Typescript (photocopy) / 4 charts in end pocket / 2 v. : ill., maps ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.) Dept. of Botany, University of Adelaide, 1980

Thesis (Ph.D.) Dept. of Botany, University of Adelaide, 1980. / Typescript (photocopy). 4 charts in end pocket.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A gradual increase of the areas abandoned for the farming one is occurring. These areas are occupied for a arboreal vegetation with a strong presence of pioneers species. This study was accomplished in the city of Encruzilhada do Sul, in abandoned areas that present forestry communities in initial to medium training of regeneration, with predominance of Dodonaea viscosa Jacq. on vegetation. The purpose was to characterize these natural populations, aiming at to supply subsidies to the forestry management of Dodonaea viscosa Jacq. For this, it was accomplished the floristic and structural analysis of the population, as well as, some parameters like heating value and macronutrients of wood. To the structural analysis 52 sub-parcels were installed and to the study of heating value, specific mass and constituents of wood 13 trees were cut down, of which disks were collected. The fragment is composed for a small number of species based basically in species of pioneering habit, without indications of the forest to be converging to a more advanced sucessional training. The species presents a high energetic production, with raised carbon text in the wood, what it leads to the use of the forest in the payment for environmental services. The nutrients present in the wood indicate that the exploration of the species can have consequences in mid-term and long-term, having to be considered in the planning of the activities. / Está ocorrendo um gradual aumento das áreas abandonadas pela agropecuária. Estas são ocupadas por uma vegetação arbórea com forte presença de espécies pioneiras. O estudo foi realizado no município de Encruzilhada do Sul, em áreas abandonadas que apresentem comunidades florestais em estágio inicial a médio de regeneração, com predomínio da Dodonaea viscosa Jacq. na vegetação. O objetivo foi caracterizar estas populações naturais, visando fornecer subsídio ao manejo florestal da Dodonaea viscosa Jacq. Para isso, foi realizada a análise florística e estrutural do povoamento, assim como, determinado parâmetros como poder calorífico e macronutrientes da madeira. Para análise da estrutura foram instaladas 52 sub-parcelas e para o estudo do poder calorífico, massa específica e constituintes da madeira foram abatidas 13 árvores, das quais foram coletados discos. O fragmento é composto por um pequeno número de espécies, baseados basicamente em espécies de habito pioneiro, sem indício de a floresta estar convergindo para um estágio sucessional mais avançado. A espécie apresenta uma alta produção energética, com elevado teor de carbono na madeira, o que remete ao uso da floresta no pagamento por serviços ambientais. Os nutrientes presentes na madeira indicam que a exploração da espécie pode ter consequencias no médio e longo prazo, devendo ser considerado no planejamento das atividades.

<p>Human disturbance has led to excessive deforestation and to a very limited forest cover in the Afromontane zone of Ethiopia, which forms a large part of the country. Thus urgent conservation measures are required to ameliorate the situation. Understanding the natural regeneration processes and the dynamics of plant populations of tree and shrub species has a practical application in the restoration of these habitats. </p><p>The present study focuses on the population dynamics and regeneration of an early successional shrub <i>Dodonaea angustifolia</i> and a late successional tree <i>Olea europaea</i> ssp. <i>cuspidata </i>in southern Wello, Ethiopia. Population structure and dynamics, regeneration and seed banks in dry Afromontane habitats were considered. </p><p>For both species, three population structure patterns were identified: 1) high density, reversed J-shape structure with many seedlings and few large individuals, 2) lower density, unimodal structure with higher proportions of plants of intermidiate size, 3) high density with higher proportions of large plants , in some cases bimodal with small and large individuals. Vegetation type and protection time were found to have a significant effect on the population structure of both species. <i>Dodonaea</i> can establish itself on degraded land, once the disturbance has ceased</p><p>Projection matrix analysis on observations from permanent plots in <i>Dodonaea</i> populations in protected and unprotected sites resulted in one declining population, and one increasing in the protected site and declining populations at the unprotected site. The overall projected growth rate in <i>Dodonaea</i> calculated from a pooled matrix indicated positive population growth. The factors influencing the population growth, recruitment and survival are discussed.</p><p>The persistence of <i>Olea </i>populations seems to depend on the more stable environmental conditions in later successional stages of forest vegetation. There are possibilities of natural regeneration of <i>Olea</i> if regenerating individuals still occur in the area. Rainfall seasonality is a dominant factor in regulating establishment, recruitment, survival and growth, particularly during the seedling stage. Moreover, shade and herbivory are factors that need consideration. Since <i>Olea</i> grows better under shade than in the open sun, successful regeneration for this species relies on shade from other plants and on protection from grazing, at least during the seedling stage.</p><p>Most of the species that germinated from the seed banks were herbs and grasses with very few shrub and tree species. There was low correspondence between species composition of the seed banks and that of the standing vegetation. </p><p>Spatial and temporal variation in demographic parameters among populations of <i>Dodonaea</i> and <i>Olea </i>can be attributed to human and environmental influence. Under protection, both <i>Dodonaea</i> and <i>Olea</i> seem to have a possibility to regenerate naturally. Further research should consider factors mentioned in detailed investigations of other dominant Afromontane forest species.</p>

Human disturbance has led to excessive deforestation and to a very limited forest cover in the Afromontane zone of Ethiopia, which forms a large part of the country. Thus urgent conservation measures are required to ameliorate the situation. Understanding the natural regeneration processes and the dynamics of plant populations of tree and shrub species has a practical application in the restoration of these habitats. The present study focuses on the population dynamics and regeneration of an early successional shrub Dodonaea angustifolia and a late successional tree Olea europaea ssp. cuspidata in southern Wello, Ethiopia. Population structure and dynamics, regeneration and seed banks in dry Afromontane habitats were considered. For both species, three population structure patterns were identified: 1) high density, reversed J-shape structure with many seedlings and few large individuals, 2) lower density, unimodal structure with higher proportions of plants of intermidiate size, 3) high density with higher proportions of large plants , in some cases bimodal with small and large individuals. Vegetation type and protection time were found to have a significant effect on the population structure of both species. Dodonaea can establish itself on degraded land, once the disturbance has ceased Projection matrix analysis on observations from permanent plots in Dodonaea populations in protected and unprotected sites resulted in one declining population, and one increasing in the protected site and declining populations at the unprotected site. The overall projected growth rate in Dodonaea calculated from a pooled matrix indicated positive population growth. The factors influencing the population growth, recruitment and survival are discussed. The persistence of Olea populations seems to depend on the more stable environmental conditions in later successional stages of forest vegetation. There are possibilities of natural regeneration of Olea if regenerating individuals still occur in the area. Rainfall seasonality is a dominant factor in regulating establishment, recruitment, survival and growth, particularly during the seedling stage. Moreover, shade and herbivory are factors that need consideration. Since Olea grows better under shade than in the open sun, successful regeneration for this species relies on shade from other plants and on protection from grazing, at least during the seedling stage. Most of the species that germinated from the seed banks were herbs and grasses with very few shrub and tree species. There was low correspondence between species composition of the seed banks and that of the standing vegetation. Spatial and temporal variation in demographic parameters among populations of Dodonaea and Olea can be attributed to human and environmental influence. Under protection, both Dodonaea and Olea seem to have a possibility to regenerate naturally. Further research should consider factors mentioned in detailed investigations of other dominant Afromontane forest species.