Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2009. / Härtill 5 uppsatser.

<p>The aim of the study was to quantify the extent of inorganic chemical pollution of the Franschhoek River and draw relationships between contaminants in water, sediment and plants. The invasive Acacia mearnsii and Salix babylonica and indigenous Brabejum stellatifolium species were chosen as biomonitors due to their wide spread distribution along the river and their apparent ability to accumulate heavy metals. The sites chosen allowed for comparison of the river quality upstream with that of the river further down stream as it meandered through residential, agricultural and recreational areas, until it joined with the Berg River further downstream. The general aim of the study was to assess the degree of inorganic pollution in the Franschhoek River to evaluate its contribution to pollution of the Berg River, of which it is an important tributary. Also understanding the sources of the pollution would contribute to the ability to reduce pollution.</p>

Multiple shoots were produced from nodal explants of thirty-day-old in vitro grown seedlings and from pretreated three, five- and nine-month-old greenhouse grown Acacia mearnsii plants, respectively. Explants were sterilized for 15 minutes using 0.1 % HgCl₂ for the three-month-old explants and 0.2 % for the five and nine-month-old explants. Nodal explants were induced to form multiple shoots when placed on Murashige and Skoog (MS) medium supplemented with 2.0 mg l ¯¹ benzyladenine (BA). Rooting of these shoots was achieved on MS medium supplemented with 1.0 mg l ¯¹ indole-3-butyric acid (IBA). Plantlets were acclimatized in transparent plastic containers under greenhouse conditions with a 90 % success rate. These plantlets were successfully acclimatised under greenhouse conditions and planted in the field together with plants regenerated by cuttings. In an attempt to overcome maturation effects and loss of juvenile characteristics, when using adult plant material in vitro, investigations were undertaken into the use of coppice material, as an alternative explant source. A. mearnsii trees from five ages (two, four, six, eight and ten-years old, respectively) were decapitated to a height of 1.5 m. After three weeks, coppice was noted on the stumps of trees from all ages. A linear response to coppice production was noted, with the greatest coppice production being on the two-year-old tree stumps and the least on the ten-year old tree stumps. Decontamination of the coppice was successful and multiple shoot production was obtained from coppice taken from all age groups on MS medium supplemented with 2.0 mg l ¯¹ BA. The effect of various sucrose concentrations were investigated. Greater shoot production occurred with increased sucrose concentrations (20 and 30 g l ¯¹). It was evident that rejuvenation of mature tissue could be achieved through the use of coppice material. A second approach to rejuvenate adult material and to overcome the deleterious effects of maturation, was in the use of apical meristems. Meristems were taken from 30-day-old in vitro grown plants, from coppice (rejuvenated tissue) and adult material of five various tree ages (two, four, six, eight and ten-years-old, respectively). Plant material were taken over two seasons (1997 to 1999) and the use of agar and liquid support media were tested under both light and dark conditions. The coppice and adult material was successfully decontaminated in both seasons. In the first season (1997/1998), shoot production was obtained from meristems of in vitro grown plants, coppice and adult material from all trees on MS medium alone or MS medium supplemented with 2.0 mg l ¯¹ BA. In the following season (1998/1999), the use of a solidified agar medium was superior to the use of a liquid culture. There appeared to be no significant difference (p<0.05) between the use of light or dark culture conditions. Various media were tested and maximum shooting occurred on half-strength MS medium and Woody Plant Medium (WPM). However, once multiple shoot primordia were initiated, shoot elongation posed a problem. It was for this reason that the size of the meristems excised from the coppice material was increased from 0.5 mm to 1.0 mm in the 1997/1998 season, to 1.0 to 2.0 mm in the 1998/1999 season. The use of gibberellic acid and 100 ml jars were also investigated to see if this might enhance shoot elongation. Sufficient plant material was not available for a thorough investigation. Environmental conditions under which the plant material (adult or coppice) was harvested was similar in both seasons, with respect to temperature, but differed in rainfall. Rainfall was high (105.1 mm) in 1997/1998 season and low (ranging from 59.8 to 71.45 mm) in the 1998/1999 season. Shoot production from meristems taken from coppice material in the 1998/1999 season was significantly greater (p>0.05) than that in the 1997/1998 season, whereas shooting from the adult plant material remained unchanged. The disadvantage with using coppice material is that its production on decapitated tree stumps is dependant on rainfall, which is unpredictable. The differences in results from coppice material could be attributed to the fact that the trees felled in the two seasons were not related to each other in any way. In both seasons meristems, tree age was not a limiting factor, for meristems from adult and from coppice material. Meristems from the ten-year-old trees were as productive as those taken from the two-year-old trees. In the 1997/1998 season the results from the meristems from the adult material was equal if not greater than those obtained from the coppice material. In the 1998/1999 season, there was no significant difference (p<0.05) in percentage shoot production between the meristems from the adult and coppice material throughout the age groups. This suggests that the use of rejuvenated tissue in the form of coppice is not essential. This re-emphasized the advantage of using meristems taken from adult plant material. This study provided suitable protocols for the micropropagation of both in vitro and ex vitro grown nodal explants of A. mearnsii. However, as the plant material obtained from the field matures so the ease of obtaining sterile material decreased, thus reducing the chances of in vitro micropropagation. For this reason suitable pretreatments and rejuvenation methods are necessary if explants from mature field tissue are to be introduced into culture and successfully micropropagated. This study has shown that through the use of nodal material (taken from coppice produced on adult tree stumps) and apical meristems taken from both coppice and mature plant material, adult material can be successfully decontaminated, introduced into culture and stimulated to produce shoots. Analysis of tannin production was conducted to see if there was any indication that the presence of tannins in the plant material effected in vitro culture of nodal explants. However, no trends were obtained suggesting any influence of tannins on in vitro performance. In future years after further optimisation, these techniques could be incorporated in an A. mearnsii clonal programme, with the advantage of possibly eliminating maturation effects, commonly noted in vegetative practices. This will allow for easy manipulation and amplification of superior quality adult material. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1999.

Acacia mearnsii (black wattle) is one of the few tree crops of which both timber and bark are utilised, with branches sometimes being collected for fuel wood. There is a great potential for nutrient loss from plantations with intense harvesting practices. Allometric relationships were developed to estimate above-ground biomass across four ages and three site qualities of A. meamsii stands. The three sites were based on high, medium and low site quality classes of productivity. Differences in biomass and the distribution of biomass between the stem, bark, live branches, dead branches and foliage components are described in relation to site and age. Relationships between biomass and light interception and plant area index are investigated and show some merit. Nutrient concentrations were used with the above-ground biomass data to estimate quantities of nutrients held in the various biomass components in each of the stands. Nutrient distributions in the above-ground biomass (AGB) were examined and compared to other studies. Foliar phosphorus (P) and potassium (K) concentrations were shown to be sub optimal, agreeing with results and recommendations of South African fertilisation stupies. Some concentration differences were observed between site and age classes for certain nutrients, although these differences may have been due to seasonal effects. Biomass and nutrient quantities were adjusted to yield a wood production of 100 t ha01 and compared with adjusted calculations for similar studies on other plantation crops. Total nutrients contained in the AGB of the adjusted calculations were 540.8 kg ha01 nitrogen (N), 20.4 kg ha-I P, 200.6 kg ha01 K, 241 kg ha-I calcium (Ca), 55.7 kg ha-I magnesium (Mg), with a half to two thirds of the nutrients held in the stem and bark alone. Nutrients losses vary with harvesting intensity as bark and branches may be harvested with the stem wood. Levels of nutrient removal with harvesting intensity are discussed with reference to estimated losses and gains from natural processes and management practices. An incomplete nutrient budget calculation indicated that P, K, Ca and Mg might potentially be removed in quantities greater than replaced by natural processes under stem and bark harvesting. The budget calculations lack processes such as leaching and N-fixation. It is highly probable that these processes, once quantified, may yield more negative budget results, especially for the base cations K, Ca and Mg. / Thesis (M.Sc.)-University of KwaZulu- Natal, Durban, 2005.

In South Africa, invasive black wattle trees (Acacia mearnsii D. Wild) are a major threat to ecosystem functionality causing widespread social, economic and environmental degradation. It is important that environmental managers are provided with rapid, regular and accurate information on the location of invasive black wattle trees to coordinate removal efforts. This study investigated the potential of an automated image classification algorithm to accurately identify black wattle (A. mearnsii De Wild.) trees using imaging spectroscopy. Hyperspectral data acquired by the EO-1 Hyperion sensor was used to identify black wattle trees in two study areas near Greytown, KwaZulu-Natal, South Africa. Image classifications were performed by the classification algorithm to identify black wattle trees using general and age specific spectral signatures (three to five years, seven to nine years, eleven to thirteen years). Results showed that using the general spectral signature an overall accuracy of 86.25% (user’s accuracy: 72.50%) and 84.50% (user’s accuracy: 69%) was achieved for study area one and study area two respectively. Using age specific spectral signatures, black wattle trees between three to five years of age were mapped with an overall accuracy of 62% (user’s accuracy: 24%) and 74.50% (user’s accuracy: 49%) for study area one and study area two respectively. The low user’s accuracies for the age specific classifications could be attributed to the use of relatively low resolution satellite imagery and not the efficacy of the classification algorithm. It was concluded that the classification algorithm could be used to identify black wattle trees using imaging spectroscopy with a high degree of accuracy. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.

No abstract available. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Urban open spaces are of strategic importance to the quality of life of our increasingly urbanized society. Trees and related vegetation are planted and managed within the communities and cities to create or add value to the busy lives of the city dwellers. Trees in towns and cities form an important part of complex urban ecosystems and provide significant ecosystem services and benefits for urban dwellers, for example: reducing particulate pollution, carbon sequestration, decreasing air temperature, decreasing water runoff, aesthetic value and an increase in human health. Trees are solarpowered technology that can help restore balance to dysfunctional urban ecosystems. Trees form strands in the urban fabric that connect people to nature and to each other. The urban environment puts tremendous strain on trees by trenching, limited space for root growth and emission of pollutants into the atmosphere, water and soil. The problem is that the real impact of the urban environment on the trees within our community is unknown. The aim of this investigation was to assess the overall anthropogenic and environmental impacts on urban trees by measuring the tree vitality of Acacia karroo using chlorophyll fluorescence kinetics (JIP-test) and the leaf water potential using a pressure chamber. Tree vitality was quantified as the chlorophyll fluorescence-based performance index (PIABS)T. ree vitality measurements were also correlated with soil physical and chemical data. In the comparative study, an urbanization gradient approach was followed in which results of trees in rural areas were regarded as controls. The gradient approach is used worldwide and provides a background for questions of ecological structure and function. The urbanization gradient was quantified using the V-I-S model, based on % cover of vegetation, impervious surface and soil. Additionally, a model to determine the monetary value of trees in urban environments (SATAM) was tested. All this information could eventually contribute to develop an urban tree management program for Potchefstroom. It was evident from the current study that urbanization has a negative impact on tree vitality. The leaf water potential of a tree was, however, not necessarily negatively impacted upon. Although trees in urban environments did not always have a high vitality (PIABS)t, hey still played a major role in the urban environment. According to the tree appraisal method (SATAM), some of these trees have a value of R60 000. / Thesis (M. Environmental Science (Ecological Remediation and Sustainable Utilisation))--North-West University, Potchefstroom Campus, 2007.

Promotion of agroforestry practices in sub-Sahara Africa may help sustain subsistent food and wood production by integrating trees and crops on farmlands to replenish soil fertility and improve crop yield. Using rotational woodlot and pigeonpea intercropping systems in semi-arid Tanzania as case studies, my research screened suitable tree species to increase fuelwood supply and examined mechanisms for reducing tree-crop competition. By adopting nutrient use efficiency (the ratio of biomass yield to nutrient uptake) as a criterion, I found that selecting tree species of low wood nutrient concentrations would minimize nutrient exports by 42 – 60 %, thus reducing soil nutrient depletion while concurrently sustaining local fuelwood supply harvested from rotational woodlots. Currently smallholder farmers cannot afford to replenish soil fertility because of high fertilizer costs. However, 5-year tree fallowing raised soil N and P levels for maize culture as high as those from recommended fertilizer applications. Post-fallow maize yield was also increased significantly over natural fallow practices. Apparently there is a trade-off between yields of maize and fuelwood under rotational woodlot culture providing farmers the choice to proportion tree and crop composition based on priority demands. An alternative practice of intercropping pigeonpea with maize may also rapidly replenish soil fertility as well as enhance maize yield when competitive interactions between trees and crops are controlled. Vector analysis revealed that such interactions suppressed biomass yields of maize and pigeonpea by 30 % and 60 %, respectively, due to limited soil nutrients and/or moisture. Optimizing yields of both crops would require prescribed fertilizer addition when intercropped, but dose rates can be lowered by half under the improved fallow system due to alleviating interspecific competition. My findings form the basis of a plea for greater use of rotational woodlot and pigeonpea intercropping systems in semi-arid areas. I conclude that smallholder farm management of rotational agroforestry systems can be significantly improved by refining tree selection criteria and mitigating nutrient competition between trees and crops to maintain food and fuelwood production.

Acacia species producing gum Arabic are of great (socio)-economic, and ecological importance in Sudan. Insect attacks are one of the main causal agents in the decline in the gum Arabic yielding trees. Infested trees are almost totally damaged if the infestation is left untreated. The beetle family Cerambycidae is one of the largest groups of insects. Commonly referred to as long-horned beetles, these pests destroy host trees, having a great affect during times of drought. Many studies have been completed about the effect of long-horned beetles in various global settings. However, in Sudan, there is limited information about the insects’ ecological, biological, and even basic, profile. Thus, in this dissertation I study the spectrum, relative abundance, and phenology of the long-horned beetle species that are infesting Acacia species in Kordofan region (Sudan). Seven species were recorded using interception traps. These included Anthracocentrus arabicus (Thomson, 1877), Crossotus strigifrons (Fairmaire, 1886), Crossotus subocellatus subocellatus (Fairmaire, 1886), Doesus telephoroides Pascoe, 1862, Gasponia gaurani Fairmaire, 1892, Titoceres jaspideus (Serville, 1835) and Tithoes sp.. Two species were recorded using ground - photoeclectors: Crossotus albicollis (Guérin, 1844) and Coelodon servum White, 1853. Most of the species are known from other Arabian and African countries. However Coelodon servum White, 1853, Doesus telephoroides Pascoe, 1862, and Gasponia gaurani Fairmaire, 1892 were recorded in this study for the first time in Sudan. Results from flight interception traps indicated peak activity density of long-horned beetles during the rainy season (June – September), with maximum occurrence in June and peak occurrence in August. All study sites showed infestations of long-horned beetles, but the level of infestation varied between sites and Acacia species. The El Demokeya reserve forest indicated the highest percentage of infestation out of all the sites surveyed in this study. The infestation ranged between 57.1% and 100.0% for Acacia senegal, between 5.9% and 26.7% for Acacia mellifera, and 0% to 23.1% for Acacia seyal study sites. Acacia species differed also with respect to the spatial infestation pattern. Results indicated the maximum (95.5%) presence of holes of infestation in the branches of A. senegal when compared to the trunk. Holes of infestation were recorded in all directions, with a minimal occurrence on the south side (18.2%). Opposite results were obtained for A. mellifera with the maximum number of holes in the trunks (46.2%), while branches were less affected. In addition results obtained showed no presence of holes in the branches of A. seyal. Moreover, this study focuses on the assessment of tree characteristics that may trigger the infestation. Logistic regression indicated that tree age was the only predictor for the infestation with long-horned beetles – at least for Acacia senegal. A significance difference was obtained for the stand height curve between non-infested and infested trees of Acacia species, except A. senegal stands at El Demokeya. The study was supplemented by qualitative data, produced from a survey of gum landowners. This questionnaire indicated the level of awareness that gum landowners had with regard to long-horned beetles and their infestations. The results of this survey denoted that 95.0% of gum farmers were aware of the long-horned beetles, while 49.2% indicated an awareness about infestations, mentioning the emergence holes as damage characteristics.

Vegetation sampling is an effective exploration technique in areas of transported cover where other techniques have been of limited success. Several plant species were sampled along transects across 9 known Au ore bodies; Triodia pungens was found give a Au, As, ±Zn, ±S, ±Ce and ±La signature which represented mineralisation through cover materials and Eucalyptus brevifolia was found to give a geobotanical and ±Ca, ±Mg, P, S and Zn signature of underlying geological structure. The Hyperion prospect was used as a ‘blind’ target as there was no background information available until after interpretation was carried out. Mineralisation was located at the contact between granite and dolerite, biogeochemical signatures from E. brevifolia and Acacia bivenosa showed areas of change in ±Au, Ba, Ce, ±Cu, La, ±Mn, Nd, P, S, Sm, Y and Zn which corresponded to this contact. All species in the Pine Creek Orogen were able to present areas elevated in Au, As, ±Zn, ±S, ±Mo and ±Cu which provide future drilling targets. Biogeochemical sampling was able to determine the location of mineralisation at each site and identify underlying substrate changes, however, background knowledge relating to regolith, geology, hydrology and geophysics are important in aiding the interpretation of the elemental data as each component of the substrate influences the elements which a plant will uptake. Mineral exploration in Australia has been driven by the search for large ore deposits close to the surface. This has led to the need to develop technologies for detecting mineral deposits under cover, which can be up to several hundred metres of transported sediments. The aim of this research was to test the feasibility of using vegetation biogeochemical sampling over known Au deposits within semi-arid and arid terrains. Biogeochemical sampling has the advantages of being cost effective, sustainable, environmentally friendly and relatively easy to perform. Nine field sites were covered, 4 in the Tanami Region (Coyote, Larranganni, Hyperion and Titania), 4 in the Pine Creek Orogen (Johns Hill, Great Northern, Glencoe and McKinlay) and 1 in the Gawler Craton (Tunkillia). At each of these sites the dominant species were sampled and the elemental concentrations of the plant were analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to test if they were able to detect buried mineralisation. In general, all species identified as being deep rooted (larger trees, paperbarks and spinifex) were able to detect mineralisation in each location within multi-element dispersion haloes centring over the projected ore body. Variations were dependant upon species differences and root structures, groundwater influences, and the potential for detrital contamination. In arid Australia, Triodia spp. were shown to be ideal for closely spaced tenement/prospect scale exploration, and Heteropogon spp. show similar trends for the humid tropics. Eucalyptus/Corymbia spp. are more suitable for widely spaced regional sampling exploration as they amalgamate a wider signal with strong groundwater influences. It was found that all plant species were effective at expressing buried mineralisation in a multi-element suite (pathfinders: Au, As, S, Zn, +(Ce/La), _Mo and _Cu) through cover in these terrains provided care was taken with sampling and interpretation. Regolith materials, botanical properties and landforms are essential background knowledge for determining the effectiveness of biogeochemical sampling. Plants with deep root systems with little lateral spread are ideal for prospect/tenement mineral exploration programs, and plants with wide lateral spreads and large chemical uptake potentials are ideal for regional mineral exploration programs. This exploration strategy would be quick, sustainable and relatively cheap compared to other methods of exploration. This is not to say that biogeochemical sampling would be the only tool needed for further mineral exploration in Australia. This process would work best if used in conjunction with other sampling methods like geophysics and some soil sampling techniques. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1351318 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, School of Earth and Environmental Sciences, 2009