O padrão espacial das árvores em uma floresta é influenciado por variáveis abióticas e bióticas. Entre as principais variáveis abióticas estão o relevo, a disponibilidade de luz, nutrientes e água, e a caracterização do solo. Entre as principais variáveis bióticas estão os processos dependentes da densidade, tais como a competição intraespecífica e interespecífica, a herbivoria, a ocorrência de doenças, a fenologia e dispersão de sementes. Desse modo, investigar o padrão espacial das árvores, segundo suas classes de tamanho, e segundo suas espécies mais abundantes, pode fornecer evidências sobre a estrutura da comunidade vegetal. A descrição do padrão espacial das árvores e das espécies mais abundantes em diferentes formações florestais foi realizada usando ferramentas estatésticas mais apropriadas para investigar mapas das árvores. A Função K de Ripley tem como principais vantagens a possibilidade de detectar o padrão espacial em diversas escalas de distâncias simultaneamente, e avaliar a dependência espacial entre grupos de árvores. Os padrões observados foram comparados com os modelos de Completa Aleatoriedade Espacial, para a função univariada, e de Completa Independência Espacial, para a função bivariada. Diferentes formações florestais, típicas da região sudeste do Brasil, foram comparadas neste estudo: Floresta Ombrófila Densa Submontana, Savana Florestada (Cerradão), Floresta Estacional Semidecidual e Formação Pioneira com Influência Marinha (Restinga). Esta dissertação de mestrado integra o Projeto "Diversidade, dinâmica e conservação em florestas do Estado de São Paulo: 40 ha de parcelas permanentes", do Programa Biota da FAPESP. Neste projeto, uma parcela de 10,24 ha foi montada em cada formação florestal, e todas as árvores com circunferência na altura do peito a partir de 15 cm foram medidas, mapeadas e identificadas. Os resultados obtidos neste estudo ressaltam o caráter agregado em florestas tropicais, uma vez que o padrão agregado foi observado em todas as florestas estudadas. As árvores do Cerradão e da Restinga apresentaram padrões muito próximos, com uma agregação definida até uma certa escala de distâncias. Para a Floresta Ombrófila, o padrão agregado foi significativo em toda a escala de distâncias. Na Floresta Estacional, tendência à aleatoriedade foi observada, embora uma agregação significativa tenha sido notada para curtas distâncias. A análise do padrão espacial segundo classes de tamanho mostrou que as primeiras classes possuem, em geral, padrões agregados significativos, enquanto para as classes seguintes o padrão aleatório foi predominante. Em linhas gerais, o padrão espacial das espécies acompanhou o padrão geral de cada formação florestal. O padrão das espécies dominantes é sempre muito semelhante ao padrão espacial da floresta como um todo. Como era esperado, as espécies dominantes desempenham importante papel na ocupação do espaço horizontal em tais florestas, contribuindo de modo decisivo para a caracterização do padrão espacial da comunidade. Espécies que ocorreram em diferentes florestas apresentaram pequenas diferenças no seu padrão espacial, ressaltando-se assim a importância da sua autoecologia e dos processos ecológicos intrínsecos a cada comunidade. / Tree spatial patterns are influenced by abiotic and biotic environment. Among the main abiotic factors are topography, light, nutrients, soil and water availability. Among biotic factors are density-dependent processes, as intraespecific and interespecific competition, herbivory, pathogens, phenology and seed dispersion. Investigation of tree spatial patterns, patterns in size classes, and dominant species patterns can show evidences about the structure of plant communities. Description of trees spatial pattern was made using the most appropriate statistical tools for mapped data. Ripley’s K Function has as its main attributes the power to detect the spatial patterns in different distance scales simultaneously, and to investigate spatial independence among groups of trees. Observed patterns were compared to Complete Spatial Randomness model, in univariate function, and to Complete Spatial Independence model, in bivariate function. Different forests, typical from Southeastern Brazil, were compared in this study: Forest Savanna (Cerrad˜ao), Dense Rain Forest, Seasonal Semideciduous Forest and Restinga. This mastership thesis is part of Project "Diversity, dynamics and conservation in forests in the State of São Paulo: 40 ha of permanent plots", from FAPESP Biota Program. In this project, one permanent plot of 10.24 ha was located in each forest stand, and all its trees with circunference at breast height equals 15 cm or higher were measured, mapped and identified. The results obtained in this study shows the aggregated pattern as the most common pattern in tropical forests. The trees spatial pattern in Cerradão and Restinga were very similar, aggregation was observed in the same distance scales. For the Dense Rain Forest, the spatial pattern was significant for all the distance scales. In Semidecidous Forest, a tendency towards randomness was observed, but a significant aggregation appeared for short distances. The spatial analysis for size classes showed that the newer classes have aggregated patterns, while the following classes have random ones. The dominant species spatial patterns were close to the general patterns of its community. As expected, dominant species play important rules in characterizing the horizontal pattern of their forests. Common species between different forests showed small differences in its spatial pattern, indicating the importance of its autoecology and the intrinsic ecological processes of each community.

Orientador: Carlos Alfredo Joly / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-19T20:04:39Z (GMT). No. of bitstreams: 1 Pereira_LarissadeSouza_M.pdf: 11241886 bytes, checksum: 8b5154d6804f87f26cade4a1982ff657 (MD5) Previous issue date: 2011 / Resumo: Descrevemos a composição florística e a estrutura fitossociológica de um trecho de Mata Atlântica (FODM) do Núcleo Santa Virgínia, do Parque Estadual da Serra do Mar através da coleta de informações sobre as espécies arbóreas (DAP ? 4,8 cm) presentes em um hectare de floresta. A amostragem foi realizada em 100 parcelas contíguas de 10x10m e seguiu o padrão do Projeto Temático Biota Gradiente Funcional, no qual este trabalho se insere. Registramos 152 espécies, distribuídas em 80 gêneros e 41 famílias. As famílias com mais indivíduos são: Arecaceae, Myrtaceae, Monimiaceae, enquanto que as famílias com mais espécies são: Myrtacaeae, Lauraceae, Fabaceae e Monimiaceae. Euterpe edulis, o palmito Jussara, é a espécie mais abundante na área. Eugenia spp, Mollinedia spp e Ocotea spp são os gêneros com os maiores números de espécies. O software FITOPAC 2.1.2 foi utilizado para as análises quantitativas. Somados os parâmetros fitossociológicos de apenas 15 espécies - E. edulis, Licania hoehnei, Indeterminada sp. 1, Ocotea catharinensis, Alchornea triplinervia, Mollinedia argyrogyna, Calyptranthes lucida, Chrysophyllum viride, Inga lanceifolia, Myrcia crocea, Marlierea tomentosa, Calyptranthes strigipes, Bathysa australis, Mollinedia engleriana e Miconia sp 1 - correspondem a cerca de 50% do valor de importância representado pelos parâmetros fitossociológicos analisados. A área estudada apresenta uma alta densidade de indivíduos de pequeno porte, com diâmetros próximos do limite de inclusão na amostragem. Apresenta também uma prevalência de espécies não-pioneiras e zoocóricas, uma alta diversidade (índice de Shannon-Wiener H '= 4.06 nats/individuo) e uma alta equabilidade (J' = 0,80) entre as espécies arbóreas lenhosas. A alta declividade da área e a freqüência de árvores caídas observadas durante o período de estudo, sugerem que esta é uma floresta onde a ocorrência de perturbações naturais é freqüente e talvez este seja um dos fatores que promove a diversidade local. Conforme relatado por moradores antigos do Núcleo Santa Virgínia, até 40 anos atrás a área estudada foi sujeita a corte seletivo de espécies. Ainda que de baixa intensidade, este tipo de perturbação pode explicar parcialmente a alta densidade de indivíduos de pequeno porte / Abstract: In this paper we describe the floristic composition and structure of 1ha of Tropical Mountain Moist Forest (Floresta Ombrófial Densa Montana/FODM) situated in Nucleo Santa Virgínia of the Serra do Mar State Park, based in trees with DBH ? 4,8 cm. We collected and identified 152 species, distributed among 80 genera and 41 families, within witch Myrtacaeae, Lauraceae, Fabaceae and Monimiaceae are the ones with higher number of species and Arecaceae, Myrtaceae and Monimiaceae the most abundant in number of individuals. Eugenia spp, Mollinedia spp and Ocotea spp are the genus with higher number of species. While the most abundant species is the arborescent palm Euterpe edulis Martius (Arecaceae), also known as palm hart, a delicatessen that is illegally exploited in the region. Using the software FITOPAC 2.1.2 to perform data analyses, we concluded that 15 species combined - E. edulis., Licania hoehnei Pilg., Indeterminada sp. 1, Ocotea catharinensis Mez, Alchornea triplinervia (Spreng.) Müll.Arg., Mollinedia argyrogyna Perkins, Calyptranthes lucida Mart. ex DC., Chrysophyllum viride Mart. & Eichler, Inga lanceifolia Benth., Myrcia crocea (Vell.) Kiaersk, Marlierea tomentosa Cambess., Calyptranthes strigipes O.Berg, Bathysa australis (A.St.-Hil.) K.Schum., Mollinedia engleriana Perkins and Miconia sp1 - account for 50% of the value of the phytosociological parameters studied. The area studied presents a high frequency of individuals in lower classes of diameter close to the limit for inclusion in the sample. A prevalence of nonpioneer and animal dispersed species, and a high diversity (Shannon-Wiener's H '= 4,359 nats/individual) and evenness (Pielou's J' = 0, 887) was found between the woody trees. The steep slope of the area studied and the high frequency of fallen trees observed suggest that natural disturbances are common disturbance is this type of forest and may be one of the promoting factors of local diversity. Land use history of the area, recovered from longtime residents, indicate that up to 40 years ago some selective logging may have occurred in the area, what can be related to the high frequency of smaller trees, and may be another factor influencing local diversity / Mestrado / Biologia Vegetal / Mestre em Biologia Vegetal

Please read the abstract in the section 00front of this document / Dissertation (MSc(Botany))--University of Pretoria, 2005. / Plant Science / unrestricted

Please read the abstract in the section 06back of this document / Dissertation (MSc)--University of Pretoria, 2009. / Centre for Wildlife Management / unrestricted

Patterns in algal community structure and physiochemical characteristics of streams and one impounded subalpine lake in the mountainous North Alouette River watershed, British Columbia, were described for one year from June 1977 to June 1978. In this period, 266 algal taxa were recognized, of which 59 were previously unrecorded in the province. The streams were characterized by an epilithic flora consisting predominantly of. unbranched Chlorophyta and secondarily by both branched and unbranched Cyanophyta. Bacillariophyta (diatoms) were species rich (over 100 taxa), but were at all times relatively unimportant in the streams, although frequently dominant in the epipelon of Jacob's Lake. Species of Rhodophyta were locally abundant only in shaded habitats. Many epilithic and epiphytic species were "host" specific in their substrate preferences. Stream water in the North Alouette was slightly acid (pH 6-7) and nutrient poor, the relative order of anions being S0₄²⁻ > SiO₂ > CI⁻ >N0₃⁻ > PO₄³⁻ and cations Ca²⁺ = Na⁺ > Mg²⁺ > K > NH₄⁺ > Fe²⁺/³⁺, Mn²⁺, and Al³⁺ were not detected in the dissolved fraction. Other variables indicated this to be a rapidly flowing (often > 1m sec⁻¹), cool (2-18°C seasonally), poorly buffered (HCO₃⁻ = .06-.40 meq 1⁻¹), and highly heterogeneous environment. Stations along the stream gradient differed in conditions of slope, current velocity, degree of shading, and substrate size, but not in temperature, pH, and possibly nutrient chemistry. A principle coordinates analysis (P-Co-A) of seasonal succession at one station (Station 1) revealed a cyclic pattern characterized by sequences of gradual and abrupt changes in species composition. Temporal extinction of dominant species did not occur, as has been shown for phytoplankton populations in lakes. Current velocity, depth, temperature, CI⁻, and SO₄²⁻ were significantly correlated (P<0.05) with most of the seasonal variability in the algal community. A smaller amount of the seasonal change was correlated with the flux of dissolved cations. P-Co-A also exposed similarities between six stations within the watershed which were not consistent seasonally, and gave no evidence of distinct zones. Distribution of algal species within Station 1 in May shown by cluster analysis, occurred roughly in two groups, corresponding to near-shore and midstream habitats. The general heterogeneity of algal distribution and the occasional disturbance by flooding gave rise to periodic peaks in diversity, although many common species never became abundant. Hence, no clear-cut relation was realized between the physiochemical environment and species diversity. Hypotheses are generated, suggesting that (1) distribution of red algae was shade limited; (2) diatom dominance was limited by nutrient chemistry; (3) the even pattern of seasonal succession was interrupted by periodic events, such as nutrient pulses and floods; and (4) a large degree of species coexistence was provided by these periodic disturbances. / Science, Faculty of / Botany, Department of / Graduate

An ecological classification of high elevation range provides a framework for proper resource management. Alpine and subalpine vegetation in the Southern Chilcotin Mountains was studied to characterize the plant communities of the high elevation rangelands in the southern interior of British Columbia. The impacts of grazing on the structure and composition of the vegetation were evaluated. Two hundred and thirty-nine sites were sampled in a 10,000 ha area. Plots were selected randomly within homogeneous units delineated on 1:30,000 (40 chain) air photos prior to the field season. These were classified on the basis of physiognomy, dominant species and environmental conditions. The following nineteen community types were described: Picea engelmanii-Abies lasiocarpa forest, Pinus albicaulis-Juniperus communis forest, Salix bare layi-Carex aquatilis shrub wetland, Salix barrattiana alpine shrub wetland, Salix brachycarpa-Salix barclayi shrubland, Salix brachycarpa-Festuca spp. shrubfieId, Salix brachycarpa-Phleum alpinum shrubfieId, Arctostaphylos uva-ursi-Amelanchier alnifolia dry shrubland, Salix cascadensis dwarf willow shrubland, Dryas octopetala fellfield, Dryas octopetala-Festuca altaica alpine grassland, Carex aquatilis/rostrata wetland, Carex nigricans late snowbed meadow, Festuca altaica-Festuca brachyphylla meadow, Festuca brachyphylla meadow, Festuca brachyphylla-Phleum alpinum meadow, Phleum alpinum-Carex phaeocephala meadow, Koeleria cristata dry meadow, and crustose lichen rock-land or talus terrain unit. Changes in the structure and composition of plant communities in response to grazing pressure were evident on the more heavily used valley bottom meadow community types. After many years of use, Festuca altaica appears to have, been eliminated from heavily grazed meadows, there is a decrease in the height of the vegetation, an increase in the exposed bare ground, and an increase in the abundance of weedy species in all community types. Many of the community types described from this region are floristically and/or ecologically comparable with plant communities described from other high elevation areas in British Columbia, the southern Yukon, and the Pacific Northwest of the United States. / Land and Food Systems, Faculty of / Graduate

Please read the abstract in the section 15back of this document Without maps in separate bound folder / Dissertation (MSc (Wildlife Management))--University of Pretoria, 2000. / Animal and Wildlife Sciences / MSc / unrestricted

Background: Coastal ecosystems in Mexico remain understudied in spite of their ecological, economic and conservation value and are being impacted by human activities along the coast. Knowledge on spatial patterns of plant species distribution that helps preserve these fragile ecosystems is crucial. Aims: We evaluated differences in species richness, species diversity and species dominance patterns in 16 plant communities as well as the degree to which differences were driven by climatic conditions in sandy dunes in Yucatán. We evaluated the importance of invasive species in mediating patterns of species diversity and species dominance patterns. Results: We found wide variation in plant species richness, species diversity and species dominance patterns among communities that stems from broad climatic differences along dune systems. Invasive plants represent almost one-third of total species richness and seem to be drastically changing the species dominance patterns in these communities. Conclusions: Regional climatic differences along the Yucatán north coast seems to be a major driver of plant diversity and species composition. Our findings suggest that invasive plants have successfully colonised and spread along the coast over the past 30 years. Even though invasive species do not alter spatial patterns of species diversity, they are becoming more dominant with potential detrimental consequences for native plants.

The variation that exists in both time and space in riparian plant communities was explored in five streams within the Salmon National Forest and surrounding Bureau of Land Management (BLM) lands of central-eastern Idaho that are managed for cattle grazing. In this study, we evaluated the ability of commonly used vegetation metrics (live vegetation cover, species richness, % forb, litter, bare ground, wetland indicator rating, % graminoid, bank alteration, soil compaction, and % native) and different plot types (static or dynamic) to assess changes in plant communities over time and in areas grazed by cattle. We were particularly interested in evaluating the stability of metrics over time and the responsiveness of metrics to cattle grazing. We found that the metrics wetland indicator rating, % graminoid, and % native were stable across the season, while live vegetation cover, species richness, % forb, litter, bare ground, bank alteration, and soil compaction were affected by seasonal variation. The metrics that responded to grazing similarly at all streams and sites were live vegetation cover, litter, bare ground, and bank alteration, while species richness, % forb, wetland indicator rating, % graminoid, soil compaction, and % native responded differently to cattle grazing at individual streams. The metrics that were most sensitive to cattle grazing within the season were live vegetation cover, species richness, % forb, litter, and bare ground. Plot type did not have an effect on the majority of the metrics at the majority of the streams. This information can be used by land managers to determine which metrics are suitable for short- and long-term monitoring, and which ones are appropriate for monitoring the effects of cattle grazing.

The nitrogen budgets of Eurotia lanata (Pursh.) Moq. and Atriplex confertifolia (Torr. and Frem.) S. Wats salt desert shrub plant communities were investigated. In each, a complete biomass and organic nitrogen inventory was made. In addition, investigations of the nitrogen fixation potential of soil surface microflora and inorganic soil nitrogen relationships were carried out. Greater total biomass and organic nitrogen was found in the above-ground portions, annual shoot productivity, and litter of the Atriplex community. However, the Atriplex community was exceeded by the Eurotia community in root biomass. Roots accounted for 74 and 87 percent of the plant biomass and 83 and 90 percent of the associated organic nitrogen in Eurotia and Atriplex communities respectively. Root biomass distribution at various depths was markedly different in the two communities. Differences between communities in relative amounts of various plant parts and litter are related to contrasting plant growth habit, and differences in soil texture and soil salinity. Total plant biomass estimates, which were 18,480 and 17,300 kilograms per hectare for Eurotia and Atriplex communities, were not significantly different and reflect the overriding influence of macroclimate and associated moisture limitation. Under laboratory conditions the soil surface microflora of the Atriplex community was able to fix significant amounts of atmospheric nitrogen while that of the Eurotia community did not. Nitrogen fixation potential in the Atriplex community was associated with the presence of abundant lichen cover and associated heterocvstcontaining blue-green algae of lichen interspaces. Differences between communities were found in rates of mineralization, downward flux, and pattern of utilization of inorganic soil nitrogen. Soil salinity appeared to strongly limit inorganic soil nitrogen mineralization as well as root growth and nitrogen uptake in the lower part of the Atriplex soil profile; however, this lack of biological activity was compensated for by a greater downward flux of inorganic soil nitrogen from decomposing litter and surface soil in the Atriplex community. Shoot and root litter appears to be the most readily available source of inorganic soil nitrogen for plant growth in salt desert shrub plant communities.