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Planet Earth is undergoing a rapid rate of ecosystem conversion and degradation and one of the major challenges of current environmental science is to contribute to the management and conservation of biodiversity through the development of tools for assessing environmental change. The main goal of this doctoral dissertation is to contribute to the scientific literature on remote sensing tools for monitoring tropical dry forests, which is one of most important global change frontiers. This thesis is composed of five chapters which have the goals of covering the following specific goals: 1) To estimate the extent and geographic distribution of the neotropical dry forest. 2) To evaluate the potential use of satellite-detected fires as deforestation predictors in tropical dry forest and 3) To evaluate the potential of remote sensing techniques to detect edge effects in tropical dry forest. Before assessing the main goals of the thesis, in chapter two, Integrating Remote Sensing and Biodiversity research, we stress out the necessity of integrated assessments using multiple spatial and spectral resolution sensors over a wide array of ecosystems in order to find relevant ecosystem properties that would be sensitive to species richness. Chapter three, Extent and Conservation of tropical dry forests in the Americas, describes a regional scale mapping effort using coarse-scale imagery (MODIS 500-m) of the extent and geographical distribution of tropical dry forests that introduces several innovations to previous assessments. Based on these techniques, the total current extent of tropical dry forest in the Americas is 519,597 Km2. I also found that 66% of the ecosystem has been already converted to other land uses while only 4.5 % of is under protected areas. Chapter four, MODIS Active fires and deforestation in tropical dry forest landscapes, we show correlations patterns between the number of MODIS Active Fires and forest cover change in four tropical dry forest landscapes in Latin America. At the Santa Cruz site (Bolivia), correlations were strong and significant while at Chamela Site (Mexico) and the Mata Seca site (Brazil) correlations were moderate but significant as well. In the Machango site (Venezuela), active fires showed no correlation to deforestation events. In general, our findings show that fires detected by the MODIS sensor may be used as predictors of deforestation in tropical dry forest ecosystems. Chapter five, Edge influence on canopy openness and understory microclimate in two Neotropical dry forest fragments, addresses one of the most characteristic features of fragmented tropical forests: the increase in disturbance near the edges of the fragment or what is known as edge effects. Results in gap fraction and Fraction of Intercepted Photosynthetically Active Radiation (FiPAR) show that edge influence at tropical dry forest sites extend to at least 300-m. Finally, Chapter Six, Remote sensing of edge effects in dry forest fragments using CHRIS/Proba Imagery, shows an assessment of changes in the fraction of intercepted photosynthetically active radiation (FiPAR) across four edge-to-interior transects in tropical dry forests fragments and their correlation to spectral vegetation indices (SVIs) computed from the hyperspectral and multiangular CHRIS sensor on board the Proba platform. Results show that the use of spectral vegetation indices for identifying and quantifying edge effects in tropical forests have the potential to improve modeling of forest disturbance in fragmented landscapes. The work contained in these five chapters address issues that are critical to the advancement of tropical dry forest monitoring. These studies contribute to the current scientific literature on the use and application of optical remote sensing tools, not only applicable in tropical dry forests, but for tropical forest conservation at the continental, regional and local level.

Our knowledge of whether hurricanes cause lasting changes in forest composition and the patterns and role of fire in Caribbean dry forests are lacking. This project combines paleoecological and paleotempestological methods to document the disturbance and environmental history of the last 1000 yrs at Laguna Alejandro, situated in the lowland dry forests of arid SW Dominican Republic. I analyzed multiple proxy data sources of a 160 cm coastal lagoon sediment profile. High-resolution (1 cm) sampling for loss-on-ignition and magnetic susceptibility indicated multiple erosion and hurricane events, including a hurricane ~996 cal YBP, and several erosion events and hurricanes between ~321 cal YBP and present day. Pollen analysis documented 32 plant families with most levels dominated by pollen of Fabaceae (legumes), the Urticales order, and Cyperaceae (sedges), though families of upland and montane vegetation are also present ~510-996 cal YBP. All pollen slides contained microscopic charcoal indicating the occurrence of regional or extra-local fires over the last ~1000 yrs. Local fires, as indicated by macroscopic charcoal, occurred before ~434 cal YBP and may be tied to hurricanes, increased moisture in the region (thereby increased fuel and ignition chances), or prehistoric human activities. Pollen spectra representing periods before and after disturbance events were similar and may support the idea of forest resilience, but more samples are needed. Multiple erosion events between ~294 cal YBP and present may be tied to hurricanes or tropical storms and increasing late-Holocene aridity in the region as documented by several studies from the Caribbean. / Master of Science

Climate models predict changes to the frequency and intensity of extreme events, with large effects on tropical forests likely. Predicting these impacts requires understanding how landscape configuration and land-use change influence the susceptibility of forests to disturbances such as wind, drought, and fire. This is important because most tropical forests are regenerating from anthropogenic disturbance, and are located in landscape mosaics of forest, agriculture, and other land use. This dissertation consists of four chapters that combine remote sensing and field data to examine causes and consequences of disturbance and land-use change in tropical second-growth forests. In Chapter 1, I use satellite data to identify factors associated with permanence of second-growth forest, and assess how estimates of carbon sequestration vary under different assumptions about second-growth forest permanence. I show that most second-growth forest is cleared when young, limiting carbon sequestration. In Chapter 2, I combine data from weather stations, remote sensing, and landowner surveys to model fire activity on 732 farms in the study area over ten years. The relative importance of these factors differs across scales and depending on the metric of fire activity being considered, illustrating how implications for fire prevention and mitigation can be different depending on the metric considered. Chapter 3 combines Landsat imagery and field data to map wind damage from a severe convective storm, providing strong empirical evidence that vulnerability to wind disturbance is elevated in tropical forest fragments. Finally, in Chapter 4 I integrate annual forest census data with LiDAR-derived topography metrics and tree functional traits in a hierarchical Bayesian modeling framework to explore how drought, topography, and neighborhood crowding affect tree growth, and how functional traits modulate those effects. The results from these studies demonstrate innovative approaches to understanding spatial variation in forest vulnerability to disturbance at multiple scales, and the results have implications for managing forests in a changing climate.

Over the last 2000 years, climatic and anthropogenic factors have influenced vegetation in Madagascar, but the contribution of these two factors has been the subject of intense debate, a debate hampered by the scarcity of palaeoecological studies on the island. Southwest Madagascar is semi-arid and comprises fragmented tropical dry forests where human subsistence strategies are diverse. Therefore, it provides a perfect setting to generate new palaeoecological records and investigate vegetation response to changes in human land-use and rainfall variability. The aim of this thesis is to understand how and when land-use changed, and rainfall variability impacted the landscape in the southwest region, using dendroclimatological and palaeoecological approaches. Carbon isotopes in the rings of four baobab trees (Adansonia spp.), were compared with pre-existing palaeoclimate data to produce rainfall records for the past 1700 years. Pollen, carbon isotopes, and charcoal in sediment cores from two lakes namely Lake Longiza and Lake Tsizavatsy (located in the northern and southern sites respectively in southwest Madagascar) were analysed to produce vegetation and fire records during the late Holocene in the region. Combination of the four baobab isotope records yields a new 700-year record for the southwest, which suggests an aridity trend over time, associated with a long-term reduction and increase in the duration of wet and dry periods respectively. Drying was more pronounced for the southern site than the northern site. A comparison with a high-resolution record from the northwest region allowed the rainfall of the southwest to be extended back to the last 1700 years as follows: from AD 300-500, the southwest region experienced a dry period which was followed by a wet period until AD 1000. Subsequently, there was a dry period from AD 1000-1250, followed by a wet period in the southwest. The period from AD 1300-1400 represented the wettest period in the record, followed by a decreasing wet period until AD 1600. The period between AD 1600 and 1800 represented the driest period, peaking around AD 1700. This was followed by a relatively wet period of about 50 years and another 100-year dry period. The last period assessed, from AD 1985 to 2000, was a relatively wet period. Such variability of the rainfall might have affected ecosystems and human land-use in the region. The tropical dry forest biome of southwest Madagascar has taxa from the dry forest, riparian forest and savanna woodland in the pollen records of both sites. In the core from the northern site (Lake Longiza), the pollen record suggests a heterogeneous mosaic of dry forest and riparian forest that was present over the last 2400 years. In the earliest part of the record, the community was dominated by trees from both the dry forest and riparian ecosystems. The onset of changes was recorded around AD 420, with a decrease in dry forest and riparian trees and an increase in grasses and xerophytics, possibly driven by dry conditions. This was followed by a short recovery of trees and C3 plants around AD 870 punctuated by a decrease in dry forest taxa around AD 980, possibly associated with the suggested expansion of pastoralism. After this period, the landscape became more open and grassier, as indicated by the dominance of C4 plants in the stable isotope record. Similar patterns of change in the pollen record, with a further increase in grasses and pioneer taxa, were recorded around AD 1900. Charcoal influx also started to increase drastically at this time, suggesting fire and forest clearance associated with a shift to agriculture. These large shifts in human land-use (probably a combination of both pastoralism and agriculture) coincided with the decline of floral diversity of the landscape, as indicated by pollen rarefaction. However, the diversity of the floral community gradually recovered, because of the persistent heterogeneity of the landscape. The core from the southern site (Lake Tsizavatsy) had a basal date of approximately 700 years BP but presented a hiatus of about 500 years from AD 1420-1910. The preceding period of AD 1300-1420 was marked by a decrease in the abundance of trees during the wettest period in the region, which was most likely because of human activities (foraging and pastoralism), as inferred by the increase in charcoal influx and pioneer taxa. During the second period, from AD 1910- 2010, there was an increase in xerophytic taxa, which suggests a long dry climate, recorded prior to this period. In addition, from AD 1950, trees decreased while pioneer taxa increased, despite the stable influx of charcoal recorded during this period. This possibly indicates the effect of human activities that did not involve the use of fire, probably conducted by ethnicities other than the forager communities, which are still present in the area today. This thesis contributes significantly to the understanding of palaeoclimate, palaeoecology and the history of human subsistence in a biodiverse region of Madagascar, where no other record is currently available. Results from stable isotope analysis from baobabs showed a drying trend over the past 700 years, which has interacted with land-use to affect vegetation structure and composition over time. The pollen and charcoal results suggest the northern site, where vegetation was a mosaic of dry forest and riparian forest, experienced an impact of human activities through a shift to agriculture especially in the last 100 years. The savanna woodland of the southern site, however, was less affected by humans, probably as occupants were subsistence foragers, but the vegetation had a higher response to aridity. The results show that two distinctive human subsistence (pastoralism and foraging) were present simultaneously in the region until modern times. The northern site has evolved possibly from foraging into extensive agriculture, probably related to the fertility of the alluvial soil in the area, while the southern community remained dominated by foragers, while adopting today a seasonal practice of agriculture. From a conservation perspective, strategies of conservation for each ecosystem investigated here are proposed. In the northern site, monitoring and reducing fire-use within the dry forest ecosystem would allow tree recovery. In addition, restoring and establishing protected areas within the riparian forest would allow these ecosystems to act as refugia for regional biodiversity. Such measures will likely reduce the pressure on these ecosystems, where agriculture is a threat due to the availability of both water and fertile soil in their surroundings. Alternative livelihoods are required for the northern populace, for example through the exploitation of invasive aquatic plants such as Typha, which can be used in making of handcrafted artefacts, to reduce pressure on forest ecosystems through agricultural practices. For the southern site, maintaining the resilience of the savanna woodland through reforestation of functional species is also important to allow sustainability of services provided by these ecosystems. These strategies are applicable locally for Madagascar and for worldwide tropical dry forests, one of the globally most threatened vegetation types due to anthropogenic pressure and climate change.

Ecological restoration has the potential to provide a multitude of benefits, such as conserving biodiversity and supporting natural-resources dependent livelihoods. Tropical dry forests (TDFs) occur in densely populated human-modified landscapes in the tropics and are susceptible to degradation, making them an important biome to restore when degraded. TDFs are also socio-ecological systems, where local people rely on the forest for subsistence and livelihoods and effectively manage them for desire outcomes. People’s reliance on TDFs necessitates restoration projects to take into account more than biophysical and abiotic considerations when they are designed. In this decade of restoration, while there is the much-needed impetus to restore degraded land, to achieve enduring and just outcomes at large spatial scales, restoration projects need to more intentionally address local considerations, such as traditional land tenure systems and livelihood strategies, and goals such as socio-economic development. At the same time, to guide restoration efforts and realistically forecast the consequences of these efforts in the future, there is a need for rapid and accurate assessment tools to quantify the impact of restoration on biodiversity and people at several time steps. In Chapter 1, I use India, a country with high biophysical potential for restoration, as a case study to demonstrate a people-centric approach for identifying restoration opportunities. I find that there is a large overlap between areas of high biophysical restoration potential and high poverty, indicating potential and need to pursue restoration in a manner that addresses both ecological and social goals. In Chapter 2, I study a commonly adopted livelihood strategy, seasonal migration, in forest-dependent communities in India. I find that households in more agricultural and prosperous districts experience lower rates of migration but are more sensitive to climatic variability than households in poorer districts. In Chapter 3, I examine the impact of ecological restoration of a tropical dry forest in central India (CI). I find no significant difference in the cumulative number of bird species detected, but a significant difference in bird communities across the sites. In the lower frequencies dominated by birds and insects, I find that restored sites were positively associated with acoustic space occupancy in comparison to unrestored and low Lantana density (LLD) sites. In Chapter 4, I study the combined socio-ecological outcomes of restoration in the same sites in CI. I find that in the absence of alternative, people rely on Lantana camara, an invasive shrub, for subsistence and livelihoods, in the form of firewood and farm boundaries. I do not find any significant effect of restoration or LLD on people’s perception of ease of forest use, except for the distances covered for grazing, an important indicator of restoration success in this landscape. Finally, I also find that restoration is not associated with any significant changes in soundscapes in the higher frequency ranges dominated by insects and bats. Taken together, my chapters contribute to a greater understanding of the potential for restoration to meet social and ecological goals, the vulnerability of the livelihoods of people living on forest-fringes of TDFs to climate variability and expected and unexpected socio-ecological outcomes of restoration.

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.

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.

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.

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.