Explaining global increases in water use efficiency: why have we overestimated responses to rising atmospheric CO(2) in natural forest ecosystems?

BackgroundThe analysis of tree-ring carbon isotope composition (δ(13)C) has been widely used to estimate spatio-temporal variations in intrinsic water use efficiency (iWUE) of tree species. Numerous studies have reported widespread increases in iWUE coinciding with rising atmospheric CO(2) over the past century. While this could represent a coherent global response, the fact that increases of similar magnitude were observed across biomes with no apparent effect on tree growth raises the question of whether iWUE calculations reflect actual physiological responses to elevated CO(2) levels.Methodology/resultsHere we use Monte Carlo simulations to test if an artifact of calculation could explain observed increases in iWUE. We show that highly significant positive relationships between iWUE and CO(2) occur even when simulated data (randomized δ(13)C values spanning the observed range) are used in place of actual tree-ring δ(13)C measurements. From simulated data sets we calculated non-physiological changes in iWUE from 1900 to present and across a 4000 m altitudinal range. This generated results strikingly similar to those reported in recent studies encompassing 22 species from tropical, subtropical, temperate, boreal and mediterranean ecosystems. Only 6 of 49 surveyed case studies showed increases in iWUE significantly higher than predicted from random values.Conclusions/significanceOur results reveal that increases in iWUE estimated from tree-ring δ(13)C occur independently of changes in (13)C discrimination that characterize physiological responses to elevated CO(2). Due to a correlation with CO(2) concentration, which is used as an independent factor in the iWUE calculation, any tree-ring δ(13)C data set would inevitably generate increasing iWUE over time. Therefore, although consistent, previously reported trends in iWUE do not necessarily reflect a coherent global response to rising atmospheric CO(2). We discuss the significance of these findings and suggest ways to distinguish real from artificial responses in future studies

Comment on Zwally and others (2015)-mass gains of the Antarctic ice sheet exceed losses

In their article ‘Mass gains of the Antarctic ice sheet exceed losses’ Zwally and others (2015) choose Vostok Subglacial Lake as an exemplary region to demonstrate their inference of surface height change rates from a portion of the ICESat mission’s laser altimetry data (2003–08). In their appendix, they discuss some of the remarkable differences between their results and those reported by Richter and others (2008, 2013, 2014). However, the selective consideration of our works and the misleading or incorrect interpretation of our results call for clarificationFil: Richter, Andreas Jorg. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Technische Universitaet Dresden; AlemaniaFil: Horwath, M.. Technische Universitaet Dresden; AlemaniaFil: Dietrich, R.. Technische Universitaet Dresden; Alemani

The Structure of Lie Algebras and the Classification Problem for Partial Differential Equations

The present paper solves completely the problem of the group classification of nonlinear heat-conductivity equations of the form\ $u_{t}=F(t,x,u,u_{x})u_{xx} + G(t,x,u,u_{x})$. We have proved, in particular, that the above class contains no nonlinear equations whose invariance algebra has dimension more than five. Furthermore, we have proved that there are two, thirty-four, thirty-five, and six inequivalent equations admitting one-, two-, three-, four- and five-dimensional Lie algebras, respectively. Since the procedure which we use, relies heavily upon the theory of abstract Lie algebras of low dimension, we give a detailed account of the necessary facts. This material is dispersed in the literature and is not fully available in English. After this algebraic part we give a detailed description of the method and then we derive the forms of inequivalent invariant evolution equations, and compute the corresponding maximal symmetry algebras. The list of invariant equations obtained in this way contains (up to a local change of variables) all the previously-known invariant evolution equations belonging to the class of partial differential equations under study.Comment: 45 page

The image of the lesson in the field of language training in a secondary school

Artykuł przedstawia wyniki badań prowadzonych w ramach projektu IBE "Dydaktyka literatury i języka polskiego w świetle nowej podstawy programowej". Tekst poświęcony jest sposobom pracy nauczycieli na lekcjach z zakresu kształcenia językowego w gimnazjum. Analizie poddano materiał uzyskany podczas obserwowanych i nagrywanych lekcji w wybranych reprezentatywnie szkołach, biorących udział w badaniach IBE. Uwzględniono nie tylko strategie, metody, techniki i pomoce dydaktyczne, ale także przebieg interakcji między nauczycielami a uczniami.The article presents the results of a research conducted within the Project "Polish language and literature didactics in a secondary school in the light of the new curriculum". The text is devoted to the ways how teachers work in the classroom on language training in secondary schools. The author analyzes material obtained during the observed and recorded lessons in representatively selected schools involved in the project. It includes not only the strategies, methods, techniques and teaching, but also interactions between teachers and students

Stress and Coping in an Inner-City Environment: The Cities Mentor Project Coping Intervention with Youth Living in Urban Poverty

Stress theory posits that exposure to stress predicts negative outcomes (Grant et al., 2003). Children residing in urban poverty are often exposed to multiple stressors which deleteriously impacts social, emotional, and academic well-being. The current study, which is derived from the Cities Mentor Project intervention, is a randomized control trial (RCT) designed to assess the impact of a coping curriculum (along with mentor support) on how adolescents cope with stressors. Participants were 54 6th grade students (31 intervention, 23 control), who ranged in age from 11-13 years old (M= 11.35, SD= 0.52), and 59.3% of participants were female. All participants identified as African-American. This study explores the coping strategies used by the groups receiving the coping and mentor intervention versus a demographically similar control group. Results suggest that children were able to learn and increase usage of more optimal coping strategies for dealing with academic stress (i.e., engagement coping) and violence stress (i.e., disengagement coping). However, results also suggest that children may have learned to overgeneralize coping strategies as they also showed a pattern of increased usage of sub-optimal coping strategies for dealing with academic stress (i.e., disengagement coping) and violence stress (i.e., engagement coping). Future research should be conducted to better understand how different mechanisms of the intervention influence how children use coping strategies. The ability to adapt to stress and adversity often dictates how an individual’s developmental trajectory unfolds. Successful adaptation to stressors includes multiple processes, such as cognitive, emotional, and behavioral regulation. Through these processes, an individual develops coping mechanisms and strategies to deal with stress, which can lead to well-adjusted or maladjusted outcomes (Grant et al., 2003)

Integrating effects of species composition and soil properties to predict shifts in montane forest carbon-water relations.

This study was designed to address a major source of uncertainty pertaining to coupled carbon-water cycles in montane forest ecosystems. The Sierra Nevada of California was used as a model system to investigate connections between the physiological performance of trees and landscape patterns of forest carbon and water use. The intrinsic water-use efficiency (iWUE)-an index of CO2 fixed per unit of potential water lost via transpiration-of nine dominant species was determined in replicated transects along an ∼1,500-m elevation gradient, spanning a broad range of climatic conditions and soils derived from three different parent materials. Stable isotope ratios of carbon and oxygen measured at the leaf level were combined with field-based and remotely sensed metrics of stand productivity, revealing that variation in iWUE depends primarily on leaf traits (∼24% of the variability), followed by stand productivity (∼16% of the variability), climatic regime (∼13% of the variability), and soil development (∼12% of the variability). Significant interactions between species composition and soil properties proved useful to predict changes in forest carbon-water relations. On the basis of observed shifts in tree species composition, ongoing since the 1950s and intensified in recent years, an increase in water loss through transpiration (ranging from 10 to 60% depending on parent material) is now expected in mixed conifer forests throughout the region

Design and Measurement of a Millimeter-wave 2D Beam Switching Planar Antenna Array

A millimeter-wave 2-D beam switching microstrip patch antenna array excited by a 4x4 substrate integrated waveguide (SIW) Modified Butler Matrix is designed and experimentally evaluated in this thesis. A novel architecture is introduced for the Butler Matrix feed network to give designers a choice for phase shifter location to pursue a smaller circuit area. In addition, it enables the designer to control the BM phased outputs for achieving a set of desired 2-D beam directions, e.g., ϕ0=45°, 135°, 225°, and 315° at θ0=45°, with a passive beam switching network for a given array geometry. Full-wave simulation results show when the so designed 4x4 Butler Matrix feeds a 2x2 planar patch antenna array, 4-quadrant beam switching is achieved. To meet the goal of providing a low cost small footprint solution, the presented Modified Butler Matrix features straight SIW phase shifter using periodic apertures. The Modified Butler Matrix is fabricated on a single layer Rogers RO4350B substrate, achieving a circuit area of 222.5 mm2, which is a 54% improvement over previously published 60 GHz results. The fully-integrated antenna array system is created by development of a new SIW to planar patch antenna transition structure which maintains a total antenna frontend area of 333 mm2, just 42% of the area of the next closest SIW 2-D beam switching publication at 60 GHz. For verification of beam switching via over the air (OTA) measurements at 60 GHz, a benchtop anechoic chamber with proper transmitter and receiver antenna positioners is designed and fabricated using in-house maker laboratory resources. 2-D beam steering is proved in the intended 4 quadrants of radiation space at ϕ0=50°, 140°, 220°, and 300° and θ0=30±5° demonstrating meeting the design specifications with a very good margin. As well, for each switched beam the gain of antenna array was measured to be between 4.8 to 6 dBi at 60 GHz which is within 1dB deviation from the simulated results

Implications of using On-Farm Flood Flow Capture to recharge groundwater and mitigate flood risks along the Kings River, CA

Two large hydrologic issues face the Kings Basin, severe and chronic overdraft of about 0.16M ac-ft annually, and flood risks along the Kings River and the downstream San Joaquin River. Since 1983, these floods have caused over $1B in damage in today’s dollars. Capturing flood flows of sufficient volume could help address these two pressing issues which are relevant to many regions of the Central Valley and will only be exacerbated with climate change. However, the Kings River has high variability associated with flow magnitudes which suggests that standard engineering approaches and acquisition of sufficient acreage through purchase and easements to capture and recharge flood waters would not be cost effective. An alternative approach investigated in this study, termed On-Farm Flood Flow Capture, involved leveraging large areas of private farmland to capture flood flows for both direct and in lieu recharge. This study investigated the technical and logistical feasibility of best management practices (BMPs) associated with On-Farm Flood Flow Capture. The investigation was conducted near Helm, CA, about 20 miles west of Fresno, CA. The experimental design identified a coordinated plan to determine infiltration rates for different soil series and different crops; develop a water budget for water applied throughout the program and estimate direct and in lieu recharge; provide a preliminary assessment of potential water quality impacts; assess logistical issues associated with implementation; and provide an economic summary of the program. At check locations, we measured average infiltration rates of 4.2 in/d for all fields and noted that infiltration rates decreased asymptotically over time to about 2 – 2.5 in/d. Rates did not differ significantly between the different crops and soils tested, but were found to be about an order of magnitude higher in one field. At a 2.5 in/d infiltration rate, 100 acres are required to infiltrate 10 CFS of captured flood flows. Water quality of applied flood flows from the Kings River had concentrations of COC (constituents of concern; i.e. nitrate, electrical conductivity or EC, phosphate, ammonium, total dissolved solids or TDS) one order of magnitude or more lower than for pumped groundwater at Terranova Ranch and similarly for a broader survey of regional groundwater. Applied flood flows flushed the root zone and upper vadose zone of nitrate and salts, leading to much lower EC and nitrate concentrations to a depth of 8 feet when compared to fields in which more limited flood flows were applied or for which drip irrigation with groundwater was the sole water source. In demonstrating this technology on the farm, approximately 3,100 ac-ft was diverted, primarily from April through mid-July, with about 70% towards in lieu and 30% towards direct recharge. Substantial flood flow volumes were applied to alfalfa, wine grapes and pistachio fields. A subset of those fields, primarily wine grapes and pistachios, were used primarily to demonstrate direct recharge. For those fields about 50 – 75% of water applied was calculated going to direct recharge. Data from the check studies suggests more flood flows could have been applied and infiltrated, effectively driving up the amount of water towards direct recharge. Costs to capture flood flows for in lieu and direct recharge for this project were low compared to recharge costs for other nearby systems and in comparison to irrigating with groundwater. Moreover, the potentially high flood capture capacity of this project suggests significant flood avoidance costs savings to downstream communities along the Kings and San Joaquin Rivers. Our analyses for Terranova Ranch suggest that allocating 25% or more flood flow water towards in lieu recharge and the rest toward direct recharge will result in an economically sustainable recharge approach paid through savings from reduced groundwater pumping. Two important issues need further consideration. First, these practices are likely to leach legacy salts and nitrates from the unsaturated zone into groundwater. We develop a conceptual model of EC movement through the unsaturated zone and estimated through mass balance calculations that approximately 10 kilograms per square meter of salts will be flushed into the groundwater through displacing 12 cubic meters per square meter of unsaturated zone pore water. This flux would increase groundwater salinity but an equivalent amount of water added subsequently is predicted as needed to return to current groundwater salinity levels. All subsequent flood flow capture and recharge is expected to further decrease groundwater salinity levels. Second, the project identified important farm-scale logistical issues including irrigator training; developing cropping plans to integrate farming and recharge activities; upgrading conveyance; and quantifying results. Regional logistical issues also exist related to conveyance, integration with agricultural management, economics, required acreage and Operation and Maintenance (O&M)