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Disturbances, such as herbivory and fire are commonplace in savanna ecosystems. The effects of herbivory and fire on growth and defences of adult trees is a much studied filed in plant ecology. However, there are comparatively few studies that have investigated the effects of herbivory and fire on seedling growth, defences and establishment. African Acacia trees are common and widespread, and are suggested to be keystone species in savanna ecosystems. They have been shown to significantly positively increase soil characteristics, such as soil moisture and infiltration, while also increasing spatial heterogeneity of savannas. These trees are distinguishable by their array of physical and chemical defences. Physical defences are either in the form of spines (physiologically costly to produce, thus considered inducible) or prickles (physiologically cheap to produce, thus considered constitutive), while condensed tannins are the most common form of chemical defences. Adult Acacia trees have been shown on several occasions to be highly resilient to disturbance events, primarily due to their large size. However, the effects of herbivory and fire on Acacia seedlings have been little studied despite their apparent importance for our understanding of African savanna ecosystem functioning. In two separate experiments, this thesis aimed to investigate the individual and combined effects of simulated herbivory and fire on the regrowth, defences, and total non-structural carbohydrates (TNC) of the seedlings of several Acacia species, while also testing the Resource Availability Hypothesis (RAH) (14 Acacia species) and the Expanded Growth-Differentiation Balance Hypothesis (GDBH) (three Acacia species). The RAH (Coley, Bryant & Chapin 1985) and the GDBH (Loomis 1932) both assume that arid-adapted (resource-poor) species are slow growing, with low tissue turnover rates. Contrastingly, humid-adapted (resource-rich) species have fast growth rates and thus a high tissue turnover rate. Therefore, arid-adapted species are predicted to invest more carbohydrate reserves in defence after a disturbance event, in order to defend new photosynthetic material. Conversely, humid-adapted (resource-rich) species are predicted to invest carbohydrate reserves into increased growth after a disturbance event, in order to compensate for tissue loss. The first greenhouse experiment found that, in accordance with the RAH, humid-adapted species displayed elevated growth rates compared to arid-adapted species. Overall, defences significantly increased after herbivory, but significantly decreased after fire. Herbivory was also shown to significantly reduce TNC stores in roots more than fire. We found that arid-adapted species did indeed invest more carbohydrate stores (TNC) into defence, and displaying an increase in spine and prickle abundance, spine and prickle length, and condensed tannin concentration. Humid-adapted species displayed an increase in growth rather than in defence, with the majority of species only increasing one defensive trait. Humid-adapted species also displayed significant trade-offs (negative correlations) between new stem growth and defence traits, while arid-adapted species overall did not display any significant trade-offs between stem growth and increased defences. The majority of arid-adapted species also displayed an allometric effect for spine abundance and length, with an increase in one trait led to an increase in the other. Prickles were found to be inducible, despite the assumption that due to low physiological cost, they are no inducible. Herbivory and fire were shown to not be substitutable in their effects on Acacia seedlings in a controlled experimental setting. The second greenhouse experiment tested the Expanded Growth-Differentiation Balance Hypothesis (GDBH) in the seedlings of A. erioloba, A. karroo, and A. nilotica using five levels of nutrient availability. Overall, spine abundance and spine length displayed a unimodal trend in all three species, with spine abundance and spine length being greatest at a nutrient availability of 800 mg/ ℓ. Spine abundance, spine length and condensed tannins increased significantly after herbivory, but were shown to significantly decrease after fire. We found that with an increase in nutrient availability, the growth of stems and roots, along with the production of TNC in roots and stems of all species significantly increased. Our data provide mixed support for the assumptions and predictions of the expanded GDBH. The regrowth of stems and physical defences were consistent with the GDBH. Chemical defences (i.e. condensed tannins) were however, inconsistent with the predictions of the GDBH. We have shown that Acacia seedlings are highly resilient to disturbance events, while the growth responses of Acacia seedlings are underpinned by TNC stores in roots. Simulated herbivory and fire are often substituted for one another in controlled experiments. However, we have shown that the effects of herbivory and fire have significantly different effects on regrowth patterns of Acacia seedlings. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Maize (Zea mays L.) is the most important grain crop in the country. Approximately 12 million tons of maize grain is produced annually on approximately 2.5 million ha of land. However, increased farming intensity can lead to fragmentation of habitat and has a tendency to decrease the biodiversity of an area. Therefore, to ensure the continued functionality of agro-ecosystems, methods in agriculture must be assessed and adapted when necessary to ensure the persistence of biological diversity. Unfortunately, the effect of crop production on species diversity and composition in South Africa is still relatively unknown, and no baseline data exists with which to gauge the possibility of unknown extinction risks of important biological elements. The objectives of this study were to compare plant and arthropod diversity patterns and species turnover of maize agro-ecosystems between biomes (grassland and savanna) and along a maize field-field margin gradient (MAFFMAG). Surveys of maize agro-ecosystems were conducted in six provinces of South Africa, namely North-West, Mpumalanga, KwaZulu-Natal, Limpopo, Free State and the Eastern Cape. Repeated measures ANOVA revealed a significantly lower plant and arthropod species diversity and richness in maize fields compared to field margins. Non-metric multidimensional scaling revealed that arthropod species composition differed between biomes although not along MAFFMAGs, indicating that arthropod species composition is dependent on biome rather than distance from maize field. Floristic data revealed unique species compositions for maize fields and field margins and also for biomes. Furthermore, maize fields and field margins of grassland sites were more similar in plant species composition than the savanna localities, suggesting higher regional beta diversity for savanna regions. Spearman‘s rank order correlations revealed generally positive but weak or no relationships between plant and arthropod diversity. This study provides baseline data for identification, monitoring and conservation of priority species and will allow the future evaluation of ecosystem services provided by plants and associated arthropods, especially natural enemies of pests, in maize agro-ecosystems. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

The structure and composition of savanna vegetation is influenced by resource availability and disturbance. Grasses, a major component of savannas, influence this resource availability by competing directly with trees for light, water and soil nutrient resources. The direct causes of bush encroachment are not always apparent, but are commonly ascribed to overgrazing and consequent decreased grass competition. The interaction, both above and belowground, between tree and grass seedlings and the surrounding grass sward is dependant on many factors, such as soil depth, seedling species and sward composition. These factors, as well as the presence or absence of defoliation, in the form of grazing or fire dictate whether the system will remain in a transition state as savanna or move towards a stable woodland state. The major competitive effects experienced by the tree seedlings were dependant on grass species and nutrient level. A. nilotica was affected by aboveground competition while A. karroo was affected by belowground competition. E. capensis caused the greatest decrease in A. karroo plant biomass. Both E. capensis and H. hirta had large competitive effects on the aboveground biomass of A. nilotica, while S. africanus had the greatest effect on belowground biomass. Increasing nutrient availability resulted in an increase in the competitive effect exerted on A. karroo, while little to no change was seen in the competitive effect exerted on A. nilotica. Soil depth constrained plant size in both tree species. The intensity of belowground interactions on tree biomass was unaffected by soil depth, while aboveground competition had a significant effect on shallow soils. Belowground competition was also of greater importance than aboveground competition in dictating tree seedling height. Grass seedlings growing on all three soil depths differed in mean mass, with E. racemosa having the least mass and T. triandra having the greatest. Simulated grazing by cutting the surrounding sward resulted in biomass increases in all three grass species. Changes in savanna composition and structure are thus likely to be influenced by initial species composition and soil depth and soil nutrient composition. While grazing creates niches for grass seedling establishment, heavy grazing has been observed to increase grass seedling mortality. Encroachment is thus more likely to occur on intensively grazed shallow and deep soils than on medium depth soils. This highlights the importance of ensuring the grass sward remains vigorous by resting and monitoring stocking rates to ensure veld is not over-utilized. It is then possible to maintain some form of tree-grass coexistence at a level where available grazing is not compromised. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

The long-term economic viability and ecological integrity of savanna rangelands is being undermined by increasingly dense woody thickets at the expense of palatable herbaceous cover. This process is known as shrub- or bush-encroachment. Bush encroachment is a subset of a broader ecological riddle underlying the coexistence of woody and herbaceous vegetation that has been the subject of many ecological models. The ecophysiological mechanisms and interactions between trees and grasses on which most assumptions of ecological models are premised have seldom been tested empirically. This document synthesises the results of greenhouse and field-based investigations of the underlying ecological mechanisms and ecophysiological interactions between encroaching Acacia mellifera trees and grasses in a semi-arid environment. In a greenhouse study, I determined the contribution of N2 fixation to the N-budget of Acacia mellifera under conditions of both varying N availability and competition from grass. Tree seedlings had longer shoots and greater total dry mass in the absence of grass. The leaf δ15N values were lower with grass than without grasses. Thus, trees were more reliant on N2 fixation in the presence of grasses. N2 fixation may enable the tree seedlings to survive competition with grass at critical and vulnerable developmental stages of germination and establishment. In a field removal experiment, I monitored the growth rates, water relations and mortalities of shrubs around which neighbouring woody plants were removed (target) and control shrubs over three years. Results showed target trees to have benefitted from removal of neighbours, which was manifested in significantly faster growth rates, less negative predawn water potential and a relatively small degree of canopy die-back. Nonetheless, neighbouring trees appeared to prevent the whole plant mortalities resulting from severe environmental stress. Growing in close proximity with neighbours could therefore yield positive and negative ecophysiological effects. In another greenhouse experiment, I tested the effects of the separation of moisture uptake with depth between tree seedlings and grasses on two common substrate types. I also examined the influence of repeated grass clipping on the persistence of soil moisture. Results indicated a three-tier rooting pattern with a top layer exclusively exploited by grasses, an intermediate layer occupied by both grass and tree roots and deeper layers exclusively tapped by trees. Tree seedling biomass was negatively affected by grass competition although the biomass of grass was enhanced in the presence of tree seedlings on sandy substrates only. The repeated clipping of grass benefitted tree seedlings on rocky substrate more than it did on sandy substrate. The effects of heavy grazing on soil moisture availability to woody shrubs and thus bush encroachment may be contingent on substrate type, being more acute on rocky terrains. Grass competition suppresses tree seedlings but the removal of grass by grazing weakens this suppressive effect, particularly on rocky substrates. The insufficiency of space and soil resources on rocky substrates may necessitate increased investment in root biomass by plants. It is not known why grasses have lower densities on rocky substrates than on sandy substrates, but the obstruction by rocks disadvantages grasses against tree seedlings, leaving grasses vulnerable to grazing pressure. This may allow the woody plants on rocky substrates to benefit more from grass removal than on sandy substrates. Root restriction by rock barriers and, perhaps, sparse soil volume further lead to small tree sizes on the rocky substrate. Small shrubs are less likely to compete intensively for resources and cause density-dependent mortality. Intraspecific competition may maintain shrub sizes within the threshold that can be supported by available resource pools. I conclude from my results that the two-layer hypothesis of niche separation between savanna vegetation is valid although there is an overlap in the grass and tree rooting depth/moisture uptake. An additional factor that affects the success of A. mellifera is the substrate.Trees are more dense on rocky substrates but grow larger on sand. I have further shown that A. mellifera trees fix nitrogen when competing with grasses but do not do so when grasses are absent. A mechanistic model of savanna dynamics will need to integrate water use patterns, substrate and nutrients to make effective predictions about encroachment patterns. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Extensive drought - and elephant-related dieback of Colophospermum mopane and Acacia tortitis, respectively, offered an opportunity for increasing understanding of the causes of drought-related patch dieback, the factors influencing elephant utilization of woody plants, and the response of woody plants to both aforementioned determinants of savanna structure and function. The dendrochronological analysis of both species was undertaken to estimate potential rates of replacement, following extensive mortality. Areas of discrete dieback were compared with adjacent paired areas of 'healthy' vegetation, which revealed, on average, 87% and 13% loss of basal area by mortality, respectively. 'Live' and 'dead' plots did not differ in soil type, topography or mean slope, but differed in vegetation structure, soil surface condition, and soil chemistry. Although there was evidence of self-thinning, neither inter - nor intra-specific competition explained dieback. 'Dead', by comparison with 'live' plots, had changed from functioning as sinks of sediment and water to sources, were less likely to retain water because of a poor soil surface condition, and were predisposed to drought effects because of a greater proportion of fines, and Na concentration. Dieback resulted from insufficient soil water for survival during a drought owing to the development of a dysfunctional landscape during 50 years of livestock ranching. Spatial heterogeneity within a landscape was suggested to enhance woodland resilience to severe droughts by ensuring the survival of plants in run-on sinks or 'drought refuge' sites. Stem sections were removed from 40 multi-stemmed C. mopane trees and prepared for examination under a dissecting microscope. It was impossible to age C. mopane, owing to a hollow and/or dark heartwood. Nevertheless, the distribution of stem diameters suggested a single recruitment event. Fire scars attributed to the last recorded fire in 1948 could explain the trees' multi-stemmed growth form and indicate that most trees of VLNR were > 50 years of age. Growth rings were identified in 29 A. tortilis trees of unknown age, but were not correlated with annual rainfall records. Growth rates varied between trees; mean ring width ranged from 1.4 to 3.5 mm (overall mean 2.4 ± 0.1 mm). A technique was proposed for predicting growth rate from annual rainfall, using selected data, and several factors potentially influencing ring width in semiarid environs were identified. Permanent ground-based transects were located within riparian (n = 16) and Acacia (n = 5) woodlands to monitor elephant utilization. Elephant had not changed the population structure of the woodlands by 2000, but had reduced stem density from 215.6 stems ha -1 (1996) to 84.4 stems ha -I (2000). Acacia tortitis trees in the woodlands had branches removed, were debarked, uprooted and broken. Acacia tortitis trees in the riverine had lower levels of utilization, whilst Acacia nilotica trees were mostly debarked. The method of elephant feeding varies within and between woody species, provided it is within the mechanical constraints of a certain size or species. Elephant behaviour is concluded to depend on spatiotemporal variation of forage abundance/quality, abundance of a preferred species, and species response (coppice or mortality). Elephant can cause a change of vegetation state, and increase spatial homogeneity of a plant population. The remnant population of woodland trees should provide the potential for recolonization, in which case the system would reflect the stable limit cycle. However, if browsing inhibits seedling recruitment, the system could reflect either a multiple stable state system or an artificial equilibrium imposed on a stable limit cycle. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Herbivory often influences the fitness and development of attacked trees, acting as an important factor of evolutionary pressure on a species ecology. However, there are few studies that show the effects of insect herbivores on Cerrado tree species. In this study I evaluated the impact of the leaf-cutter ant Atta laevigata on the vegetative and reproductive phenology, survival, growth, architecture and leaf nutrients of six tree species of a Cerrado vegetation. For three years, I visited individuals of Cardiopetalum callophylum, Coussarea hydrangeaefolia, Guapira graciliflora, Maprounea guianensis, Vochysia tucanorum and Xylopia aromatica, and determined the intensity of phenological events and leaf-cutter ant attacks. In addition, based on the recurrence frequency and intensity of ant-attacks (often 100% of leaf removal) previously observed, I created two artificial defoliation experimental treatments that simulated high and low Atta laevigata s attack frequency. I then evaluated how the different frequencies of high intensity attacks influenced the survival, growth, flower production, leaf nutrient content and architecture of the trees. The results showed that the defoliation by leaf-cutter ants reduced the photosynthetic area of attacked trees and reduced flower and fruit production of preferred species. However, it did not affect the synchrony and timing of leaf and flower/fruit production. Herbivory frequency had a negative effect on the plant tolerance to herbivory, survival, flower production and architecture in all six species. However, for some species, the leaf content of N and P were significantly higher in defoliated trees than in control trees. These results indicated that leaf-cutter ants can be considered chronic herbivores in some areas of the Cerrado, and that their continued activities can, in the long-term, affect the structure and dynamics of the vegetation. / A herbivoria influência o sucesso reprodutivo e o desenvolvimento das plantas, atuando como um importante agente de pressão evolutiva na ecologia de algumas espécies. Porém, há poucos estudos que mostram o efeito da atividade dos insetos herbívoros nas espécies arbóreas do Cerrado. Neste estudo apresento evidências dos efeitos da formigas cortadeira Atta laevigata, sobre a fenologia, sobrevivência, crescimento, arquitetura e nutrientes foliares de seis espécies arbóreas. Durante três anos acompanhei indivíduos de Cardiopetalum callophylum, Coussarea hydrangeaefolia, Guapira graciliflora, Maprounea guianensis, Vochysia tucanorum e Xylopia aromatica e determinei a intensidade de cada evento fenológico e dos ataques por saúvas. Baseado no tempo de recorrência e na intensidade dos ataques (normalmente 100% das folhas removidas) previamente observados, criei duas categorias de desfolha que simulando uma alta e uma baixa freqüência de ataque por Atta laevigata. Dessa maneira, examinei como diferentes freqüências de ataques de alta intensidade influenciaram a sobrevivência, o crescimento, a floração, o teor de nutrientes foliares e a arquitetura das plantas. Meus resultados mostraram que a desfolha por saúvas diminuiu a área fotossintética das plantas e reduziu a produção de frutos das espécies preferidas. Porém, a sincronia e a época de produção de folhas e frutos não foram afetadas. Os resultados indicam também que a freqüência de desfolhas tem um efeito negativo na capacidade de tolerância, na sobrevivência, na produção de flores, e na arquitetura das árvores. Entretanto, para algumas espécies, as concentrações foliares de N e P foram significativamente maiores em plantas cortadas do que em não-cortadas. Estes resultados indicam que as saúvas podem ser consideradas herbívoros crônicos em áreas do Cerrado e que a atividade contínua destas formigas pode, a longo prazo, afetar a estrutura e dinâmica da vegetação. / Mestre em Ecologia e Conservação de Recursos Naturais

Submitted by LUÍS FELIPE DAIBES DE ANDRADE null (luipedaibes@hotmail.com) on 2017-12-09T19:13:02Z No. of bitstreams: 1 TeseVersaoFinal_LFD.pdf: 4542971 bytes, checksum: dc820c668f873e34980831a5f5f98979 (MD5) / Approved for entry into archive by Adriana Aparecida Puerta null (dripuerta@rc.unesp.br) on 2017-12-11T16:56:37Z (GMT) No. of bitstreams: 1 andrade_lfd_dr_rcla.pdf: 4542971 bytes, checksum: dc820c668f873e34980831a5f5f98979 (MD5) / Made available in DSpace on 2017-12-11T16:56:37Z (GMT). No. of bitstreams: 1 andrade_lfd_dr_rcla.pdf: 4542971 bytes, checksum: dc820c668f873e34980831a5f5f98979 (MD5) Previous issue date: 2017-12-01 / Outra / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O fogo é o principal distúrbio em diversas vegetações ao redor do mundo, denominadas ecossistemas inflamáveis. Neste contexto, muitas espécies possuem estratégias de regeneração e colonização do ambiente pós-fogo, o que tipicamente envolve a sobrevivência (tolerância) das sementes e/ou quebra da dormência. Em especial, muitas sementes de leguminosas possuem o tegumento impermeável (dormência física), que pode ser rompido por meio de choques térmicos relacionados ao fogo. Outro fator que pode auxiliar no processo de quebra da dormência física é a flutuação térmica no solo, cuja amplitude é aumentada nas clareiras formadas pela remoção da vegetação durante a queima. Ambos os fatores, fogo e flutuação térmica, são relativamente bem estudados nos ecossistemas inflamáveis da Austrália e em vegetações Mediterrâneas. Por outro lado, os padrões relacionados à quebra da dormência e germinação das sementes ainda são controversos e menos conhecidos nas savanas tropicais da África e da América do Sul. Assim, esta Tese de doutorado teve como objetivo avaliar o papel do fogo na germinação e sobrevivência das sementes de leguminosas do Cerrado. Para tanto, realizamos tratamentos em campo, incluindo queimas experimentais, e também aplicamos tratamentos no laboratório, simulando a flutuação térmica nas clareiras e a passagem do fogo (choques térmicos). Após os tratamentos, observamos a germinação em condições ótimas, fazendo contagens três vezes por semana, e realizamos testes de viabilidade ao final de 30 dias dos experimentos. As análises estatísticas consistiram basicamente em GLMMs com distribuição binomial, considerando as réplicas como efeitos aleatórios. Os resultados apontam que as sementes morrem quando diretamente expostas ao fogo na superfície do solo. Por outro lado, há uma maior probabilidade de sobrevivência quando as sementes estão localizadas em clareiras (gaps) da vegetação. Nos gaps, a maior porcentagem de solo nu proporciona temperaturas do fogo mais amenas, queimando por menos tempo. Quando enterradas 1-cm sob o solo, as sementes sempre sobrevivem e pode haver quebra de dormência. A flutuação térmica também pode quebrar uma proporção significativa da dormência em condições de campo, especialmente em Mimosa leiocephala. Em laboratório, ao contrário do esperado, não há quebra da dormência, indicando que a flutuação térmica em si não consiste um mecanismo para quebra da dormência física em espécies do Cerrado. Nos choques térmicos, poucas espécies (seis de 46) apresentaram quebra da dormência. Observamos também que a mortalidade das sementes está relacionada a um trade-off entre forma de crescimento, tamanho das sementes e presença de dormência. Isso se deve ao tamanho pequeno das sementes de arbustos, que a despeito de tipicamente ocorrerem em savana aberta, podem morrer sob condições severas dos choques térmicos, mais do que as espécies arbóreas. Dentre as espécies arbóreas, a filogenia influencia no tamanho e, consequentemente, na mortalidade das sementes frente ao fogo. Concluímos que a germinação das sementes não está diretamente ligada à presença do fogo no mosaico Cerrado-floresta, contrastando com os padrões reconhecidos para outros ecossistemas inflamáveis. / Fire is the principal disturbance in several vegetation types around the world, being called flammable ecosystems. In this context, many species have strategies to regenerate and colonize the post-fire environment, which typically involve seed survival (tolerance) and/or breaking of dormancy. In special, legume seeds usually have an impermeable seed coat (physical dormancy), which may be disrupted by fire-related heat shocks. Another factor that can help in the process of dormancy-breaking is the temperature fluctuation in the soil, which amplitude is increased in gaps formed by the removal of vegetation as a result of the passage of fire. Both factors, fire and temperature fluctuation, are relatively well studied in flammable ecosystems from Australia and Mediterranean vegetation. On the other hand, the patterns related to dormancy-breaking and seed germination are still controversial and less known in tropical savannas from Africa and South America. Therefore, this doctoral Thesis has aimed to evaluate the role of fire on germination and survival of legume seeds from Cerrado. Therefore, we conducted experiments in the field, including experimental burning, and also applied treatments in the laboratory, simulating temperature fluctuation in the gaps and fire passage (heat shocks). After the treatments, we observed germination under optimal conditions, making counting three times a week, and accomplishing viability tests by the end of 30 days of the experiment. The statistical analyses basically consisted on GLMMS with binomial distribution, considering replicates as random effects. Results pointed that seeds die when directly exposed to fire in the soil surface. On the other hand, there is a higher probability of survival when seeds are placed in vegetation gaps. In the gaps, the higher percentage of bare soil provides milder fire temperatures, lasting for less time. When buried at 1-cm belowground, seeds always survive and dormancy-breaking may occur. Temperature fluctuation can also break a significant proportion of dormancy under field conditions, especially for Mimosa leiocephala. In the laboratory, there is no dormancy-breaking, showing that temperature fluctuation itself might not be a mechanism for physical dormancy-breaking in Cerrado species. When heat shocks were applied, six out of 46 species showed dormancy-breaking. We also observed that seed mortality is related to a trade-off between growth-form, seed size and the presence of dormancy. This is due to the small size of seeds from shrubs, that although typically occurring in the open savannas, they might die under severe conditions of temperatures. Among the tree species, phylogeny influences on size and, consequently, mortality of seeds in face to fire. We concluded that seed germination is not directly linked to the presence of fire in the Cerrado-forest mosaic, contrasting to the patterns recognized for other flammable ecosystems. / Fundação Grupo Boticário 0153_2011_PR / FAPESP 2015/06743-0 / CAPES/PDSE 88881.131702/2016-01 / CNPq 455183/2014-7

The purpose of this diploma thesis is to create a educational programme The Characteristic of the distribution of the worlďs land biomes. This programm is create for teaching of students with educational programmes in ZOO Ohrada Hluboká nad Vltavou. The educational programme consists of the text book, worksheets and methodical manual for teachers. The thesis consists of an analysis and evaluation of selected textbooks for the second grade of primary schools.

xvii, 160 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Restoring oak habitats is an emerging conservation priority in Oregon's Willamette Valley. Both private and public landowners face multiple challenges to conservation and restoration of oak habitats, including a lack of knowledge about the potential tradeoffs and constraints for achieving multiple priorities on a given site. This study simulated 25 alternative oak habitat restoration scenarios to develop estimates of outcomes related to six different restoration priorities: costs, income potential, habitat value, scenic quality, fire hazard reduction potential, and time requirements. Model results indicated that initial land conditions strongly influence a landowner's ability to optimize among these different priorities. To assist landowners with decision-making, model estimates were organized into a digital decision matrix that communicates advantages and tradeoffs associated with each alternative scenario. In doing so, it aims to help landowners choose restoration goals that better meet their broader needs and objectives. / Committee in Charge: Dr. Bart Johnson, Chair; Dr. Robert Ribe