The objective of the study was to assess the farmers’ knowledge and perceptions of P. incana invasion and impacts on rangeland, livestock production and livelihood in four communal grazing areas. Twenty households per village that own livestock were randomly selected to conduct an interview using an open and closed ended questionnaire. In each household, an old and knowledgeable respondent about P. incana invasion was used as a selection criterion. For scientific assessment of range condition, the experiment was conducted in a 270 m x 100 m trial plots that were established in 2014. The area was divided into 3 open and 3 fenced subplots each having an area of 45 m x 100 m established laid down a slope gradient. Each plot was divided into four equal subplots to apply the control treatments. Therefore, the trial layout was a stratified block experiment of four treatments replicated three times. The four control treatments applied to P. incana invasion were chopping and resting (CR), resting without chopping (RWOC), grazing and chopping (GC), grazing without chopping (GWOC). A step point method was applied in each transect to monitor species composition and P. incana cover. On the fenced plots two exclosures of 1mx1m size were randomly distributed to make sure that resting is maintained. Within exclosures 0.25 m2quadrates in each were put randomly to measure biomass. Density of P. incana was determined from 5 m x 5 m quadrates that were placed randomly within each sub-plot. The density and height of individual shrub plant was measured. All rooted live woody plants were recorded and counted in each quadrate. The results revealed that species composition was not affected (P>0.05) by the treatments applied. The herbage height and basal cover had greater values (P<0.05) under rested plus chopping (CR) treatment followed by grazed plus chopping (GC). Grass biomass production and essential nutrients showed a greater concentration (P<0.05) under CR treatment than any treatments applied. The results on perceptions revealed that goats had the highest mean household holding number than any other livestock species across the selected villages in all the villages. Respondents indicated that both goats and cattle had equal or more importance than sheep. Three out of four villages raised cattle primarily for income generation and secondarily for cultural purposes like slaughtering during weddings ceremonies, amazila and also during woman circumcisions (Ntonjane). Similarly, goats and sheep were primarily raised for cash income generation. The results revealed that livestock population decreased over ten to twenty years (one-two decades) and poor rangeland condition is assumed to be the cause of the situation as feed is the key factor for production. The area was dominated by the grasses rather than by browse woody species so the above results are possible as the P. incana is more competitive than grasses. It was concluded that P. incana is detrimental to both rangeland and animal production. Forage and animal performance as well as farmers’ economic status (livelihoods) were negatively affected by P. incana invasion and the scientific assessment reported it to be detrimental to agriculture. Thus chopping and resting (CR) treatment resulted in a greater improvement of the basal cover, biomass production, soil nutrients as well as grass height than the other treatments applied. Therefore it can be concluded that chopping and resting the veld invaded with P. incana can improve the range and consequently animal production.

No Sul do Brasil ocorrem mosaicos naturais de vegetação campestre e florestal, sob um clima que é favorável às formações florestais. O processo de expansão florestal tem sido observado principalmente sobre áreas de campo excluído de perturbações de fogo e pastejo. Estudos sobre padrões de vegetação lenhosa associados a variáveis ambientais locais em áreas de campo sujeitas à expansão florestal constituem uma importante ferramenta para avaliação da dinâmica da vegetação considerando mudanças ambientais ou de regime de perturbação. No intuito de inferir sobre os processos relacionados à expansão florestal sobre campos no Sul do Brasil, este estudo busca os padrões atuais na composição e estrutura da vegetação lenhosa sobre uma área de campo excluído de manejo há 34 anos e as possíveis associações destes com variáveis espaciais e ambientais. Para tanto, amostramos a vegetação lenhosa em 110 unidades amostrais circulares (6m de raio) estabelecidas de forma sistemática (equidistantes 100m) sobre áreas originalmente mapeadas, em 1985, como vegetação campestre ou vassoural. A amostragem foi estratificada para o critério de inclusão baseado no diâmetro do caule a altura do solo (DAS). As unidades amostrais de 6m de raio contemplavam os indivíduos com DAS5cm e estas incluíram três sub-parcelas de 1m de raio para amostragem proporcional de indivíduos menores (DAS<5cm, mas com altura superior a 1m). Como variáveis ambientais, a distância mínima de uma área-fonte florestal e fatores químicos e físicos do solo foram avaliados para cada unidade amostral. Os dados de vegetação foram analisados através de parâmetros fitossociológicos, sendo os padrões, e suas relações com o ambiente, acessados por análise exploratória conjugando técnicas estatísticas uni e multivariadas. Os resultados revelam que em áreas campestres excluídas de fogo e pastejo, como a que foi estudada, ocorre um processo espacial e temporal relacionado com a distância da área fonte florestal, mostrando um gradiente sucessional. Quanto mais próximo da antiga borda florestal, as comunidades de espécies lenhosas são mais antigas e caracterizadas por espécies mais tipicamente florestais. A medida que o processo se afasta da borda encontram-se comunidades em estágios sucessionais intermediários, onde os arbustos campestres gradualmente cedem lugar a espécies florestais pioneiras, nucleadoras de vegetação florestal, as quais atraem dispersores e criam condições favoráveis ao estabelecimento de mais espécies florestais. E nas áreas mais distantes da borda ainda predominam arbustos campestres (e.g. Baccharis uncinella). Eles gradativamente suprimem o estrato herbáceo de gramíneas pela sua abundância e, em alguma medida, facilitam o estabelecimento das espécies florestais pioneiras. Nesses processos, o solo se modifica em direção a condições de maior acúmulo de matéria orgânica e de maior fertilidade, mais favoráveis ao estabelecimento de espécies florestais. / In South of Brazil there are forest-grassland mosaics under a climate suit for forest development. The forest expansion process has been observed mainly over grasslands excluded from cattle grazing and fire disturbances. Studies accessing patterns of woody vegetation linked to local environmental variables in grasslands areas subject to forest expansion constitute an important tool for vegetation dynamics evaluation considering environmental or disturbance management changes. Our purpose is access the current woody vegetation patterns and their potential linking with spatial and environmental variables on a grassland area excluded from management since 34 years ago. For this we surveyed woody species on 110 sampling units systematically plotted (halfway 100m) over areas that were originally mapped at 1985 as grasslands or shrublands. The sampling was stratified according to the inclusion criterion based on the stem diameter at the height of the soil (DHS). In the 6m ray sampling units all individuals with DHS5cm were surveyed and, inside them, three sub-plots of 1m of ray were used to sample proportional smaller individuals (DHS<5cm, but with more than 1m height). As environmental variables, the minimum distance of a forest area-source, and chemical and physical soil characteristics were considered for each sampling unit. The vegetation data and patterns were analyzed through phytosociological parameters and by exploratory analysis conjugating united and multivariate statistical techniques. The results revealed that grassland areas excluded of fire and grazing, as the one that it was studied, are suitable to spatial and temporal processes related to the distance of the source-forest area, showing a sucessional gradient. Close to the old forest border, the woody species communities are older and characterized by typical forest species. As the process stands back of the border the communities are in intermediate sucessional stage, where grassland shrubs gradually give up place to pioneer forest species, nurse species, which attract dispersers and create favorable conditions to the establishment of more forest species, allowing forest expansion process. In the most distant border areas grassland shrubs still prevail (e.g. Baccharis uncinella). They gradually suppress the grasses stratum because of their abundance and, in some way, facilitate the establishment of pioneer forest species. In those processes, the soil modifies towards conditions of larger accumulation of organic matter and larger fertility, more favorable to the establishment of forest species.

No Sul do Brasil ocorrem mosaicos naturais de vegetação campestre e florestal, sob um clima que é favorável às formações florestais. O processo de expansão florestal tem sido observado principalmente sobre áreas de campo excluído de perturbações de fogo e pastejo. Estudos sobre padrões de vegetação lenhosa associados a variáveis ambientais locais em áreas de campo sujeitas à expansão florestal constituem uma importante ferramenta para avaliação da dinâmica da vegetação considerando mudanças ambientais ou de regime de perturbação. No intuito de inferir sobre os processos relacionados à expansão florestal sobre campos no Sul do Brasil, este estudo busca os padrões atuais na composição e estrutura da vegetação lenhosa sobre uma área de campo excluído de manejo há 34 anos e as possíveis associações destes com variáveis espaciais e ambientais. Para tanto, amostramos a vegetação lenhosa em 110 unidades amostrais circulares (6m de raio) estabelecidas de forma sistemática (equidistantes 100m) sobre áreas originalmente mapeadas, em 1985, como vegetação campestre ou vassoural. A amostragem foi estratificada para o critério de inclusão baseado no diâmetro do caule a altura do solo (DAS). As unidades amostrais de 6m de raio contemplavam os indivíduos com DAS5cm e estas incluíram três sub-parcelas de 1m de raio para amostragem proporcional de indivíduos menores (DAS<5cm, mas com altura superior a 1m). Como variáveis ambientais, a distância mínima de uma área-fonte florestal e fatores químicos e físicos do solo foram avaliados para cada unidade amostral. Os dados de vegetação foram analisados através de parâmetros fitossociológicos, sendo os padrões, e suas relações com o ambiente, acessados por análise exploratória conjugando técnicas estatísticas uni e multivariadas. Os resultados revelam que em áreas campestres excluídas de fogo e pastejo, como a que foi estudada, ocorre um processo espacial e temporal relacionado com a distância da área fonte florestal, mostrando um gradiente sucessional. Quanto mais próximo da antiga borda florestal, as comunidades de espécies lenhosas são mais antigas e caracterizadas por espécies mais tipicamente florestais. A medida que o processo se afasta da borda encontram-se comunidades em estágios sucessionais intermediários, onde os arbustos campestres gradualmente cedem lugar a espécies florestais pioneiras, nucleadoras de vegetação florestal, as quais atraem dispersores e criam condições favoráveis ao estabelecimento de mais espécies florestais. E nas áreas mais distantes da borda ainda predominam arbustos campestres (e.g. Baccharis uncinella). Eles gradativamente suprimem o estrato herbáceo de gramíneas pela sua abundância e, em alguma medida, facilitam o estabelecimento das espécies florestais pioneiras. Nesses processos, o solo se modifica em direção a condições de maior acúmulo de matéria orgânica e de maior fertilidade, mais favoráveis ao estabelecimento de espécies florestais. / In South of Brazil there are forest-grassland mosaics under a climate suit for forest development. The forest expansion process has been observed mainly over grasslands excluded from cattle grazing and fire disturbances. Studies accessing patterns of woody vegetation linked to local environmental variables in grasslands areas subject to forest expansion constitute an important tool for vegetation dynamics evaluation considering environmental or disturbance management changes. Our purpose is access the current woody vegetation patterns and their potential linking with spatial and environmental variables on a grassland area excluded from management since 34 years ago. For this we surveyed woody species on 110 sampling units systematically plotted (halfway 100m) over areas that were originally mapped at 1985 as grasslands or shrublands. The sampling was stratified according to the inclusion criterion based on the stem diameter at the height of the soil (DHS). In the 6m ray sampling units all individuals with DHS5cm were surveyed and, inside them, three sub-plots of 1m of ray were used to sample proportional smaller individuals (DHS<5cm, but with more than 1m height). As environmental variables, the minimum distance of a forest area-source, and chemical and physical soil characteristics were considered for each sampling unit. The vegetation data and patterns were analyzed through phytosociological parameters and by exploratory analysis conjugating united and multivariate statistical techniques. The results revealed that grassland areas excluded of fire and grazing, as the one that it was studied, are suitable to spatial and temporal processes related to the distance of the source-forest area, showing a sucessional gradient. Close to the old forest border, the woody species communities are older and characterized by typical forest species. As the process stands back of the border the communities are in intermediate sucessional stage, where grassland shrubs gradually give up place to pioneer forest species, nurse species, which attract dispersers and create favorable conditions to the establishment of more forest species, allowing forest expansion process. In the most distant border areas grassland shrubs still prevail (e.g. Baccharis uncinella). They gradually suppress the grasses stratum because of their abundance and, in some way, facilitate the establishment of pioneer forest species. In those processes, the soil modifies towards conditions of larger accumulation of organic matter and larger fertility, more favorable to the establishment of forest species.

No Sul do Brasil ocorrem mosaicos naturais de vegetação campestre e florestal, sob um clima que é favorável às formações florestais. O processo de expansão florestal tem sido observado principalmente sobre áreas de campo excluído de perturbações de fogo e pastejo. Estudos sobre padrões de vegetação lenhosa associados a variáveis ambientais locais em áreas de campo sujeitas à expansão florestal constituem uma importante ferramenta para avaliação da dinâmica da vegetação considerando mudanças ambientais ou de regime de perturbação. No intuito de inferir sobre os processos relacionados à expansão florestal sobre campos no Sul do Brasil, este estudo busca os padrões atuais na composição e estrutura da vegetação lenhosa sobre uma área de campo excluído de manejo há 34 anos e as possíveis associações destes com variáveis espaciais e ambientais. Para tanto, amostramos a vegetação lenhosa em 110 unidades amostrais circulares (6m de raio) estabelecidas de forma sistemática (equidistantes 100m) sobre áreas originalmente mapeadas, em 1985, como vegetação campestre ou vassoural. A amostragem foi estratificada para o critério de inclusão baseado no diâmetro do caule a altura do solo (DAS). As unidades amostrais de 6m de raio contemplavam os indivíduos com DAS5cm e estas incluíram três sub-parcelas de 1m de raio para amostragem proporcional de indivíduos menores (DAS<5cm, mas com altura superior a 1m). Como variáveis ambientais, a distância mínima de uma área-fonte florestal e fatores químicos e físicos do solo foram avaliados para cada unidade amostral. Os dados de vegetação foram analisados através de parâmetros fitossociológicos, sendo os padrões, e suas relações com o ambiente, acessados por análise exploratória conjugando técnicas estatísticas uni e multivariadas. Os resultados revelam que em áreas campestres excluídas de fogo e pastejo, como a que foi estudada, ocorre um processo espacial e temporal relacionado com a distância da área fonte florestal, mostrando um gradiente sucessional. Quanto mais próximo da antiga borda florestal, as comunidades de espécies lenhosas são mais antigas e caracterizadas por espécies mais tipicamente florestais. A medida que o processo se afasta da borda encontram-se comunidades em estágios sucessionais intermediários, onde os arbustos campestres gradualmente cedem lugar a espécies florestais pioneiras, nucleadoras de vegetação florestal, as quais atraem dispersores e criam condições favoráveis ao estabelecimento de mais espécies florestais. E nas áreas mais distantes da borda ainda predominam arbustos campestres (e.g. Baccharis uncinella). Eles gradativamente suprimem o estrato herbáceo de gramíneas pela sua abundância e, em alguma medida, facilitam o estabelecimento das espécies florestais pioneiras. Nesses processos, o solo se modifica em direção a condições de maior acúmulo de matéria orgânica e de maior fertilidade, mais favoráveis ao estabelecimento de espécies florestais. / In South of Brazil there are forest-grassland mosaics under a climate suit for forest development. The forest expansion process has been observed mainly over grasslands excluded from cattle grazing and fire disturbances. Studies accessing patterns of woody vegetation linked to local environmental variables in grasslands areas subject to forest expansion constitute an important tool for vegetation dynamics evaluation considering environmental or disturbance management changes. Our purpose is access the current woody vegetation patterns and their potential linking with spatial and environmental variables on a grassland area excluded from management since 34 years ago. For this we surveyed woody species on 110 sampling units systematically plotted (halfway 100m) over areas that were originally mapped at 1985 as grasslands or shrublands. The sampling was stratified according to the inclusion criterion based on the stem diameter at the height of the soil (DHS). In the 6m ray sampling units all individuals with DHS5cm were surveyed and, inside them, three sub-plots of 1m of ray were used to sample proportional smaller individuals (DHS<5cm, but with more than 1m height). As environmental variables, the minimum distance of a forest area-source, and chemical and physical soil characteristics were considered for each sampling unit. The vegetation data and patterns were analyzed through phytosociological parameters and by exploratory analysis conjugating united and multivariate statistical techniques. The results revealed that grassland areas excluded of fire and grazing, as the one that it was studied, are suitable to spatial and temporal processes related to the distance of the source-forest area, showing a sucessional gradient. Close to the old forest border, the woody species communities are older and characterized by typical forest species. As the process stands back of the border the communities are in intermediate sucessional stage, where grassland shrubs gradually give up place to pioneer forest species, nurse species, which attract dispersers and create favorable conditions to the establishment of more forest species, allowing forest expansion process. In the most distant border areas grassland shrubs still prevail (e.g. Baccharis uncinella). They gradually suppress the grasses stratum because of their abundance and, in some way, facilitate the establishment of pioneer forest species. In those processes, the soil modifies towards conditions of larger accumulation of organic matter and larger fertility, more favorable to the establishment of forest species.

Biodiversity is declining faster than at any other time in the Earth's history, driven mostly by land use change and degradation. Overberg Renosterveld, some of the most species diverse mediterranean type shrublands, are no exception with about 95% of their original extent lost to agriculture. Historically, large herds of indigenous grazing mammals roamed these landscapes. Today the Overberg's agricultural lands are fragmented by land cover change and divided by fences. In the contemporary landscape animals, largely domestic livestock, and plant resources are closely coupled, and overgrazing of remaining renosterveld fragments a significant threat, with potential to cause irreversible damage. The Conservation of Agricultural Resources Act (CARA) (Act 43 of 1983) states that farmers must not exceed the grazing capacity of the veld unless it is protected against deterioration and destruction, and that any land that is degraded or denuded must be effectively restored or reclaimed. Despite this legislation, there is little empirical research on the impacts of livestock grazing on renosterveld, as well as on restoration of overgrazed areas. It was the aim of this thesis to contribute to this gap in understanding. The thesis assessed the role of grazing by different livestock types, namely cattle and sheep, on biodiversity, the soil seed bank, and the restoration potential of renosterveld vegetation from resting the veld. The effect of livestock grazing by sheep and cattle on plant species richness and diversity and growth form diversity was assessed using Modified Whittaker plots and presented in Chapter 3. It was hypothesised that livestock grazing by cattle would have less effect on species richness and diversity and growth form diversity than sheep grazing and that both cattle and sheep grazing would lead to a reduction in species richness and diversity in comparison to renosterveld sites with a treatment of no grazing. Thirty sites where either no grazing has taken place or that have been grazed by cattle or sheep were selected with sites being evenly distributed between Eastern, Central and Western Rûens Shale Renosterveld. At each of the thirty sites, vegetation data were collected from a series of nested subplots of ten 1 m2 , two 10 m2 and one 100 m2 subplots nested within a 1 000 m2 plot. One soil sample was also collected from each 1 000 m2 plot to a depth of 10 cm for nutrient analysis. Findings revealed that sites grazed by sheep had significantly lower plant species richness (median richness = 29 species, mean Shannon-Weiner = 3.39) and diversity when compared to sites with a treatment of no grazing (median richness = 49 species, mean Shannon Weiner = 3.83). Sites with a treatment of no grazing had significantly higher richness of geophyte species (mean = 14.7) than sites grazed by cattle (mean = 7.0) and sheep (mean = 7.1) during the study. The results obtained were in line with the hypothesis that livestock grazing by sheep resulted in a reduction in species richness and diversity and vegetation cover in Overberg Renosterveld in comparison to sites where no grazing has taken place. Sites with a treatment of no grazing showed higher species richness and vegetation cover of non-succulent shrubs, annual forbs and perennial forbs than sites grazed by sheep. It was concluded that livestock grazing of Overberg Renosterveld by sheep needs to be done with care. This can be done by adopting a passive adaptive management approach. Here one set of management protocols can be developed and implemented and through science-based monitoring to inform management, these can be adapted as needed based on the key findings. Chapter 4 investigated ecosystem resilience and the restoration potential of Overberg Renosterveld through an exploration of its soil seed bank as a source for potential recovery. A glasshouse germination experiment investigated the effect of livestock grazing by cattle and by sheep in comparison with a grazing treatment of no grazing on the soil seed bank in Overberg Renosterveld, as well as the similarity between the standing vegetation and the soil seed bank. It was hypothesised that cattle and sheep grazing would reduce species richness, species diversity and growth form diversity in the soil seed bank in comparison with sites with a treatment of no grazing. Soil samples were collected from 30 sites that were also used in Chapter 3. The soil was then spread on top of a 6 cm layer of compost in seed trays, and smoke treated to enhance germination. Seedlings were assigned to growth form categories including forbs, geophytes, annuals, graminoids, succulent shrubs and nonsucculent shrubs and then identified to family, genus or species level. The results of the soil seed bank study were correlated with the vegetation results from Chapter 3 to examine the relationship between the standing vegetation and the soil seed bank. A total of 48% of taxa in the standing vegetation had seed present in the germinable seed bank. However, there were no differences in species richness, species diversity or number of individuals between grazing treatments. The results indicated that livestock grazing has a far less significant impact on the composition, species diversity and growth form diversity of the soil seed bank in Overberg Renosterveld than hypothesised. Instead, the results showed that there was a well-developed seed bank comprising mainly indigenous species with a variety of different growth forms including palatable grasses and shrubs. This indicates that Overberg Renosterveld vegetation has high restoration potential. Chapter 5 showed results on the effects of livestock grazing by cattle and sheep over time on plant species richness, diversity and growth form diversity in comparison with sites protected from grazing. Following collection of a baseline dataset, four years of follow up data were collected. A total of 22 fenced plots across Western, Central and Eastern Rûens Shale Renosterveld had a baseline dataset collected prior to being monitored on an annual basis over four years in grazed/ungrazed paired plots. Results on vegetation recovery from the fenced exclosures showed a significant increase in plant cover over time at sites that were not grazed. Mean species richness increased from 20.6 species to 25.4 species at sites with no grazing. Mean vegetation cover increased from 71% at T0 (the baseline time step) to 120% at T4 (the final time step) at the end of the study. Sites grazed by sheep had a decrease in vegetation cover over time each year from T0 to T4 from 75% to 50%. Results from a linear mixed model revealed that species richness between grazing treatments was significantly different at all time steps in the study. However, the significant differences were primarily due to comparisons between grazed sites and sites with a treatment of no grazing. Therefore, livestock grazing by sheep has a significant effect on renosterveld vegetation over time. Findings from this component of the study indicates that Overberg Renosterveld degraded by continuous heavy grazing has significant passive restoration potential by fencing renosterveld patches to facilitate more effective grazing management. Most of the renosterveld of the Overberg has been lost through habitat transformation for agriculture, and the future of that which remains is uncertain. This thesis affirms concerns around the impact of livestock grazing and shows the importance of improved ecological understanding around grazing management. Grazing by sheep was shown to cause greater impacts on renosterveld than other domestic livestock studied and is therefore a threat to renosterveld. These findings warrant closer attention to management practices around sheep grazing. However, the state of renosterveld soil seed banks offer considerable hope. Findings revealed a diverse indigenous seed bank, showing that renosterveld degraded by overgrazing has high restoration potential. Furthermore, fencing renosterveld to exclude livestock improves species richness and diversity over time. These findings highlight the need for caution when grazing renosterveld. However, where the damage has been done, the potential for recovery is high. Harnessing the soil seed bank in combination with excluding livestock grazing by fencing are effective tools in this critically endangered vegetation for achieving restoration and conservation goals.

No description available.

In the southwest United States, the current prolonged warm drought is similar to the predicted future climate change scenarios for the region. This study aimed to determine patterns in vegetation response to the early 21st century drought across multiple biomes. We hypothesized that different biomes (forests, shrublands, and grasslands) would have different relative sensitivities to both climate drivers (precipitation and temperature) and legacy effects (previous-year's productivity). We tested this hypothesis at eight Ameriflux sites in various Southwest biomes using NASA Moderate-resolution Imaging Spectroradiometer Enhanced Vegetation Index (EVI) from 2001 to 2013. All sites experienced prolonged dry conditions during the study period. The impact of combined precipitation and temperature on Southwest ecosystems at both annual and sub-annual timescales was tested using Standardized Precipitation Evapotranspiration Index (SPEI). All biomes studied had critical sub-annual climate periods during which precipitation and temperature influenced production. In forests, annual peak greenness (EVImax) was best predicted by 9-month SPEI calculated in July (i.e., January-July). In shrublands and grasslands, EVImax was best predicted by SPEI in July through September, with little effect of the previous year's EVImax. Daily gross ecosystem production (GEP) derived from flux tower data yielded further insights into the complex interplay between precipitation and temperature. In forests, GEP was driven by cool-season precipitation and constrained by warm-season maximum temperature. GEP in both shrublands and grasslands was driven by summer precipitation and constrained by high daily summer maximum temperatures. In grasslands, there was a negative relationship between temperature and GEP in July, but no relationship in August and September. Consideration of sub-annual climate conditions and the inclusion of the effect of temperature on the water balance allowed us to generalize the functional responses of vegetation to predicted future climate conditions. We conclude that across biomes, drought conditions during critical sub-annual climate periods could have a strong negative impact on vegetation production in the southwestern United States.

Mecanismos de dispersão de diásporos e de recrutamento de plântulas evitam a competição intra-específica e possibilitam a colonização de novos ambientes, sendo etapas muito importantes para o estabelecimento de populações em novos sítios. Em áreas de transição entre florestas e vegetação campestre esses processos não são aleatórios, e sim associados muitas vezes a indivíduos lenhosos isolados em tais áreas de campo ou a formações arbustivas. No sul do Brasil, as Florestas com Araucária formam mosaicos com áreas campestres e observa-se o avanço da floresta sobre os campos. A dissertação tem como objetivo avaliar a cuva de sementes e o padrão de estabelecimento de plântulas de espécies lenhosas florestais associadas a áreas de ecótonos de Floresta com Araucária e campos e a indivíduos lenhosos isolados na matriz campestre. Os estudos foram realizados no Centro de Pesquisas e Conservação da Natureza Pró-Mata PUCRS, em São Francisco de Paula, em vegetação campestre excluída de fogo e de pastejo há 14 anos, circundada por florestas. A dispersão de diásporos foi avaliada mensalmente por um período de oito meses com o uso de coletores de sementes que foram posicionados em ecótonos de floresta e campos com diferentes fisionomias e sob indivíduos lenhosos isolados na matriz campestre. Paralelamente, foi realizada em parcelas permanentes a amostragem de plântulas, no início e no final desse período, sendo assim verificada sua sobrevivência e recrutamento. Os diferentes ambientes foram comparados através de análise de variância univariada e multivariada para verificar padrões de chuva de sementes e de estabelecimento de plântulas. Os resultados indicaram que tanto a dispersão de sementes quanto o estabelecimento de plântulas em áreas campestres ocorrem preferencialmente associados a indivíduos isolados de Araucaria angustifolia e a formações arbustivas de Baccharis uncinella e que tais ambientes funcionariam como extensões de condições mais semelhantes à floresta na matriz campestre. / Mechanisms of seed dispersal and recruitment avoid intraspecific competition and are crucial steps for the establishment of populations in new sites. In transition areas between forest and grassland, these processes are not spatially random, but often associated to isolated woody individuals in the grassland or to areas with continuous shrub cover. In southern Brazil, Araucaria forest form mosaics with grassland (Campos) and advance of forest over grassland is observed. This dissertation aims at evaluating diaspore dispersal and the pattern of woody plants seedling establishment associated to ecotones between Araucaria forest and grassland and to isolated woody individuals in the grassland matrix. The study was performed in the Centro de Pesquisas e Conservação da Natureza Pró-Mata PUCRS, in São Francisco de Paula, in grassland vegetation excluded from fire and grazing from 14 years, and which is surrounded by forest. Diaspore dispersal was evaluated for eight months by using seed colectors positioned in forest-grassland ecotones with different physiognomies and under isolated woody individuals in the grassland matrix. In a parallel study, permanent plots were evaluated for seedling establishment at the begining and at the end of the period, which allowed the evaluation of seedling survival and new recruitment. The different types of environment were compared by univariate and multivariate analysis of variance to reveal patterns of seed rain and seedling establishment. The results indicated that both seed dispersal and seedling establishment occur preferentially associated to isolated woody individuals of Araucaria angustifolia and to continuous patches of Baccharis uncinella. We sugest such environments would function as extensions of more similar forest conditions within the grassland matrix.

Mecanismos de dispersão de diásporos e de recrutamento de plântulas evitam a competição intra-específica e possibilitam a colonização de novos ambientes, sendo etapas muito importantes para o estabelecimento de populações em novos sítios. Em áreas de transição entre florestas e vegetação campestre esses processos não são aleatórios, e sim associados muitas vezes a indivíduos lenhosos isolados em tais áreas de campo ou a formações arbustivas. No sul do Brasil, as Florestas com Araucária formam mosaicos com áreas campestres e observa-se o avanço da floresta sobre os campos. A dissertação tem como objetivo avaliar a cuva de sementes e o padrão de estabelecimento de plântulas de espécies lenhosas florestais associadas a áreas de ecótonos de Floresta com Araucária e campos e a indivíduos lenhosos isolados na matriz campestre. Os estudos foram realizados no Centro de Pesquisas e Conservação da Natureza Pró-Mata PUCRS, em São Francisco de Paula, em vegetação campestre excluída de fogo e de pastejo há 14 anos, circundada por florestas. A dispersão de diásporos foi avaliada mensalmente por um período de oito meses com o uso de coletores de sementes que foram posicionados em ecótonos de floresta e campos com diferentes fisionomias e sob indivíduos lenhosos isolados na matriz campestre. Paralelamente, foi realizada em parcelas permanentes a amostragem de plântulas, no início e no final desse período, sendo assim verificada sua sobrevivência e recrutamento. Os diferentes ambientes foram comparados através de análise de variância univariada e multivariada para verificar padrões de chuva de sementes e de estabelecimento de plântulas. Os resultados indicaram que tanto a dispersão de sementes quanto o estabelecimento de plântulas em áreas campestres ocorrem preferencialmente associados a indivíduos isolados de Araucaria angustifolia e a formações arbustivas de Baccharis uncinella e que tais ambientes funcionariam como extensões de condições mais semelhantes à floresta na matriz campestre. / Mechanisms of seed dispersal and recruitment avoid intraspecific competition and are crucial steps for the establishment of populations in new sites. In transition areas between forest and grassland, these processes are not spatially random, but often associated to isolated woody individuals in the grassland or to areas with continuous shrub cover. In southern Brazil, Araucaria forest form mosaics with grassland (Campos) and advance of forest over grassland is observed. This dissertation aims at evaluating diaspore dispersal and the pattern of woody plants seedling establishment associated to ecotones between Araucaria forest and grassland and to isolated woody individuals in the grassland matrix. The study was performed in the Centro de Pesquisas e Conservação da Natureza Pró-Mata PUCRS, in São Francisco de Paula, in grassland vegetation excluded from fire and grazing from 14 years, and which is surrounded by forest. Diaspore dispersal was evaluated for eight months by using seed colectors positioned in forest-grassland ecotones with different physiognomies and under isolated woody individuals in the grassland matrix. In a parallel study, permanent plots were evaluated for seedling establishment at the begining and at the end of the period, which allowed the evaluation of seedling survival and new recruitment. The different types of environment were compared by univariate and multivariate analysis of variance to reveal patterns of seed rain and seedling establishment. The results indicated that both seed dispersal and seedling establishment occur preferentially associated to isolated woody individuals of Araucaria angustifolia and to continuous patches of Baccharis uncinella. We sugest such environments would function as extensions of more similar forest conditions within the grassland matrix.

Mecanismos de dispersão de diásporos e de recrutamento de plântulas evitam a competição intra-específica e possibilitam a colonização de novos ambientes, sendo etapas muito importantes para o estabelecimento de populações em novos sítios. Em áreas de transição entre florestas e vegetação campestre esses processos não são aleatórios, e sim associados muitas vezes a indivíduos lenhosos isolados em tais áreas de campo ou a formações arbustivas. No sul do Brasil, as Florestas com Araucária formam mosaicos com áreas campestres e observa-se o avanço da floresta sobre os campos. A dissertação tem como objetivo avaliar a cuva de sementes e o padrão de estabelecimento de plântulas de espécies lenhosas florestais associadas a áreas de ecótonos de Floresta com Araucária e campos e a indivíduos lenhosos isolados na matriz campestre. Os estudos foram realizados no Centro de Pesquisas e Conservação da Natureza Pró-Mata PUCRS, em São Francisco de Paula, em vegetação campestre excluída de fogo e de pastejo há 14 anos, circundada por florestas. A dispersão de diásporos foi avaliada mensalmente por um período de oito meses com o uso de coletores de sementes que foram posicionados em ecótonos de floresta e campos com diferentes fisionomias e sob indivíduos lenhosos isolados na matriz campestre. Paralelamente, foi realizada em parcelas permanentes a amostragem de plântulas, no início e no final desse período, sendo assim verificada sua sobrevivência e recrutamento. Os diferentes ambientes foram comparados através de análise de variância univariada e multivariada para verificar padrões de chuva de sementes e de estabelecimento de plântulas. Os resultados indicaram que tanto a dispersão de sementes quanto o estabelecimento de plântulas em áreas campestres ocorrem preferencialmente associados a indivíduos isolados de Araucaria angustifolia e a formações arbustivas de Baccharis uncinella e que tais ambientes funcionariam como extensões de condições mais semelhantes à floresta na matriz campestre. / Mechanisms of seed dispersal and recruitment avoid intraspecific competition and are crucial steps for the establishment of populations in new sites. In transition areas between forest and grassland, these processes are not spatially random, but often associated to isolated woody individuals in the grassland or to areas with continuous shrub cover. In southern Brazil, Araucaria forest form mosaics with grassland (Campos) and advance of forest over grassland is observed. This dissertation aims at evaluating diaspore dispersal and the pattern of woody plants seedling establishment associated to ecotones between Araucaria forest and grassland and to isolated woody individuals in the grassland matrix. The study was performed in the Centro de Pesquisas e Conservação da Natureza Pró-Mata PUCRS, in São Francisco de Paula, in grassland vegetation excluded from fire and grazing from 14 years, and which is surrounded by forest. Diaspore dispersal was evaluated for eight months by using seed colectors positioned in forest-grassland ecotones with different physiognomies and under isolated woody individuals in the grassland matrix. In a parallel study, permanent plots were evaluated for seedling establishment at the begining and at the end of the period, which allowed the evaluation of seedling survival and new recruitment. The different types of environment were compared by univariate and multivariate analysis of variance to reveal patterns of seed rain and seedling establishment. The results indicated that both seed dispersal and seedling establishment occur preferentially associated to isolated woody individuals of Araucaria angustifolia and to continuous patches of Baccharis uncinella. We sugest such environments would function as extensions of more similar forest conditions within the grassland matrix.