The tropical hardwood forests of Mozambique are among its most important natural resources. Long-term sustainable management of these resources will require proper forest management, which depends on understanding the growth rates and the life history of important commercial species as well as the impacts of natural forces (e.g., climate variability) and human management. This study analyzes radial growth rate dynamics and climate-growth relationships of Millettia stuhlmannii and examines its dendrochronological potential. This tree locally known as Panga-panga or Jambirre is one of the most important timber species in Mozambique. Ranked as a first class commercial timber in Mozambique, it is frequently harvested in an unsustainable way and sustainable management of the species is urgently needed for the continued utilization of this resource. Five different methods demonstrate that the semi-ring porous tree rings of M. stuhlmannii are annual: (1) Ring structure and anatomy; (2) Successful cross-dating within and between trees; (3) Ring counting in trees with known age (young trees collected from an experimental "plantation") (4) Cambial wounding and (5) Correlation between ring width and climate data. Through these methods, M. stuhlmannii trees showed distinct reaction to pinning, adding one annual ring after one year. Cross dating of annual ring width growth was successful within and among selected M. stuhlmannii trees, which indicates that this species forms annual rings and that growth responds to an external climate variability. M. stuhlmannii annual growth ring boundaries were characterized by alternating patterns of parenchyma and fibre vessels and marginal parenchyma. Precipitation during previous December (r= 0.30; p<0.05), current February (r=0.30; p<0.05) and the entire rainy season (NDJFM; r=0.43, p<0.01) over a long period (1900-1996) showed a significant influence on Panga-panga tree ring growth. Declining rainfall has caused a growth increment decrease since 1940. The results of this study show that the mean annual increment of M. stuhlmannii is 0.51 cm/year and it takes about 75 years for an average M. stuhlmannii tree to reach the minimum lawful cutting diameter of 40 cm DBH (diameter at breast height). Temporal differences in movement through increasing diameter classes are large among and within classes. The median time necessary for trees to grow into the next diameter class was not statistically significant (Kruskal-Wallis chi-squared = 9.568, p>0.001). The relationship between stem diameter and percentage of heartwood is significantly high (R2 = 0.9701, p < 0.0001) and results suggest that from 33cm diameters on, the HW% remain stable. Partial correlation coefficients show that significant effects on growth to minimum cutting diameter occur while stems move through the 20-30 cm DBH class. This indicates the specific sizes at which silviculture treatments have to be started in order to maximize the productivity of this species. Correlation analyses revealed that heartwood width (HW) is positively correlated with total stem diameter (TSD), cambial Age (Ac), number of rings in heartwood (HWR), heartwood area (HWA), Total stem diameter area (TSDA) and Mean annual increment (MAI). This study suggests that further studies to improve diameter growth rate models as well as volume increment models need to be carried out. Strong correlation with precipitation during the rainy season suggests that this species is potentially useful for future climate reconstruction studies in Mozambique.

Experiments were carried out with the objectives of developing propagation protocols for Uapaca kirkiana and Pappea capensis tree species of southern Africa, and evaluating the graft compatibility within U. Kirkiana tree clones, provenances and species. Reverse phase high performance liquid chromatography (RP-HPLC), Folin-Ciocalteau reagent, fluorescence microscopy and callus fusion methodologies were used to diagnose graft compatibility. Results indicated that U. Kirkiana culture asepsis was achieved with 0.1% w/v mercuric chloride HgCl2) and using pre-conditioned grafted trees. Sodium hypochlorite (NaOCl) improved P. Capensis seed asepsis and germination, and discarding floating seeds improved germination. Murashige and Skoog (MS) medium with 2.0 mg l-1 benzylaminopurine (BAP) and 0.3 mg l-1 casein hydrolysate (CH) was superior in shoot multiplication and 0.5 mg l-1 indole-3-butyric acid (IBA) for rooting of P. Capensis microshoots. For somatic embryogenesis, three quarter strength MS medium with 0.05 mg l-1 thidiazuron (TDZ) and 0.3 mg l-1 CH, or 0.2 mg l-1 BAP with 0.3 mg l-1 CH, were effective in germination of P. Capensis somatic embryos. For U. Kirkiana lateral shoot explants, shoot multiplication was superior on three quarter strength MS medium with 0.1 mg l-1 BAP and 0.3 mg l-1 CH. Rooting of micro-cuttings (36%) was achieved on ½ MS with 2.5 mg l-1 IBA. RP-HPLC, fluorescence microscopy and callus fusion studies showed that phenolic compounds play a major role in U. Kirkiana graft incompatibility. Less graft compatible combinations showed an increase in phenol deposits above the union and graft incompatibility was more pronounced above the union than below the union. Proliferation of parenchymatous tissues was better below the union than above the union. Fluorescence microscopy showed presence of flavonoids and polymers above the union of less graft compatible combinations. The chromatograms showed that ferulic acid was abundant and responsible for wood discolouration. The chromatograms also isolated ρara-coumaric acids which were predominant above the union of the less compatible combinations. Therefore, ρara-coumaric acids, flavonoids and polymers were implicated in graft incompatibility of U. kirkiana trees. Copyright / Thesis (PhD)--University of Pretoria, 2008. / Plant Production and Soil Science / unrestricted

Africa's miombo woodlands constitute one of the most important dry tropical forests on earth, yet the hydraulic function of these woodlands remains poorly researched. Given the current predictions of increased aridity by the end of this century in the miombo ecoregion, understanding the likely response of miombo woodlands tree species to water stress is crucial in planning adaptation strategies. Predicting the response of miombo woodlands to future climate trends is hampered by a lack of knowledge on the physiology of the common miombo woodlands tree species. In particular, plant-water relations for this woodlands type are not well understood. An understanding of plant-water relations for this woodlands type will provide insights into how water limits tree species distribution in this ecosystem. This will also improve our prediction model on the likely response of this ecosystem to predicted climate change. For this reason, the overall objective of this research was to evaluate the hydraulic architecture and xylem vulnerability to cavitation for nine principal miombo woodlands tree species differing in drought tolerance ability and habitat preference. This was achieved by; examining the hydraulic properties and evaluating the extent to which each hydraulic design was vulnerable to water stress-induced xylem cavitation; investigating how seasonal changes in plant-water relations influences seasonal patterns of leaf display and; analyzing the relationship between stem hydraulic supply and leaf functional traits related to drought tolerance ability. This research has found that drought-intolerant tree species with mesic specialization have more efficient stem hydraulic systems than co-occurring habitat broad ranging species. Broad ranging tree species attain wider habitat distribution by adjusting their hydraulic supply in response to changing ecosystem water availability. The finding that hydraulic properties differ significantly between tree species with contrasting habitat preference suggests that tree hydraulic design may have some adaptive ecological role in influencing species habitat preferences in miombo woodlands. The evaluation of xylem vulnerability to cavitation revealed that mesic specialized tree species were more vulnerable to water stress-induced cavitation than habitat broad ranging tree species. Vulnerability to cavitation in individuals from the same broad-ranging species growing in contrasting habitats showed only marginal and statistically insignificant (P > 0.05) differences between wet and dry sites. In the investigation of the influence of seasonal changes in stem water relations on seasonal leaf display, seasonal rhythms in stem water status were found to exert significant controls on leaf phenology. Mesic specialists had strong stem water controls throughout the year in comparison to broad ranging tree species. An analysis of the relationship between stem hydraulic supply and leaf functional traits suggests that stem hydraulic supply constrains leaf biomass allocation patterns among miombo tree species. Mesic specialists tend to invest more in leaf longevity than broad ranging tree species. This thesis has uncovered some interesting relationships between plant-water-relations and the distribution of miombo woodlands tree species. These results lead to the conclusion that in an event of increased ecosystem drying under future climate trends, tree species with mesic specialisation are at a greater risk of experiencing cavitation related species mortality than broad ranging ones.

African elephants are ‘keystone’ species with respect to biodiversity conservation in Africa since they maintain habitats that support several animal communities by changing vegetation structure through foraging and by dispersing seeds between landscapes. Elephants are also ‘flagship’ species because, given their impressive size, they can make people sympathetic and stimulate local and international concerns for their protection. Economically, elephants contribute to national revenues as tourists are willing to pay to watch them. Despite all these factors, little is known however about elephant movement and how they utilize resources, especially in miombo-wetland ecosystems. This thesis investigates how elephants utilize resources in a miombo-wetland ecosystem in the Ugalla landscape of Western Tanzania over different protected areas containing different resource users. Using Global Positioning System (GPS) collars fitted to six elephants, it was observed that some elephant families are not confined in one protected area in the Ugalla landscape. Rather, they moved readily between different protected areas. Elephant movements were restricted to areas near the rivers, especially the Ugalla River, during the dry season and were dispersed widely during the wet season. As they move, elephants in the miombo woodlands of Ugalla selected the most abundant woody plants for browsing. Common to many woody plants, the browsed plants were short of mineral nutrients (e.g., sodium, calcium). Elephants obtained additional minerals by eating soils from certain termite mounds. Soils from termite mounds are richer in mineral elements (e.g., sodium, calcium, iron) compared to soils from the surrounding flood plain or compared to the browsed plants. However, the recorded termite mounds from which elephants eat soils were not evenly distributed in the landscape but confined mainly to the flood plains in the Ugalla Game Reserve. The Ugalla River, which is the main source of water for the elephants and other animals and also supports fishing activities by the local people in Ugalla during the dry seasons, is infested by the water hyacinth (Eichhornia crassipes). Such infestation potentially limits access to these precious surface water supplies. In addition at the regional level, the Ugalla River is among the major rivers that flow into the Lake Tanganyika which is shared by the countries of Tanzania, Burundi, Democratic Republic of Congo and Zambia. Thus, the spread of water hyacinth if left unchecked threatens to impact Lake Tanganyika, affecting many countries and ecosystem services. This thesis highlights that sustainable conservation of biodiversity in different protected areas in the Ugalla landscape requires an integrated management approach that will embrace conservation of different interrelated landscape resources required by both wildlife and the rural poor populations for their livelihoods. Regular coordinated wildlife anti-poaching patrols should be initiated across the entire Ugalla landscape because the elephants, among other wildlife, utilize different protected areas in Ugalla. Local communities should also be engaged in conservation initiatives (e.g., controlling the spread of the water hyacinth) as these directly impact local livelihoods. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p> / INTEGRATED NATURAL RESOURCES MANAGEMENT

<p>This thesis aims to show how biogeophysical and social processes are interlinked in landscape change, and to propose approaches for interdisciplinary environmental assessments (such as EIAs), concentrating on developing countries’ situations, and representation of findings from such studies. </p><p>Landscape in its holistic sense is a very good concept and basis for intellectual and practical use in environmental dialogues. However, landscapes are valued and assessed differently, depending on cultural background along with individual characteristics. </p><p>Methods of conducting interdisciplinary environmental assessments need to vary, but it is important to follow a structure to avoid too broad and general studies that only assemble a few factors and present them without an integrated synthesis. This thesis has suggested one research sequence and structure that has proven to be practical and possible to execute in areas where data is scarce and where local involvement is a major component. It extends the observation period in time and space where remote sensing analyses are integrated with interviews, archive material, land-cover assessments and soil analyses.</p><p>Case studies from Tanzania have been used to investigate how perceptions of land and resources manifest themselves at local scales and how this information can contribute to sustainable environmental planning. Preferences and perceptions of land as being ‘important’ and ‘good’ do not always correlate with favourable biogeophysical conditions, indicating that both social services, such as health care, access to markets, education and employment, as well as “non-rational” factors are essential to consider in environmental planning and management.</p><p>This study has partly been part of a larger research project investigating the links between human livelihood and biodiversity in <i>miombo</i> woodlands. It has been shown how <i>miombo</i> woodland is important to local populations as it provides material goods as well as many intangible services. However, it is also associated with problems and dangers, which are important to consider and understand in planning for the environment and sustainable development.</p>

This thesis aims to show how biogeophysical and social processes are interlinked in landscape change, and to propose approaches for interdisciplinary environmental assessments (such as EIAs), concentrating on developing countries’ situations, and representation of findings from such studies. Landscape in its holistic sense is a very good concept and basis for intellectual and practical use in environmental dialogues. However, landscapes are valued and assessed differently, depending on cultural background along with individual characteristics. Methods of conducting interdisciplinary environmental assessments need to vary, but it is important to follow a structure to avoid too broad and general studies that only assemble a few factors and present them without an integrated synthesis. This thesis has suggested one research sequence and structure that has proven to be practical and possible to execute in areas where data is scarce and where local involvement is a major component. It extends the observation period in time and space where remote sensing analyses are integrated with interviews, archive material, land-cover assessments and soil analyses. Case studies from Tanzania have been used to investigate how perceptions of land and resources manifest themselves at local scales and how this information can contribute to sustainable environmental planning. Preferences and perceptions of land as being ‘important’ and ‘good’ do not always correlate with favourable biogeophysical conditions, indicating that both social services, such as health care, access to markets, education and employment, as well as “non-rational” factors are essential to consider in environmental planning and management. This study has partly been part of a larger research project investigating the links between human livelihood and biodiversity in miombo woodlands. It has been shown how miombo woodland is important to local populations as it provides material goods as well as many intangible services. However, it is also associated with problems and dangers, which are important to consider and understand in planning for the environment and sustainable development.