Temperature sensitivity in aboveground net primary productivity in semi-arid grasslands

2014 Fall.Includes bibliographical references.Although climate models forecast warmer temperatures with a high degree of certainty, precipitation is the primary driver of aboveground net primary productivity (ANPP) in most grasslands. In contrast, variations in temperature seldom are related to patterns of ANPP. Thus forecasting responses to warming is a challenge, and raises the question: how sensitive will grassland ANPP be to warming? I evaluated climate and multi-year ANPP data (67 years) from eight western US grasslands arrayed along substantial mean annual temperature (MAT, ~7-14 °C) and mean annual precipitation (MAP, ~300 - 500 mm) gradients. I used regression and analysis of covariance (ANCOVA) to assess relationships between ANPP and temperature, as well as precipitation (annual and growing season) to evaluate temperature sensitivity of ANPP. I also related ANPP to the Standardized Precipitation Evaporation Index (SPEI), which combines precipitation and evapotranspiration estimates. Regression models indicated that variation in growing season temperature was negatively related to total and graminoid ANPP, but precipitation was a better predictor than temperature. Growing season temperature was also a significant parameter in more complex models, but again precipitation was consistently a stronger predictor of ANPP. Surprisingly, neither annual nor growing season SPEI was as strongly related to ANPP as was precipitation alone. I conclude that warming will affect ANPP in these grasslands, but that predicting temperature effects from natural climatic gradients is difficult. This is because unlike precipitation, warming effects are likely to be complex and site specific as well as moderated by regional shifts in the C3/C4 ratios of plant communities

The transformative meanings of viewing or not viewing the body after sudden death

This study investigates the experience of viewing or not viewing the body for 64 relatives bereaved after a sudden and unexpected death1. Thematic analyses of in-depth interviews reveal the importance of viewing and the challenges in providing choice. Some participants experienced difficulties including regret and intrusive images. These are discussed alongside the transformative meanings of seeing or not seeing the body for bereaved relatives

Help-seeking experiences of bereaved adolescents: A qualitative study

Despite the potentially devastating effects of a death on the lives of adolescents, little is known about their help-seeking experiences. We interviewed by telephone 39 bereaved adolescents on their help-seeking experiences. Thematic analysis resulted in three themes: Formal support, Informal support and School-related support. Participants provided a critical appraisal of positive and negative experiences, and noted barriers and facilitators for help-seeking. As adolescents bereaved through suicide may receive less social support, professional help is a much needed auxiliary. Parental encouragement is important in accessing adequate professional help

Climatic controls of aboveground net primary production in semi‑arid grasslands along a latitudinal gradient portend low sensitivity to warming

Although climate models forecast warmer temperatures with a high degree of certainty, precipitation is the primary driver of aboveground net primary production (ANPP) in most grasslands. Conversely, variations in temperature seldom are related to patterns of ANPP. Thus forecasting responses to warming is a challenge, and raises the question: how sensitive will grassland ANPP be to warming? We evaluated climate and multi-year ANPP data (67 years) from eight western US grasslands arrayed along mean annual temperature (MAT; ~7–14 °C) and mean annual precipitation (MAP; ~250–500 mm) gradients. We used regression and analysis of covariance to assess relationships between ANPP and temperature, as well as precipitation (annual and growing season) to evaluate temperature sensitivity of ANPP. We also related ANPP to the standardized precipitation evaporation index (SPEI), which combines precipitation and evapotranspiration to better represent moisture available for plant growth. Regression models indicated that variation in growing season temperature was negatively related to total and graminoid ANPP, but precipitation was a stronger predictor than temperature. Growing season temperature was also a significant parameter in more complex models, but again precipitation was consistently a stronger predictor of ANPP. Surprisingly, neither annual nor growing season SPEI were as strongly related to ANPP as precipitation. We conclude that forecasted warming likely will affect ANPP in these grasslands, but that predicting temperature effects from natural climatic gradients is difficult. This is because, unlike precipitation, warming effects can be positive or negative and moderated by shifts in the C3/C4 ratios of plant communities

Differential effects of extreme drought on production and respiration: synthesis and modeling analysis

This is the published version, also available here: http://dx.doi.org/10.5194/bg-11-621-2014, 2014.Extremes in climate may severely impact ecosystem structure and function, with both the magnitude and rate of response differing among ecosystem types and processes. We conducted a modeling analysis of the effects of extreme drought on two key ecosystem processes, production and respiration, and, to provide a broader context, we complemented this with a synthesis of published results that cover a wide variety of ecosystems. The synthesis indicated that across a broad range of biomes, gross primary production (GPP) was generally more sensitive to extreme drought (defined as proportional reduction relative to average rainfall periods) than was ecosystem respiration (ER). Furthermore, this differential sensitivity between production and respiration increased as drought severity increased; it occurred only in grassland ecosystems, and not in evergreen needle-leaf and broad-leaf forests or woody savannahs. The modeling analysis was designed to enable a better understanding of the mechanisms underlying this pattern, and focused on four grassland sites arrayed across the Great Plains, USA. Model results consistently showed that net primary productivity (NPP) was reduced more than heterotrophic respiration (Rh) by extreme drought (i.e., 67% reduction in annual ambient rainfall) at all four study sites. The sensitivity of NPP to drought was directly attributable to rainfall amount, whereas the sensitivity of Rh to drought was driven by soil drying, reduced carbon (C) input and a drought-induced reduction in soil C content – a much slower process. However, differences in reductions in NPP and Rh diminished as extreme drought continued, due to a gradual decline in the soil C pool leading to further reductions in Rh. We also varied the way in which drought was imposed in the modeling analysis; it was either imposed by simulating reductions in rainfall event size (ESR) or by reducing rainfall event number (REN). Modeled NPP and Rh decreased more by ESR than REN at the two relatively mesic sites but less so at the two xeric sites. Our findings suggest that responses of production and respiration differ in magnitude, occur on different timescales, and are affected by different mechanisms under extreme, prolonged drought

Influence of metals and metalloids on the composition and fluorescence quenching of the extracellular polymeric substances produced by the polymorphic fungus <i>Aureobasidium pullulans</i>

Aureobasidium pullulansis a ubiquitous and widely distributed fungus in the environment, and exhibits substantial tolerance against toxic metals. However, the interactions between metals and metalloids with the copious extracellular polymeric substances (EPS) produced byA. pullulansand possible relationships to tolerance are not well understood. In this study, it was found that mercury (Hg) and selenium (Se), as selenite, not only significantly inhibited growth ofA. pullulansbut also affected the composition of produced EPS. Lead (Pb) showed little influence on EPS yield or composition. The interactions of EPS fromA. pullulanswith the tested metals and metalloids depended on the specific element and their concentration. Fluorescence intensity measurements of the EPS showed that the presence of metal(loid)s stimulated the production of extracellular tryptophan-like and aromatic protein-like substances. Examination of fluorescence quenching and calculation of binding constants revealed that the fluorescence quenching process for Hg; arsenic (As), as arsenite; and Pb to EPS were mainly governed by static quenching which resulted in the formation of a stable non-fluorescent complexes between the EPS and metal(loid)s. Se showed no significant interaction with the EPS according to fluorescence quenching. These results provide further understanding of the interactions between metals and metalloids and EPS produced by fungi and their contribution to metal(loid) tolerance

Nurses' experiences of caring for the suddenly bereaved in adult acute and critical care settings, and the provision of person-centred care: A qualitative study

Aim To explore nursing interventions for person-centred bereavement care in adult acute and critical care settings. Design A descriptive exploratory study, involving focused, face-to-face interviews. Participants comprised nine registered nurses and one auxiliary nurse, working in environments where sudden death was known to occur, i.e. emergency, cardiac and critical care. Interviews were transcribed verbatim and data subjected to directed content analysis. The provision of person-centred care was examined by applying a validated Person-Centred Nursing Framework. Findings Five main themes were identified. Participants’ accounts contained descriptions of bereavement care and the presence of person-centred interventions. Contextual, professional and attitudinal factors influenced the degree to which person-centred care operated. Conclusion Caring for suddenly bereaved families was important to nurses, but also a source of tension and unrest. An important consideration for person-centred practice is movement away from sudden bereavement as a ‘here and now’ event, towards a pathway of supportive care that envisions the longer-term. Further research is required to gain a deeper understanding of person-centred care for the suddenly bereaved and the perceived effectiveness of nursing interventions.University of Wolverhampton, Early Researcher Award Schem

Impact of multi-metals (Cd, Pb and Zn) exposure on the physiology of the yeast Pichia kudriavzevii

Metal contamination of the environment is frequently associated to the presence of two or more metals. This work aimed to study the impact of a mixture of metals (Cd, Pb and Zn) on the physiology of the non-conventional yeast Pichia kudriavzevii. The incubation of yeast cells with 5 mg/l Cd, 10 mg/l Pb and 5 mg/l Zn, for 6 h, induced a loss of metabolic activity (assessed by FUN-1 staining) and proliferation capacity (evaluated by a clonogenic assay), with a small loss of membrane integrity (measured by trypan blue exclusion assay). The staining of yeast cells with calcofluor white revealed that no modification of chitin deposition pattern occurred during the exposure to metal mixture. Extending for 24 h, the exposure of yeast cells to metal mixture provoked a loss of membrane integrity, which was accompanied by the leakage of intracellular components. A marked loss of the metabolic activity and the loss of proliferation capacity were also observed. The analysis of the impact of a single metal has shown that, under the conditions studied, Pb was the metal responsible for the toxic effect observed in the metal mixture. Intracellular accumulation of Pb seems to be correlated with the metals toxic effects observed.The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the Project "BioInd-Biotechnology and Bioengineering for improved Industrial and Agro-Food processes" (NORTE-07-0124-FEDER-000028), Co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. Manuela D. Machado gratefully acknowledges the post-doctoral grant from FCT (SFRH/BPD/72816/2010). Vanessa A. Mesquita gratefully acknowledges the grant from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES). The authors also thank to Doctor Rosane Freitas Schwan to offer the yeast strain and to Doctor Helena M.V.M. Soares, from the Faculty of Engineering of Porto University, for the use of analytical facilities (AAS with flame atomization and AAS with electrothermal atomization)