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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Changing forest-woodland-savanna mosaics in Uganda : with implications for conservation /

Nangendo, Grace. January 1900 (has links)
Thesis (doctoral)--Wageningen Universiteit, 2005. / "Propositions" inserted. Includes bibliographical references (p. 107-122).
32

Comunidade de lianas e sua associação com arvores em uma floresta estacional semidecidual

Rezende, Andreia Alves 04 August 2018 (has links)
Orientador: Neusa Taroda Ranga / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-04T02:57:19Z (GMT). No. of bitstreams: 1 Rezende_AndreiaAlves_D.pdf: 680315 bytes, checksum: 35c8e450ad258314b9f2c48dbcf0cd7a (MD5) Previous issue date: 2005 / Resumo: Lianas são plantas que germinam no solo, mantêm-se enraizadas durante toda a vida e necessitam de suporte físico para alcançarem o dossel. Elas são membros característicos das florestas tropicais, onde contribuem com cerca de 25% da diversidade vegetal. Às vezes, dominam a vegetação, principalmente em áreas perturbadas. Lianas competem com árvores por nutrientes e luz, e influenciam a taxa de crescimento e a mortalidade de sua árvore hospedeira. Embora as lianas iniciem sua escalada a partir do chão, muitas colonizam árvores vizinhas pelo dossel da floresta, ¿amarrando-se¿ às outras, podendo ocasionar a queda de várias árvores quando uma delas cai. Devido a sua abundância e o seu impacto sobre as árvores, é de grande importância conhecer os fatores que governam a distribuição e dinâmica das lianas na floresta tropical e, assim, desenvolver estratégias de uso sustentável. Assim, os objetivos desta tese foram: (1) avaliar a riqueza e abundância das lianas e (2) a relação das lianas com as características do hospedeiro e com a estrutura da floresta. O trabalho foi realizado em um fragmento de floresta estacional semidecidual, com cerca de 435,73 ha, na Estação Ecológica de Paulo de Faria, SP. Foram amostradas 100 parcelas de 10 x 10 m (1 ha). As lianas com diâmetro ³ 1 cm e as árvores ³ 3 cm enraizadas nas parcelas foram medidas no DAP (diâmetro à altura do peito - 1,30m) e identificadas. Amostrou-se 1427 indivíduos de 45 espécies de lianas, pertencentes a 14 famílias, sendo as mais ricas: Bignoniaceae (14 espécies), Sapindaceae (nove) e Malpighiaceae (seis), e as mais abundantes Bignoniaceae, Sapindaceae e Apocynaceae. A riqueza de lianas foi aproximadamente igual à metade (razão 0,51) da riqueza de árvores (87 espécies). A densidade média de lianas e árvores foi semelhante, cerca de 1400 indivíduos/ha. Melloa quadrivalvis (Bignoniaceae) foi a espécie mais comum na área estudada. Do total de indivíduos de lianas amostrados, 57,6% apresentaram diâmetros entre 1 - 2,5 cm, correspondendo a 95% da riqueza total amostrada. Das 1419 árvores amostradas, 53% carregavam pelo menos uma liana. As espécies menos infestadas que a média geral foram Inga marginata, Piper amalago, Trichia catigua e T. claussenii, e somente uma, Machaerium paraguariense, foi mais infestada que a média, considerando todas as espécies. Os resultados, de modo geral, não apoiaram a hipótese de especificidade entre espécies de lianas e espécies de árvores, pois a riqueza e a diversidade de espécies de lianas aumentaram com a proporção de infestação. Se houvesse especificidade, esperar-se-ia que uma espécie de árvore fosse mais infestada por uma determinada espécie de liana. O mecanismo de escalada das lianas não influenciou o número de árvores que cada liana escalou, embora tenha ocorrido associação positiva entre árvores com casca rugosa e lianas com gavinhas. Considerando-se as características individuais do hospedeiro, as árvores com diâmetros maiores apresentaram maior densidade de lianas. Com relação às características da vizinhança, as diferenças encontradas provavelmente se devem as condições de luminosidade do ambiente. As parcelas com maior proporção de árvores com DAP > 30 cm apresentaram relação negativa significativa com a densidade de lianas. A relação foi positiva em parcelas com maior proporção de árvores com copas £ 3 m de altura. Assim, as evidências deste estudo sugerem que a distribuição das lianas foi mais influenciada por características da comunidade do que pelas características das espécies de árvores presentes / Abstract: Lianas are soil-germinating plants, perennially rooted and which need support to reach the canopy. They are characteristically from the rain forests, where they contribute with near 25% of vegetal diversity. Lianas compete with trees for nutrients and light, influencing growth and mortality rates of its host tree. Although lianas begin their life on the ground, many of them colonize vicinity trees through the forest canopy, ¿tying¿ themselves to the others, and may cause the fall of many trees. Due to their abundance and impact over other trees, it is important to know the factors governing distribution and dynamics of the lianas in order to better understand the rain forest and to develop sustainable strategies. Thus, the aims of this study were: (1) to assess the richness and abundance of lianas, and (2) to establish the relation of lianas with the characteristics of the hosts and the structure of the forest. The research was carried out in a fragment of a Semideciduous Stational Forest with 435.73 ha, at the Paulo de Faria Ecological Station. The sampling consisted of 100 plots of 10 x 10 m (1 ha), allotted in an area of 4 ha. Lianas with a diameter ³ 1 cm and trees ³ 3 cm rooted in the plots were measured in DBH (diameter at breast height ¿1.30m) e identified. In the study area, 1427 individuals were sampled from 45 species of lianas, belonging to 14 families, the richest ones being Bignoniaceae (14 species), Sapindaceae (nine) e Malpighiaceae (six), and the more abundant Bignoniaceae, Sapindaceae e Apocynaceae, adding up to 80% of the sampled individuals. The liana richness was approximately equal to half (ratio 0.51) the tree richness (87 species). Average density of lianas and trees was similar, around 1400 individuals/ha. Melloa quadrivalvis (Bignoniaceae) was the most common species in the study area. From the total number of the sampled liana individuals, 57.6% presented diameters between 1- 2.5 cm, corresponding to 95% of the total sampled richness. Only 26 individuals presented diameter higher than 10 cm. From the 1419 trees with diameter ³ 3 cm, 53% carried at least one liana, with the higher rate of infestation (79%) occurred in the individuals with diameters > 10 cm. Species less infested than the expectation were Inga marginata, Piper amalago, Trichia catigua e T. claussenii. One species, Machaerium paraguariense, was more infested than the expectation. In general, results did not support the hypothesis of species-specificity between lianas and trees, since the richness and diversity of liana species increased with the infestation rate. Climbing mechanism did not influence the number of trees climbed by each liana, although we have found positive association between wrinkled bark and tendrils. Considering the individual characteristics of the host, trees with larger diameters showed higher density of lianas. In relation to the vicinity characteristics, the plots with higher rate of big trees (DBH > 30 cm) showed significant negative relation with the density of lianas. The relation was positive in plots with higher rate of trees with small crown (£ 3 m). Thus, our study showed the association between tree and vicinity characteristics with infestation and density of lianas / Doutorado / Biologia Vegetal / Mestre em Biologia Vegetal
33

Nutrição e adubação da paineira (Ceiba speciosa) /

Spada, Grasiela, 1988. January 2014 (has links)
Orientador: Iraê Amaral Guerrini / Banca: Roberto Boyd Harrison / Banca: Jacob Silva Souto / Resumo: A literatura sobre adubação e nutrição de espécies nativas é escassa, as espécies florestais apresentam comportamentos distintos, sobretudo quanto às exigências nutricionais, o desafio deste trabalho foi encontrar qual a melhor condição nutricional para o desenvolvimento da paineira (Ceiba speciosa A. St. Hil). Objetivou-se avaliar e monitorar o crescimento inicial e a nutrição mineral da paineira em resposta a diferentes doses de adubação. O ensaio foi composto por quatro experimentos distintos (doses de N, P, K e V%), cada um com seis tratamentos e quatro repetições dispostos em delineamento inteiramente casualizado, utilizando-se vasos plásticos preenchidos com 50 dm³ de um Latossolo Vermelho Escuro, alocados em estufa plástica. Mensalmente avaliou-se o diâmetro do colo, altura das mudas e teor de clorofila nas folhas. O ensaio foi encerrado 150 dias após o plantio das mudas e além das avaliações anteriores, foram determinados a área foliar, a massa seca de raízes, caules e folhas, e os teores e quantidades absorvidas de macro e micronutrientes pelo material vegetal. Dos elementos estudados, o fósforo é o nutriente mais exigido, sendo que o potássio e o nitrogênio não afetaram o crescimento inicial da espécie. Para o tipo de solo e condições estudadas, recomenda-se adubação fosfatada de 250 mg dm-3 e saturação por bases do solo de 50% para o plantio em condições de campo. / Abstract: The literature about nutrition and fertilization of native species is scarce, forestry species exhibit different behavior, especially regarding nutritional requirements, the challenge of this work was to find what the best nutritional conditions for the development of the cotton tree (Ceiba speciosa A. St. - Hil). This study aimed to evaluate and monitor the initial growth and mineral nutrition of paineira in response to different doses of fertilizer. The test consisted of four separate experiments (doses of N, P, K and V%), each with six treatments and four replications arranged in a completely randomized design, using plastic pots filled with 50 dm- ³ of a Dark Rhodic Hapludox allocated in greenhouse. Monthly evaluated the lap diameter, plant height and chlorophyll content in the leaves. The research was terminated 150 days after seedlings planting and beyond previous evaluations were determined leaf area, dry weight of roots, stems and leaves, as well as the levels and amounts of macro and micronutrients absorbed by plant material. The elements studied, the phosphorus is the most required nutrient, being that nitrogen and potassium did not affect the initial growth of the specie. For soil type and measurements conditions is recommended phosphorus fertilization of 250 mg dm-3 and liming of 50% for planting under ... / Mestre
34

A floristic and vegetational analysis of the Mill Creek drainage area of the San Bernardino Mountains, California

O'Casey, Carol Elaine 01 January 1988 (has links)
No description available.
35

Global change and tropical forests : functional groups and responses of tropical trees to elevated CO

Ellis, Alexander, 1972- January 1997 (has links)
No description available.
36

Fine-scale habitat use related to crop depredation by female white-tailed deer in an agricultural landscape

Adams, Kent Allen, January 2003 (has links) (PDF)
Thesis (M.S.)--University of Tennessee, Knoxville, 2003. / Title from title page screen (viewed Mar. 18, 2004). Thesis advisor: Lisa I. Muller. Document formatted into pages (v, 61 p. : col. ill., maps (some col.)). Vita. Includes bibliographical references (p. 55-60).
37

The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon

Broshot, Nancy Ellen 01 January 1999 (has links)
The effects of urbanization and continual human disturbance on the plant and avian communities of Forest Park and forested lands surrounding Portland, Oregon, were studied. I examined characteristics of plant and avian communities at 25 sites, 24 which were in Forest Park and surrounding areas and one which was in the Ancient Forest Preserve (old-growth stand) northwest of Forest Park. Data were analyzed using multiple regression, ANOV A, and Bonferonni/Dunn. Seven variables were selected representing different urbanization gradients. An additional covariable coded for the old-growth stand, allowing it to be used as a control. Many tree variables, especially those related to shade-tolerant species, were positively correlated with both the distance from downtown Portland and the number of houses in the surrounding area, and negatively correlated with the distance from the nearest forest edge; however, many shrub and herbaceous variables were negatively correlated with the distance from downtown Portland. Species diversity for herbaceous and shrub species was greater at more urban sites, but diversity of trees was lower at more urban sites. There were significantly more non-native species of plants in the city section. I found significantly fewer saplings and small trees, especially shade-tolerant species, in the section of Forest Park closest to downtown Portland, although tree mortality was positively correlated with distance from Portland. Summer bird data revealed significant increases in the abundances of urban and edge species at more urban sites, with concomitant reductions in forest species. There were significantly more ground gleaning birds and short distance migratory species. I also found a significantly greater abundance of birds in the old-growth stand during the winter. This increase was positively correlated with the depth of snow in the nearby Cascade Mountains. My results indicate that Forest Park is apparently progressing in a normal successional pattern with the exception of the city section. The reduction in shade tolerant saplings and small trees in the city section suggest that rate of succession has been slower at more urban sites. Avian data suggest that urbanization affects bird species abundance and guild composition in the more urban areas.
38

A Study of Understory Plant Recovery After a Forest Fire in the Columbia River Gorge

Pittsenbarger, Mark Alan 03 May 1994 (has links)
Between October 9, 1991 and October 16, 1991 a fire burned 577 hectares in the Columbia River Gorge near the west end on the Oregon side. All of the area burned consisted of second growth Pseudotsuga menziesii and the accompanying understory. This was the first disturbance of this magnitude in this part of the Columbia River Gorge since 1902. The purpose of this study was to examine the pattern of understory recovery in the first two years following the fire. This study also sought to learn: 1) how Pseudotsuga menziesii seedlings are recruited into the population, 2) how quickly the litter layer is a reforming, and 3) how quickly snags and downed logs are recruited into the understory. Four 800 square meter circular plots were established within the burned area of the Columbia River Gorge. Two plots were designated sun plots since the fire had killed the overstory. The other two were designated shade sites since the canopy over them was still intact. Twenty five randomly placed sample units (20 x 50 centimeters) were placed in each main plot. The plots were then sampled at approximately onemonth intervals from May through September of 1992 and 1993. The frequency and percentage of cover was recorded for all plant species that occurred in each sample unit. The data from 1992 and 1993 were compared by date of visit and type of plot, either (sun or shade) using the Pearson Goodness-of-Fit Test to examine and compare differences in the extent of cover and distribution of understory species. No significant differences were found. An increase in species richness and relative abundance of understory species was noted between pre-fire data collected by the US Forest Service and what I found. However, statistical analysis was not possible because of the limited data collection in the pre-fire sample.
39

PRODUCTIVITY OF THE UNDERSTORY COMMUNITY IN AN ARIZONA PONDEROSA PINE FOREST

McLaughlin, Steven Paul January 1978 (has links)
No description available.
40

The ecological value of hedgerows for conserving temperate forest herbs in agricultural landscapes /

Roy, Valérie, 1981- January 2006 (has links)
There is growing evidence that the achievement of biodiversity conservation objectives at the regional scale will have to take into account not only habitats within reserves, but also the contribution of semi-natural habitats in production landscapes. This requires knowledge of the conditions that maintain or enhance biodiversity in these suboptimal habitats. I focused on a system of forest patches and hedgerows in an agricultural landscape as habitats for dispersal-limited native forest herbs to (1) identify species-specific traits that appear to either limit or facilitate survival or colonization of forest herbs in hedgerows compared to forest patches, and (2) to evaluate the relative contribution of landscape and local variables in explaining patterns of forest herb species richness, abundance, and diversity in hedgerows. A fourth-corner analysis revealed that traits such as early spring flowering, ant dispersal or a lack of vegetative propagation can reduce the likelihood of native forest species to benefit from hedgerows. Conditional autoregressive models showed that landscape variables, specifically hedgerow age and neighboring forest area, largely account for species diversity in hedgerows.

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