Thesis (M. Agric. (Plant Production)) -- University of Limpopo, 2018 / The evergreen Red Milkwood (Mimusops zeyheri Sond.) is being targeted as a rural and urban-greening tree in Limpopo Province, due to its excellent nutritional, pharmaceutical and aesthetic attributes. Slow growth of M. zeyheri seedlings is the main drawback in the potential domestication and commercialisation of this tree species. The objectives of this study were to determine (1) the influence of soil type on root growth and foliar nutrient elements in M. zeyheri seedlings, (2) the degree of salt tolerance in M. zeyheri seedlings and (3) the influence of vesicular arbuscular mycorrhiza (VAM) fungi on growth of M. zeyheri seedlings. Objective 1 was achieved in clay, calcareous, loam and sandy soils. At 60 days after the treatments, soil type effects were significant on plant height, leaf number, chlorophyll content of primary leaves (dicots), chlorophyll content of secondary leaves, root length, number of root branches and dry root mass, contributing 60, 72, 84, 85, 74, 80 and 40% in total treatment variation (TTV) of the respective variables. Objective 2 was achieved by exposing seedlings to 0, 2, 4, 8, 16, 32, 64 and 128 NaCl + CaCl2 mM/m3 at 3:1 ratio. At 90 days after the treatments, salinity effects were significant on leaf number, dry shoot mass, root length and leaf length, contributing 73, 60, 50 and 64% in TTV of the respective variables. Leaf number, dry shoot mass, root length and leaf length each against increasing concentration of salinity exhibited positive curvilinear quadratic relations, with 74, 91, 95 and 66% associations, respectively. Responses of essential nutrient accumulation in leaf tissues of M. zeyheri to salt treatments had significant effects on K and Na, contributing 28 and 19% in TTV of the respective variables. Potassium over increasing salt concentrations exhibited positive quadratic relations and Na over increasing salt concentrations, exhibited negative quadratic relations. The models for each relation were explained by 95 and 86%, respectively. Objective 3 was achieved by exposing seedlings to 0, 10, 20, 30, 40, 50, 60 and 70 g VAM per plant. At 90 days after the treatments, VAM effects were significant on plant height, leaf number, stem diameter and chlorophyll content contributing, 49, 65, 60 and 61% in TTV of the respective variables. Plant height, leaf number and chlorophyll content each against increasing VAM levels exhibited negative quadratic relations, with 97, 83 and 80% associates, respectively. In conclusion, the use of soil type to promote growth and accumulation of essential nutrient elements on M. zeyheri seedlings demonstrated that clay soil could be suitable for cultivation of M. zeyheri. Also chloride salt concentrations included all three phases of density-dependent growth (DDG) patterns, whereas VAM levels used in the study were already in the last two phases of DDG patterns. Vesicular arbuscular mycorrhiza treatment did not have significant effects on Ca, Fe, K, Na and Zn in leaf tissues of M. zeyheri seedlings. In conclusion, soil with high clay content could be ideal when raising M. zeyheri seedlings. However, salt concentration of 8.11 mM/m3 exhibited the stimulation of M. zeyheri seedlings growth, Therefore, lower concentration less than 8.11 mM/m3 shown to be toxic by reducing the plant growth. In contrast, 5.554 g per plant of VAM will supreme for growth and development of M. zeyheri seedlings.

Regional variation in nitrogen (N) deposition increases plant productivity and decreases species diversity, but landscape- or local-scale influences on N deposition are less well-known. Using ion-exchange resin, we measured variation of N deposition and soil N availability within Elk Island National Park in the ecotone between grassland and boreal forest in western Canada. The park receives regionally high amounts of atmospheric N deposition (22 kg ha⁻¹ yr⁻¹). N deposition was on average higher ton clayrich luvisols than on brunisols, and areas burned 1 – 15 years previously received more atmospheric N than unburned sites. We suggest that the effects of previous fires and soil type on deposition rate act through differences in canopy structure. The magnitude of these effects varied with the presence of ungulate grazers (bison, moose, elk) and vegetation type (forest, shrubland, grassland). Available soil N (ammonium and nitrate) was higher in burned than unburned sites in the absence of grazing, suggesting an effect of deposition. On grazed sites, differences between fire treatments were small, presumably because the removal of biomass by grazers reduced the effect of fire. Aspen invades native grassland in this region, and our results suggest that fire without grazing might reinforce the expansion of forest into grassland facilitated by N deposition.

A modificação da paisagem e a fragmentação de habitats são consideradas ameaças à biodiversidade mundial. Áreas cobertas por vegetação primária ainda preservadas e unidades de conservação são insuficientes para garantir a conservação de espécies. Cultivos de florestas homogêneas passaram a ser considerados como possíveis habitats alternativos para espécies florestais e podem contribuir para a conservação da biodiversidade. O Brasil é o país com maior área ocupada com plantio de eucalipto e essa vem crescendo nos últimos anos. Identificar quais fatores influenciam a diversidade da biota nos plantios é importante para a conservação de espécies. O objetivo do presente estudo foi conhecer a composição florística do sub-bosque de plantios de Eucalyptus saligna Sm. e avaliar se o tipo de solo e a idade do plantio influenciam a riqueza e a composiçao da vegetação que ocupa esse ambiente. Para isso foi realizado o levantamento das espécies vegetais que ocorrem nos cultivos localizados em solo argiloso e arenoso, nos quais os indivíduos de E. saligna tinham três e sete anos. Foram avaliados como fatores ambientais características do solo, produção de serapilheira pelas árvores do plantio, abertura do dossel, uso do solo no entorno do cultivo e tamanho do plantio. No total, foram encontradas 218 espécies vegetais. As análises estatísticas foram realizadas apenas com as espécies que estavam presentes em pelo menos duas unidades amostrais. Plantios em solo argiloso apresentaram maior riqueza que no solo arenoso e houve diferença significativa na composição de espécies entre os dois tipos de solo. Grande parte dos fatores ambientais mensurados também foram diferentes entre os solos. Não foi possível verificar diferenças na riqueza, na composição de espécies e nos fatores ambientais entre os plantios de diferentes idades. O tipo de solo pode ser um fator mais limitante do que a idade da floresta plantada para determinar a riqueza e composição das espécies que compõem o sub-bosque dos plantios. Embora a riqueza de espécies no solo arenoso seja menor, esse também é importante para a conservação, porque abriga espécies adaptadas à menor disponibilidade de recursos, que não ocorrem em outros ambientes. O grande número de espécies encontrado no sub-bosque destes plantios indica que eles podem auxiliar na conservação de espécies nativas, mas esse potencial deve ser melhor investigado. São recomendados estudos de outros fatores, como a biologia de espécies importantes ecológica e econômicamente, interações entre animais e plantas e diferentes estratégias de manejo, para investigar de que forma eles afetam a biodiversidade e como eles podem ajudar a avaliar e aumentar o potencial de conservação das florestas industriais. / Landscape change and habitat fragmentaiton are recognized as threats to global biodiversity.Areas with remaining primary vegetation and protected areas are insufficient to ensure species conservation. Forest monocultures are potencial alternative habitats for native species and may contribute to the conservation of biodiversity. Brazil is the country with the largest area occupied with eucalypt plantations, this area is also growing in the last years. Identifying which factors influence the biodiversity on plantations is important to species conservation. The objective of this study was to know the understory species composition in Eucalyptus saligna Sm. plantations and to evaluate the influence of soil type and stand age on species richness and species composition. Surveys of vegetation were performed in stands on clay and sandy soils where the eucalypt trees were three and seven years old. Other soil characteristics, litter production by stand trees, canopy open and land use surrounding stands were evaluated as environmental factors. 218 plant species were found in plantations understory. The stands on clay soil were richer than those on sandy soil. Most of the environmental factors evaluated were also different among stands on different soils type. It was not possible to verify differences on species richness and species composition nor environmental factors between stand ages. Soil type could be a more limiting factor than forest age to determine species richness and species composition on plantations understory. Sandy soils are poorer in species, but they are also important to conservation, since species that happen on sandy soils are adapted to low resources availability and do not occur at other locations. The large number of native species founded in eucalypts plantation understory indicates that these plantations may assist some native species conservation. Nevertheless, further research is needed to understand the conservation potential from eucalypt plantations. It is recommended other studies to be done for a better comprehension and to increase the importance of plantation forests to conservation, mainly studies about biology of key species, interactions between animals and plants and the effect of different management options.

A modificação da paisagem e a fragmentação de habitats são consideradas ameaças à biodiversidade mundial. Áreas cobertas por vegetação primária ainda preservadas e unidades de conservação são insuficientes para garantir a conservação de espécies. Cultivos de florestas homogêneas passaram a ser considerados como possíveis habitats alternativos para espécies florestais e podem contribuir para a conservação da biodiversidade. O Brasil é o país com maior área ocupada com plantio de eucalipto e essa vem crescendo nos últimos anos. Identificar quais fatores influenciam a diversidade da biota nos plantios é importante para a conservação de espécies. O objetivo do presente estudo foi conhecer a composição florística do sub-bosque de plantios de Eucalyptus saligna Sm. e avaliar se o tipo de solo e a idade do plantio influenciam a riqueza e a composiçao da vegetação que ocupa esse ambiente. Para isso foi realizado o levantamento das espécies vegetais que ocorrem nos cultivos localizados em solo argiloso e arenoso, nos quais os indivíduos de E. saligna tinham três e sete anos. Foram avaliados como fatores ambientais características do solo, produção de serapilheira pelas árvores do plantio, abertura do dossel, uso do solo no entorno do cultivo e tamanho do plantio. No total, foram encontradas 218 espécies vegetais. As análises estatísticas foram realizadas apenas com as espécies que estavam presentes em pelo menos duas unidades amostrais. Plantios em solo argiloso apresentaram maior riqueza que no solo arenoso e houve diferença significativa na composição de espécies entre os dois tipos de solo. Grande parte dos fatores ambientais mensurados também foram diferentes entre os solos. Não foi possível verificar diferenças na riqueza, na composição de espécies e nos fatores ambientais entre os plantios de diferentes idades. O tipo de solo pode ser um fator mais limitante do que a idade da floresta plantada para determinar a riqueza e composição das espécies que compõem o sub-bosque dos plantios. Embora a riqueza de espécies no solo arenoso seja menor, esse também é importante para a conservação, porque abriga espécies adaptadas à menor disponibilidade de recursos, que não ocorrem em outros ambientes. O grande número de espécies encontrado no sub-bosque destes plantios indica que eles podem auxiliar na conservação de espécies nativas, mas esse potencial deve ser melhor investigado. São recomendados estudos de outros fatores, como a biologia de espécies importantes ecológica e econômicamente, interações entre animais e plantas e diferentes estratégias de manejo, para investigar de que forma eles afetam a biodiversidade e como eles podem ajudar a avaliar e aumentar o potencial de conservação das florestas industriais. / Landscape change and habitat fragmentaiton are recognized as threats to global biodiversity.Areas with remaining primary vegetation and protected areas are insufficient to ensure species conservation. Forest monocultures are potencial alternative habitats for native species and may contribute to the conservation of biodiversity. Brazil is the country with the largest area occupied with eucalypt plantations, this area is also growing in the last years. Identifying which factors influence the biodiversity on plantations is important to species conservation. The objective of this study was to know the understory species composition in Eucalyptus saligna Sm. plantations and to evaluate the influence of soil type and stand age on species richness and species composition. Surveys of vegetation were performed in stands on clay and sandy soils where the eucalypt trees were three and seven years old. Other soil characteristics, litter production by stand trees, canopy open and land use surrounding stands were evaluated as environmental factors. 218 plant species were found in plantations understory. The stands on clay soil were richer than those on sandy soil. Most of the environmental factors evaluated were also different among stands on different soils type. It was not possible to verify differences on species richness and species composition nor environmental factors between stand ages. Soil type could be a more limiting factor than forest age to determine species richness and species composition on plantations understory. Sandy soils are poorer in species, but they are also important to conservation, since species that happen on sandy soils are adapted to low resources availability and do not occur at other locations. The large number of native species founded in eucalypts plantation understory indicates that these plantations may assist some native species conservation. Nevertheless, further research is needed to understand the conservation potential from eucalypt plantations. It is recommended other studies to be done for a better comprehension and to increase the importance of plantation forests to conservation, mainly studies about biology of key species, interactions between animals and plants and the effect of different management options.

Dung beetles is a group of coprophagous beetles in the family Scarabaeidae. Dung beetles have an important function by improving nutrient circulation and biological control of parasites. Dung is a short-lived resource, making dung beetles tied to habitats continuously grazed. Decline in pasture combined with shorter grazing seasons has resulted in a decrease in available dung. Other reasons can be the use of chemicals to control internal parasites on the grazing animals. This has contributed to the fact that half of the dung beetles in Sweden are endangered. The aim of the present study was to analyze data on dung beetles from the County Administration Board in Östergötland and see if species communities have changed between 2001-2019. In addition, the effect of sand as soil type was studied by comparing the species richness between pastures with and without sand. Analysis whether there was any variation among species richness and species communities depending of grazing animals was also performed. Results showed that the number of species had increased over time and that changes in species communities had occurred. Pastures with sand had more species, however, the amount of sand in the nearest surroundings was of less importance. Dung beetles were found to have a preference when choosing dung-type. Pastures with dung from multiple species of grazing animals were found having the highest species richness. Studies on this would clarify even further what seems to favor dung beetles, this could then be applied to other areas to counteract the loss of species.

No description available.

The problem has consisted, first, of a mapping of the soil types present in Haskell County; second, a collection of the existing vegetation of each soil type; third, an identification of the vegetation collected and observed; fourth, and lastly, a comparative study of the vegetation of each soil type in an effort to establish a correlation between the vegetation and the soil type.

Landslides are one of the most widespread, yet difficult to predict, geohazards in the world. Theyrepresent a major threat to society, which is why it is so important to understand and study them.Landslide detection is one of the approaches that help scientists to gain a better knowledge of landslides,how they form and the characteristics they hold. In this work, a new landslide detection technique istested in the Klarälven Region, Sweden. The method involves using multi-temporal DEMs generatedfrom LiDAR point clouds from 2010 and 2020. Once two respective DEMs are generated from theoriginal point cloud data sets, a DEM of Difference (DoD) is obtained by subtracting the 2010 DEMfrom the 2020 DEM. The DoD highlights areas of vertical change over the ten-year period. In order todetect potential landslides, a Level of detection (LoD) threshold is applied, as well as a second upperthreshold filtering out elevation difference resulting from anthropogenic activities. Lastly, a spatialthreshold is applied to eliminate any remaining potential errors clusters that are too small to belandslides. Once this stage is completed, the study area is surveyed, focusing on certain areacharacterised by particular slope angles and soil types most likely to exhibit mass movement. Thishelped in the analysis and interpretation of the data. In order to discuss the results as fully as possible,four types of region were studied in more detail using four representative examples. Since a few doubtfulcases were found, potential sources of error are also being explored. Despite minor inaccuracies, themethod appears to be a relevant technique for detecting differences in altitude, even if it also considersunnatural mass movements.

付記する学位プログラム名: グローバル生存学大学院連携プログラム / 京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21465号 / 農博第2308号 / 新制||農||1064(附属図書館) / 学位論文||H31||N5160(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 舟川 晋也, 教授 間藤 徹, 教授 縄田 栄治 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

The main goal of this study was to evaluate the effectiveness of two biological control agents in reducing population growth and spread of the invasive tree Melaleuca quinquenervia, a subtropical tree native to Australia, and invasive in Florida, Puerto Rico, and the Bahamas. While in Florida two insects Oxyops vitiosa (weevil), and Boreioglycaspis melaleucae (psyllid) have been established as biocontrol agents, in Puerto Rico only psyllids are present, and in the Bahamas no biocontrol agents are present. This study combined demographic data, experiments and mathematical models to investigate the influence of the biocontrol agents on M. quinquenervia's spatial population dynamics. In the field, permanent plots were established and demographic data was collected in populations in the native and exotic ranges. Australian populations are comprised mostly of tall adult trees, while in the exotic ranges populations are comprised mostly of short trees (<1.3m in height), and small adult trees. In a shade-house, I performed an experiment to investigate the effects of insect type and density on survival and growth of M. quinquenervia seedlings. I found that high density of insects, independently or in combination, reduce seedling performance, thus having the potential to alter the seedling-short plant transition of the M. quinquenervia life cycle. Based on the demographic data, I developed integral projection models (IPMs) to determine population growth rates in each region. Populations in Australia and the Bahamas are increasing, while populations in Florida and Puerto Rico are decreasing. Population growth is most sensitive to the seedling-short plant transition in all regions, except Florida, where it is most sensitive to survival of tall plants. Simulations combining the results of the IMPs and experiment indicated the biocontrol damage results in reductions in population growth rate in Puerto Rico and the Bahamas. Seed dispersal and demographic data was combined to develop an integrodifference structured model of population spread. Simulations indicated that by reducing seedling performance, insects have the potential to reduce the rate of population spread. Overall this study shows that individual-level effects of biocontrol agents have translated into reductions in population growth rate and rate of spread of M. quinquenervia.