Добірка наукової літератури з теми "Woodland mopane"

SummaryThe near-threatened Lilian’s Lovebird Agapornis lilianae is a small parrot endemic to the Zambezi basin in south-east Africa. The species has a fragmented distribution predominantly within mopane woodlands and is widely referred to as a mopane specialist. The harvesting of mopane trees for charcoal production and timber are having widespread impacts on this woodland habitat, raising concerns over its capacity to support biodiversity. This study aimed to understand the key drivers determining the occurrence of Lilian’s Lovebird in the mopane woodlands of Zambia, focusing particularly on aspects of woodland structure, including the size and density of trees. We used a MaxEnt species distribution model based on historical species occurrence data, to inform selection of 116 survey plots in the Luangwa, Luano and Zambezi valleys. Each plot was sampled for Lilian’s Lovebirds and woodland structure described. Occurrence of Lilian’s Lovebird was found to be positively associated with the size of mopane trees (both height and diameter at breast height) suggesting that large ‘cathedral’ mopane trees provide a key resource for the species and that conservation efforts should focus on the protection of sites containing large trees. No Lilian’s Lovebirds were recorded in areas where they previously occurred to the west of Lower Zambezi National Park, and there was an absence of ‘cathedral’ mopane habitat in this area.

Thirteen termite mounds and 13 similar-sized control plots were surveyed in central Zimbabwe in order to study large mammalian browsing and vegetation characteristics. The mounds supported almost twice as many tree species as the control plots and the woody vegetation was denser on mounds compared with the woodland plots. Species of woody plants were recorded along with the percentage of branches browsed (cumulative browsing score) by black rhino, Diceros bicornis, elephant, Loxodonta africana and other browsers combined. In addition we measured how the cumulative browsing score on three woody plant species, Acacia nilotica, Colophospermum mopane and Dichrostachys cinerea, which were common both on and off mounds, was related to the distance from mound centre. Both black rhino and elephant cumulative browsing scores were significantly higher on the mound plants compared with the woodland plots. Cumulative browsing score was negatively related to distance from the mound centre for Dichrostachys cinerea, Colophospermum mopane and Acacia nilotica. We propose that termite mound construction in miombo woodland contributes to sustaining populations of megaherbivores and perhaps some woody species in these areas.

AbstractStudies were made of the behaviour of Glossina pallidipes Austen and G. morsitans morsitans Westwood during the hot season (September–November) in Zimbabwe, and attributes of samples of tsetse from refuges, odour-baited traps, targets and mobile baits were compared. Various arrangements of electric nets were used to study tsetse as they entered or left artificial refuges. The peak time of entry into a refuge varied between 0800 h and 1400 h and coincided with the time when the air temperature reached 32°C; the response was stronger if 32°C occurred earlier in the day. The peak time of exit varied between 1500 h and 1700 h, being significantly later on hotter days, but did not show a clear temperature threshold. Micro-meteorological measurements showed that refuges were significantly cooler than the surrounding riverine woodland during the day but warmer at night. There was no significant difference between the air temperatures in leafless mopane woodland and semi-evergreen riverine woodland during the day but at night the riverine woodland was significantly cooler. Combining the micro-meteorological data with the estimated local movements of tsetse suggested that during the hot season, tsetse experienced temperatures 2°C cooler than the daily mean in a Stevenson screen located in mopane woodland. Compared with the catches of tsetse from traps, refuges had higher proportions of G. m. morsitans, males, young flies and females in the later stages of reproduction, and it is suggested that during the hot season, samples from refuges were less biased than traps with respect to species and sex composition, age and reproductive status. During the hot season, tsetse populations declined by c. 90% and although air temperatures exceeded lethal levels (c. 40°C), the refuge-entering responses meant that adult flies probably experienced a maximum of only c. 35°C. It is suggested that the decline in numbers is not due to direct mortality effects of temperature on adults but may be due, in part, to a doubling in the rates of reproductive abnormality during the hot season and an increase in adult mortality related to a temperature-dependent decrease in pupal period.

Abstract. We compare assimilation and respiration rates, and water use strategies in four divergent ecosystems located in cold-continental central Siberia and in semi-arid southern Africa. These seemingly unrelated systems have in common a harsh and highly seasonal environment with a very sharp transition between the dormant and the active season, with vegetation facing dry air and soil conditions for at least part of the year. Moreover, the northern high latitudes and the semi-arid tropics will likely experience changes in key environmental parameters (e.g., air temperature and precipitation) in the future; indeed, in some regions marked climate trends have already been observed over the last decade or so. The magnitude of instantaneous or daily assimilation and respiration rates, derived from one to two years of eddy covariance measurements in each of the four ecosystems, was not related to the growth environment. For instance, respiration rates were clearly highest in the two deciduous systems included in the analysis (a Mopane woodland in northern Botswana and a Downy birch forest in Siberia; >300 mmol m−2 d−1), while assimilation rates in the Mopane woodland were relatively similar to a Siberian Scots pine canopy for a large part of the active season (ca. 420 mmol m−2 d−1). Acknowledging the limited number of ecosystems compared here, these data nevertheless demonstrate that factors like vegetation type, canopy phenology or ecosystem age can override larger-scale climate differences in terms of their effects on carbon assimilation and respiration rates. By far the highest rates of assimilation were observed in Downy birch, an early successional species. These were achieved at a rather conservative water use, as indicated by relatively low levels of λ, the marginal water cost of plant carbon gain. Surprisingly, the Mopane woodland growing in the semi-arid environment had significantly higher values of λ. However, its water use strategy included a very plastic response to intermittently dry periods, and values of λ were much more conservative overall during a rainy season with low precipitation and high air saturation deficits. Our comparison demonstrates that forest ecosystems can respond very dynamically in terms of water use strategy, both on interannual and much shorter time scales. But it remains to be evaluated whether and in which ecosystems this plasticity is mainly due to a short-term stomatal response, or alternatively goes hand in hand with changes in canopy photosynthetic capacity.

Thesis (MScConsEcol)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: The Mopane woodlands are some of the most economically and ecologically important vegetation types of southern Africa, providing an array of services and products for sustaining livelihood of local communities in dry and low lying areas. Although Mopane woodlands, like other African savannas, have received attention in the last decades, few studies were carried out using an integrated approach that combines socio-economic and environmental considerations. The aim of this study was to document the impact of harvesting woody resources in order to recommend ways of meeting ecological and economic objectives for sustainable use of communal resources in a rural community in the Mahel area, Mozambique. This was achieved by looking at the pattern of species composition, resource availability and dynamics of the woody vegetation and how the woodland is used. The study found that woodland resources in the area have a promising potential. Local communities who also recognised the crucial importance of these resources for their livelihood corroborated this. Thus, conservation measures are needed because the current unsustainable utilisation of the resources may lead to degradation of the woodland resource base. The species richness and diversity of the vegetation appeared to be influenced by a number of ecological and anthropogenic factors, but soil characteristics are the most important determinant of distribution and composition of the Mopane and Acacia woodlands in Mahel. The harsh environmental conditions on hard clay soils lead to dominance of over 80% of the Mahel area by Colophospermum mopane. There was evidence of high variation of species richness per plot at a distance from the villages. On the other hand species diversity near the villages was higher because of human activities. Colophospermum mopane formed mono-specific stands far from the villages. One of the most important aspects of the study is the invaluable contribution of baseline information for long-term studies for biodiversity assessment and monitoring of vegetation changes caused by impact of harvesting in the Mopane woodland. The availability of woody resources in the Mahel area was higher in Mopane woodland (937 stems ha-I) than in Acacia woodland (271 stems ha -1). The population structure of most tree species was shown to be stable in Mopane woodland. Therefore, sustainable harvesting in the woodland for firewood, construction material and poles, other than charcoal production could be encouraged. The preference across use types and species depended mostly on availability of resources in the woodland. Colophospermum mopane was the species with highest multiple use, including for firewood, charcoal, construction material, fencing poles and edible caterpillars. Local people perceived that crop production was a more important source of benefits for their livelihoods than cattle farming, woodland use and cash income. Application of strategic management planning is crucial in the Mahel area. This will require a suitable zoning scheme for appropriate use of the woodland resources and conservation of the vegetation as a guarantee for sustainable development of the local communities.
AFRIKAANSE OPSOMMING: Mopanie bosveld is een van die mees ekonomies en ekologies belangrike plantegroei tipes en voorsien 'n reeks dienste en produkte wat bydrae tot die lewensonderhoud van plaaslike gemeenskappe in die droeë en laagliggende dele van Suider Afrika. Alhoewel Mopanie bosveld, soos ook ander savanna tipes in Afrika, in die afgelope dekades aandag geniet het, is daar 'n tekort aan studies wat sosio-ekonomiese, sowel as omgewingsaspekte, integreer en aanspreek. Die doel van die studie was om die impak van oes en benutting van houtagtige hulpbronne te dokumenteer en sodoende aanbevelings te maak aangaande die ekologiese en ekonomiese aspekte van die volhoudbare benutting van gemeenskaplike hulpbronne in die Mahel gebied, Mosambiek. Dit is gedoen deur ondersoek in te stel na die patroon van spesie samestelling, die beskikbaarheid en gebruik van bosveld hulpbronne en die dinamiese prosesse van die houtagtige plantegroei. In die studie is gevind dat daar belowende potensiaal in die gebruik van die houtagtige hulpbronne in die studiegebied, opgesluit is. Die bevinding is bevestig deur die plaaslike gemeenskappe wat die belangrikheid van die hulpbronne in hul lewensonderhoud herken. In die lig van die huidige onvolhoudbare verbruik van die hulpbron, is maatreëls vir die bewaring hiervan nodig om moontlike oorbenutting van houtagtige hulpbronne te voorkom. Dit wil voorkom asof die spesierykheid en diversiteit deur 'n aantal antropogeniese faktore beinvloed word, maar grondeienskappe is die belangrikste faktor wat die verspreiding en samestelling van Mopanie en Akasia bosveld in die Mahel, bepaal. Die ongunstige omgewingstoestande op harde, klei grond, lei daartoe dat tot 80 % van die Mahel gedomineer word deur Colosphospermum mopane. Daar was verder aanduidings van hoër spesierykheid per plot soos daar van plaaslike nedersettings wegbeweeg word. Daar was egter 'n hoër spesiediversiteit nader aan nedersettings, as gevolg van menslike aktiwiteite. Daar was 'n tendens vir Colosphospermum mopane om mono-spesifieke opstande met groter afstand van nedersettings te vorm. Een van die mees belangrike aspekte van die studie is die bydrae wat dit lewer tot grondbeginsels vir langtermyn studies, wat fokus op die impak van menslike gebruik van Mopanie bosveld op die biodiversiteit en plantegroeisamestelling van die hulpbron. Die beskikbaarheid van houtagtige hulpbronne was hoër in die Mahel Mopanie bosveld (937 stamme ha-I) as in Akasia bosveld (271 stamme ha-I). Daar is gevind dat die populasiestruktuur, sowel as regenerasie van die populasie, stabiel is in Mopanie bosveld. Derhalwe kan benutting van die bosveld vir vuurmaakhout (uitsluitende charcoal) en boumateriaal aangemoedig word. Die voorkeur van sekere spesies en aanwending vir sekere gebruike het meestal afgehang van die beskikbaarheid van die verkillende hulpbronne in die bosveld. Colosphospermum mopane is die spesie wat die meeste aangewend is vir gebruik vir onder andere, vuurmaakhout, charcoal, boumateriaal, heining pale en die voorsiening van eetbare ruspus. Daar is verder bevind dat die plaaslike inwoners gewasproduksie as 'n belangriker ondersteuningsfaktor vir lewensonderhoud sien as lewendehawe produksie, bosveld benutting en kontant inkomste. Die toepassing van strategiese bestuursbeplanning is van kardinale belang in die Mahel. Dit sluit die ontwikkeling van 'n sonerings skema in, om die toepaslike gebruik van bosveld hulpbronne en die bewaring van die plantegroei te verseker vir die toekomstige volhoudbare gebruik van die hulpbron deur plaaslike gemeenskappe.

Includes bibliographical references.
African elephants are known to be important agents of structural and compositional changes in several vegetation types in southern Africa. This is of concern for biodiversity conservation and management of wildlife areas in the region. This study assesses how increasing elephant numbers have already altered and are likely to continue to modify the structure and composition of mopane woodlands in the south-eastern lowveld of Zimbabwe. Several features of vegetation structure and composition were quantified and compared across areas under three different elephant densities: low, intermediate and high. We assessed the degree, nature and patterns of damage incurred by woody plants within these woodlands to determine how elephants are both driving and responding to the changes in the vegetation. Increasing elephant densities were associated with increased losses of tall trees and the resultant development of a coppiced shrub layer. As elephant densities increased from low to intermediate levels, so did the level of damage to both shrubs and trees. However, elephants appeared to exhibit a functional response such that the increase in damage to the shrub layer was proportionately higher than to trees, probably because the coppiced shrub layer was a preferable food source. Nevertheless if elephant density increases further to high levels, damage to trees is likely to continue increasing suggesting that tree losses are likely to continue. In particular, the high level of bark damage to emergent trees is predicted to contribute greatly to further tree losses. This study provides evidence to suggest that increasing elephant impact is capable of completely converting tall mopane woodlands to shrublands. This is likely to have indirect effects on the ecosystem functioning and diversity of these areas as well as tourism, and is consequently of concern for local management. Continued monitoring of these woodlands and management of elephant abundance is advisable if a total conversion to shrubland is to be avoided.

The savanna woodlands of Southern Africa, colloquially termed the miombo, are poorly described in terms of biodiversity compared to other biomes. They have therefore been underrepresented in the wider understanding of how land use intensification is shaping global biodiversity. Land use change is known to reduce biodiversity and disrupt intactness of ecological communities with consequences for ecosystem functioning, resilience, and services. Miombo woodlands are described as biodiversity hotspots due to a high endemism of species and the presence of megafauna. At the same time, they are also considered dynamic socio-ecological systems shaped by disturbances and the land use activities of people. The patterns of biodiversity change in these tropical ecosystems may, therefore, have their own unique contexts, understanding of which will be essential for biodiversity and land use management in these ecosystems. In this thesis, I identified the patterns of biodiversity change in response to the two major land use practices in the two dominant woodland types in southern African woodlands: the selective logging due to charcoal production in the mopane woodlands, and agricultural expansion in the miombo. I also examined the impact of two main disturbance agents, humans and elephants, on habitat structure and biodiversity in mopane woodlands. Across all chapters in this thesis, I investigated the effects of land use change and habitat modification on biodiversity empirically using chronosequences. To understand biodiversity change, I employed a hierarchical multilevel modelling approach making inferences at the three levels of ecological communities: species, community, and meta-community (set of ecological communities at different sites). I selected six villages in the charcoal production hotspot of southern Mozambique and carried out field surveys for three taxonomic groups: trees, mammals and ground beetles. I modelled the counts of trees and beetles and incidence of mammals using meta-community occurrence models in a Bayesian framework with the intensity class of the villages, above-ground biomass and land cover type as predictors. The results suggested that the species richness of trees and mammals declined by 12 and 8.5 % respectively while that of beetles increased by 3.5%, albeit non-significantly. In addition, the beta diversity of trees decreased while that of mammals increased. The results show that while both trees and mammals reduced in richness, they responded differently to charcoal production in terms of community organisation. The trees underwent subtractive homogenisation (decrease in alpha and beta diversities) primarily because of deterministic processes induced by selective harvesting of tree stems for charcoal. Mammal communities, on the other hand, showed subtractive heterogenization (decrease in alpha, but increase in beta diversity) mainly due to random extinctions. In the agriculture frontier of miombo-dominated northern Mozambique, I investigated the effects of fragmentation and habitat loss caused by agricultural expansion on diversity and composition of trees and mammals. I modelled the occurrences of trees and mammals using occupancy models with the fragmentation and quantity of woodland cover as predictors. The model showed that most tree species (n=10), mainly the timber and firewood species, linearly declined in population size as fragmentation increased. Mammals, on the other hand, showed a nonlinear response. Seven mammal species increased at the lower levels of fragmentation. However, at the higher levels, none of the mammal species increased while two declined. Similarly, the species richness of trees linearly declined, while that of mammals increased up to a fragmentation level of 55-65% and declined above this limit. The beta diversity of trees increased with fragmentation while that of mammals decreased. The results suggest that, although fragmentation reduces species richness of both trees and mammals, it affects their species compositions in different ways. Trees undergo subtractive heterogenization due to random species losses while mammals experience subtractive homogenisation mainly due to the combined effects of fragmentation-led habitat loss and intensified hunting. Finally, this study concludes that, above 75% fragmentation or below 26% habitat quantity, both taxonomic groups endure biodiversity loss. The threshold results here corroborate similar habitat quantity thresholds (20-30%) observed elsewhere in different ecosystems. However, they differ with the widespread notion that above 30% habitat quantity, the effect of fragmentation is non-existent. The results here emphasize that taxonomic groups respond differently, the diversity and population size of mammals reduced only after the habitat threshold, whereas, those of trees showed linear decrease with fragmentation most likely due to fragmentation-led habitat loss. Lastly, I examined the effects of disturbance by humans and elephants on habitat structure and bird diversity by conducting a space for time substitution comparison in the mopane woodlands of Zambia. To examine the woodland structure, I modelled the structural attributes of habitat (stem diameter, stand density, and basal area) using mixed models with the proportion of affected stems by humans and elephants as explanatory variables. I found that elephant disturbance was associated with higher stem diameters, low stand densities, but no change in basal area. Human disturbance, on the other hand, was related to reductions in stand density and basal area, but no change in the stem diameter. Further, I tested species and functional diversity of birds against the covariates of habitat structure and disturbance. I found that bird communities reduced in species richness in both, human as well as elephant disturbed areas. However, the functional diversity did not change with elephant disturbance. I concluded that human disturbance reduces woody biomass (basal area is correlated with woody biomass) of mopane woodlands and functional diversity of birds whilst elephants do not. In this thesis, I conclude that human driven land use change in the miombo woodlands erodes alpha diversity of all taxonomic groups. However, increases in beta diversity of mammals with charcoal land use and trees in agricultural land use may maintain their diversities at the meta-community level.

Thesis (Ph. D. (Botany)) -- University of Limpopo, 2020
Colophospermum mopane (Benth.) J. Léonard, commonly known as mopane, is a dominant tree or shrub in the mopane woodland. It is distributed in the low-lying areas of southern Africa’s savannas. Mopane maintains its foliage well into the dry season, and thus provides nutritional forage for browsers such as Tragelaphus strepsiceros, commonly known as the greater kudu. Despite its wide distribution and value as a source of forage for browsers, especially during the dry season, knowledge of the effect of browsers on mopane leaf quality is limited. There is also inadequate knowledge of the diet composition of the greater kudu during different seasons in the mopane woodland. Such information is important for proper management of browsers in the mopane woodland. As a result, a field experiment was conducted at Musina Nature Reserve, Limpopo Province, South Africa to determine the effect of pruning on mopane leaf phenology, production, macronutrients, trace elements and secondary metabolites. Pruning was conducted to simulate the effect of browsing by large herbivores such as the greater kudu on mopane leaf quality. In addition, rumen content analysis of greater kudu was conducted in order to quantify the amount of mopane and other plants browsed during the dry and wet seasons. Collected datasets were analysed using descriptive and inferential statistics. A two-tailed Mann-Whitney U-test was used to test the effect of pruning on mopane leaf phenology and production. The effect of pruning on the monthly concentration of macronutrients, trace elements and secondary metabolites was tested using a two-tailed t-Test: Two-Sample Assuming Equal Variance. The seasonal and annual effect of pruning on the concentration of macronutrients, trace elements and secondary metabolites was tested using One-Way Anova. Rumen datasets were analysed using the Pearson Correlation Coefficient. This study found that the rate of leaf phenology and production, including the concentration of certain macronutrients (Ca, K, N, P, S, Cl, Na, protein and fibre), trace elements (Fe, Mn, Mo, Cu, Zn and Se) and secondary metabolites (TP, CT and PPT) increased during leaf flush in October and then declined as the leaves ii matured and aged. However, the concentration of selected macronutrients (Mg and NO3) and trace elements (B, Co and F) increased when the leaves reached maturity in June, particularly during the leaf senescence stage, and declined thereafter. The concentration of macronutrients, trace elements and secondary metabolites between the control and pruned trees was statistically insignificant at P>0.05 for most samples. This study further showed that C. mopane contributed most (47%) to the diet of the greater kudu during the dry season. Other important dry season browse plants were Dichrostachys cinerea (30%), Commiphora edulis (12%), Grewia bicolor (6%) and Combretum apiculatum (5%). However, when gender was considered, the diet of the female greater kudu during the dry season consisted mainly of C. mopane (71%) and D. cinerea (22%). The diet of the male greater kudu contained less C. mopane (33%), but similar proportions of D. cinerea (31%) and other browse species. However, during the wet season, the diet of the greater kudu was mainly composed of C. apiculatum (43%). Other wet season browse plant species were Sclerocarya birrea (24%), C. mopane (12%) and Senegalia nigrescens (8%), with the contribution of the remaining species to the diet being insignificant. The diet of the female greater kudu in the wet season consisted mainly of C. apiculatum (44%) and C. mopane (20%), while the diet of the male mostly contained S. birrea (38%) and C. apiculatum (34%). It is concluded that the concentration of macronutrients, trace elements and secondary metabolites in mopane leaves is not dependent on <10% pruning, but seems to be associated with leaf growth stages. It is further concluded that the concentration of nutrients and chemical compound in mopane leaves has implications on the diet composition of browsers such as the greater kudu in the mopane woodland. The dependency of the greater kudu on species such as C. mopane and C. apiculatum as main sources of browse indicates the importance of these species to the diet of the greater kudu in the mopane woodland.
Deutscher Akademischer Austausch Dienst (DAAD) , National Research Foundation (NRF) and University of Limpopo (Biodiversity Research Chair)

Mopane (Colophospermum mopane) woodlands are a source of valuable resources that contribute substantially to rural economies and nutrition across Southern Africa. However, a number of factors such as over-harvesting and climate change have brought the sustainability of the mopane woodland resources into question. Insect defoliation remains a major factor contributing to the depletion of woodland resources in rural areas resulting in low vitality and productivity of the woodland. Conventional methods (e.g. visual evaluation) have been used in monitoring insect defoliated areas in the past. These methods are costly and timeconsuming, because of the need to collect data immediately before and after an extreme event. In this regard, remote sensing techniques offer a practical and economical means of quantifying woodland degradation over large areas. Remote sensing is capable of providing rapid, relatively inexpensive, and near-real-time data that could be used for monitoring insect defoliation especially in semi-arid areas where data collection may be difficult. The present study advocates the development of techniques based on remotely sensed data to detect and map defoliation levels in Mopane woodland. The first part of the study provides an overview of remote sensing of insect defoliation, the implications for detecting and mapping defoliation levels as well as the challenges and need for further research especially within Mopane woodland. Secondly, the study explored whether Mopane species can be discriminated from each of its co-existing species using remote sensing. This was done as a prerequisite for classifying defoliation on mopane trees. Results showed that, with limited training samples, especially in semi-arid areas, Mopane trees can be reliably discriminated from its co-existing species using machine learning algorithms and multispectral sensors with strategic bands located in sensors such as RapidEye. These positive results prompted the need to test the use of ground based hyperspectral data and machine learning algorithm in identifying key spectral bands to discriminate different levels of insect defoliation. Results showed that the random forest algorithm (RF) simplified the process and provided the best overall accuracies by identifying eight spectral wavelengths, seven of which belongs to the red-edge region of electromagnetic spectrum. Furthermore, we tested the importance of the red-edge region of a relatively cheaper RapidEye imagery in discriminating the different levels of insect defoliation. Results showed that the red-edge region played an important role in mapping defoliation levels within Mopane woodland with NDVI-RE performing better than the traditional NDVI. Thirdly, the study tested the reliability and strength of the internal validation technique of RF in classifying different defoliation levels. It was observed that the bootstrapping internal estimate of accuracy in RF was able to provide relatively lower error rates (0.2319) for classifying a small dataset as compared to other validation techniques used in this study. Moreover, it was observed that the errors produced by the internal validation methods of RF algorithm was relatively stable based on the confidence intervals obtained compared to other validation techniques. Finally, in order to evaluate the effects of insect defoliation on the biophysical properties of mopane canopies at different defoliation levels, the study estimated leaf area index (LAI) of different defoliation levels based on simulated data. This was done using PROSAILH radiative transfer model inverted with canopy spectral reflectance extracted from RapidEyeRapidEye imagery by means of a look-up-table (LUT). It was observed that the significant differences exist between the defoliation levels signifying reduction in the LAI as a result of the defoliation. Furthermore, results showed that the estimated LAI was in the range of those reported in literature. The NDVI-RE index was the most strongly correlated with the estimated LAI as compared to other variables (RapidEye bands and NDVI). Overall, the study demonstrated the potential of remote sensing techniques in discriminating the state of Mopane woodland after insect defoliation. The results are important for establishing an integrated strategy for managing defoliation processes within Mopane veldt, thereby satisfying both the needs of local populations for Mopane trees and the worms.
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

The majority of the vegetation types occurring on Malilangwe Estate, in the south-eastern lowveld of Zimbabwe, are dominated by Colophospermum mopane (mopane). Over the past 30-50 years the stand density of these mopane vegetation types has increased, and an investigation was undertaken to determine the effect of season of burning and type of fire on mopane woodlands. From this study the following was ascertained: 1) A single predictive equation cannot be used over all seasons to estimate standing crop (fuel load) using the standard disc pasture meter procedure. The calibration equations developed using this procedure accounted for between 39 and 72% of the variation in standing crop, illustrating the high variation in basal cover of the grass sward, as well as the variation between months. Although the revised procedure, developed for areas with low basal cover, accounts for a lot more of the variation in standing crop, this procedure was not used to estimate standing crop over the study period because the calibration equation covered a number of vegetation types, and was not specific to the mopane woodlands. 2) Standing crop tracks effective rainfall (monthly rainfall divided by monthly pan evaporation) closely, with a lag period of less than one month. Standing crop can be estimated using a predictive equation that utilizes effective rainfall from the previous month. There is a positive relationship between peak standing crop and rainfall. A predictive equation was developed to estimate peak standing crop, using annual rainfall. Standing crop declines through the dry season as effective rainfall decreases, and this 'decrease function' allows for the estimation of the standing crop for a particular month, after peak standing crop is reached. 3) Two leaf quantification equations were developed for mopane trees in the south-eastern lowveld of Zimbabwe, one for coppicing and for non-coppicing individuals. These allow for the estimation of leaf dry mass from measured canopy volume. 4) There was no significant difference between the fire intensities attained for the three seasons of burning. Over all seasons, head fires were significantly more intense than back fires. 5) Percentage topkill after late dry season burns was significantly higher than topkill after early dry season burns. There was no significant difference between mid and late dry season burns, and head fires led to significantly more topkill than back fires. Plants < 150 cm experienced significantly more topkill (80 %) than did individuals > 150 cm (44%). 6) Fire per se led to an increase in stand density over all seasons and types of fire, but this change was not significant. Fire did not influence the nett recruitment of new individuals. Height class one (0-50 cm) and three (151-350 cm) were impacted most by fire. This reflects a change in tree structure, with an increase in the amount of leaf material in height class three, and a subsequent decrease in the amount of material in height class one. 7) The effect of season of burning on the change in tree height was significant, whereas the effect of type of fire was not significant. All treatments, except early dry season back fires, led to a reduction in tree height, whereas trees in the no burn areas increased in height. 8) Burning in any season, and implementing either type of fire, led to an increase in the number of stems. Mid dry season burns led to the highest increase in number of stems. However, the more intense the fire the smaller the increase in number of stems. 9) All three seasons of burning (head and back fires) led to a significant decrease in maximum canopy diameter per tree, while the maximum canopy diameter of trees in the no burn areas increased. Mid dry season burns resulted in the greatest decrease in canopy diameter. 10) The effect of burning on the change in leaf dry mass per tree was highly significant. All three seasons of burning led to a decrease in leaf dry mass, while there was no difference between head and back fires. Leaf dry mass in the control areas increased however. High fire intensities led to the greatest decrease in leaf dry mass, late dry season head fires having the greatest decrease. This study suggests that mopane plants face a constraint due to fire and/or browsing, and a tradeoff occurs between canopy volume, canopy diameter, canopy area; and number of stems. Fire leads to an increase in the number of stems through coppicing, while canopy volume and leaf dry mass decreases. This decrease is either (i) a tradeoff in response to increasing stem number, or (ii) a reduction in canopy because additional leaves on the new stems contribute to photosynthesis. The most important response to season of burning is the altered phenophase (phenological stage) of the plant. Early dry season burns cause the trees to be leafless during the early dry season (when unburnt trees are carrying full leaf), and then to be in leaf at the end of the dry season (when unburnt trees are leafless). It would appear that fire disturbance initiates leaf senescence after burning, and then leaf expansion earlier than normal i.e the whole leaf senescence/growth process is brought forward. Trees in late dry season burn areas remain leafless at the start of the rains, while trees in unburnt areas are carrying leaf. Being leafless these trees do not photosynthesize during this time, and it is proposed that the grass sward is advantaged by the reduced competition from the tree component. The consequences of these two changes in phenophase could not be addressed in this study, but are pertinent questions that must be answered if mopane woodland dynamics are to be more fully understood. Management recommendations for (1) the removal of unacceptable moribund grass material, or (2) the reduction of encroachment by woody species on Malilangwe Estate are also given. In an attempt to combat the increase in stand density of mopane it is recommended that high intensity head fires be implemented, when standing crop (fuel load) is sufficient and climatic conditions are conducive to maintaining high intensity fires. These should be carried out at the end of the dry season, before the onset of the rains.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

Doctoral thesis submitted in fulfilment of the requirements for the Degree of Doctor of Philosophy to the Department of Development Studies, Faculty of Humanities at the University of the Witwatersrand, Johannesburg, South Africa, 2016.
Abstract This study examines the dynamics of power and the significance of local environmental knowledge in natural resource management in Zimbabwe’s communal areas. It uses a case study of Bulilima District, broken down into into 3 components (Wards) for manageability of the study, to analyse the power configurations and the role played by local environmental knowledge in influencing decision-making processes among actors in the district with regard to mopane worms (Imbrasis beilina is the scientific name while icimbi is the vernacular name) and mopane woodlands (Colophospermum mopane is the scientific name while iphane is the vernacular name). It examines the significance of local environmental knowledge, i.e. indigenous knowledge and knowledge that developed as a result of a combination of knowledges from different ethnic groups and modern science. The study further examines the dynamics of the gendered nature of mopane worms and woodlands tenure regimes by putting under the spotlight the spaces and places where men and women interact, use and exert control over mopane worms and woodlands. It places history at the centre of our understanding of contemporary power dynamics and helps us to appreciate the importance of how local environmental knowledge has changed over time. To this end, the study argues that some of the contemporary conflicts over resources have their roots in the colonial era when the colonial government appropriated land from the locals and introduced discourses and practices such as conservation. Furthermore, it argues and demonstrates that the state is a critical player in determining access, use and control of natural resources. Based on rich ethnographic data collected by means of critical observations, in-depth interviews, narratives, and archival data, as well as aided by a brief survey, the study concluded that natural resource governance is a complex phenomenon in developing states. Power and knowledge play significant roles in influencing access, use and control of mopane worms and woodlands. Furthermore, while some locals still possess indigenous knowledge, practices and belief systems related to natural resource management, these are now less significant in influencing decisions on natural resource management. Indeed, the interplay of knowledge and power in resource management sees scientific culture and outside knowledge taking precedence over local forms of knowledge in the management of natural resources in the district. Key words: power, local environmental knowledge, indigenous knowledge, ZANU PF, natural resource management, access, mopane worms and woodlands, Bulilima, Zimbabwe
GR2017