition. Local indicators for phylogenetic associations (LIPA) determined high values of sensitivity value in Pinus and Picea genera, while Carya, Juglans, Betula, and Prunus yielded low values of sensitivity. Phylogenetic signals went undetected for tree root morphology. Despite this, roots greater than 0.35 mm significantly increased woody litter decomposition by 8%. In conclusion, the findings of this study suggest trees with larger root diameters can accelerate C cycling, as can trees associated with certain phylogenetic clades. In addition, root zone macroinvertebrates can potentially limit woody C cycling, while mycorrhizal type does not play a significant role

Remarkable similarity in timing of absorptive fine-root production across 11 diverse temperate tree species in a common garden

Long-term minirhizotron observations of absorptive fine roots provide insights into seasonal patterns of belowground root production and carbon dynamics. Our objective was to compare root dynamics over time across mature individuals of 11 temperate trees species: five evergreen and six deciduous. We analyzed the timing and growth on 1st-and 2nd-order roots in minirhizotron images down to a vertical depth of 35 cm, as well as monthly and total annual length production. Production patterns were related to total annual precipitation of the actual and previous year of root production over 6 years. The main or largest peak of annual fine-root production occurred between June and September for almost all species and years. In most years, when peaks occurred, the timing of peak root production was synchronized across all species. A linear mixed model revealed significant differences in monthly fine-root length production across species in certain years (species x year, P < 0.0001), which was strongly influenced by three tree species. Total annual root production was much higher in 2000–2002, when there was above-average rainfall in the previous year, compared with production in 2005–2007, which followed years of lower-than-average rainfall (2003–2006). Compared to the wetter period all species experienced a decline of at least 75% in annual production in the drier years. Total annual root length production was more strongly associated with previous year’s (P < 0.001) compared with the actual year’s precipitation (P = 0.003). Remarkably similar timing of monthly absorptive fine-root growth can occur across multiple species of diverse phylogeny and leaf habit in a given year, suggesting a strong influence of extrinsic factors on absorptive fine-root growth. The influence of previous year precipitation on annual absorptive fine-root growth underscores the importance of legacy effects in biological responses and suggests that a growth response of temperate trees to extreme precipitation or drought events can be exacerbated across years

Nitrogen forms affect root structure and water uptake in the hybrid poplar

The study analyses the effects of two different forms of nitrogen fertilisation (nitrate and ammonium) on root structure and water uptake of two hybrid poplar (Populus maximowiczii x P. balsamifera) clones in a field experiment. Water uptake was studied using sap flow gauges on individual proximal roots and coarse root structure was examined by excavating 18 whole-root systems. Finer roots were scanned and analyzed for architecture. Nitrogen forms did not affect coarse-root system development, but had a significant effect on fine-root development. Nitrate-treated trees presented higher fine:coarse root ratios and higher specific root lengths than control or ammonium treated trees. These allocation differences affected the water uptake capacity of the plants as reflected by the higher sapflow rate in the nitrate treatment. The diameter of proximal roots at the tree base predicted well the total root biomass and length. The diameter of smaller lateral roots also predicted the lateral root mass, length, surface area and the number of tips. The effect of nitrogen fertilisation on the fine root structure translated into an effect on the functioning of the fine roots forming a link between form (architecture) and function (water uptake)