Disturbance alters relationships between soil carbon pools and aboveground vegetation attributes in an anthropogenic peatland in Patagonia

1 Vegetation attributes derived from species and plant functional types (PFTs) directly or indirectly drive the carbon (C) cycle in peatlands. However, anthropogenic-based disturbances may alter petland soil-plant interactions and their ability to sequester carbon. Likewise, it is unclear how the soil-plant linkages among different soil C decomposition-based pools and plant attributes vary under disturbance conditions. 2 We aimed to assess how anthropogenic disturbances affect the relationships between aboveground vegetation attributes and belowground C pools in a peatland located in Northern Patagonia, Chile. We further evaluated if attributes derived from PFTs are better suited to predict soil C pools than attributes derived from species. We used structural equation modeling and regression analyses to explore these differences. 3 We found that undisturbed peatland has more soil-plant significant relationships between soil C pools and vegetation attributes, yielding higher predictive accuracies than disturbed areas. The species-based attributes yielded consistently better results predicting soil C pools than PFT-based attributes. However, PFT-based information showed significant interactions with the highly-decomposed C pools in the undisturbed peatland. Likewise, plant height and diversity were only significant with C pools in the undisturbed peatland. 4 We observed that water-logged plant communities have different soil-plant interactions than dryer communities. These differences were observed in both areas but were higher in the disturbed peatland, making it impossible to find meaningful soil-plant relationships across vegetation types and taxa. 5 Our results highlight the importance of accounting for disturbance or management when linking vegetation attributes to soil C pools in peatlands. This implies that up-to-date extensive monitoring of peatland disturbances is needed to accurately monitor soil C attributes at the regional level using vegetation as proxies. We also need to aggregate species into specific plant functional types that hold these soil-plant interactions across landscapes, regions, and disturbances to generalize the soil-plant relationships accurately.

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Stochiometric control of SOM and plant derived soil C pools dynamics under elevated CO2

10.5194/egusphere-egu21-14375 ◽

2021 ◽

Author(s):

Johanna Pihlblad ◽

Louise C. Andresen ◽

Catriona Macdonald ◽

David Ellsworth ◽

Yolima Carrillo

Keyword(s):

Carbon Dioxide ◽

Species Differences ◽

Eucalyptus Grandis ◽

P Availability ◽

Soil N ◽

Nutrient Stoichiometry ◽

Soil C ◽

Nutrient Additions ◽

C Pools ◽

C Decomposition

Elevated carbon dioxide in the atmosphere (eCO2) has been found to influence soil C by altering the belowground balance between the decomposition of existing soil organic matter (SOM) and the accumulation of plant-derived C inputs. Even small changes in this balance can have a potentially large effect on future climate. The relative availability of soil nutrients, particularly N and P, are crucial mediators of both decomposition and new C accumulation, but both these two processes are rarely assessed simultaneously. We asked if the effect of eCO2 on soil C decomposition was mediated by soil N and P availability, and if the effect of CO2 and soil N and P availability on soil C decomposition was dependent on C pools (existing SOM C, newly added C). We grew Eucalyptus grandis and a C3 grass (Microlaena stipoides) from seed in an experimentally manipulated atmosphere with altered &#948;13C signature of CO2, which allowed the separation of plant derived C, from the existing SOM C. Then we manipulated N and P relative abundance via nutrient additions. We evaluated how the existing SOM and the new plant-derived C pool, and their respiration responded to eCO2 conditions and nutrient treatments. SOM respiration significantly increased in the eucalypts when N was added but was not affected by CO2. In the grass the SOM respiration increased with eCO2 and added N and SOM respiration per unit of SOM-derived microbial was significantly higher in both the added P and added N+P nutrient treatments. The rhizosphere priming of SOM was suppressed in both the added P and added N+P nutrient treatments. The heterotrophic respiration of plant-derived C was contingent on nutrient availability rather than eCO2 and differed by species. The grass-derived respiration was significantly higher than the eucalypt and was higher in both added P and added N+P nutrient treatments. Thus, nutrient stoichiometry had similar effects on SOM and plant derived C, but e CO2 only affected SOM and only for the Eucalyptus. &#160;This study shows how species differences have large effects on rhizosphere C cycling responses to eCO2 and stoichiometric conditions.&#160;&#160; &#160;&#160;&#160;

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Temperature sensitivity of simulated soils with biochars produced at different temperatures

Soil Research ◽

10.1071/sr18226 ◽

2019 ◽

Vol 57 (3) ◽

pp. 294 ◽

Cited By ~ 1

Author(s):

Xiaojie Wang ◽

Guanhong Chen ◽

Renduo Zhang

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Temperature Sensitivity ◽

Pyrolysis Temperature ◽

Soil C ◽

Ambient Temperatures ◽

C Pools ◽

C Cycle ◽

Microbial Enzyme ◽

Different Temperatures

The temperature sensitivity of multiple carbon (C) pools in the soil plays an important role in the C cycle and potential feedback to climate change. The aim of this study was to investigate the temperature sensitivity of different biochars in soil to better understand the temperature sensitivity of different soil C pools. Biochars were prepared using sugarcane residue at temperatures of 300, 500 and 800°C (representing different C pools) and C skeletons (representing the refractory C pool in biochar) were obtained from each biochar. The sugarcane residue, biochars and C skeletons were used as amendments in a simulated soil with microbes but without organic matter. The temperature sensitivity of the amended soils was characterised by their mineralisation rate changes in response to ambient temperatures. The temperature sensitivity of treatments with relatively refractory biochars was higher than that with labile biochars. The temperature sensitivity of treatments with biochars was lower than for their corresponding C skeletons. The different temperature sensitivity of treatments was attributable to the different internal C structures (i.e. the functional groups of C=C and aromatic structure) of amendments, determining the biodegradability of substrates. Dissolved organic matter and microbial enzyme activity of biochars were lower than those of corresponding C skeletons, and decreased with increasing pyrolysis temperature. The temperature sensitivities of treatments with biochars, C skeletons and sugarcane residue were negatively correlated with the properties of dissolved organic matter and microbial enzyme activities (especially dehydrogenase) in soil.

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Carbon dynamics in the Brazilian Cerrado: stocks and fluxes estimated by a model data fusion framework (CARDAMOM)

10.5194/egusphere-egu2020-20772 ◽

2020 ◽

Author(s):

Eráclito Sousa-Neto ◽

Luke Smallman ◽

Jean Ometto ◽

Mathew Williams

Keyword(s):

Land Surface ◽

Balance Model ◽

Brazilian Cerrado ◽

Model Framework ◽

Area Index ◽

Soil C ◽

C Pools ◽

C Cycling ◽

C Cycle ◽

Different Types

Savannas are a major component of the world&#8217;s vegetation and cover a land surface of about 15 Mkm2, accounting for about 30% of the terrestrial primary production. In the South America, the Brazilian Savanna (Cerrado) is the second largest biome (2 Mkm2), after the Amazon biome, and a hotspot of biodiversity. The Cerrado region is heterogeneous, with savanna vegetation ranging from open grassland, through a gradient of increasing tree density to nearly closed-canopy woodland. The cerrado vegetation is markedly seasonal in phenology and is often burned, either naturally or as part of a management cycle. Due its large occupation, Cerrado have the potential to influence the regional and possibly the global energy, water and carbon (C) balances. The allocation of the net primary productivity (NPP) of an ecosystem between canopy, woody tissue and fine roots is an important descriptor of the functioning of an ecosystem, and an important feature to correctly represent in terrestrial ecosystem models for carbon rates estimation, as well as their residence time, variation with climate and disturbance, and in order to make better forecasts. Such estimation in Cerrado regions remains still difficult given the lack of important soil and vegetation data. Previous studies have showed that the fluxes of water and C are closely related to each other, and to the diurnal cycle of solar radiation. However, there is no study clearly assessing the allocation of C through the different types of vegetation, either in the different types of physiognomies.&#160;To help estimating the C flows across the different C pools and types of vegetation, we are using Carbon Data Model Framework (CARDAMOM) which is a computer programme that retrieves terrestrial carbon (C) cycle variables by combining C cycle observations with a mass balance model. CARDAMOM produces global dynamic estimates of plant and soil C pools, their exchanges with each other and with the atmosphere, and C cycling variables for processes driving change. It also produces a C cycle analysis consistent with C measurements and climate, and it is suited for using with global-scale satellite observations such as aboveground biomass (ABG) or leaf area index (LAI). For that, we count on field data available (AGB, BGB) and satellite data (LAI, AGB, soil C), which will help to present robust analyses of C cycling across gradients of biomass in the Brazilian Cerrado.

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Priming of soil decomposition leads to losses of carbon in soil treated with cow urine

Soil Research ◽

10.1071/sr13148 ◽

2013 ◽

Vol 51 (6) ◽

pp. 513 ◽

Cited By ~ 10

Author(s):

S. M. Lambie ◽

L. A. Schipper ◽

M. R. Balks ◽

W. T. Baisden

Keyword(s):

Dehydrogenase Activity ◽

Urease Activity ◽

Urea Hydrolysis ◽

Water Soluble ◽

Soil C ◽

C Cycle ◽

Cow Urine ◽

Artificial Urine ◽

C Decomposition ◽

Urine Treatment

The extent to which priming of soil carbon (C) decomposition following treatment with cow urine leads to losses of soil C has not been fully investigated. However, this may be an important component of the carbon (C) cycle in intensively grazed pastures. Our objective was to determine soil C losses via priming in soil treated with cow urine and artificial urine. Cow urine, water, 14C-urea artificial urine, and 14C-glucose artificial urine were applied to repacked soil cores and incubated at 25°C for 84 days. We used radio-labelled artificial urine to determine the extent to which urea hydrolysis contributed to elevated carbon dioxide (CO2) emissions in urine-treated soil and as a comparison to the priming effects of cow urine. Water-soluble C, pH, dehydrogenase activity, urease activity, and CO2 evolution were monitored during the incubation. Priming of soil C decomposition (more CO2-C evolved than was added as a C source) in the cow urine treatment was 4.2 ± 0.7 mg C g–1 (5.2 ± 0.9% of soil C concentration, corrected for water control). In the cow urine treatment, ~54% of retained urea was hydrolysed and it contributed 0.4 ± 0.1 mg CO2-C g–1 to total CO2 fluxes. Low urea hydrolysis may have been due to decreased urease activity in the cow urine treatment due to the large amounts of urea present and the increased pH. Dehydrogenase activity was elevated immediately after cow urine application, and indicates that priming was likely due to heightened microbial activity. Negative priming (less CO2-C evolved than was added as a C source) was measured in the artificial urine treatments and this may reflect the differences in composition between the cow and artificial urines. Solubilisation of soil C was also found in the artificial urine treatments, but it did not appear to be correlated with increased pH or periods of greater urea hydrolysis. While cow urine decreased soil C by positively priming soil C decomposition, our artificial urine did not. Therefore, caution is recommended when using artificial urine for C-cycling research. The mechanisms by which both increased soil pH and priming occurs in urine-treated soils require further investigation.

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Assessing a new soil carbon model to simulate the effect of temperature increase on the soil carbon cycle in three eastern Canadian forest types characterized by different climatic conditions

Canadian Journal of Soil Science ◽

10.4141/s05-080 ◽

2006 ◽

Vol 86 (Special Issue) ◽

pp. 187-202 ◽

Cited By ~ 5

Author(s):

Guy R. Larocque ◽

Robert Boutin, David Paré ◽

Gilles Robitaille ◽

Valérie Lacerte

Keyword(s):

Soil Respiration ◽

Soil Carbon ◽

Abies Balsamea ◽

Litter Production ◽

Forest Types ◽

Organic C ◽

Soil C ◽

C Pools ◽

C Cycle ◽

Process Based Models

The predictive capacity of process-based models on the carbon (C) cycle in forest ecosystems is limited by the lack of knowledge on the processes involved. Thus, a better understanding of the C cycle may contribute to the development of process-based models that better represent the processes in C cycle models. A new soil C model was developed to predict the effect of an increase in the temperature regime on soil C dynamics and pools in sugar maple (Acer saccharum Marsh.), balsam fir [Abies balsamea (L.) Mill.] and black spruce [Picea mariana (Mill.) B.S.P.] forest types in Eastern Canada. Background information to calibrate the model originated from the experimental sites of the ECOLEAP project as well as from a companion study on laboratory soil incubation. Different types of litter were considered in the model: foliage, twigs, understory species, other fine detritus and fine roots. A cohort approach was used to model litter mineralization over time. The soil organic C in the organic (F and H) and mineral layers (0–20 cm) was partitioned into active, slow and passive pools and the rates of C transfer among the different pools and the amount of CO2 respired were modelled. For each forest type, there was a synchrony of response of the C pools to soil temperature variation. The results of the simulations indicated that steady state conditions were obtained under current temperature conditions. When mean annual soil temperatures were gradually increased, the litter and active and slow C pools decreased substantially, but the passive pools were minimally affected. The increase in soil respiration resulting from a gradual increase in temperature was not pronounced in comparison to changes in mineralization rates. An increase in litter production during the same period could contribute to reducing net C losses. Key words: Soil organic matter, litter, soil respiration, climate change

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A Psychometric Study of the Quality Perception Questionnaire

Swiss Journal of Psychology ◽

10.1024/1421-0185/a000076 ◽

2012 ◽

Vol 71 (2) ◽

pp. 101-106 ◽

Cited By ~ 4

Author(s):

Raffaele Cioffi† ◽

Anna Coluccia ◽

Fabio Ferretti ◽

Francesca Lorini ◽

Aristide Saggino ◽

...

Keyword(s):

Structural Equation ◽

Factor Model ◽

Equation Modeling ◽

Fit Indices ◽

Quality Perception ◽

Italian Survey ◽

Confirmatory Factor ◽

Instrument Measuring ◽

Hospital Structures

The present paper reexamines the psychometric properties of the Quality Perception Questionnaire (QPQ), an Italian survey instrument measuring patients’ perceptions of the quality of a recent hospital admission experience, in a sample of 4400 patients (Mage = 56.42 years; SD = 19.71 years, 48.8% females). The 14-item survey measures four factors: satisfaction with medical doctors, nursing staff, auxiliary staff, and hospital structures. First, we tested two models using a confirmatory factor analysis (structural equation modeling): a four orthogonal factor and a four oblique factor model. The SEM fit indices and the χ² difference suggested the acceptance of the second model. We then did a simulation using a bootstrap with 1000 replications. Results confirmed the four oblique factor solution. Third, we tested whether there were significant differences with respect to age or sex. The multivariate general linear model showed no significant differences in the factors with respect to sex or age.

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Suicide Risk Among College Student

Crisis ◽

10.1027/0227-5910/a000340 ◽

2015 ◽

Vol 36 (6) ◽

pp. 416-423 ◽

Cited By ~ 11

Author(s):

Richard Shadick ◽

Faedra Backus Dagirmanjian ◽

Baptiste Barbot

Keyword(s):

Sexual Minority ◽

Students Of Color ◽

Structural Equation ◽

Suicide Risk ◽

Equation Modeling ◽

First Year ◽

Chi Square ◽

First Year College ◽

Marginalized Groups ◽

First Year College Students

Abstract. Background: Research on young adults in the general population has identified a relationship between sexual minority identification and risk for suicide. Differential rates of suicidal ideation and attempts have also been found across racial and ethnic groups. Aims: This study examined risk for suicide among university students, based on membership in one or more marginalized groups (sexual minority and racial minority identification). Method: Data were collected from first-year college students (N = 4,345) at an urban university. Structural equation modeling was employed to model a suicidality construct, based on which a "risk for suicide" category system was derived. Chi-square and logistic regression analyses were then conducted to estimate the relationship between the background variables of interest and suicide risk. Results: Students who identified as lesbian, gay, or bisexual (LGB) were associated with higher suicide risk than their heterosexual peers. Students of color were slightly less at risk than their heterosexual peers. However, LGB students of color were associated with elevated suicide risk relative to heterosexual peers. Conclusion: Results indicate that belonging to multiple marginalized groups may increase one's risk for suicide, though these effects are not simply additive. Findings highlight the complexity of the intersection between marginalized identities and suicidality.

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Low Self-Control of Emotions as an Antecedent of Self-Reported Physical Symptoms: A Longitudinal Perspective

European Psychologist ◽

10.1027//1016-9040.6.1.26 ◽

2001 ◽

Vol 6 (1) ◽

pp. 26-35 ◽

Cited By ~ 4

Author(s):

Marja Kokkonen ◽

Lea Pulkkinen ◽

Taru Kinnunen

Keyword(s):

Structural Equation ◽

Negative Emotions ◽

Physical Symptoms ◽

Self Control ◽

Personality Characteristics ◽

Equation Modeling ◽

Eysenck Personality Questionnaire ◽

Positive Direction ◽

Data Collections ◽

Low Self Control

The study was part of the Jyväskylä Longitudinal Study of Personality and Social Development, underway since 1968, in which children's low self-control of emotions was studied using teacher ratings at age 8 in terms of inattentiveness, shifting moods, aggression, and anxiety. The study was based on data from 112 women and 112 men who participated in the previous data collections at ages 8, 27, and 36. At age 27, the participants had been assessed in Neuroticism (N) using the Eysenck Personality Questionnaire , and at age 36 they filled in several inventories measuring, among others, conscious and active attempts to repair negative emotions in a more positive direction as well as physical symptoms. The present study used structural equation modeling to test the hypothesis that personality characteristics indicating low self-control of emotions at ages 8 and 27 are antecedents of self-reported physical symptoms at age 36; and that this relationship is indirect, mediated by attempts to repair negative emotions in a more positive direction. The findings showed, albeit for men only, that inattentiveness at age 8 was positively related to self-reported physical symptoms at age 36 via high N at age 27 and low attempts to repair negative emotions at age 36. Additionally, N at age 27 was directly linked to self-reported physical symptoms at age 36. The mediation of an active attempt to repair negative emotions was not found for women. Correlations revealed, however, that shifting moods and aggression in girls were antecedents of self-reported physical symptoms in adulthood, particularly, pain and fatigue.

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Validating the Factor Structure of the Stigma of Suicide Scale–Short Form Spanish Version Among Healthcare Students

Crisis ◽

10.1027/0227-5910/a000728 ◽

2020 ◽

pp. 1-5

Author(s):

Ruthmarie Hernández-Torres ◽

Paola Carminelli-Corretjer ◽

Nelmit Tollinchi-Natali ◽

Ernesto Rosario-Hernández ◽

Yovanska Duarté-Vélez ◽

...

Keyword(s):

Factor Structure ◽

Structural Equation ◽

Short Form ◽

Small Sample Size ◽

Small Sample ◽

Spanish Version ◽

Equation Modeling ◽

Cross Sectional ◽

Healthcare Students ◽

Spanish Speaking

Abstract. Background: Suicide is a leading cause of death among Spanish-speaking individuals. Suicide stigma can be a risk factor for suicide. A widely used measure is the Stigma of Suicide Scale-Short Form (SOSS-SF; Batterham, Calear, & Christensen, 2013 ). Although the SOSS-SF has established psychometric properties and factor structure in other languages and cultural contexts, no evidence is available from Spanish-speaking populations. Aim: This study aims to validate a Spanish translation of the SOSS-SF among a sample of Spanish-speaking healthcare students ( N = 277). Method: We implemented a cross-sectional design with quantitative techniques. Results: Following a structural equation modeling approach, a confirmatory factor analysis (CFA) supported the three-factor model proposed by Batterham and colleagues (2013) . Limitations: The study was limited by the small sample size and recruitment by availability. Conclusion: Findings suggest that the Spanish version of the SOSS-SF is a valid and reliable tool with which to examine suicide stigma among Spanish-speaking populations.

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Risk Factors and Mediators of Suicidal Ideation Among Korean Adolescents

Crisis ◽

10.1027/0227-5910/a000438 ◽

2018 ◽

Vol 39 (1) ◽

pp. 4-12 ◽

Cited By ~ 9

Author(s):

Yi Jin Kim ◽

Sung Seek Moon ◽

Jang Hyun Lee ◽

Joon Kyung Kim

Keyword(s):

High School Students ◽

Suicidal Ideation ◽

Structural Equation ◽

Equation Modeling ◽

Outcome Variable ◽

Suicidal Behaviors ◽

Thwarted Belongingness ◽

Perceived Burdensomeness ◽

Korean Adolescents ◽

Related Stress

Abstract. Background: A significant number of Korean adolescents have suicidal ideations and it is more prevalent among adolescents than any other age group in Korea. Aims: This study was conducted to attain a better understanding of the contributing factors to suicidal ideation among Korean adolescents. Method: We recruited 569 high school students in Grades 10 and 11 in Pyeongtaek, Korea. The Beck Scale for Suicidal Ideation was used to measure suicidal ideation as the outcome variable. The Interpersonal Needs Questionnaire, the Beck Hopelessness Scale, the School Related Stress Scale, the Olweus Bully/Victim Questionnaire, and the Youth Risk Behavior Surveillance questions were used to measure thwarted belongingness and perceived burdensomeness, hopelessness, school-related stress, bullying, and previous suicidal behaviors, respectively. Data analyses included descriptive statistics and structural equation modeling. Results: The findings suggest that perceived burdensomeness, hopelessness, school-related stress, and previous suicidal behaviors have significant direct effects on suicidal ideation. Hopelessness fully mediated the relation between thwarted belongingness and suicidal ideation, and partially mediated between perceived burdensomeness, school-related stress, and suicidal ideation. Conclusion: These findings provide more specific directions for a multidimensional suicide prevention program in order to be successful in reducing suicide rates among Korean adolescents.

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