Fired Plants Research Articles

Growth-Form Responses to Fire in Nama-Karoo Escarpment Grassland, South Africa

Fire is a rare phenomenon in the semi-arid Nama-Karoo region of South Africa, but appears to have become more common in recent years, possibly as a result of climate change. The ecological effects of fire in this vegetation are poorly understood, but are likely to involve changes in structural composition, that of the shrub-grass ratio in particular. A fire burned an area of Karoo escarpment grassland (a mixture of shrubs and grasses) on the Nuweveld Mountains in October 2013. We assessed changes in plant structural composition and fire survival or persistence strategies of perennial shrubs at 2.5 years post fire. The canopy cover abundance of grasses, herbs, and dwarf shrubs increased post fire, while that of large shrubs decreased. Despite all large shrub species (except Elytropappus rhinocerotis [L.f.] Less.) exhibiting post-fire resprouting and reseeding, vigor varied widely within species. Localized post-fire extinctions appeared possible in many large shrub species, including Cliffortia arborea Marloth (Vulnerable; Raimondo et al.2015). Increases in fire frequency or fire intensity are predicted to result in persistent negative feedbacks (the grass-fire cycle) whereby the herbaceous stratum would increase in dominance at the expense of larger woody growth forms. This process may be hindered by actions to prevent and suppress fires.

Effects of fire regime on plant species richness and composition differ among forest, woodland and heath vegetation

AbstractQuestionDo the effects of fire regimes on plant species richness and composition differ among floristically similar vegetation types?LocationBooderee National Park, south‐eastern Australia.MethodsWe completed floristic surveys of 87 sites in Sydney Coastal dry sclerophyll vegetation, where fire history records have been maintained for over 55 years. We tested for associations between different aspects of the recent fire history and plant species richness and composition, and whether these relationships were consistent among structurally defined forest, woodland and heath vegetation types.ResultsThe relationship between fire regime variables and plant species richness and composition differed among vegetation types, despite the three vegetation types having similar species pools. Fire frequency was positively related to species richness in woodland, negatively related to species richness in heath, and unrelated to species richness in forest. These different relationships were explained by differences in the associations between fire history and species traits among vegetation types. The negative relationship between fire frequency and species richness in heath vegetation was underpinned by reduced occurrence of resprouting species at high fire frequency sites (more than four fires in 55 years). However, in forest and woodland vegetation, resprouting species were not negatively associated with fire frequency.ConclusionsWe hypothesize that differing relationships among vegetation types were underpinned by differences in fire behaviour, and/or biotic and abiotic conditions, leading to differences in plant species mortality and post‐fire recovery among vegetation types. Our findings suggest that even when there is a high proportion of shared species between vegetation types, fires can have very different effects on vegetation communities, depending on the structural vegetation type. Both research and management of fire regimes may therefore benefit from considering vegetation types as separate management units.

Integrated assessment of safety distances for rescue work in chemical plant fires involving domino effects

This study employed the Suite for the Assessment of Flammable, Explosive, and Toxic Impacts to synergize the environmental data, risk frequency, and physical and chemical properties of chemical‐induced fires and explosions at accident sites and thereby establish an integrated assessment model. In addition, the suite was used to visualize fires and explosions resulting from domino effects caused by thermal radiation and blast overpressure in initial accidents at chemical plants.The simulation results were successfully utilized to respond to a chemical plant fire, assist the fire command officer to determine the range of domino effects during rescue, and extinguish the ignition source. In addition, the model provided safety distances for rescue to enable the proper deployment of rescuers and vehicles and to prevent their exposure to deadly hazards.The simulation results also provided the integrated safety distances including acceptable safety distances for rescuers with the appropriate protective equipment and the range of domino effect during the first accident and the second accident. © 2017 American Institute of Chemical Engineers Process Saf Prog 37: 186–193, 2018

Blend design tools for Medium Combustion Plants (MCP) firing biomass wastes

A feasible alternative for agricultural or forestry waste management is the operation of a distributed network of sustainable Medium Combustion Plants (MCPs). However, one of the main factors that hinder its development is the propensity to operational problems derived from corrosion, slagging and fouling characteristics of both bottom and fly ashes. Therefore, a cost-effective approach for these multi-product MCP could be based on predictive tools for an optimal formulation of a fuel blend. This work focuses on the assessment of the ability of these methods to provide guidance for preventing ash-related operational problems and to provide fuel-blending rules.The more widespread tools pertain to two types: compositional classification based on chemical analysis of laboratory ashes, and thermodynamic prediction of the most likely species and phases. Both criterion numbers and compositional maps are ranking methods based on the chemical analysis at a given ashing temperature. Thermodynamic equilibrium modeling is not constrained by any difference in the physical conditions of the MCP compared to those in the laboratory.Both kind of prediction tools have been validated in an MCP firing olive tree pruning residues as well as its typical blends in order to mimic a plausible pattern of fuels along a full year operating campaign. An intensive experimental campaign encompasses plant monitoring and off-line analysis of the ashes along the process line.Interpretation of compositional plots has revealed to be potentially sensitive to ashing temperature. Here are presented examples showing how this variable could lead to either insignificant differences or to a substantial disparity in the a priori fuel diagnosis.Some inconsistencies have been observed between the predictions based on criterion numbers, even for the same fuel and for ranking rules specifically formulated for biomasses. Moreover, it does not match consistently with the information obtained from phase diagrams. Therefore, their use should be limited to the case of a well-established selection of a fuel index for a well-defined fuel provided empirical evidence of an enough good description of the ash behavior, which is not the most frequent case.Thermodynamic equilibrium calculations allow a more precise prediction of the main species in the condensed phase, without the constraint of the ashing temperature. Elemental closure of main ash-forming elements with the chemical analysis of the process ashes presents small differences, and their proximity localization on the phase diagrams denote similar prediction between predicted and process ashes.

Imaging of Flames in Cement Kilns To Study the Influence of Different Fuel Types

The cement industry aims to use an increased amount of alternative fuels to reduce production costs and CO2 emissions. In this study three cement plants firing different kinds and percentages of alternative fuel were studied. A specially developed camera setup was used to monitor the flames in the three cement kilns and assess the effect of alternative fuels on the flame. It was found that co-firing with solid recovered fuel (SRF) would delay the ignition point by about 2 meters and lower the intensity and temperature of the kiln flame compared to a fossil fuel flame. This is related to a larger particle size and moisture content of the alternative fuels, which lowers the conversion rate compared to fossil fuels. The consequences can be a lower kiln temperature and cement quality. The longer conversion time may also lead to the possibility of localized reducing conditions in the cement kiln, which can have a negative impact on the clinker quality and process stability. The burner design may alleviate some...

Application and validation of the API analytical fire method in pressure-relieving and depressuring systems

Accounting for fire scenarios is critical when analyzing pressure-relieving and depressuring systems. This is particularly true in systems such as oil refineries, petrochemical facilities, gas plants, and oil and gas production facilities where the flowing fluids are highly flammable. Because operating safely is of paramount importance in these industries, standards and recommended practices have been developed by trade associations such as the American Petroleum Institute Standard 521 (API 521) to aid in the analysis of the system. In the case of fire scenarios, the traditional recommendation of API 521 has been an empirical model based on the wetted area of the vessel. However, in the most recent 6th edition released in 2014, the standard added an analytical equation based on the Stefan-Boltzmann law that can be used for modeling the dynamic response of pressurized vessels in fire scenarios. Using BLOWDOWN™ Technology in Aspen HYSYS, this analytical fire equation was validated with available experimental data and compared with the traditional wetted area model. This also included evaluating the effects of the parameters in the analytical equation such as surface emissivity of the equipment wall and external heat transfer coefficient, which have significant uncertainties. As plant fires can impact a wide area, this study further investigated using the analytical equation to model fire on a detailed geometry of a pressurized vessel with associated piping.

The 2016 Al-Mishraq sulphur plant fire: Source and health risk area estimation

On October 20, 2016, Daesh (Islamic State) set fire to the sulphur production site Al-Mishraq as the battle of Mosul in northern Iraq became more intense. An extensive plume of toxic sulphur dioxide and hydrogen sulphide caused comprehensive casualties. The intensity of the SO2 release was reaching levels of minor volcanic eruptions and the plume was observed by several satellites. By investigation of the measurement data from instruments on the MetOp-A, MetOp-B, Aura and Soumi satellites we have estimated the time-dependent source term to 161 kilotonnes sulphur dioxide released into the atmosphere during seven days. A long-range dispersion model was utilized to simulate the atmospheric transport over the Middle East. The ground level concentrations predicted by the simulation were compared with observation from the Turkey National Air Quality Monitoring Network. Finally, the simulation data provided, using a probit analysis of the simulated data, an estimate of the health risk area that was compared to reported urgent medical treatments.

Operation and maintenance of a biomass fired – Organic Rankine Cycle – CHP plant: the experience of Cremona

Thanks to various feed-in-tariff programs, aimed to the development of electric energy production from renewable sources, several biomass firing power plants have been realized in Italy in the last few years, contributing to the reduction of greenhouse gas emissions and fossil fuel energy dependence.In particular, during 2012 there was a rush for the completion of several renewable energy conversion power plants, leading up to 986 new plants to get the first connection to the grid (+81,3% with respect to 2011); among those, 80 new plants were solid biomass firing plants (+47,1% with respect to 2011) [1].Linea Energia S.p.A., the Energy Business Unit of the multiutility company LGH, Linea Group Holding, which operates over the areas of Brescia, Cremona, Crema, Lodi and Pavia, gave its contribution in 2012 with the realization and start-up of two waste wood fueled energy conversion plants located in the Northern Italy, more exactly in Cremona and Rodengo Saiano (Brescia).This paper focuses on the operation and maintenance experience of the waste wood conversion power plant of Cremona, which is capable for a gross electric power production of up to 1.0 MW and a thermal power recovery of up to 5.5 MW. In the first part of this paper a description of the plant is presented, giving an insight of the engineered process.In the second part, the performance analysis of the energy conversion process is discussed by comparing actual performance of the system with the originally defined reference performance.In 2016, as a consequence of the operation of the unit in anomalous conditions (air entering in the system) the turbine blades got scaled. The output of the turbine progressively decreased but was then successfully re-established after an extraordinary maintenance carried out by the turbine supplier.

Long‐term trends in restoration and associated land treatments in the southwestern United States

Restoration treatments, such as revegetation with seeding or invasive species removal, have been applied on U.S. public lands for decades. Temporal trends in these management actions have not been extensively summarized previously, particularly in the southwestern United States where invasive plant species, drought, and fire have altered dryland ecosystems. We assessed long‐term (1940–2010) trends in restoration using approximately 4,000 vegetation treatments conducted on Bureau of Land Management lands across the southwestern United States. We found that since 1940, the proportions of seeding and vegetation/soil manipulation (e.g. vegetation removal or plowing) treatments have declined, while the proportions of prescribed burn and invasive species treatments have increased. Treatments in pinyon‐juniper and big sagebrush communities declined in comparison to treatments in desert scrub, creosote bush, and riparian woodland communities. Restoration‐focused treatment objectives increased relative to resource extraction objectives. Species richness and proportion of native species used in seeding treatments also increased. Inflation‐adjusted costs per area rose 750% for vegetation/soil manipulation, 600% for seeding, and 400% for prescribed burn treatments in the decades from 1981 to 2010. Seeding treatments were implemented in warmer and drier years when compared to the climate conditions of the entire study period and warmer and wetter years relative to several years before and after the treatment. These results suggest that treatments over a 70‐year period on public lands in the southwestern United States are shifting toward restoration practices that are increasingly large, expensive, and related to fire and invasive species control.

Crisis management with applicability on fire fighting plants

The paper presents a case study for a crisis management analysis which address to fire fighting plants. The procedures include the steps of FTA (Failure tree analysis). The purpose of the present paper is to describe this crisis management plan with tools of FTA. The crisis management procedures have applicability on anticipated and emergency situations and help to describe and planning a worst-case scenario plan. For this issue must calculate the probabilities in different situations for fire fighting plants. In the conclusions of paper is analised the block diagram with components of fire fighting plant and are presented the solutions for each possible risk situations.

Fire recurrence and emergency post-fire management influence seedling recruitment and growth by altering plant interactions in fire-prone ecosystems

Projections of future wildfire regimes forecast an increased frequency of large high-severity fires that create very harsh environmental conditions and constitute a challenge to post-fire ecosystem regeneration. Under these new circumstances, better knowledge of the plant interaction mechanisms underlying post-fire seedling establishment success would aid restoration management to achieve the intended targets. We evaluated the combined effect of recurrent large stand-replacing fires and conventional post-fire restoration activities (salvage logging after a single large fire, and direct seeding and linear subsoiling plus seedling planting after two subsequent large fires) on tree seedling recruitment and performance (development, annual growth, and biomass) in the early stages of succession in fire-prone maritime pine (Pinus pinaster Ait.) ecosystems. We quantified plant facilitative/competitive interactions between naturally recruited pine seedlings, neighbouring seedlings and potential nurse shrubs with different post-fire regeneration strategies (obligate seeders vs resprouters), by computing the relative interaction index (RII). The results evidenced that fire recurrence altered plant species composition and conditioned initial pine seedling recruitment and establishment, prevailing over the expected negative impact of salvage logging and positive impact of seeding. Seedling recruitment was sufficient to ensure natural tree regeneration after a single fire event and undermined by repeated fires. Both delaying burned timber removal during salvage logging operations and retaining immature dead trees without commercial value onsite in subsoiled stands enhanced seedling recruitment via facilitative interactions. Higher seedling growth and height under shrubs than in open ground resulted in lower aerial and root biomass, indicating elongation in response to shade, and net competition for resources. Inter-specific competition between naturally regenerated seedlings and shrubs was aggravated by intra-specific competition with neighbouring seedlings and by mechanical site preparation in subsoiled stands. All in all, post-burn increased soil fertility most likely counterbalanced the environmental stress created by fire, shifting the net outcome of plant interactions from positive (facilitation) to negative (competition). We recommend alternative post-fire management actions that decrease plant competition and take advantage of facilitation by residual burned wood, to ultimately accelerate ecosystem recovery after large stand-replacing fires.

The initiation and development of small peat‐forming ecosystems adjacent to lakes in the north central Canadian low arctic during the Holocene

Small peat-forming ecosystems in arctic landscapes may play a significant role in the regional biogeochemistry of high-latitude systems, yet they are understudied compared to arctic uplands and other major peat-forming regions of the North. We present a new data set of 25 radiocarbon-dated permafrost peat cores sampled around eight low arctic lake sites in northern Manitoba (Canada) to examine the timing of peat initiation and controls on peat accumulation throughout the Holocene. We used macrofossils and charcoal to characterize changes in the plant community and fire, and we explored potential impacts of these local factors, as well as regional climatic change, on rates of C accumulation and C stocks. Peat initiation was variable across and within sites, suggesting the influence of local topography, but 56% of the cores initiated after 3000 B.P. Most cores initiated and remained as drier bog hummock communities, with few vegetation transitions in this landscape. C accumulation was relatively slow and did not appear to be correlated with Holocene-scale climatic variability, but C stocks in this landscape were substantial (mean = 45.4 kg C m−2), potentially accounting for 13.2 Pg C in the Taiga Shield ecozone. To the extent that small peat-forming systems are underrepresented in peatland mapping, soil organic carbon (SOC) stocks may be underestimated in arctic regions. Mean fire severity appeared to be negatively correlated with C accumulation rates. Initiation and accumulation of soil C may respond to both regional and local factors, and substantial lowland soil C stocks have the potential for biogeochemical impacts on adjacent aquatic ecosystems.

Repowering Options for Complying with Canadian CO2 Emission Intensity Limits on Existing Coal Plants

The Canadian federal government has introduced carbon dioxide emission intensity limits of no greater than 420 kg/MWh net for new coal plants and existing coal plants more than 50 years of age. Many operating coal plants in Canada will be impacted by this legislation in the near future, requiring operators to plan a compliance strategy. The Canadian Clean Power Coalition (CCPC) investigated the performance and economics of a number of options for existing plants that could deliver compliant solutions. These options included strategies in which natural gas is available and some in which only coal firing is feasible due to cost or logistical issues.Repowering and post-combustion capture (PCC) options were studied using an eastern Canadian power plant firing bituminous coal. The base-case (BC) option was a new combined-cycle gas turbine (CCGT) plant, against which all other options were compared. The following cases were investigated:1.PCC using:a.Monoethanolamine MEA solvent with crossover steam regenerationb.Commercial advanced solvent with crossover steam regenerationc.Commercial advanced solvent with a small gas turbine (GT) and a low-pressure steam generatord.Commercial advanced solvent with a GT, triple-pressure heat recovery steam generator (HRSG) and a back pressure steam turbinee.Commercial advanced solvent with a natural gas boiler and a back pressure steam turbine2.Repowering of existing steam turbines with new a GT and HRSG3.Repowering of existing steam turbines with fuel cellsa.New solid oxide fuel cell (SOFC) topping unitb.New molten carbonate fuel cell (MCFC) topping unit4.Expanded PCC approach with:a.Third unit with full LP steam turbine bypass supplying steam to PCCb.Circulating fluidized bed (CFB) boiler and back pressure steam turbineOne of the issues with incorporating PCC in an existing facility is delivering the thermal regeneration energy to the PCC reboilers in an efficient and cost-effective manner. This can involve significant integration with the low-pressure stages of the steam turbine, a duty for which the turbine was not designed. Because turbine modifications (to deliver partially expanded steam to the PCC plant) can be costly and would require significant down time, alternative strategies were investigated in which the PCC facility would effectively be a “standalone” facility, with the main plant interfaces being the flue gas to be treated and some shared services.The costing analysis was carried out on the following basis: 30-year plant design life (with life-extension costs included for existing plant), 90% capacity factor for the first year cost of electricity (COE), and a coal cost of $4.73/GJ and a natural gas cost of $10.00/GJ (based on 2013 forecasted costs). Case 2 (repowering existing steam turbines with new natural gas combined-cycle plant) without any additional CO2 abatement, delivered both the lowest capital costs and cost of electricity. If the existing coal boiler plant remains operational, the lowest costs were achieved by installing a molten carbonate fuel cell (Case 3b) followed closely with an advanced solvent PCC unit with solvent regeneration thermal energy being delivered by an efficient, small, dedicated gas turbine with a triple pressure HRSG (Case 1d). Where there is no existing infrastructure to deliver natural gas, the traditional methodology of extracting crossover steam from the unit for PCC solvent regeneration proved to be the lowest-cost option.

Sparrow nest survival in relation to prescribed fire and woody plant invasion in a northern mixed‐grass prairie

ABSTRACTPrescribed fire is used to reverse invasion by woody vegetation on grasslands, but managers often are uncertain whether influences of shrub and tree reduction outweigh potential effects of fire on nest survival of grassland birds. During the 2001–2003 breeding seasons, we examined relationships of prescribed fire and woody vegetation to nest survival of clay‐colored sparrow (Spizella pallida) and Savannah sparrow (Passerculus sandwichensis) in mixed‐grass prairie at Des Lacs National Wildlife Refuge in northwestern North Dakota, USA. We assessed relationships of nest survival to 1) recent fire history, in terms of number of breeding seasons (2, 3, or 4–5) since the last prescribed fire, and 2) prevalence of trees and tall (>1.5 m) shrubs in the landscape and of low (≤1.5 m) shrubs within 5 m of nests. Nest survival of both species exhibited distinct patterns related to age of the nest and day of year, but bore no relationship to fire history. Survival of clay‐colored sparrow nests declined as the amount of trees and tall shrubs within 100 m increased, but we found no relationship to suggest nest parasitism by brown‐headed cowbirds (Molothrus ater) as an underlying mechanism. We found little evidence linking nest survival of Savannah sparrow to woody vegetation. Our results suggest that fire can be used to restore northern mixed‐grass prairies without adversely affecting nest survival of ≥2 widespread passerine species. Survival of nests of clay‐colored sparrow may increase when tall woody cover is reduced by fire. Our data lend support to the use of fire for reducing scattered patches of tall woody cover to enhance survival of nests of ≥1 grassland bird species in northern mixed‐grass prairies, but further study is needed that incorporates experimental approaches and assessments of shorter term effects of fire on survival of nests of grassland passerines. © 2017 This article is a U.S. Government work and is in the public domain in the USA.

Climate‐biomes, pedo‐biomes or pyro‐biomes: which world view explains the tropical forest–savanna boundary in South America?

AbstractAimIt remains poorly understood why the position of the forest–savanna biome boundary, in a domain defined by precipitation and temperature, differs in South America, Africa and Australia. Process based Dynamic Global Vegetation Models (DGVMs) are a valuable tool to investigate the determinants of vegetation distributions; however, many DGVMs fail to predict the spatial distribution or indeed presence of the South American savanna biome. Evidence suggests that fire plays a significant role in mediating forest–savanna biome boundaries; however, fire alone appears to be insufficient to predict these boundaries in South America. We hypothesize that interactions between precipitation, constraints on tree rooting depth and fire affect the probability of savanna occurrence and the position of the savanna–forest boundary.LocationTropical forest and savanna sites in Brazil and Venezuela north of 23S.MethodsWe tested our hypotheses using a novel DGVM, aDGVM2, which allows plant trait spectra, constrained by trade‐offs between traits, to evolve in response to abiotic and biotic conditions. Plant hydraulics is represented by the cohesion–tension theory, this allowed us to explore how soil and plant hydraulics control biome distributions and plant traits. The resulting community trait distributions are emergent properties of model dynamics.ResultsWe showed that across much of South America the biome state is not determined by climate alone. Interactions between plant rooting depth, fire and precipitation affected the probability of observing a given biome state and the emergent traits of plant communities. Simulations where plant rooting depth varied in space provided the best match to satellite derived biomass estimates and generated biome distributions that reproduced contemporary biome maps well.Main conclusionsOur findings support the contention that areas where multiple vegetation states are possible are widespread and highlight the importance of considering the influence of fire and constraints on plant rooting depth for predicting biome boundaries.

Plant community response to prescribed fire varies by pre-fire condition and season of burn in mountain big sagebrush ecosystems

Artemisia tridentata ssp. vaseyana ecosystems evolved with periodic fire, but invasive grasses, conifer encroachment, fire suppression, and climate change have resulted in altered fire regimes and plant communities. Post-fire increases in invasive annual grasses such as Bromus tectorum and reductions in native vegetation are common across the sagebrush steppe. Where fire has been excluded though, there are increases in the native tree Juniperus occidentalis, which outcompetes the native understory. We applied prescribed fire in spring and fall at three sites (native-dominated, B. tectorum-dominated, and J. occidentalis-dominated). We documented 65% survival of A. tridentata following fall burns and 33% survival following spring burns in native-dominated plots, with evidence of post-fire sprouting in Purshia tridentata and Tetradymia canescens. At the B. tectorum-dominated site, shrub cover was reduced to <1%. Fires at the J. occidentalis site were discontinuous, resulting in ∼50% mortality of trees and shrubs, with little resprouting. Native herbaceous vegetation persisted following fires, with no increases in B. tectorum. There were higher plant survival rates following fall fires and native-dominated sites than in spring burns or where exotics dominated. These results show that burn season and prefire condition are important considerations when evaluating management alternatives in A. tridentata ssp. vaseyana ecosystems.

플라이애시 품질이 시멘트 페이스트 레올로지 특성에 미치는 영향

플라이애시는 시멘트 계열 재료의 혼화재료로서 널리 사용되고 있는 재료이다. 다만, 플라이애시는 화력발전소의 석탄재를 포집하여 정제과정을 거친 재료로서 정제과정의 에너지 소모 및 유통과정에서의 품질 확보가 중요하다. 이에 본 연구에서는 플라이애시 생산과정 중 발생하는 세 가지 종류의 다른 품질의 석탄재를 대상으로 각각의 입자조건과 시멘트 페이스트 상태에서 레올로지 거동을 평가하였다. 실험결과 리젝트 애시는 작은 석탄재 입자가 응집되어 굳어진 다공질의 큰 입자로 구성되어 있었고, 그러한 이유로 시멘트 페이스트에 포함될 경우 공기량이 높게 측정되는 경향이 나타났다. 유동성 측면에서는 석탄재가 치환되는 경우 유동성이 증진되는 양상을 보였으며 특히 점도 측면에서는 입자조건에 따라 점도를 조정할 수도 있었다. The aim of the research is to provide rheological properties of cement paste with various qualities of coal ash including fly ash, raw ash, and reject ash. Generally, fly ash is the well known supplementrary cementitious materials for concrete and is used to improve various properties. Although fly ash is obtained as a byproduct of fire powder plant, still reject ash is wasted from raw ash. In this research, thus, to provide a fundamental information on using not only fly ash but also raw ash or reject ash for cementitious materials, a rheological properties of cement paste was studied with three different coal ash. This research was conducted from particle conditions of three different coal ashes to rheological properties in cement paste phase. According to the expeirment, reject ash was consisted with large and coagulated particles although fly ash was consisted with a small and spherical shaped particles. based on the particle conditions of various coal ashes, rheological behaviors were tested, and it was shown as the coal ashes improved the fluidity of cement paste. Specifically, depending on the particle distributions of cement paste, it is considered that the viscosity of paste can be controlled.

Moderate grazing sustains plant diversity in Afromontane grassland

AbstractAimsNatural disturbances drive plant assemblages in Afromontane grassland. Our aim is to assess how intensity of cattle grazing and time since last fire influence plant species richness, dominance and assemblage composition.LocationCentral Midlands, KwaZulu‐Natal province, South Africa.MethodsSites differed in grazing intensity (light, moderate and heavy) and time since last fire: recently burned (RB) vs unburned (UB). We sampled plants in 24 vegetation quadrats (1‐m2) randomly located within each site (~1000 m2). We used linear regression models for species richness and dominance, IndVal to identify indicator species and CCA for assemblage composition. All analyses were conducted at quadrat and site level.ResultsSpecies richness was significantly influenced by time since last fire (RB &gt; UB), grazing intensity (light &lt; moderate &gt; heavy) and the fire–grazing interaction at quadrat level. Dominance reciprocated the response of species richness to time since last fire (UB &gt; RB), but did not respond consistently to grazing intensity (light &gt; moderate &gt; or &lt; heavy). Plant assemblage composition was significantly influenced by time since last fire, grazing intensity and vegetation structure (live vegetation cover and vegetation height). Indicator species of species‐poor, heavily grazed sites included alien species, such as Cirsium vulgare and Conyza bonariensis.ConclusionResponse of species richness to grazing intensity conforms to the predictions of the intermediate disturbance hypothesis. Burning and moderate grazing should be part of grassland management. To prevent species loss and influx of alien species, heavy grazing should be minimized. As development of grassland ecological networks in a timber matrix is being pioneered in South Africa, these findings indicate a way forward for the management of similar systems elsewhere in the world.

The ecology of population dispersal: Modeling alternative basin-plateau foraging strategies to explain the Numic expansion.

The expansion of Numic speaking populations into the Great Basin required individuals to adapt to a relatively unproductive landscape. Researchers have proposed numerous social and subsistence strategies to explain how and why these settlers were able to replace any established populations, including private property and intensive plant processing. Here we evaluate these hypotheses and propose a new strategy involving the use of landscape fire to increase resource encounter rates. Implementing a novel, spatially explicit, multi-scalar prey choice model, we examine how individual decisions approximating each alternative strategy (private property, anthropogenic fire, and intensive plant processing) would aggregate at the patch and band level to confer an overall benefit to this colonizing population. Analysis relies on experimental data reporting resource profitability and abundance, ecological data on the historic distribution of vegetation patches, and ethnohistoric data on the distribution of Numic bands. Model results show that while resource privatization and landscape fires produce a substantial advantage, intensified plant processing garners the greatest benefit. The relative benefits of alternative strategies vary significantly across ecological patches resulting in variation across ethnographic band ranges. Combined, a Numic strategy including all three alternatives would substantially increase subsistence yields. The application of a strategy set that includes landscape fire, privatization and intensified processing of seeds and nuts, explains why the Numa were able to outcompete local populations. This approach provides a framework to help explain how individual decisions can result in such population replacement events throughout human history.

Specific energy consumption and carbon intensity of ceramic tablewares: Small enterprises (SEs) in Thailand

Energy consumption and greenhouse gas (GHG) emission from ceramic tableware production in Thailand were evaluated. Activity data regarding ceramic tableware manufacture were collected from 13 small-scale ceramic tableware plants within the boundaries of gate-to-gate. The functional unit of analysis was 1 kg of ceramic tableware product. The GHG emission of ceramic tableware production per unit of kgCO2e/kg was calculated following the 2006 Intergovernmental Panel on Climate Change (IPCC) guidelines. Emission factors were taken from the Thailand Greenhouse Gas Management Organization (TGO) and IPCC databases. The SPSS independent sample t-test (IBM SPSS Statistics 22.0) was used as a statistical inferential method for comparison of energy consumption. Results showed that the energy consumptions of ceramic tableware were mainly from liquefied petroleum gases (LPG) as 19,363 MJ/tonne during the firing process (99%), followed by electricity at 243 MJ/tonne (1%) during the forming process. The average specific energy consumption (SEC) for small-scale ceramic tableware production in Thailand was 19.6 ± 4.7 GJ/tonne of product. The SPSS independent sample t-test revealed that the energy consumption in double firing plants was 10% significantly higher than single firing plants. Comparison between specific LPG consumptions and kiln loading capacities of single firing plants indicated a linear relationship, and kiln loading capacity significantly influenced the amount of specific LPG consumed. An increase in kiln loading capacity decreased specific LPG consumption. Every one kg product/m3 loading increase gave a reduction of 0.67 kg LPG/kg product. The average carbon intensity of small-scale ceramic tableware production in Thailand was 1.241 ± 0.295 kgCO2e/kg of product. The largest GHG emission was from LPG consumption during the firing process (98%), followed by electricity consumptions (1%), and decomposition of calcium and barium carbonates (1%). The average GHG emissions of double fired and single fired products were 1.340 and 1.211 kgCO2e/kg of product, respectively. Therefore, LPG consumption during the firing process was identified as the main hotspot for energy consumption and GHG emission. Increasing kiln loading capacity, reducing kiln heat leakage, and repairing ceramic insulators were recommended as good practices for energy saving which can potentially be applied to the existing small-scale ceramic tableware plants.