Pyrogenic organic matter, soil carbon dynamics and prescribed fire in temperate forests of south-eastern Australia

Fire is an important driver of carbon storage in Australian temperate forests. During vegetation fires, plant biomass is transformed into pyrogenic organic matter (pyrOM) and deposited in varying amounts and forms onto soil surfaces. To date, most studies related to soil carbon have investigated the impact of fire on carbon cycling and storage. A far less examined area is the role of pyrOM from prescribed fire in carbon cycling. The broad aim of this research was to examine the effects of prescribed fire on soil carbon and nutrients and, in particular, changes caused by deposition of pyrOM. The first study encompassed nine sites in mixed eucalypt forest in Victoria, Australia. A carefully designed sampling strategy allowed potentially confounding influences of season and site variation to be minimised. Following this sampling strategy, soil samples were collected before and after prescribed fire (one week, one month and one year). Robust evidence of the changes in total carbon and nitrogen after fire and the dynamic nature of pools of carbon and nitrogen (e.g. labile, microbial biomass and pyrogenic) over time since fire are presented. In further studies, two soil incubations were done to examine the influence of pyrOM on the dynamics of soil carbon and nutrient availability. The first incubation investigated changes in microbial respiration and available forms of carbon, nitrogen and phosphorus after the addition pyrOM to soil over a 72 h period. A second, longer term, incubation (96 d) investigated the influence of pyrOM on soil carbon balance via loses through microbial respiration. The results varied with different size fractions of pyrOM supplied, the amount of pyrOM added to the soil and with soil characteristics. Overall, pyrOM stimulated short-term microbial respiration and thus represents a substantial substrate for soil microbial activity. However, over the long-term, addition of pyrOM to soil represents a net gain of carbon and the capacity for carbon storage. The final component of this study quantified and characterised soil carbon held as pyrOM at different times since fire. Quantification was achieved using mid-infrared spectroscopy and the cubist model and a calibration model was built using spiked soil samples as measured using the Kurth-MacKenzie-DeLuca digestion method. Molecular characteristics of soil were identified using pyrolysis gas chromatography-mass spectrometry in the presence of tetramethylammonium hydroxide. This study contributes new knowledge to the complex patterns associated with redistribution of carbon after prescribed burning. Recommendations were made for land management agencies for development of fire management plans that consider protection of soil carbon in temperate forests in Australia

Pyrogenic organic matter, soil carbon dynamics and prescribed fire in temperate forests of south-eastern Australia

Fire is an important driver of carbon storage in Australian temperate forests. During vegetation fires, plant biomass is transformed into pyrogenic organic matter (pyrOM) and deposited in varying amounts and forms onto soil surfaces. To date, most studies related to soil carbon have investigated the impact of fire on carbon cycling and storage. A far less examined area is the role of pyrOM from prescribed fire in carbon cycling. The broad aim of this research was to examine the effects of prescribed fire on soil carbon and nutrients and, in particular, changes caused by deposition of pyrOM. The first study encompassed nine sites in mixed eucalypt forest in Victoria, Australia. A carefully designed sampling strategy allowed potentially confounding influences of season and site variation to be minimised. Following this sampling strategy, soil samples were collected before and after prescribed fire (one week, one month and one year). Robust evidence of the changes in total carbon and nitrogen after fire and the dynamic nature of pools of carbon and nitrogen (e.g. labile, microbial biomass and pyrogenic) over time since fire are presented. In further studies, two soil incubations were done to examine the influence of pyrOM on the dynamics of soil carbon and nutrient availability. The first incubation investigated changes in microbial respiration and available forms of carbon, nitrogen and phosphorus after the addition pyrOM to soil over a 72 h period. A second, longer term, incubation (96 d) investigated the influence of pyrOM on soil carbon balance via loses through microbial respiration. The results varied with different size fractions of pyrOM supplied, the amount of pyrOM added to the soil and with soil characteristics. Overall, pyrOM stimulated short-term microbial respiration and thus represents a substantial substrate for soil microbial activity. However, over the long-term, addition of pyrOM to soil represents a net gain of carbon and the capacity for carbon storage. The final component of this study quantified and characterised soil carbon held as pyrOM at different times since fire. Quantification was achieved using mid-infrared spectroscopy and the cubist model and a calibration model was built using spiked soil samples as measured using the Kurth-MacKenzie-DeLuca digestion method. Molecular characteristics of soil were identified using pyrolysis gas chromatography-mass spectrometry in the presence of tetramethylammonium hydroxide. This study contributes new knowledge to the complex patterns associated with redistribution of carbon after prescribed burning. Recommendations were made for land management agencies for development of fire management plans that consider protection of soil carbon in temperate forests in Australia

Pre | Digital Liminalities: A Hermeneutics of the Intermedial and Materiality in the Print Intermedial Novel

How can print novels renew a digitally literate readers awareness of media materiality and medial differences? This dissertation develops a hermeneutics capable of analyzing media not only for their unique specificities or their convergence into a represented sameness, but also for the liminal site of their fusions, exchanges, and slippages of representationthe intermedial, or, the in between of media. Digital media amplify the mediating practices of exact recording devices such as the camera, representing other media through a technique that blurs their differences and inciting an illusion of a represented mediums presence or immediacy. The pretense that predigital (and thus old) media are available for such convergence occurs through the weakened instantiation of medias contexts and conditions of materiality. A closer examination of the way media engage with each other from the perspective of a so-called old mediumthe print novelprovides the grounds for an approach to media encounters that avoids sameness and encourages material awareness. This dissertation focuses on the contemporary print intermedial novel, a form of writing where references to three stages of technological inscription abound: the textual symbolic stage in the written word; the orthographic in exact recording devices; and the post-orthographic in digital media. The intermedial novels that I study use prints material medium to evoke these inscription functions, demonstrating the collaboration of older and newer media representational forms in todays cultural imagination and practice. First, I examine how orthographic immediacy is used to elicit absent objects as physically present. Next, I explore how post-orthographic immediacy is used to represent symbolic images as visualized and virtual objects. Finally, I analyze how post-orthographic inscription is used to complicate the relationship between material objects and representations of reality. Print in intermedial novels can restore a readers awareness of media materiality by creating what I call a dynamic media juxtaposition: a dissonance between the material medium of print and the visual and digital media that it represents. These novels thus demonstrate the need for an intermedial hermeneutics that is capable of analyzing this dissonance laterally (a comparative reading of media) and dynamically (a negotiation of their encounters)

Komponen-Komponen Liken Dari Bukit Bendera

Kajian fitokimia dijalankan ke atas tumbuhan liken Parmotrama mellisaii, Usnea sp. dan Ramalina peruviana. Dengan menggunakan kaedah spektroskopi dan kimia. beberapa sebatian telah dikenal pasti

Using prosody in Cantonese-speaking children with severe dysarthria: caregiver and speaker variables

Thesis (B.Sc)--University of Hong Kong, 2007.Also available in print.A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, June 30, 2007.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science

On Possibility of Determining Neutrino Mass Hierarchy by the Charged-Current and Neutral-Current Events of Supernova Neutrinos in Scintillation Detectors

One of the unresolved mysteries in neutrino physics is the neutrino mass hierarchy. We present a new method to determine neutrino mass hierarchy by comparing the events of inverse beta decays (IBD), $\bar{\nu}_e + p\rightarrow n + e^+$, and neutral current (NC) interactions, $\nu(\overline{\nu}) + p\rightarrow\nu(\overline{\nu}) + p$, of supernova neutrinos from accretion and cooling phases in scintillation detectors. Supernova neutrino flavor conversions depend on the neutrino mass hierarchy. On account of Mikheyev-Smirnov-Wolfenstein effects, the full swap of $\bar{\nu}_e$ flux with the $\bar{\nu}_x$ ($x=\mu,~\tau$) one occurs in the inverted hierarchy, while such a swap does not occur in the normal hierarchy. In consequence, the ratio of high energy IBD events to NC events for the inverted hierarchy is higher than in the normal hierarchy. Since the luminosity of $\bar{\nu}_e$ is larger than that of $\nu_x$ in accretion phase while the luminosity of $\bar{\nu}_e$ becomes smaller than that of $\nu_x$ in cooling phase, we calculate this ratio for both accretion and cooling phases. By analyzing the change of this event ratio from accretion phase to cooling phase, one can determine the neutrino mass hierarchy.Comment: one column, 16 pages, 3 figure