Air pollution has changed from an urban environmental problem to a phenomenon spreading to state, country and even global scales. In response, a variety of regulations, standards, and policies have been enacted world-wide. Policy-making and development of efficient and effective control strategies requires understanding of air quality impacts from different sources, which are usually estimated using source-oriented air quality models and their corresponding uncertainties should be addressed. This thesis evaluates emission uncertainties and their impacts on air quality modeling (Models-3/Community Multiscale Air Quality Model (CMAQ)), with special attention to biomass burning. Impacts of uncertainties in ozone precursors (mainly NOX and VOC) emissions from different sources and regions on ozone formation and emission control efficiencies are evaluated using Monte Carlo methods. Instead of running CMAQ multiple of times, first and higher order ozone sensitivities calculated by Higher-order Decoupled Direct method in Three Dimensions (CMAQ-HDDM-3D) are employed to propagate emission uncertainties. Biomass burning is one of the major sources for PM2.5. Impacts of uncertainties in biomass burning emissions, including total amount, temporal and spatial characteristics, and speciation on air quality modeling are investigated to identify emission shortcomings. They are followed by estimation of seasonal PM2.5 source contributions over the southeastern US focusing on Georgia. Results show that prescribed forest fires are the largest individual biomass burning source. Forest fire emissions under different forest management practices and ensuing air quality impacts are further studied. Forest management practices considered here include different burning seasons, fire-return intervals (FRIs), and controlling emissions during smoldering. Finally, uncertainties in prescribed forest fire emissions are quantified by propagation of uncertainties in burned area, fuel consumption and emission factors, which are required inputs for emissions estimation and quantified by various fire behavior models and methods. In summary, this thesis has provided important insights regarding emission uncertainties and their impacts on air quality modeling.

A research report submitted to the Faculty of Science, University of the Witwatersrand, and Johannesburg in partial fulfillment of the requirements for the degree Master o f Science (Geographical Information System and Remote Sensing) Johannesburg, 2017. / The purpose of this analysis was to map the frequency of veld fires using remote sensing data from 2012 to 2016. The analysis successfully answered three objectives which are mapping the spatio-temporal pattern of veld fires in Mazowe district from 2012 to 2016, assessing the strength of association between burnt area and land cover classes and to determine the degree of veld fires in Mazowe district. The analysis of the veld fire frequency was undertaken in ENVI 5.3 and Arc Map software. Landsat imagery and MODIS fire products were collected and processed. For each year two Landsat images were used, one image before the season of fire starts which was used to classify the land cover classes and one image after fire season which was used to classify the burnt and unburnt classes. The MODIS fire products data were used to validate the burnt and the unburnt classification. The evaluations of the classifiers were done through accuracy assessment using confusion matrix and the results ranged from 85 to 95%.The study quantified the relationship between burnt areas land cover classes. The study also calculated the fire frequency. The results revealed that the veld fire frequency was high in A1 farms which measures 5 hectares, A2 farms which measures average of 318 hectares and grasslands compared to other land tenure and land cover classes. Areas with high frequency were observed in south, south west and some central parts of Mazowe district. There was high fire occurrence in 2012 and 2014. The study also noted that the fire occurrence was gradually decreasing, however the levels of fire occurrence remains high. The study concluded that A1, A2 farms and grasslands are prone to veld fires. The study recommends adaption of remote sensing techniques in eradicating veld fires. / MT 2017

Chewings fescue [Festuca rubra L. subsp. fallax (Thuill.) Nyman] is a desired turfgrass with dense sod forming capabilities and superior shade tolerance. Thermal residue management (open-field burning) has traditionally been used to remove post-harvest residue and maintain seed yield over the life of the stand. However, alternative non-thermal residue management practices have been observed to produce adequate seed yields dependent upon cultivar. Strong creeping red fescue (F. rubra L. subsp. rubra) is desired for its prolific tillering capacity and creeping rhizomatous growth habit. In contrast to Chewings fescue, maintenance of seed yield in strong creeping red fescue has only been profitably produced under thermal residue management. Slender creeping red fescue [F. rubra L. var. littoralis (Vasey)] is a desired turfgrass with a compact, less rhizomatous growth habit, similar to Chewings fescue in desirable turf attributes. However, little is known about the effects of post-harvest residue management in slender creeping red fescue. The objectives of this study were: 1) to evaluate seed yield and yield components among different cultivars to thermal (open-burning), and non-thermal (flail low and flail high) post-harvest residue management; 2) to evaluate harvest index and percent cleanout to thermal and non-thermal residue management in different cultivars; and 3) and to provide an economic analysis of thermal and non-thermal residue management in all cultivars based on partial budgeting. Three post-harvest residue management treatments (burn, flail low and flail high) were applied over the course of two years. Seed yield components measured included: total dry weight, fertile tiller number, spikelets per panicle, florets per spikelet, and panicle length. Final seed yield in each cultivar and residue management treatment method was determined after seed harvest and conditioning. Seed yield component analysis was conducted over three production seasons. Chewings fescue, strong creeping red fescue, and slender creeping red fescue cultivars responded differently to residue management as indicated by a residue management by cultivar interaction. In 2003 and 2004, residue management by cultivar interactions were evident in seed number, seed weight, fertile tiller number, percent cleanout, harvest index, and seed yield. Residue management by cultivar interactions occurred in spikelets per panicle in 2003, whereas in 2004 a residue management by cultivar interaction occurred in panicle length and florets per spikelet. In 2004, non-thermal flail low, and thermal residue management resulted in significantly greater spikelets per panicle in all cultivars. Thermal residue management resulted in the greatest number of spikelets per panicle. Results indicate that thermal residue management best maintained seed yield in most subspecies and cultivars across both years. However, in 2003, non-thermal flail low residue management produced profitable seed yield in only Marker slender creeping red fescue. In contrast, thermal residue management resulted in poor seed yields in Marker slender creeping red fescue and enhanced yields in Seabreeze slender creeping red fescue in 2003. However, following the second year of thermal treatment in 2004, Marker and Seabreeze both had lower seed yields, thus exhibiting the only negative impact of thermal management among the cultivars tested in this study. Moreover, upon review of an economic analysis, Marker slender red fescue was the only cultivar that produced a positive net return of $78 and $4 ha⁻¹ under non-thermal residue management in 2003 and 2004, respectively. Furthermore, in 2003, thermal residue management net return increases ranged from $104 ha⁻¹ to -$996 ha⁻¹ in Barnica and Shademark, respectively. In 2004, thermal residue management net return increases ranged from $115 ha⁻¹ and $1,332 ha⁻¹ in Seabreeze and Shademark, respectively. Poor seed yields were observed in all strong creeping red fescue cultivars under non-thermal residue management across both years of the study. This may be attributed to an observed reduction in fertile tiller number and seed yield. In addition, percent seed cleanout was increased with non-thermal residue management. In 2004, as stand age increased, thermal residue management resulted in greater seed yields in all cultivars and species, except both cultivars of slender creeping red fescue. Thus, this study provided substantial evidence that thermal residue management has the potential to maintain or increase fine fescue seed yield as stands age as well as to maintain stand profitability. / Graduation date: 2005

No description available.

Open-field burning has been an effective, economical, and widespread method of post-harvest residue management in creeping red fescue seed production in the Willamette Valley since the late 1940s. However, the use of field burning has been legislatively restricted due to air quality and safety issues. The foliar-applied plant growth regulator trinexapac-ethyl (TE), commercialized in the USA as Palisade, has been accepted by producers as a yield enhancing agent and is considered here as an alternative to open-field burning over a four-year period. The effects of open-field burning versus mechanical removal (flailing) of post-harvest residue, and spring versus fall applications of TE on seed yield, dry matter partitioning, and seed yield components were evaluated in a split-plot design. The response to the different treatment combinations differed across years. The young stand responded with a seed yield increase to spring TE applications, regardless of residue management treatment. However, as the stand aged, field burning became critical for maintaining high yields and, in 2003 and 2004, only spring TE applications resulted in seed yield increases in burned plots. The higher potential seed yield achieved in burned plots over flailed plots, as a result of a higher number of panicles per unit area and spikelets per panicle, was critical for maintaining high seed yields as the stand aged. Spring applications of TE, further increased seed yield over the untreated check by increasing the number of florets per spikelet, reducing fertile tiller height and lodging and consequently, favoring pollination and fertilization of the florets. Late spring TE applications also increased 1000-seed weight in 2003 and 2004. Although spring applications of TE were a promising alternative to open-field burning early during the life of the stand, as the stand aged they did not increase seed yield on flailed plots. Fall TE applications did not have a consistent effect on seed yield, dry matter partitioning or seed yield components, and were found not to be a viable management practice. / Graduation date: 2005

Total organic carbon, total nitrogen, microbial respiration and enzyme activity (β-glucosidase) were measured on several horizons of a Dayton silt loam (fine, montmorillonitic, mesic, Typic Albaqualf) soil cropped to annual ryegrass under two straw residue management systems. The study evaluated the effects of annual burning of straw residues or annual incorporation of straw residues on the content, distribution and bioavailability of soil organic carbon. Four fields were selected to represent the burn management system which have been annually burned for a minimum of 40 years. Four fields were selected to represent the straw incorportated system (mold board plow) which had been annually burned for approximately 30 years, followed by incorporation of straw residues into soil for a minimum of 10 years. One native site was selected to represent non-cultivation conditions. Straw management system strongly influenced both the total organic C and N and microbial activity the surface soil horizon. Soil organic C and N content were significantly greater (p < 0.05) in the Ap horizons of soils under the plowed management system than soils under the burned management system. The collective evidence suggests, however, that the significant differences observed between the two residue management systems are not due to greater losses of soil organic C and N as a result of burning but rather that organic C levels have increased as a result of a change in management. Soil C:N ratios are slightly higher in the Ap horizons of soils as a result of straw residue incorporation in comparison to burning of straw residues. When expressed on a mass soil basis, both C0₂ evolution from microbial respiration, during a 32 day incubation period, and enzyme activity were significantly greater (p < 0.10) for the Ap horizon of soils where straw residue had been incorporated than in soils where residues had been annually burned. When expressed on a per gram C basis, neither C0₂ evolution from microbial respiration or enzyme activity were significantly different between the two management systems. These results indicate that long-term annual burning of straw residues has not decreased the bioavailability of soil organic C. / Graduation date: 1992

The work has consisted of the measurement of processes connected with the normal management of grouse moors in the Glen Clova area of Angus. The problems associated with burning have been summarised together with the remits of previous work. The geology and topography of Glen Clova have been described briefly, and the vegetation of the Rottal area of the glen has been described in detail with respect to the particular parts under consideration. A method of ring counts has been used to define the age of Calluna stands. The methods used for analysis of mineral nutrients have been described. One method, Atomic Absorption Spectroscopy, has required extensive calibration and has been described in more detail. It has been shown that the temperature and duration of heath fires depends upon the age of the vegetation. The temperature and duration of a fire determined the loss of nitrogen in the form of smoke. The temperature of a fire has been shown to affect the solubility of nutrients in ash. Increase in temperature caused a greater release of soluble potassium and calcium, but a decrease in soluble phosphate, The release of mineral nutrients from Calluna leaf litter has been compared with that from ash. Experiments were instigated to measure the effect of grazing upon the yield and mineral content of Calluna, the greatest effect being found 5 - 10 years after burning. The addition of mixed fertiliser to some of the stands was found to increase the yield and nutrient content of the leaven of Calluna. Soil samples from 22 stands of Calluna were analysed in November each year, for three years, and the total content of nitrogen, phosphate, potassium, magnesium, calcium and iron estimated. In the first instance other analyses including pH, conductivity, organic carbon and mechanical analysis were performed in order to distinguish between the two soil types present. Significant changes in the nutrient content of the soils have been discussed. A balance sheet of the losses and gains to the ecosystem was prepared to indicate the changes in mineral nutrients. it has been calculated that the potential losses of individual nutrients by leaching, ignition and grazing could be replaced over a period of 15 years from rainwater, with the exception of phosphate which is only present in small quantities in rainwater. The implications of the results have been discussed.