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The potential roles of forest farmers' organizations in wood value chain upgrading in Eastern AfricaHintz, Kendisha Illona Soekardjo 06 February 2024 (has links)
Eastern African countries have been confronted with forest landscape degradation and the consequently growing gap between the supply and demand of wood products. Small-scale farmers growing trees on farm have been increasingly acknowledged as a major wood supplier. Value chain analysis studies pointed out the challenges faced by the smallholders, as they are commonly engaged in informal wood markets, associated with weaker bargaining power and market asymmetry. From the Social and Solidarity Economy lens, collective action approaches through farmers’ organizations can counter the challenges of individual smallholders, while facilitating the upgrading of wood value chains. Thus, the objective of this dissertation was to analyze the (potential) roles of forest farmers’ organizations (FFOs) in wood value chain upgrading, with two case studies in Ethiopia and Tanzania.
Through a systematic literature review worldwide, the study first sought to provide a knowledge base for FFO research grounded on (i) the policy context within which FFOs operate, and (ii) the typology of their performance with reference to resource mobilization, commercialization of wood products and benefit sharing mechanisms. Value chain analyses of wood products from smallholders each in Ethiopia and Tanzania were the point of departure for the empirical work, consequently treated as the case studies. A collective of smallholders and individual smallholders were embedded as the units of analysis in the two independent case studies. The two-country study setting permitted the analytical generalization of collective action approaches to value chain upgrading and the development of a research agenda and policy recommendations.
Grounded on the value chain upgrading approach, FFO business models were co-developed to assess the interlinkages between the business model and (i) the organizational governance and (ii) the implications on wood value chain upgrading. Participatory workshops with existing farmers’ organizations were conducted to co-develop the business models, while focus group discussions and key informant interviews served to frame and triangulate the contextual conditions. Semi-structured household interviews were employed to examine the perception of FFOs and the main factors influencing farmers’ willingness to participate. Binary logistic regression analysis and descriptive statistics were employed in tandem with thematic analysis to analyze the data.
The global review represented 57 FFOs distributed globally across 20 countries, which were manifested as associations, cooperatives, and small- and medium-sized enterprises. Research in FFOs has gained scholarly traction in the last three decades, emphasizing the emerging trend of smallholders managing forest farm forestry plots across the tropics. The review revealed three categories of FFOs, depending on the extent of the organization’s product portfolio, the value addition captured at the organizational level, and the linkages to market channels.
The empirical findings revealed that southern Ethiopia and southern Tanzania had contrasting regulatory framework for the establishment of FFOs. Given the existing foreign donor program targeted at smallholders in Tanzania, institutional and financial start-up support exist. In both cases, farmers were able to envisage an FFO business model that would allow product and process upgrading of wood value chains. The FFO was perceived differently across the two cases. The Ethiopian case study referred to it as a tree marketing cooperative, which shall facilitate the production of members’ woodlots and the commercialization of wood products of members and non-members alike at a timber yard in a nearby urban area. The Tanzanian case study termed it as a tree growers’ association, which shall facilitate the production of members’ wood and non-wood products, and the commercialization of members’ sawn timber to existing traders. Achieving functional upgrading would necessitate concerted efforts by various governmental and non-governmental stakeholders.
The household interviews revealed that 74% (n = 185) and 90% (n = 190) of smallholders would be willing to participate in an FFO in the Ethiopian and Tanzanian case, respectively. In Ethiopia, farmers perceived it as a collective wood marketing enterprise. A relatively small group size with substantial monetary contribution characterize farmers’ preferences to undertake a joint business on wood marketing. In Tanzania, the perception of a tree growers’ association centered on social learning elements to improve wood production and find alternative buyers, while regulating fire incidences. In both cases, the significant factors influencing farmers’ willingness to participate were (1) household socio-economic characteristics, e.g. household head’s age group or household size; and (2) experiences with tree growing activities, e.g. price satisfaction in the last sales or difficulty in market access.
The synthesis permitted the derivation of the following conceptual assertion: that FFOs have the potential in upgrading the wood value chains, as long as farmers can envision a business model of an FFO that accommodates the factors influencing farmers’ willingness to participate. Overall, the study demonstrates the changing narratives of farmers’ organizations in the study countries and contributes to the commons-cooperative alliance theory – the integration of collective action and cooperative management. Furthermore, the key findings provide the groundwork to springboard future research avenues, specifically to test the derived assumptions, and recommendations for policy and development. / Die ostafrikanischen Länder sind mit der Degradierung der Waldlandschaft und der daraus resultierenden wachsenden Kluft zwischen Angebot und Nachfrage nach Holzprodukten konfrontiert. Kleinbauern, die auf ihren Höfen Bäume anbauen, werden zunehmend als wichtige Holzlieferanten anerkannt. In Studien zur Analyse von Wertschöpfungsketten wurde auf die Herausforderungen hingewiesen, mit denen die Kleinbauern konfrontiert sind, da sie in der Regel auf informellen Holzmärkten tätig sind, die mit einer schwächeren Verhandlungsposition und Marktasymmetrie verbunden sind. Aus der Sicht der Sozial- und Solidarökonomie können kollektive Handlungsansätze durch Bauernorganisationen den Herausforderungen einzelner Kleinbauern begegnen und gleichzeitig die Aufwertung von Holzwertschöpfungsketten erleichtern. Ziel dieser Dissertation war es daher, die (potenzielle) Rolle von Waldbauernorganisationen (FFOs) bei der Aufwertung von Holzwertschöpfungsketten anhand von zwei Fallstudien in Äthiopien und Tansania zu analysieren.
Durch eine systematische weltweite Literaturrecherche versuchte die Studie zunächst eine Wissensbasis für die FFO-Forschung zu schaffen, die sich auf (i) den politischen Kontext, in dem FFOs agieren, und (ii) die Typologie ihrer Leistungen in Bezug auf Ressourcenmobilisierung, Kommerzialisierung von Holzprodukten und Mechanismen zum Gewinnausgleich stützt. Ausgangspunkt für die empirische Arbeit waren Wertschöpfungskettenanalysen von Holzprodukten von Kleinbauern in Äthiopien und Tansania, die folglich als Fallstudien behandelt wurden. Ein Kollektiv von Kleinbauern und einzelne Kleinbauern wurden als Analyseeinheiten in die beiden unabhängigen Fallstudien eingebettet. Der Rahmen der Zwei-Länder-Studie ermöglichte die analytische Verallgemeinerung von kollektiven Handlungsansätzen zur Verbesserung der Wertschöpfungskette und die Entwicklung einer Forschungsagenda und politischer Empfehlungen.
Auf der Grundlage des Ansatzes zur Aufwertung der Wertschöpfungskette wurden gemeinsam FFO-Geschäftsmodelle entwickelt, um die Zusammenhänge zwischen dem Geschäftsmodell und (i) der Organisationsführung und (ii) den Auswirkungen auf die Aufwertung der Wertschöpfungskette für Holz zu bewerten. Zur gemeinsamen Entwicklung der Geschäftsmodelle wurden partizipative Workshops mit bestehenden Bauernorganisationen durchgeführt, während Fokusgruppendiskussionen und Interviews mit Schlüsselinformanten dazu dienten, die Kontextbedingungen zu erfassen und zu triangulieren. Halbstrukturierte Haushaltsbefragungen wurden eingesetzt, um die Wahrnehmung der FFOs und die wichtigsten Faktoren, die die Bereitschaft der Landwirte zur Teilnahme beeinflussen, zu untersuchen. Zur Analyse der Daten wurden binäre logistische Regressionsanalysen und deskriptive Statistiken in Verbindung mit einer thematischen Analyse eingesetzt.
Die globale Untersuchung umfasste 57 FFOs in 20 Ländern, die in Form von Verbänden, Genossenschaften sowie kleinen und mittleren Unternehmen organisiert sind. Die Forschung zu FFOs hat in den letzten drei Jahrzehnten an wissenschaftlicher Bedeutung gewonnen, wobei der aufkommende Trend zu Kleinbauern, die in den Tropen forstwirtschaftliche Flächen bewirtschaften, hervorgehoben wurde. Die Untersuchung ergab drei Kategorien von FFOs, je nach Umfang des Produktportfolios der Organisation, der Wertschöpfung auf Organisationsebene und der Anbindung an Marktkanäle.
Die empirischen Ergebnisse zeigen, dass der Süden Äthiopiens und der Süden Tansanias unterschiedliche rechtliche Rahmenbedingungen für die Gründung von FFOs haben. Angesichts des bestehenden Programms ausländischer Geber, das auf Kleinbauern in Tansania abzielt, gibt es institutionelle und finanzielle Starthilfe. In beiden Fällen waren die Landwirte in der Lage, sich ein FFO-Geschäftsmodell vorzustellen, das eine Produkt- und Prozessverbesserung der Holzwertschöpfungsketten ermöglichen würde. Die FFO wurde in den beiden Fällen unterschiedlich wahrgenommen. In der äthiopischen Fallstudie wurde sie als Baumvermarktungsgenossenschaft bezeichnet, die die Produktion der Holzflächen der Mitglieder und die Vermarktung der Holzprodukte von Mitgliedern und Nichtmitgliedern auf einem Holzlagerplatz in einem nahe gelegenen städtischen Gebiet erleichtern soll. Die tansanische Fallstudie bezeichnete sie als eine Baumzüchtervereinigung, die die Produktion von Holz- und Nichtholzprodukten der Mitglieder und die Vermarktung des Schnittholzes der Mitglieder an bestehende Händler erleichtern soll. Um eine funktionale Aufwertung zu erreichen, bedarf es konzertierter Anstrengungen verschiedener staatlicher und nichtstaatlicher Akteure.
Die Haushaltsbefragungen ergaben, dass 74% (n = 185) bzw. 90% (n = 190) der Kleinbauern in Äthiopien und Tansania bereit wären, sich an einer FFO zu beteiligen. In Äthiopien verstanden die Landwirte die FFO als kollektives Holzvermarktungsunternehmen. Eine relativ kleine Gruppengröße und ein erheblicher finanzieller Beitrag kennzeichnen die Präferenzen der Landwirte für ein gemeinsames Holzvermarktungsunternehmen. In Tansania konzentrierte sich die Wahrnehmung einer Baumzüchtervereinigung auf Elemente des sozialen Lernens, um die Holzproduktion zu verbessern, alternative Abnehmer zu finden und gleichzeitig das Auftreten von Bränden einzudämmen. In beiden Fällen waren die wichtigsten Faktoren, die die Bereitschaft der Landwirte zur Teilnahme beeinflussten, (1) sozioökonomische Merkmale des Haushalts, z. B. die Altersgruppe des Haushaltsvorstands oder die Haushaltsgröße, und (2) Erfahrungen mit Baumzuchtaktivitäten, z. B. die Preiszufriedenheit beim letzten Verkauf oder Schwierigkeiten beim Marktzugang.
Die Synthese ermöglichte die Ableitung der folgenden konzeptionellen Behauptung: FFOs habe das Potenzial, die Wertschöpfungsketten im Holzsektor aufzuwerten, sofern sich die Landwirte ein Geschäftsmodell für ein FFO vorstellen können, das die Faktoren in Betracht zieht, die die Bereitschaft der Landwirte zur Teilnahme beeinflussen. Insgesamt zeigt die Studie die sich wandelnden Narrative von Bauernorganisationen in den Studienländern auf und leistet einen Beitrag zur Theorie der Allmende-Kooperation - der Integration von kollektivem Handeln und genossenschaftlichem Management. Darüber hinaus bilden die wichtigsten Ergebnisse die Grundlage für künftige Forschungsansätze, insbesondere für die Überprüfung der abgeleiteten Annahmen, sowie für Empfehlungen für Entscheidungsträger.
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Effects of acidic precipitation on calcium and magnesium uptake by pinus patulaCarlson, Colleen Anne January 1992 (has links)
A dissertation submitted to the Faculty of Science, University
of the Witwatersrand Johannesburg for the degree of Master of
Science. Johannesburg, 1992. / Acidified rain is thought to have the potential to affect the ability of plants to acquire nutrients. The effects of artificially acidified rain on calcium (Ca) and magnesium (Mg) uptake by Pinus patula were investigated in terms of changes in the Ca and Mg-levels in the soil and changes in root growth and mycorrhizal coloniZation that might result from exposure to acidified precipitation. The uptake of these ions was also investigated in order to determine the possible effects of acid rain on the uptake process [Abbreviated Abstract. Open document to view full version] / AC2017
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The effect of the grass setaria megaphylla on the growth of pinus patula.Christie, Stuart, Ian January 1995 (has links)
Submitted in partial fulfillment of the requirements
for the degree of Doctor of Philosophy
Faculty of Science
University of Witwatersrand
Johannesburg
SOUTH AFRICA / A three-year study was undertaken In the province of Mpumalanga, South Africa to Investigate the competitive effects of the grass Setaria megaphylla on the growth of the tree species Pinus patula. A replacement series field trial, where six different competition regimes were Implemented, clearly demonstrated the suppressive effects of S.
( Abbreviation abstract ) / AC2017
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Litter accumulation in Pinus patula plantations and the role of ectomycorrhizal fungi in a forest ecosystemDames, Joanna Felicity January 1996 (has links)
A thesis submitted in the Faculty of Science, University of Witwatersrand, Johannesburg
for the degree of Doctor of Philosophy. Johannesburg, 1996. / Litter accumulates on the forest floor in Pinus patula plantations in Mpumalanga, South Africa and as a result nutrients become immobilized and site productivity is reduced. Studies have correlated litteraccumulation with abiotic factors, such as high altitude sites, high rainfall soils derived from the timeball series (shale) have thick litter layers. This study focuses on the biotic factors involved in litter accumulation. [Abbreviated Abstract. Open document to view full version] / GR 2017
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Site relationships for Pinus patula in the Eastern Transvaal escarpment area.Schutz, Christopher John. January 1990 (has links)
The largest area of commercial timber plantations in southern Africa is
situated along the Eastern Transvaal Drakensberg Escarpment north of
Nelspruit. The site requirements of tree species in this area are poorly
understood. The purpose of this study was to examine site-tree relationships
in the region and the implications of such relationships for the science of
forestry. Pinus patula Schiede & Deppe in Schlecht. & Cham. was selected for
the study as it is the most widely planted species in the region.
In Chapter 1 the geology, geomorphology, climate, soils and vegetation of the
study area are described. A geological map was compiled. Soil descriptions
were based on 439 soil pits distributed so as to cover the range of site
conditions in the area.
The regression techniques used to identify key environmental factors and to
model their relationships with tree parameters are described in Chapter 2, in
which site-growth relationships specifically are investigated. In mature
stands of P. patula 159 plots were established in such a way as to cover the
widest variation in both site conditions and tree growth. The relationship
between site index (mean top height at 20 years) and 100 site plus 10 stand
parameters recorded at each plot was modelled by means of best-subsets,
multiple and ridge regression. Several candidate models were compared on the
basis of coefficient of determination and validation using independent data.
The best model predicted the site index of the validation plots within 60 cm
of the measured site index. The possible roles of the site variables
identified by the models are discussed.
In Chapter 3 site-foliar nutrient relationships are described. A close
relationship was found between foliar and soil nutrient levels for the six
major geological substrates. Site index was more accurately predicted from
concentrations of individual foliar nutrients than from ratios of these
nutrients. The Diagnosis and Recommendation Integrated System (DRIS),
however, appeared to have greater potential for nutrient diagnosis.
Provisional ORIS norms for P. patula were computed.
In Chapter 4 the excessive accumulation of litter in P. patula stands was
examined. Undecomposed litter layers were greater than 15 cm in thickness on
nearly 25% of the 159 sites studied. Average litter layers contained greater
amounts of nutrients than the underlying topsoil. Due to the colonization of the litter by tree roots, the degree of immobilization of nutrients in litter
is not known. Environmental factors associated with variation in litter
thickness were identified by models which explained up to 73% of the total
variation. These factors are considered to act indirectly by promoting or
retarding decay organisms. The possible implications of litter accumulation
for the maintenance of site productivity are discussed.
In Chapter 5 relationships between site and some wood properties are
described. Although between-tree variation was larger than between-site
variation, some important relationships with site were identified. 10% of all
trees on the 159 plots had severe stem bumps. Most of the variables in a
model to predict the severity of bumps could be interpreted as being
associated with stem stability or exposure. The conclusion was that wind is
probably the major cause of this defect.
The findings of the study are summarized in Chapter 6. Particular attention
is given to a synthesis of the possible roles of site factors in their
relationships with the tree parameters investigated. There were strong
relationships between tree parameters and mainly rainfall, altitude, soil
wetness, exchangeable bases, effective rooting depth, slope position and
geology. The single most deficient nutrient element appeared to be calcium.
The implications for both research and management are outlined. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1990.
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A method for the non-destructive determination of the knotty core sizes of standing Pinus patula trees, based on ring width assessments at breast height and the pruning historyMunalula, Francis 03 1900 (has links)
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The objective of this study was to develop and assess a methodology of using pruning information (age and height) and ring width measurements on increment core samples taken at breast height from standing pruned Pinus patula trees for modeling the knotty core sizes in the pruned section of a tree. A total of 170 trees from 17 compartments, representing a wide variety of growth sites from the Mpumalanga escarpment, were selected and destructively sampled. Sample trees were selected to represent the productive timber volume available from the compartments using stratified sampling. Sample discs were removed at breast height (1.3m) and at six meter height. After drying and sanding, the cross-sectional surfaces of one surface of each of the discs were scanned on a document scanner and the ring widths measured, using an image analysis program. A preliminary study, using 30 discs, was undertaken to ascertain the appropriate number of radii per disc to measure. A comparison between results of two opposite radii, as opposed to four radii, showed that the difference in mean ring width resulting from the two approaches was statistically not significant. In practice this means that for ring width assessment, sampling of increment cores opposite to one another at breast height would be sufficiently accurate to study average ring width variation across the radius of a tree. A study was also conducted to determine to what accuracy ring widths at six metre height could be predicted from breast height measurements. It was shown that cumulative growth at six metre height can be predicted from cumulative growth at breast height, site index and cambial age at breast height as independent variables (R2 = 0.96). Ring width measurements at breast height can, therefore, be used to predict incremental growth throughout the pruned section. Combined with available information on the pruning history of a stand (pruning heights and pruning age), this study proved that quantitative knowledge on incremental growth can be used as a basis for estimating changes in knotty core sizes along the entire pruned section of the stem.
Analysis of variation for the entire data set from ring width measurements showed that there was far greater variation in knotty core percentages (the percentage of diameter occupied by knotty core) between different compartments than within compartments. Within a tree, the knotty core percentages between three stem sections, 0-2.4m, 2.4–4.8m, and 4.8-7m, were found to increase significantly from the bottom section (49.1%) to the top section (65.4%).
A single 2.4m log from the pruned section of each tree was removed and processed into sawn timber at a sawmill. After drying of the boards, a sub-sample of sawn boards from 17 logs, one log from each compartment, was selected and reconstructed into log form. From the reconstructed log (reconstructed to represent their original position in the log) the actual knotty core size was estimated by measuring the distance from the pith to the end of the branch stub. A comparison of the actual knotty core sizes and the modelled knotty core sizes of a sub-sample of trees showed only a modest relationship (R2 = 0.62). Reasons for this might be variability in pruning quality, inaccurate pruning records, nodal swellings and the methodology used to measure the actual knotty core sizes.
Knowledge of knotty core sizes of standing trees can be used for many different purposes. Two applications that were assessed and found to be useful include decision support for cross cutting logs and for sawmill production planning purposes. Sawmill simulation software was used to evaluate value -and grade recoveries under different scenarios. Results showed that cross-cutting the pruned sections of logs from a compartment with large within-tree knotty core size variation into shorter logs, as opposed to keeping the pruned sections as single logs, result in increases in grade and value recovery. It was also shown that sawing of pruned logs from compartments with relatively small knotty cores, results in much better grade recoveries than logs from compartments with relatively large knotty cores (this information will be useful for production planning purposes). It can be concluded that the methodology proposed to reconstruct knotty cores from tree ring measurements has the potential to be used as a decision aid in the forest and forest products industry.
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Impact of exotic tree plantations on carbon and nutrient dynamics in abandoned farmland soils of southwestern Ethiopia /Lemma, Bekele, January 2006 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.
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Fuel load characterisation and quantification for the development of fuel models for Pinus patula in South AfricaRoss, Timothy Ian 12 1900 (has links)
Thesis (MScBosb)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The characteristics and total fuel load of the forest floor (FF) and harvest residue (HR) are
needed to develop tools that can be used for fuel load management, fire risk analysis and
fire behaviour prediction for P. patula grown in the summer rainfall area of South Africa (SA).
Forest floor depth, mass and ash-free mass were measured and there was generally a
greater range in depth under sawtimber (ST) stands than under pulpwood (PLP) stands.
Forest floor loads, prior to ashing, ranged from 21 - 168 t ha-1 and 27 - 72 t ha-1, for ST and
PLP stands, respectively and loads increased linearly with stand age. Sawtimber and PLP
stands were analysed together, which resulted in a significant correlation between depth and
mass (r2 = 0.78, n = 31). A loss on ignition procedure carried out on sub-samples of the FF
improved the relationship between the FF depth and the ash-free mass for the different
stands, and provided a more accurate model for the prediction of mass from depth. A
multiple regression analysis revealed that age, altitude and mean annual precipitation (MAP)
provided the best subset and accounted for 72% of the variation in the FF mass observed.
The effect of increasing FF load and increasing moisture content on the fireline intensity
(FLI) was examined using the fire behaviour prediction programme, BehavePlus.
Harvest residue was quantified and characterised in terms of fuel size classes, under current
silvicultural regimes for ST and PLP, for the development of fuel models for this species over
its planted range in SA. An investigation into the proportion (by mass) of the 1- (0.0 - 0.6
cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6 cm) and 1000-hr (> 7.6 cm diameter) fuel classes of
the total HR mass indicated that there was a significant difference between the mass of the
1-, 10- and 1000-hr fuel classes of the two silvicultural regimes, and no significant difference
for the 100-hr fuel class. Two fuel models for P. patula HR and two models for standing
timber were developed using the new model (NEWMDL) programme of BEHAVE and tested
in BehavePlus.
Nutrient concentrations were used with FF layer and HR size class load data to estimate the
quantities of nutrients held in the fuel and to describe nutrient distributions in the fuel
complex. Significant differences in the nutrient concentration of the FF layers and fuel
components were observed which has important implications for fuel management. The
concentration of N determined in this study, relative to that determined in other similar
studies on P. patula was low. Forest floor loads were predicted and nutrient pools calculated
for typical ST and PLP stands at both low and high altitude to provide insight into the nutrient
distributions within the fuel complex. / AFRIKAANSE OPSOMMING: Die karaktereienskappe en totale brandstoflading van die bosvloer (FF) en kaalkap oorskot
(HR) word benodig om instrumente te ontwikkel wat gebruik kan word vir brandstoflading
bestuur, brandgevaar ontleding en brandgedrag voorspelling vir P. patula, wat in die somer
reënvalgebied van Suid-Afrika groei. Die bosvloer diepte, massa en asvrye massa is gemeet
en daar was oor die algemeen ‘n groter variasie in diepte onder saaghout (ST) opstande as
onder pulphout (PLP) opstande. Die bosvloerladings, voor verassing, het varieer van 21 –
168 t ha-1 en 27 – 72 t ha-1 vir ST en PLP opstande respektiwelik. Ladings het linieêr
vermeerder met opstand ouderdom. Saaghout en PLP opstande is saam geanaliseer en het
tot ‘n betekenisvolle korrelasie gelei tussen diepte en massa (r2 = 0.78, n = 31). ‘n Verliestydens-
ontbranding prosedure is uitgevoer op die FF monsters en het die verhouding tussen
FF diepte en die asvrye massa van die verskillende opstande verbeter. Dit het ook gelei tot
akkurater model vir die voorspelling van massa vanaf diepte. ‘n Veelvoudige regressie
analise het aan die lig gebring dat ouderdom, hoogte en gemiddelde jaarlikse reënval (MAP)
die beste sub-groep verskaf, en het 72% van die variasie in die FF massa verklaar.
Ondersoek is ingestel op die effek van toenemende FF lading en toenemende voginhoud op
die brandlyn intensiteit (FLI) deur die brandgedrag program, BehavePlus, toe te pas.
Die kaalkap oorskot is gekwantifiseer en gekarakteriseer volgens brandstof grootteklasse,
onder die huidige boskultuurstelsels vir ST en PLP, vir die ontwikkeling van
brandstofmodelle vir hierdie spesie oor die betrokke groeistreek in SA. ‘n Ondersoek in die
verhouding (volgens massa) van die 1- (0.0 – 0.6 cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6
cm) en 1000-uur (> 7.6 cm deursnee) brandstofklasse van die totale HR massa het
aangedui dat daar ‘n betekenisvolle verskil is tussen die massas van die 1-, 10- en 1000-uur
brandstofklasse van die twee boskultuurstelsels, en geen betekenisvolle verskil vir die 100-
uur brandstofklas nie. Twee brandstofmodelle is ontwikkel vir P. patula HR en twee modelle
vir staande hout deur gebruik te maak van die nuwe model (NEWMDL) program van
BEHAVE en getoets in BehavePlus.
Voedingstof konsentrasies is gebruik, tesame met die FF laag en HR klasgrootte ladingdata,
om die voedingstof inhoud van die brandstof te skat en om die voedingstof verspreiding te
beskryf in die brandstofkompleks. Betekenisvolle verskille is waargeneem in die voedingstof
konsentrasies van die FF lae en brandstof komponente wat belangrike implikasies inhou vir
brandstofbestuur. Die konsentrasie wat vir N in hierdie studie bepaal is, was laag relatief tot
ander soortgelyke studies vir P. patula. Die bosvloer ladings is voorspel en voedingstofpoele
bereken vir tipiese ST en PLP opstande vir beide lae en hoë hoogtes om insig te verkry,
sodat insig verkry kon word in die voedingstof verspreidings binne die brandstofkompleks.
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Enhanced adsorption of base metal, phenol and aldehyde from aqueous solutions on low-cost activated carbon.Mukosha, Lloyd. January 2014 (has links)
D. Tech. Chemical Engineering / Aims of this research project was to add value to largely wasted South African sawdust by development of low-cost AC of high efficiency for removal of toxic Cr (VI), phenol and glutaraldehyde from dilute aqueous media. The main objectives of the research project were: a) To develop low-cost AC based on South African P. patula sawdust using economical physical superheated steam activation.Characterization of carbon samples for selection of optimum preparation conditions for development of low-cost AC of effective microporosity mesoporosity and surface functionality for enhanced adsorption capacity of Cr (VI) and/or phenol and/or glutaraldehyde from dilute aqueous solution. Acid-amine surface groups modification of optimally developed AC for further enhancement of adsorption capacity for mixed polarized glutaraldehyde molecules from aqueous solution. b) To evaluate the aqueous phase batch adsorption properties of developed AC for Cr (VI) and phenol and, of acid-amine modified developed AC for glutaraldehyde. Determination of optimum pH for adsorption; accurate adsorption isotherm modelling for determination of maximum adsorption capacity, comparison of maximum adsorption capacities for Cr (VI) and phenol of developed AC with commercial AC and literature ACs, and attempt to establish average micropore size for enhanced capacity for Cr (VI) and phenol from dilute aqueous solution.Kinetics reaction and diffusion modelling for determination of adsorption rate constants and diffusion parameters; and determination of adsorption thermodynamic parameters.Evaluation of equilibrium selectivity of developed AC for Cr (VI) and/or phenol in binary aqueous solutions. c) To evaluate aqueous phase fixed-bed adsorption characteristics of developed AC for single Cr (VI) and mixed solution using Rapid Small Scale column Tests (RSSCTs). Generation of breakthrough curves at optimum adsorption conditions for evaluation of column performance indicators at different process conditions, bed regeneration-reusability potential, and dynamic adsorption selectivity of developed AC for Cr (VI) from solution of base metals. Determination of column diffusion parameters; accurate mass transfer and empirical modelling of breakthrough data; determination of applicable RSSCT scaling equation; and optimization of breakthrough data for accurate RSSCT scale-up.
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Remote sensing of forest health : the detection and mapping of Pinus patula trees infested by Sirex noctilio.Ismail, Riyad. January 2008 (has links)
Sirex noctilio is causing considerable mortality in commercial pine forests in KwaZulu-
Natal, South Africa. The ability to remotely detect S. noctilio infestations remains
crucial for monitoring the spread of the wasp and for the effective deployment of
suppression activities. This thesis advocates the development of techniques based on
remote sensing technology to accurately detect and map S. noctilio infestations. To date,
no research has examined the potential of remote sensing technologies for the detection
and mapping of Pinus patula trees infested by S. noctilio.
In the first part of this thesis, the focus was on whether high spatial resolution
imagery could characterize S. noctilio induced stress in P. patula forests. Results
showed that, the normalized difference vegetation index derived from high spatial
resolution imagery has the potential to accurately detect and map the later stages of
S. noctilio infestations. Additionally, operational guidelines for the optimal spatial
resolutions that are suitable for detecting and mapping varying levels of sustained
S. noctilio mortality were defined. Results showed that a pixel size of 2.3 m is
recommended to detect high (11-15%) infestation levels, and a pixel size of 1.75 m is
recommended for detecting low to medium infestation levels (1-10%).
In the second part of this thesis, the focus was on the ability of high spectral
resolution (hyperspectral) data to discriminate between healthy trees and the early
stages of S. noctilio infestation. Results showed that specific wavelengths located in the
visible and near infrared region have the greatest potential for discriminating between
healthy trees and the early stages of S. noctilio infestation. The researcher also evaluated
the robustness and accuracy of various machine learning algorithms in identifying
spectral parameters that allowed for the successful detection of S. noctilio infestations.
Results showed that the random forest algorithm simplified the process by identifying
the minimum number of spectral parameters that provided the best overall accuracies.
In the final part of this thesis spatial modelling techniques were used to
proactively identify pine forests that are highly susceptible to S. noctilio infestations.
For the first time the random forest algorithm was used in conjunction with geographic
information systems for mapping pine forests that are susceptible to S. noctilio
infestations. Overall, there is a high probability of S. noctilio infestation for the majority
(63%) of pine forest plantations located in Mpumalanga, South Africa. Compared to
previous studies, the random forest model identified highly susceptible pine forests at a
more regional scale and provided an understanding of localized variations of
environmental conditions in relation to the distribution of the wasps. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.
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