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Plant functional traits associated with shoot flammability: A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Lincoln University
Get PDFFire is a common natural disturbance in many parts of the world, which changes species composition and ecosystem processes, shaping many of the world’s biomes. Fire has been an important disturbance for hundreds of millions of years, since the origin of terrestrial plants. Several factors interact to determine fire behaviour, including the prevailing weather conditions, the topography of the landscape, and the fuels available for the fire to burn. The main fuels available to initiate and sustain wildfires are plants. Hence, to understand wildfire behaviour, it is essential to know how easily plants ignite and how well they burn; that is, we must be able to measure plant flammability.
Flammability is a complex plant trait that is not easy to measure and which differs across different plant parts or components. Flammability studies conducted on small plant components in the laboratory may not reflect how a plant will burn in nature. Furthermore, flammability research lacks a standard way of quantifying plant flammability in the laboratory. In this thesis, I seek to help address these shortcomings and gain a better understanding of plant flammability, first by comparing the flammability measurements at two different plant components (leaves and shoots) in the laboratory. Next, I investigated the influence of leaf morphological, chemical, and fuel architectural traits on flammability. Finally, I examined the role of species mixtures in causing variation in flammability, by burning fuel mixtures consisting of species of varying levels of flammability.
Comparing the flammability of fuels from different plant components (leaf- and shoot-level) (Chapter 2), I showed that flammability measurements between these fuels were uncorrelated and provided evidence that shoot flammability is likely to be better than leaf flammability at estimating the flammability of plants in the field, at least for canopy fuels. When investigating the relationship between leaf traits and shoot flammability using leaf-level morphological and chemical traits of 43 species collated from trait databases (Chapter 2), I demonstrated that leaf traits such as leaf dry matter content (LDMC), leaf thickness, leaf phenolics, and leaf lignin were correlated with shoot flammability, and thus have potential as useful and easily-measured surrogates for flammability. To further investigate trait flammability relationships, I measured leaf and architectural traits of 65 indigenous and exotic New Zealand species, along with shoot flammability, on the same individuals of a species (Chapter 3). I provided further evidence that LDMC and leaf thickness were strongly correlated with shoot flammability, and that branching pattern (number of ramifications and sub-branches) was the most important architectural trait influencing shoot-level flammability. Other architectural traits, such as foliage and twig fraction mass and fuel bulk density, were also shown to be correlated to shoot flammability.
Given that fires often burn through vegetation that contains plant species of varying flammability, I investigated how the flammability of fuel mixtures was affected by the flammability of constituent species. Using shoot samples from two high flammability and two low flammability species (Chapter 4), I showed that the flammability of species mixtures was non-additive (i.e. disproportionately influenced by the flammability of the constituent species), and that the low flammability species significantly reduced flammability variables, such as burning time and total heat release of the species mixture.
I have demonstrated that shoot-level flammability measurements represent a more suitable laboratory-based means of quantifying canopy flammability than the more widely-used approach of measuring leaf-level flammability. Furthermore, I have quantified the effects of leaf and architectural traits on shoot flammability and identified key traits, such as LDMC, which can be used as surrogates for plant flammability. Finally, I have identified the role of plant species of varying flammability in changing the fire behaviour of species mixtures, demonstrating the mechanisms by which low flammability plants can be used to reduce fire impacts. These findings not only contribute to a greater understanding of how plants burn, they should prove useful for model-based approaches to predicting changes to fire regimes, and provide crucial information to fire managers seeking to mitigate fire damage in an increasingly fire-prone world
Night time temperature and day time irradiance on photosynthesis and growth of cucumber: Potential and possibilities for energy saving
No full textGrowth chamber experiments were conducted with seedless cucumber cv. Odeon to examine the effect of night temperature on photosynthesis and growth with compensation possibilities of daytime irradiance level. Further, the effects of night temperature and the level of daytime irradiance on carbohydrate composition in different plant parts were also assessed with high performance liquid chromatography (HPLC). Daily average temperature was mainly responsible for the growth of cucumber seedling by increasing the height, leaf number, total leaf area and total dry weight. It enhances the potential of lowering night temperature in combination with high day temperature. Lowering night temperature from 22 °C to 14 °C reduced almost 34% growth as dry matter production. As long as the daily mean temperature is equal, the split night temperature had no effect on daily net photosynthesis, height; leaf area and plant dry weight. Increasing level of irradiance increased the plant’s daily net photosynthesis and the magnitude of increment was significantly high at low night temperature than at high night temperature. At low night temperature (14 °C), net photosynthesis was doubled when light intensity was increased from 200 to 400 μmol m-2 s-1. This was reflected in the total dry weight of the plants as well. The dry matter production of cucumber seedling increased almost 30% at low night temperature (14 °C) and 7% at high night temperature (22 °C) when light intensity was doubled. This indicated the potential of irradiance on compensation of losses caused by low temperature although, it will be extra energy costs related to increased light level if that has to be done by artificial lighting. Carbohydrate profiling revealed that the total carbohydrate content was significantly affected by irradiance level than temperature. Total carbohydrate concentration was increased by 8% at low night temperature (14 °C) and 20% at high light intensity (400 μmol m-2 s-1). Among the different plant parts analyzed, the total carbohydrate content was significantly high in stem in all temperature and irradiance combinations. However, night temperature or daytime irradiance did not affect the proportion of total carbohydrate partitioned between plant parts.M-P
Growth chamber experiments on lichens : temperature and humidity regimes rapidly shape growth rates and carbohydrate contents
Get PDFThis study assesses relative growth rates and carbohydrate contents of three lichen species under different temperature and humidity regimes in a short-term growth chamber experiment. Representatives from three functional groups: chlorolichens (Parmelia sulcata; green algal), cyanolichens (Peltigera canina; cyanobacterial) and cephalolichens (Peltigera aphthosa; green alga + cyanobacteria) were cultivated for 14 days (150 µmol photon m-2 s-1; 12 h photoperiod) at four temperature regimes (28/23 °C, 20/15 °C, 13/8 °C, and 6/1 °C; day/night temperatures) and two hydration regimes (12 h day-time hydration; 12 h day-time + 12 h night-time hydration). These lichens showed much higher growth than earlier reported, particularly at 13/8 °C. A two-way ANOVA with temperature, humidity regimes as factors and specific thallus mass as a co-variate explained 57.8, 53.2 and 38.1 % of the variation in RGR for P. aphthosa, P. canina and P. sulcata, respectively. Significantly higher relative biomass (RGR) as well as thallus area growth rates (RTAGR) were recorded when the thalli were hydrated day and night compared to hydration in day-time only in all species. Chronic photoinhibition was substantial in P. apthosa and P. canina when kept at lowest temperature regimes and also for the thalli kept dry at night, whereas P. sulcata was photoinhibited at the highest temperature for thalli kept dry at night. Strong, positive linear regressions occurred between RGR and maximal PSII efficiency (Fv/Fm) in all species. Metabolic activity at night improved recovery of photoinhibition and/or may enhance the conversion rate of photosynthates into thallus growth. Moreover, the carbohydrate pools in all the species were measured through HPLC. Unlike the dynamic growth patterns, carbohydrate concentrations varied little with temperature and humidity regimes. After 14 days cultivation, total carbohydrate pool decreased in P. aphthosa and P. canina, but slightly increased in P. sulcata. Mannitol occurred in all the species. Quantitatively, the largest carbohydrate pool was mannitol, glucose and arabitol for P. aphthosa, P. canina and P. sulcata, respectively. The RGR was significantly correlated with photobiont carbohydrate in all species
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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