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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.
11

Composição florística e fitossociologia de duas áreas de caatinga no Parque Nacional do Catimbau, Buíque, Pernambuco, Brasil / Floristic composition and phytosociology of two savanna sand areas of Parque Nacional do Catimbau, Buíque, Pernambuco, Brazil

SERAFIM FILHO, Gilvan Lopes 19 February 2014 (has links)
Submitted by (ana.araujo@ufrpe.br) on 2016-08-22T17:56:25Z No. of bitstreams: 1 Gilvan Lopes Serafim Filho.pdf: 2224258 bytes, checksum: 45a9e6e7b216bf0f05534a40929c2a23 (MD5) / Made available in DSpace on 2016-08-22T17:56:26Z (GMT). No. of bitstreams: 1 Gilvan Lopes Serafim Filho.pdf: 2224258 bytes, checksum: 45a9e6e7b216bf0f05534a40929c2a23 (MD5) Previous issue date: 2014-02-19 / Despite the existence of floristic-phytosociological studies of savanna vegetation, very little is known about the vegetation types in this biome as a whole. In this sense there is a consensus among various authors about the need to recognize the heterogeneity and floristic his face. Climate and soil, or together, these two factors are considered key in determining this floristic heterogeneity. The aim of this work was to floristic and phytosociological study in two fragments of woody savanna (Trilha do Cânion¹ and Casa do Artesão²), located in the municipality of Buíque - PE, in sedimentary areas (Quartzipsamments Neosol). Through the method of the quadrants, we studied 10 transects parallel and equidistant 30m transects were demarcated in 10 points every 10m, being sampled individuals (trees, saplings, shrubs and succulents), closer to the center of each quadrant, dead or alive (standing still) with the girth ≥ 9 cm from ground level. For each zone were sampled quadrants 100, 400 points, resulting in 400 individuals. In one area, we sampled 16 families, 24 genera and 26 species, as in area 2, the inventory indicated nine families, 20 genera and 27 species. The families with the largest number of species in area 1 were Fabaceae, Cactaceae and Myrtaceae, in area 2 were: Fabaceae, Euphorbiaceae and Verbenaceae. Already the most abundant taxa were Byrsonima gardneriana and Chamaecrista brachystachya (1), followed by Pityrocarpa moniliformis and Amburana cearensis (2). In area 1, and Fabaceae families Cactaceae showed the highest values of sampled individuals, 18,52 and 14.81% spp. In area 2 highlights were Fabaceae (28.57%), Euphorbiaceae (28.57%) and Verbenaceae (10.71%), households with higher (spp%) include those typically found in sedimentary environments. The vegetation structure was evaluated by the usual parameters by making use of the software FITOPAC (Shepherd, 1995), we determined the number of individuals (NInd), relative density (RelDe), relative frequency (RelFr), relative dominance (RelDo), IVI and IVC for Family / species in the two areas surveyed, among other parameters phytosociological. The analysis results showed that the two areas differ both in physiognomy and in vegetation structure and low species richness. / Apesar da existência de estudos florístico-fitossociológicos da vegetação de caatinga, muito pouco se conhece sobre as fitofisionomias desse bioma como um todo. Neste sentido há um consenso entre vários autores sobre a necessidade em reconhecer a heterogeneidade florística e sua fisionomia. Clima e solo, ou o conjunto desses dois fatores, são considerados os principais quanto à determinação dessa heterogeneidade florística. O objetivo do presente trabalho foi realizar um estudo florístico e fitossociológico em dois fragmentos de caatinga arbustivo-arbóreo (Trilha do Cânion1 e Casa do Artesão2), localizados no município de Buíque - PE, situados em áreas sedimentares (Neossolos quartzarênicos). Através do método dos quadrantes, foram estudados 10 transectos paralelos e equidistantes 30m, nos transectos foram demarcados 10 pontos a cada 10m, sendo amostrados os indivíduos (árvores, arvoretas, arbustos e suculentas), mais próximos do centro de cada quadrante, vivos ou mortos (ainda de pé), com perímetro do caule ≥ 9cm ao nível do solo. Para cada área foram amostrados 100 quadrantes, 400 pontos, resultando em 400 indivíduos. Na área 1, foram amostradas 16 famílias, 24 gêneros e 26 espécies, já na área 2, o inventário apontou nove famílias, 20 gêneros e 27 espécies. As famílias com maior número de espécies na área 1 foram Fabaceae, Cactaceae e Myrtacee, na área 2 foram: Fabaceae, Euphorbiaceae e Verbenaceae. Os táxons mais abundantes foram Byrsonima gardneriana e Chamaecrista brachystachya (1), seguido de Pityrocarpa moniliformis e Amburana cearensis (2). Na área 1, as famílias Fabaceae e Cactaceae apresentaram os maiores valores de indivíduos amostrados, 18,52 e 14,81% spp. Na área 2 destacaram-se as famílias Fabaceae (28,57%), Euphorbiaceae (28,57%) e Verbenaceae (10,71%), as famílias com maior (%spp) compreendem as tipicamente encontradas em ambientes sedimentares. A estrutura da vegetação foi avaliada através dos parâmetros usuais fazendo-se uso do software FITOPAC (Shepherd, 1995), foram determinados o número de indivíduos (NInd), Densidade relativa (RelDe), Frequência relativa (RelFr), Dominância relativa (RelDo), IVI e IVC para Família/Espécies nas duas áreas inventariadas, entre outros parâmetros fitossociológicos. Os resultados das análises evidenciaram que as duas áreas apresentaram diferenças tanto na fisionomia quanto na estrutura vegetacional, bem como baixa riqueza florística.
12

The big effects of small-scale environmental variation: Exploring spatial patterns of tree community composition and greenhouse gas production in a tropical forest

Quebbeman, Andrew W. January 2021 (has links)
Tropical forests represent major uncertainties in climate models and have the potential to act as both net carbon sources and sinks in the future. Projections that hurricanes will be an increasingly powerful disturbance in many tropical forests further complicate our ability to predict how these ecosystems will respond to climate change. By understanding how environmental variation at small spatial scales affects ecosystem processes shaping present-day forests, it may be possible to improve our predictions for how these forests will change in the future. This dissertation consists of three chapters examining the spatial patterns of tree species and soil greenhouse gas fluxes in a tropical forest in the Luquillo Experimental Forest, Puerto Rico. Disentangling the forces that drive the spatial distribution of tree species has been a foundational question in ecology and determining the relative importance of these forces is central to understanding spatial variation in soil biogeochemistry. In chapter 1, I use percolation threshold analysis to examine the clustering patterns of simulated and real tree spatial point patterns to understand the role that environmental filtering and density dependent processes play in shaping tree species distributions. I demonstrate that percolation threshold analysis successfully distinguishes thinning by random, environmental filtering, and density dependent processes. Additionally, the relative importance of these thinning processes varies by species’ traits; fast growing species with low LMA and shade intolerance have stronger evidence of density dependent processes compared to species with high LMA and shade tolerance. In chapter 2, I examine the spatial relationships between soil greenhouse gas fluxes and two proximal drivers of soil environmental variation: tree species and topography. I also examine how incorporating small-scale variation in greenhouse fluxes affects our scaled-up estimates of ecosystem greenhouse gas emissions. I show that including species effects improves estimates of soil CO2 fluxes, and including measures of topography improve estimates of CH4 and N2O fluxes. Incorporating spatial variation in GHG fluxes related to tree species and topography into our estimates of ecosystem GHG emissions decreased estimates of the total CO2-equivalent emissions in this forest by 5%. Finally, in chapter 3 I examine how the GHG fluxes in this forest change after an intense hurricane. I demonstrate that GHG emissions shift following a hurricane; this shift is primarily driven by a 176% increase in N2O emissions that represent a significant net loss of gaseous nitrogen from this forest. N2O fluxes accounted for 4.2% of the post-hurricane GHG-induced radiative forcing (compared to 1.8% pre-hurricane) and the combined increase in CO2, CH4, and N2O emissions observed translates to a 25% increase in CO2-equivalent emissions compared to pre-hurricane conditions. This dissertation focuses on the role of small-scale environmental variation in shaping forest communities and spatial patterns of GHG fluxes and aims to highlight how this variation can help us to better understand the role tropical forests play in the biosphere.
13

Sistem?tica e biogeografia da linhagem Tetramerium (Acanthaceae) na Am?rica do Sul

C?rtes, Ana Luiza Andrade 22 August 2013 (has links)
Submitted by Verena Bastos (verena@uefs.br) on 2015-09-16T23:48:41Z No. of bitstreams: 1 TESE FINAL_Cortes.pdf: 14573536 bytes, checksum: 6e4acc2810a61d9e5ab81fe6e248b786 (MD5) / Made available in DSpace on 2015-09-16T23:48:41Z (GMT). No. of bitstreams: 1 TESE FINAL_Cortes.pdf: 14573536 bytes, checksum: 6e4acc2810a61d9e5ab81fe6e248b786 (MD5) Previous issue date: 2013-08-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The genera Schaueria, Streblacanthus, Pachystachys and Thyrsacanthus represent 25% of the Tetramerium lineage (Acanthaceae: Justicieae), currently with about 40 species, distributed mainly in wetlands and drylands in South America. They are herbaceous or shrubs, with large or filiform bracts and diverse floral morphology, revealing adaptations to different pollinators. Systematic studies in the group are scarce, and the only phylogenetic study (Daniel et al. 2008) included only 10% of the species, not solving the generic limits within the lineage. The biogeography of Neotropical Tetramerium lineage is quite complex, structured in three biomes: the Amazon Forest, the Atlantic Forest and Seasonally Dry Forest. Still, there are no investigations on its diversification. Using phylogenetic and biogeographic methods based on plastid (trnL-F, trnT-L, trnS-G andrps16) and nuclear (ITS)data, we complemented and assessed the previous phylogenetic hypothesis, time-calibrated the phylogeny and reconstructed the ancestral area of Tetramerium lineage, focusing particularly on the South American genera. The analysis showed three well-defined clades and the need for a new circumscription for the genera:1- Schaueria, (excluding S. azaleiflora, S. hirsuta, S. humuliflora, S. malifolia and S. parviflora) including three new species and Justicia paranaensis; 2- Pachystachys, encompassing three species of Streblacanthus (except Streblacanthus monospermus) Schaueria azaleiflora and two new species; and 3- Thyrsacanthus, comprising also Carlowrightia sulcata, Justicia angustissima and Schaueria humuliflora, and another Mexican clade (Justicia zopilotensis, J. gonzalezii, Mirandea hyssopus and Yeatesia mabryi). The lineage originated in the Old World and dispersed to the Neotropics between the Miocene and Pliocene, reaching North America, Central America and Amazon. Between the late Miocene and early Pleistocene, the dry forests lineage expanded and, concomitantly, the rainforests lineageretracted, supporting the idea of a South American dry vegetation belt during this period. The vicariance between blocks of dry forests in southwestern South America and the Caatinga in northeastern Brazil, however, indicates a fragmentation of this vegetation at least in the Lower Pleistocene, well before the Last Glacial Maxima as proposed by the Pleistocene Arc hypothesis. Based on the phylogenetic results, we present a taxonomic revision of the genusSchaueria?including identification keys, descriptions, illustrations, comments, distribution maps and a study of pollen grains and seeds under scanning electron microscopy ? and propose a new circumscription for the genus Pachystachys. Finally, we present a color guide ofphotos for South American species ofTetramerium lineage. / Os g?neros Schaueria, Streblacanthus, Pachystachys e Thyrsacanthus representam 25%da linhagem Tetramerium (Acanthaceae: Justicieae), contando atualmente com cerca de 40 esp?cies, distribu?das principalmente em zonas ?midas e secas da Am?rica do Sul. S?o plantas herb?ceas ou arbustivas, com br?cteas largas ou filiformes e morfologia floral diversa, revelando adapta??es a diferentes polinizadores. Estudos sistem?ticos no grupo s?o parcos, e o ?nico estudo filogen?tico (Daniel et al. 2008) incluiu apenas 10% das esp?cies, n?o resolvendo os limites gen?ricos na linhagem. A biogeografia da linhagem neotropical de Tetramerium ? bastante complexa, estruturada em tr?s biomas: Floresta Amaz?nica, Floresta Atl?ntica e Floresta Sazonalmente Seca. Ainda assim, n?o existem investiga??es sobre sua diversifica??o. Utilizando m?todos filogen?ticos e biogeogr?ficos baseados em dados moleculares plastidiais (trnL-F, trnT-L, trnS-G, rps16) e nucleares (ITS), n?s complementamos e avaliamos a hip?tese filogen?tica pr?via, datamos e reconstru?mos a ?rea ancestral da linhagem Tetramerium, focando particularmente nos g?neros da Am?rica do Sul. As an?lises mostraram tr?s clados bem definidos e a necessidade de uma nova circunscri??o para os g?neros:1- Schaueria (excluindo S. azaleiflora, S. hirsuta, S. humuliflora, S. malifolia e S. parviflora) incluindo tr?s novas esp?cies e Justicia paranaensis; 2- Pachystachys englobando tr?s esp?cies de Streblacanthus (exceto Streblacanthusmonospermus), Schaueria azaleiflora e duas novas esp?cies; e 3- Thyrsacanthus compreendendo tamb?m Carlowrightia sulcata, Justicia angustissima e Schaueria humuliflora, e mais um clado mexicano (Justicia zopilotensis, J. gonzalezii, Mirandea hyssopus e Yeatesia mabryi). A linhagem originou-se no Velho Mundo e dispersou para o Neotr?pico entre o Mioceno e o Plioceno, alcan?ando Am?rica do Norte, Central e Amaz?nia. Entre o final do Mioceno e o in?cio do Pleistoceno, a linhagem de florestas secas se expandiu e, concomitantemente, as linhagens de florestas ?midas se retra?ram, sustentando a ideia de uma diagonal seca neste per?odo. A vicari?ncia entre os blocos de florestas secas no sudoeste da Am?rica do Sul e da Caatinga no nordeste do Brasil, no entanto, indica uma fragmenta??o dessa forma??o pelo menos no Pleistoceno Inferior, bem antes da ?ltima M?xima Glacial, como proposto pela hip?tese do Arco do Pleistoceno. Com base nos resultados filogen?ticos, n?s apresentamos uma revis?o taxon?mica do g?nero Schaueria ? incluindo chaves de identifica??o, descri??es, ilustra??es, coment?rios, mapas de distribui??o e estudo de microscopia de varredura de gr?os de p?len e de sementes ? e propomos uma recircunscri??o para o g?nero Pachystachys. Finalmente, ? apresentado um guia de fotos coloridas para as esp?cies sul-americanas da linhagem Tetramerium.
14

Phytogeography and conservation of neotropical dry forest, with emphasis on Columbia

Banda Rodriguez, Karina Paola January 2017 (has links)
Dry forest is one of the most threatened tropical forests in the world. Human impact has caused its massive transformation but conservation of dry forest has often been neglected across Latin America. In Colombia, less than 10% of the original extension of dry forest remains. This thesis studies the phytogeography of neotropical dry forest and its relevance for conservation using data from 1602 tree species inventories made in dry forests across Latin America and the Caribbean synthesised by The Latin American Seasonally Dry Tropical Forest Floristic Network (DRYFLOR). Clustering and ordination analyses were used to explore the floristic relationships of dry forest across the entire Neotropics, revealing distinctive regional clusters defined by their tree species composition. Colombian dry forests are shown to be part of two wider clusters, one including neighbouring forests in Venezuela and southern Central America, and the second including the inter-Andean dry forests. The high turnover of floristic diversity and endemism within and amongst the main floristic groups demonstrates that to conserve the full species diversity in dry forests across Latin America and the Caribbean will require protecting it simultaneously across multiple regions. A regionally focused study of floristic relationships in the Central American and northern South American dry tropical forest group, using quantitative approaches to conservation prioritization, including a new Conservation Priority Index (CPI), suggests that conservation priority should be placed on the South American Caribbean Coast in the cross-border area of Colombia and Venezuela. This emphasises the need for a biogeographical approach to conservation that cannot be restricted by political borders. Within Colombia, new quantitative floristic data were used to investigate controls of floristic composition in dry forests. Multivariate analyses showed that space related variables explain a larger fraction of the variance of the floristic composition than climatic or edaphic variables. The importance of spatial variables implies that biogeography is a key element in understanding the structure of communities, and that the Andean cordilleras might be acting as geographical barriers isolating these seasonally dry formations. The value of floristic inventory data for assessing the conservation status of tree species using IUCN criteria was assessed in a case of study of the Andean Piedmont dry forest. By combining inventory data from the DRYFLOR database and herbarium records, the number of species for which we have sufficient information to make conservation assessments increases by 16% and the accuracy of predictive species distribution improves for 84% of the species. Together, these results reveal the importance of ecological inventory data as a complementary data source in conservation assessment for dry forest trees in the Neotropics. Finally, the conclusions chapter places these results in the context of conservation planning for Colombian dry forests, including some suggestions for research, policies and actions. These actions include restoration programmes focusing on sustainable harvesting of native dry forest tree species, for example for firewood and other forest resources such as fruits, fibres and medicines. A land use mosaic, including forest fallows and strict conservation areas, may help to guarantee the long-term maintenance dry forest species in Colombia.
15

Restoration of plant diversity and ecosystem functioning: effects of species richness, phylogenetic distance, functional diversity and invasive plants

Pinto, Leonardo Henrique Teixeira 24 May 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-09-19T21:47:36Z No. of bitstreams: 1 LeonardoHenriqueTeixeiraPinto_TESE.pdf: 6347370 bytes, checksum: 7e4c7fd1b6d9c592bdf652c6591c248c (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-09-22T19:20:30Z (GMT) No. of bitstreams: 1 LeonardoHenriqueTeixeiraPinto_TESE.pdf: 6347370 bytes, checksum: 7e4c7fd1b6d9c592bdf652c6591c248c (MD5) / Made available in DSpace on 2017-09-22T19:20:30Z (GMT). No. of bitstreams: 1 LeonardoHenriqueTeixeiraPinto_TESE.pdf: 6347370 bytes, checksum: 7e4c7fd1b6d9c592bdf652c6591c248c (MD5) Previous issue date: 2017-05-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A biodiversidade afeta positivamente diversas fun??es ecossist?micas. No entanto, os mecanismos pelos quais a biodiversidade afeta os ecossistemas ainda s?o pouco compreendidos e requerem novos estudos experimentais destinados a identificar seus componentes. Estudos anteriores sugeriram que comunidades de plantas mais diversas podem proporcionar mais estabilidade aos ecossistemas, devido aos efeitos de complementaridade e redund?ncia. A diversidade das esp?cies de plantas pode atuar em diferentes n?veis das propriedades de um ecossistema. Um exemplo claro ? o efeito da diversidade de plantas sobre a din?mica de nutrientes nos ecossistemas terrestres. A diversidade de plants pode alterar as taxas de ac?mulo de nutrientes no solo e, tamb?m, a carga de nutrientes para os sistemas aqu?ticos. No entanto, os impactos antr?picos nos ecossistemas t?m causado a perda de habitats e, tamb?m, de biodiversidade. Tais perdas acabar?o por comprometer as fun??es dos ecossistemas e seus servi?os associados, que s?o vitais para o bem-estar humano. Portanto, o desenvolvimento de projetos de restaura??o ? fundamental para mitigar os impactos antr?picos e para a conserva??o da biodiversidade. Projetos de restaura??o oferecem a possibilidade de desenvolver um conhecimento s?lido sobre o funcionamento dos ecossistemas diante diferentes tipos de perturba??es. Para alcan?ar esse conhecimento, precisamos realizar experimentos de restaura??o baseados no conhecimento cient?fico para avaliar a variabilidade, a previsibilidade e a confiabilidade do funcionamento dos ecossistemas restaurados. Neste contexto, esta tese de doutorado ? baseada em tr?s experimentos que testaram como a diversidade de plantas e suas caracter?sticas funcionais poderiam influenciar o funcionamento dos ecossistemas restaurados. Os objetivos dessa tese foram: (i) investigar quais esp?cies de plantas e caracter?sticas funcionais s?o mais eficientes paraa reten??o de nutrientes no solo, reduzindo assim as perdas por lixivia??o e seu consequente impacto nos ecossistemas aqu?ticos; (ii) testar os efeitos da riqueza de esp?cies vegetais e da diversidade filogen?tica para o sucesso da restaura??o de uma floresta rip?ria rec?m restaurada (i.e. o sucesso foi medido como produ??o de biomassa e sobreviv?ncia das plantas); e (iii) avaliar a influ?ncia de uma esp?cie de planta invasora sobre as din?micas de nutrientes no solo e na ?gua do solo em comunidades de pastagem com diferentes n?veis de diversidade funcional. Os experimentos realizados para esta tese est?o de acordo com estudos recentes que investigam como diferentes medidas de biodiversidade e, tamb?m, diferentes fontes de estresse podem afetar o funcionamento dos ecossistemas. Os principais resultados desta tese revelam que (i) apenas uma esp?cie de planta (Mimosa tenuiflora) influenciou a limpeza da ?gua e a reten??o de nutrientes do solo. Al?m disso, tra?os funcionais relacionados ao conte?do de mat?ria seca da parte a?rea (SDMC) e ao teor de ?gua da raiz (RWC) foram mais importantes para o controle de fun??es ecossist?micas individuais relacionadas ? reten??o de ?gua e nutrientes no solo. De outro modo, somente tra?os funcionais relacionados ? produ??o de biomassa nas plantas afetaram a multifuncionalidade do ecossistema; (ii) o uso de esp?cies filogeneticamente distantes pode aumentar o sucesso da restaura??o afetando positivamente a produ??o de biomassa nas plantas; e (iii) a diversidade funcional das plantas promoveu, parcialmente, a limpeza da ?gua e, tamb?m, a fertilidade do solo em pastagens restaurados, mas n?o impediu a invas?o. Esp?cies invasoras, por sua vez, comprometem a influ?ncia da diversidade de plantas nativas na din?mica de nutrientes no solo, uma vez que afetam negativamente a produ??o de biomassa das plantas nativas. Esse efeito tem o potencial para criar um feedback positivo para novas invas?es. Tais resultados podem servir de suporte para o desenvolvimento de futuros projetos de restaura??o com ?nfase no controle de esp?cies invasoras e na restaura??o do funcionamento dos ecossistemas, uma vez que pode indicar quais esp?cies s?o mais adequadas para maximizar a fertilidade do solo e, tamb?m, a qualidade da ?gua do solo. Por fim, esta tese oferece uma contribui??o para o aprofundarmos o entendimento a respeito dos feedbacks entre plantas e solos. / Biodiversity positively affects several ecosystem functions. Nevertheless, the mechanisms by which biodiversity affects ecosystems are still poorly understood and call for new experimental studies designed to identify its underlying components. Previous studies have suggested that more diverse plant communities can provide more ecosystem stability due to complementarity and redundancy effects. Plant species diversity can act on different levels of the ecosystem properties. A clear example is the effect of plant diversity on nutrient dynamics of terrestrial ecosystems. Plant diversity can alter rates of soil nutrient accumulation and nutrient loading in aquatic systems. However, human impacts on natural ecosystems are leading to habitat and biodiversity loss. Such losses will ultimately jeopardize ecosystem functions and its associated services that are vital for human well-being. Therefore, the development of adequate restoration projects is paramount to mitigate anthropogenic impacts, while contributing to the conservation of biodiversity. Restoration projects offer the possibility to develop a solid knowledge on the functioning of ecosystems facing disturbance. For achieving this knowledge, we need to conduct theory-based restoration experiments in order to assess the variability, predictability and reliability of functioning from restored ecosystems. In this context, this PhD thesis is based on three experiments testing how plant diversity and functional traits would influence the functioning of restored ecosystems. The objectives are to investigate (i) the plant species and traits that are most efficient for retaining nutrients in the soil, thus reducing nutrient leaching losses and its consequent impact on aquatic systems; (ii) the effects of plant species richness and phylogenetic diversity on restoration success (measured as biomass production and plant survival) in a recently restored riparian forest; and (iii) the influence of an invasive alien plant species on soil and soil water nutrients in communities with different levels of functional diversity. The experiments conducted during this thesis are in accordance with recent studies that investigate how different measures of biodiversity and sources of stress could affect ecosystem functioning. The main results of this thesis reveal that (i) only one species (Mimosa tenuiflora) could influence water cleaning and soil nutrient content. Additionally, plant traits related to shoot dry matter content (SDMC) and root water content (RWC) are more important for controlling individual functions related to water and nutrient retention in the soil, while only traits related to biomass production affected ecosystem multifunctionality; (ii) the use of phylogenetically distant species can increase restoration success by positively affecting plant biomass production; and (iii) plant functional diversity partially promotes water cleaning and soil fertility in restored systems, nevertheless did not prevent invasion. In turn, invasive species disrupts the influence of plant diversity on soil nutrient dynamics by jeopardizing native plant biomass production thus, potentially, creating a positive feedback for further invasions. These results support future restoration projects focusing on invasive species control and ecosystem functions, indicating which species are most suitable for restoration to maximizing soil fertility and soil water quality. Finally, this thesis offers a contribution to the knowledge of plant-soil feedbacks.
16

Children’s Perceptions of the Surroundings Areas to the National Park Cerros de Amotape / Percepciones de los niños de la zona de amortiguamiento del Parque Nacional Cerros de Amotape acerca del bosque aledaño

Hinojosa, Milagros 10 April 2018 (has links)
The Cerros de Amotape National Park (CANP) is a vast Natural Protected Area (NPA) in northwestern Peru, which contains a great diversity of plants and animals, many of which are endangered and are unique in our country. Currently, this park is being reduced due to logging and cattle ranching. Most of the studies in the area have identified the inhabitants of the buffer zone of the CANP as responsible for its degradation, without investigating exhaustively their points of view and knowledge, which is considered essential for understanding social and environmental problems. This is the reason why I decided to investigate the deterioration ofthis park from the people´s perspective (adults and children) of the villages «Los Encuentros de Pilares» (LEP) and «El Chaylo» (ECH), both settled in the buffer zone of the park. My focusin this paper is only on the children’s perception of these villages about the CANP. The main objective is to explain the behavior linked to the park by the population of both villages, and the specific objectives are to characterize their perceptions and knowledge regarding the CANP. Researches on the perception of the populations of the NPA, and specifically the children, are very rare in our country. Thus, this study aims to provide a small contribution to the knowledge of the subject. On the methodological side, I adopted the approach and instruments of the geography of perception, and used a qualitative methodology, which demonstrated to be very effective in understanding the problematic. Also, the use of mental maps proved to be a quite valuable resource that allowed children to reveal their perceptions in a fun and dynamic way. Among the results, I found that the children’s perceptions from the two villages are contrasting. Whereas the children from ECH possess a strong ownership and identification with the CANP, they have not been instructed about their problems; in LEP instead, the children do make a difference between their village and the park, and they have a strong awareness oftheir problems and the importance of their protection. / El Parque Nacional Cerros de Amotape (PNCA) es un Área Natural Protegida (ANP) inmensa en la costa norte del Perú, que contiene una gran diversidad de especies vegetales y animales, muchas de las cuales están en peligro de extinción y son únicas en todo el Perú. Actualmente, este Parque se está reduciendo cada vez más debido a la tala y a la ganadería extensiva. La mayoría de estudios realizados sobre el área han identificado a los pobladores de la Zona de Amortiguamiento (ZA) del PNCA como unos de los principales responsables de su degradación, sin conocer a profundidad sus opiniones y conocimientos, lo cual se considera esencial. Esta es larazón por la cual se decidió investigar el proceso de deterioro del PNCA desde la óptica de los pobladores (adultos y niños) de los caseríos «Los Encuentros de Pilares» (LEP) y «El Chaylo» (ECH), asentados dentro de la ZA del parque. En este artículo nos centraremos únicamente en la percepción de los niños de estos caseríos. El objetivo principal es explicar el comportamiento ligado al PNCA por parte de la población de ambos caseríos, para lo cual se plantearon como objetivos específicos caracterizar sus percepciones y conocimientos respecto al PNCA.Las investigaciones de corte geográfico respecto a la percepción de las poblaciones de las ANP, y específicamente la de los niños, son muy escasas en nuestro país. Es así que este estudio pretende aportar una pequeña contribución al conocimiento del tema. En cuanto al aspecto metodológico, se adoptó el enfoque y los instrumentos de la geografía de la percepción, empleando una metodología cualitativa, que demostró ser muy efectiva para entender esta problemática. Así, el empleo de los mapas mentales resultó un recurso bastante valioso que permitió que los niños revelasen sus percepciones sobre el PNCA de una maneraamena y dinámica. Entre los resultados, encontramos que existe una situación contrastante respecto a las percepciones de los niños de ambos caseríos, pues mientras que en ECH existe una apropiación e identificación fuerte con el PNCA, estos no han sido sensibilizados sobre su problemática; en LEP en cambio, los niños sí marcan una diferencia entre su caserío y el Parque, y presentan una fuerte sensibilización sobre su problemática y la importancia de su protección.
17

Efeito de pertubações antrópicas crônicas sobre a diversidade da flora lenhosa da caatinga

RIBEIRO, Elâine Maria dos Santos 25 February 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-15T14:44:30Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Elâine_Ribeiro_TESE_PPGBV.final_V2.pdf: 8805946 bytes, checksum: 49c5072b57c8b0d0264ac0e02e425dc3 (MD5) / Made available in DSpace on 2016-07-15T14:44:30Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Elâine_Ribeiro_TESE_PPGBV.final_V2.pdf: 8805946 bytes, checksum: 49c5072b57c8b0d0264ac0e02e425dc3 (MD5) Previous issue date: 2015-02-25 / FACEPE / Este estudo teve como objetivo investigar quais os efeitos de perturbações antrópicas crônicas (e.g. coleta de madeira e de produtos florestais não madeireiros, pastoreio extensivo, caça e danos causados à vegetação pela introdução de espécies exóticas que ocorrem em áreas remanescentes de floresta) sobre a diversidade taxonômica e filogenética da flora lenhosa da Caatinga. Inicialmente, investigamos como se dá a questão da perturbação crônica da flora e seus efeitos sobre a biodiversidade através da revisão de 51 artigos que tratam do tema. Verificamos que estes estudos, em sua maioria, foram realizados em países em desenvolvimento, cujas populações humanas utilizam a floresta para subsistência e comércio. Os efeitos da perturbação foram acessados principalmente ao nível de populações e comunidades, sendo a coleta de produtos florestais não madeireiros a fonte de impacto mais analisada. Os efeitos sobre a biodiversidade foram em geral negativos, mas efeitos neutros e positivos também foram registrados. O segundo capítulo traz um estudo de caso que verifica a influência das perturbações humanas crônicas sobre a diversidade e composição taxonômica da flora lenhosa da Caatinga, realizado em várias propriedades privadas na cidade de Parnamirim-PE, Brasil. Neste estudo foram amostradas comunidades lenhosas de adultos, jovens e plântulas, e como preditores da perturbação crônica utilizaram-se a densidade de pessoas e animais domésticos (caprinos e bovinos), além de indicadores de acessibilidade às áreas, como a distância ao centro urbano mais próximo, à estrada mais próxima e à propriedade rural mais próxima às parcelas amostradas. Esses preditores tiveram em geral efeitos negativos sobre a diversidade taxonômica independente do estágio ontogenético, sendo a densidade de pessoas e de animais os preditores mais importantes desses efeitos. Verificouse ainda que a composição das espécies nas áreas perturbadas foi distinta, sendo pouco representada pela abundância de espécies de madeira densa nas áreas mais perturbadas. O terceiro e último capítulo verificou como as comunidades lenhosas de adultos, jovens e plântulas da Caatinga, amostradas no capítulo anterior, são afetadas pela perturbação crônica do ponto de vista de diversidade e estrutura filogenética. Neste capítulo, utilizaram-se os mesmos preditores da perturbação citados anteriormente, porém agora combinados em um índice de perturbação crônica. A diversidade de famílias esperadas para história evolutiva da região e a distância média entre os indivíduos dessas comunidades, medida em anos, foi reduzida em ambientes mais perturbados e para todos os estágios ontogenéticos. As comunidades de jovens e de plântulas apresentaram maior grau de parentesco em áreas mais perturbadas, sendo os táxons Euphorbiaceae e Cnidoscolus responsáveis por esse aumento de parentesco. Os resultados desta tese demonstram que as perturbações antrópicas crônicas na Caatinga não podem ser negligenciadas, pois conferem efeitos negativos importantes à diversidade taxonômica e filogenética da flora lenhosa. Dessa forma, estratégias de manejo que conciliem o uso dessas florestas e a manutenção da biodiversidade da Caatinga são urgentes. / The aim of this study was to investigate the effect of chronic anthropogenic disturbances (e.g. harvesting of timber and non-timber forest products, hunting, livestock, and damage to vegetation caused by exotic species that occur in natural remnant forests) on the taxonomic and phylogenetic diversity of wood flora from Brazilian Caatinga. Initially, 51 scientific papers were revised in order to investigate how chronic anthropogenic disturbances affect the flora of natural ecosystems. Most studies were conducted at developing countries, where human populations use forest resources for subsistence and commerce. Chronic disturbance effects were accessed mainly at population and community levels, and harvesting of nontimber forest products was the disturbance source more frequently analyzed in those papers. Effects of the chronic disturbances were in general negative, however positive and neutral effects were also documented. The second chapter brings a case study that evaluates the influence of chronic disturbances on the taxonomic diversity and composition of Caatinga wood flora from private propreties at the municipality of Parnamirim-PE, Brazil. Adult, sapling and seedling of wood plant communities were sampled, and the density of people and livestock (goats and catle) near the plot were used as predictors of chronic disturbance, as well as the distances to the nearest urban centre, road and rural property. In general, these disturbance predictors showed negative effects on taxonomic diversity irrespective to ontogenetic stage. Moreover, the density of people and livestock near the plot were the main predictors of these negative effects. Species composition differed between plots with low and high level of disturbance, especially in relation to hard wood species, which were rare in the plots highly disturbed. The third and last chapter analyzed how the adult, sapling and seedling communities, surveyed previously, were affected by chronic disturbances from the viewpoint of the phylogenetic diversity and structure. In this chapter the chronic disturbance predictors described above were combined into a chronic disturbance index. The diversity of families expected to the local evolutionary history and the mean phylogenetic distance between the individuals were reduced in plots with higher level of disturbance for all ontogenetic stages. Sapling and seeedling communities had higher degree of relatedness in most disturbed sites, being Euphorbiaceas and Cinidoscolus taxa responsible for this increasing in the relatedness degree. Overall, this thesis demonstrates that chronic anthropogenic disturbance at Caatinga could not continue to be neglected, as it imposes deleterious effects to the taxonomic and phylogenetic diversity of wood plant assemblages. Management strategies conciliating forest use and the maintenance of Caatinga biodiversity are urgent.
18

Ecologia da madeira e aspectos ecofisiológicos foliares de quatro espécies de florestas tropicais secas no estado de Sergipe

Aragão, José Roberto Vieira 15 February 2017 (has links)
Global climate change has severe consequences at various trophic levels, especially tree plant species. In regions of Tropical Dry Forests (TDF) these impacts are extreme and still little studied. This work evaluated how environmental conditions (local, regional and global), imminent climate changes, influenced the dendroecology, wood anatomy and foliar ecophysiology of four tree species occurring in the TDF of two sites, Sergipe, Grota do Angico Natural Monument, and in a remnant of TDF in Fazenda São Pedro, municipality of Porto da Folha, Sergipe. Samples of wood and leaves of six individuals of each species, Aspidosperma pyrifolium, Ziziphus joazeiro, Tabebuia aurea and Libidibia ferrea were randomly collected. For each individual, three wood samples were collected, two for dendroecology and one for the anatomy of the wood. Leaves, of the same plants were collected at both sites, in the dry and rainy periods, and intended for the ecophysiological analyzes. Collection data on species distribution (SpeciesLink project) were used in the construction of ecological niche models (ENM). Historical climate datas were obtained from INMET, AGRITEMPO, state data, the WolrdClim project, and the NOAA. The results of the dendroecological analyzes showed the formation of annual growth rings in the four species, that the chronologies of all the taxa have a significant relation with rainfall events in both sites, and some taxa had the chronologies related to the surface temperature of the Atlantic Ocean (TSA) and ENSO events, indicating a decrease in plant growth accompanied by lower rainfall volumes in the last decade. The ENM showed different responses of the species niche to the environmental variables (precipitation and temperature) in the TDF, with significant correlations with the anatomical and physiological data, and showed the occurrence of distinct functional groups among the taxa, changing as a function of the changes in the climate. The present study confirmed that the four TDF species have dendroecological potential for climate response, and that ENM's in line with functional (anatomical and physiological) traits analysis may be a viable solution to evaluate the responses of these taxa To xeric environments, in addition to serving as diagnoses of future global climate change, given its high correlation with the functional modifications of the species evaluated here. / As mudanças climáticas globais geram consequências severas em diversos níveis tróficos, em especial às espécies vegetais arbóreas. Em regiões de Florestas Tropicais Secas (FTS) estes impactos são extremos e ainda pouco estudados. Este trabalho avaliou como as condições ambientais (locais, regionais e globais), iminentes as mudanças do clima, influenciaram na dendroecologia, anatomia da madeira e ecofisiologia foliar de quatro espécies arbóreas ocorrentes na FTS de dois locais em Sergipe, no Monumento Natural Grota do Angico, e em um remanescente de FTS na Fazenda São Pedro, município de Porto da Folha, Sergipe. Foram coletadas aleatoriamente amostras de madeiras e folhas de seis indivíduos de cada espécie, Aspidosperma pyrifolium, Ziziphus joazeiro, Tabebuia aurea e Libidibia ferrea. Para cada indivíduo foram coletadas três amostras de madeira, duas destinadas a dendroecologia e uma a anatomia da madeira. Folhas, das mesmas plantas foram coletadas nos dois locais, nos períodos seco e chuvoso, e destinadas às análises ecofisiológicas. Dados de coleções sobre a distribuição das espécies (projeto SpeciesLink) foram utilizados na construção de modelos de nicho ecológico (MNE). Dados climáticos históricos foram obtidos das plataformas do INMET, AGRITEMPO, estações estaduais, do projeto WolrdClim, e do NOAA. Os resultados das análises dendroecológicas mostraram formação de anéis de crescimento anuais nas quatro espécies, que as cronologias de todos os táxons possuem relação significativa com eventos de chuva em ambos os locais, e alguns táxons tiveram as cronologias relacionadas com a temperatura da superfície do Oceano Atlântico (TSA) e eventos de ENOS, indicando diminuição no crescimento das plantas acompanhando menores volumes de chuvas na última década. O MNE mostrou diferentes respostas do nicho das espécies às variáveis ambientais (precipitação e temperatura) nas FTS, com correlações significativas com os dados anatômicos e fisiológicos, e mostraram a ocorrência de grupos funcionais distintos entre os táxons, se alteram em função das mudanças no clima. O presente estudo confirmou que, as quatro espécies no FTS possuem potencial dendroecológico de resposta ao clima, bem como que MNE’s em consonância com a análise de traços funcionais (anatômicos e fisiológicos) podem ser uma solução viável para avaliação das respostas destes táxons a ambientes xéricos, além de servir como diagnósticos das mudanças climáticas globais futuras, vista sua alta correlação com as modificações funcionais das espécies aqui avaliadas.
19

Linking agents, patterns and outcomes of forest disturbances to understand pathways of degradation in the Argentine Dry Chaco

De Marzo, Teresa Rita 17 November 2023 (has links)
Tropische Trockenwälder sind von großer Bedeutung für das Klima, die biologische Vielfalt und den Lebensunterhalt von Millionen von Menschen. Die Walddegradation bedroht die tropischen Trockenwälder, aber es fehlt an Wissen über ihre Muster, ihr Ausmaß und ihre Ursachen. Ziel dieser Arbeit war es, das derzeitige Verständnis der Walddegradation im argentinischen Dry Chaco mit Hilfe der Fernerkundung zu verbessern. Mithilfe des Landsat-Archivs habe ich die Störungsgeschichte des verbleibenden Waldes charakterisiert, die räumlichen und zeitlichen Muster der Störungsfaktoren bewertet und die langfristigen Auswirkungen der verschiedenen Faktoren auf die Waldstruktur untersucht. Die Ergebnisse zeigen, dass über 30 Jahre hinweg große Gebiete des argentinischen Dry Chaco (etwa 8 %) von Störungen betroffen waren. Meine Ergebnisse zeigen einen anthropogenen Zusammenhang mit den meisten Störungsarten, deuten aber auch auf einen komplexen indirekten Einfluss von Niederschlagsmustern hin, wobei Waldstörungen in Dürrejahren besonders verbreitet sind. Die Analyse der zeitlichen Muster der verschiedenen Einwirkungen zeigt Trends in der Landnutzung im Laufe der Zeit, wobei neue Landnutzungsformen wie silvopastorale Systeme entstehen und alte Praktiken wie die Abholzung jedes Jahr einen relativ stabilen Anteil der Flächen betreffen. Die Ergebnisse zu den langfristigen Auswirkungen von Störungen zeigen, dass sich die Waldstruktur bei den am weitesten verbreiteten Störungen über drei Jahrzehnte kaum oder gar nicht erholt, was auf eine großflächige Walddegradation schließen lässt. Diese Arbeit zeigt das Potenzial von Satellitenzeitreihen für eine robuste Charakterisierung der Walddynamik im Zusammenhang mit der Degradation auch in tropischen Trockenwäldern. Die aus dieser Arbeit resultierenden Karten, Ansätze und Erkenntnisse tragen zu einem besseren Verständnis der Walddegradation im Dry Chaco bei und können zu einem wirksameren Schutz der tropischen Trockenwälder beitragen. / Tropical dry forests are of great importance for climate regulation, harbour biodiversity and sustain the livelihood of millions of people. Deforestation and degradation threaten tropical dry forests but whereas our understanding of tropical deforestation has increased tremendously over the last decades, knowledge of the patterns, extent and drivers of forest degradation is lacking. This thesis aimed to advance the current understanding of forest degradation in the Dry Chaco by means of remote sensing. Using the Landsat archive, I characterized the disturbance history of the remaining Argentine Dry Chaco forest, assessed spatial and temporal patterns of disturbance agents, and investigated the long-term effect of different agents on forest structure. Results show that over 30 years large areas of the Argentine Dry Chaco (about 8%) were affected by disturbances. My findings reveal an anthropogenic link to most types of disturbances, while also suggesting complex indirect influence of precipitation patterns, with forest disturbances being particularly widespread during drought years. The analyses of temporal patterns of different agents reveals trends in land-use practices over time, with new land uses emerging, such as silvopastoral systems, and old practices such as logging, affecting a fairly stable share of areas every year. Findings on the long-term impact of disturbances indicate that for the most widespread disturbances, forest structure shows little or no recovery over three decades, which suggests forest degradation affecting large areas. This thesis demonstrates the potential of satellite time series for robust characterization of forest dynamics related to degradation also in tropical dry forests, despite the complex conditions these systems represent. The maps, approaches and knowledge resulting from this thesis contribute to a better understanding of forest degradation in the Dry Chaco and can inform more effective conservation of tropical dry forests.
20

Potential effects of climate change and fire management on fire behavior and vegetation patterns on an east Cascades landscape

Greaves, Heather E. 17 October 2012 (has links)
Climate exerts considerable control on wildfire regimes, and climate and wildfire are both major drivers of forest growth and succession in interior Northwest forests. Estimating potential response of these landscapes to anticipated changes in climate helps researchers and land managers understand and mitigate impacts of climate change on important ecological and economic resources. Spatially explicit, mechanistic computer simulation models are powerful tools that permit researchers to incorporate climate and disturbance events along with vegetation physiology and phenology to explore complex potential effects of climate change over wide spatial and temporal scales. In this thesis, I used the simulation model FireBGCv2 to characterize potential response of fire, vegetation, and landscape dynamics to a range of possible future climate and fire management scenarios. The simulation landscape (~43,000 hectares) is part of Deschutes National Forest, which is located at the interface of maritime and continental climates and is known for its beauty and ecological diversity. Simulation scenarios included all combinations of +0��C, +3��C, and +6��C of warming; +10%, ��0%, and -10% historical precipitation; and 10% and 90% fire suppression, and were run for 500 years. To characterize fire dynamics, I investigated how mean fire frequency, intensity, and fuel loadings changed over time in all scenarios, and how fire and tree mortality interacted over time. To explore vegetation and landscape dynamics, I described the distribution and spatial arrangement of vegetation types and forest successional stages on the landscape, and used a nonmetric multidimensional scaling (NMS) ordination to holistically evaluate overall similarity of composition, structure, and landscape pattern among all simulation scenarios over time. Changes in precipitation had little effect on fire characteristics or vegetation and landscape characteristics, indicating that simulated precipitation changes were not sufficient to significantly affect vegetation moisture stress or fire behavior on this landscape. Current heavy fuel loads controlled early fire dynamics, with high mean fire intensities occurring early in all simulations. Increases in fire frequency accompanied all temperature increases, leading to decreasing fuel loads and fire intensities over time in warming scenarios. With no increase in temperature or in fire frequency, high fire intensities and heavier fuel loads were sustained. Over time, more fire associated with warming or less fire suppression increased the percentage of the landscape occupied by non-forest and fire-sensitive early seral forest successional stages, which tended to increase the percentage of fire area burning at high severity (in terms of tree mortality). This fire-vegetation relationship may reflect a return to a more historical range of conditions on this landscape. Higher temperatures and fire frequency led to significant spatial migration of forest types across the landscape, with communities at the highest and lowest elevations particularly affected. Warming led to an upslope shift of warm mixed conifer and ponderosa pine (Pinus ponderosa) forests, severely contracting (under 3�� of warming) or eliminating (under 6�� of warming) area dominated by mountain hemlock (Tsuga mertensiana) and cool, wet conifer forest in the high western portion of the landscape. In lower elevations, warming and fire together contributed to significant expansion of open (<10% tree canopy cover) forest and grass- and shrubland. The compositional changes and spatial shifts simulated in the warming scenarios suggest that climate change is likely to significantly affect forests on this landscape. Warming and associated fire also tended to increase heterogeneity of forest structural stages and landscape pattern, resulting in a more diverse distribution of structural stages, especially in lower elevations, and a more divided landscape of smaller forest stands. The NMS ordination emphasized the dissimilarity between the severe +6�� scenarios and the other two temperature scenarios. The +0�� and +3�� scenarios differed from each other in composition (mainly because cool forest was lost in the +3�� scenarios), but within a given level of fire suppression they remained remarkably similar in terms of overall composition, structure, and landscape pattern, while the +6�� scenarios separated noticeably from them. Such decisive differences suggest that under the simulated ranges of precipitation and fire suppression, the interval between 3 and 6 degrees of warming on this landscape may capture an ecological threshold, or tipping point. Additional simulation research that incorporates (for example) management actions, insects and pathogens, and a wider array of precipitation scenarios could help illuminate more clearly the possible range of future landscape conditions. Still, these results provide a glimpse of potential divergent outcomes on this important landscape under possible future climates, and suggest that these forests will undergo considerable changes from both historical and current conditions in response to higher temperatures expected in this area. Some changes may be inevitable with warming, such as the upslope shift of warm forest types, but careful planning for fire and fuels management might allow land managers to modulate fire behavior and steer vegetation dynamics toward the most desirable outcome possible. / Graduation date: 2013

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