Tradeoffs and Synergies in Tropical Forest Root Traits and Dynamics for Nutrient and Water Acquisition: Field and Modeling Advances

Vegetation processes are fundamentally limited by nutrient and water availability, the uptake of which is mediated by plant roots in terrestrial ecosystems. While tropical forests play a central role in global water, carbon, and nutrient cycling, we know very little about tradeoffs and synergies in root traits that respond to resource scarcity. Tropical trees face a unique set of resource limitations, with rock-derived nutrients and moisture seasonality governing many ecosystem functions, and nutrient versus water availability often separated spatially and temporally. Root traits that characterize biomass, depth distributions, production and phenology, morphology, physiology, chemistry, and symbiotic relationships can be predictive of plants’ capacities to access and acquire nutrients and water, with links to aboveground processes like transpiration, wood productivity, and leaf phenology. In this review, we identify an emerging trend in the literature that tropical fine root biomass and production in surface soils are greatest in infertile or sufficiently moist soils. We also identify interesting paradoxes in tropical forest root responses to changing resources that merit further exploration. For example, specific root length, which typically increases under resource scarcity to expand the volume of soil explored, instead can increase with greater base cation availability, both across natural tropical forest gradients and in fertilization experiments. Also, nutrient additions, rather than reducing mycorrhizal colonization of fine roots as might be expected, increased colonization rates under scenarios of water scarcity in some forests. Efforts to include fine root traits and functions in vegetation models have grown more sophisticated over time, yet there is a disconnect between the emphasis in models characterizing nutrient and water uptake rates and carbon costs versus the emphasis in field experiments on measuring root biomass, production, and morphology in response to changes in resource availability. Closer integration of field and modeling efforts could connect mechanistic investigation of fine-root dynamics to ecosystem-scale understanding of nutrient and water cycling, allowing us to better predict tropical forest-climate feedbacks

Properties using metallic amorphous ribbons from (Fe-Co-Ni)- metalloid system, obtained by melt-quenching

The paper presents an original equipment designed and achieved at the Polytechnic Institute of Iassy , for obtaining continuous amorphous metallic ribbons through the melt quenching method and study of some properties using to ribbons from (Fe-Co-Ni)-metalloid system

The rise of digital intelligence: challenges for public relations education and practices

Purpose This research paper explores the development of four categories of skills (operational, informational, strategic and digital fluency) as dimensions of the digital intelligence. The purpose of the pilot study is to determine the consequences of these gaps on PR practices and the directions for educational adaptation.Design/methodology/approach A questionnaire was applied on a convenience sample of 98 PR students from Romania, in March 2014. The majority of students (n = 88) were of 20 to 25 years of age.Findings The results of the survey showed an approximately equal level of development for each of the four skills in the sample of PR students (with a lower degree for the information skills). The general level of development is rather good and shows that the digital literacy acquirement is a need for the specialists from older generations to communicate with younger publics.Research limitations/implications The third category of skills (strategic skills) has been coded as a set of actions - instead of being coded as a set of self-assessed abilities - which created differences in measuring.Originality/value The results showed the level of public relations students related to the development of new skills in the digital environment