1,721,033 research outputs found
Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia
No full textMustafa, Nur-Zati A., Salim, Hannah M. W., Fletcher, Christine, Kassim, Abd Rahman, Potts, Matthew D. (2011): Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia. Raffles Bulletin of Zoology 59 (2): 181-194, DOI: http://doi.org/10.5281/zenodo.1010718
Environmental and geographic factors driving dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) diversity in the dipterocarp forests of Peninsular Malaysia
No full textDoll, Hannah M., Butod, Elizabeth, Harrison, Rhett D., Fletcher, Christine, Kassim, Abd Rahman, Ibrahim, Shamsudin, Potts, Matthew D. (2014): Environmental and geographic factors driving dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) diversity in the dipterocarp forests of Peninsular Malaysia. Raffles Bulletin of Zoology 62: 549-560, DOI: http://doi.org/10.5281/zenodo.535447
Fig. 3 in Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia
No full textFig. 3. Species rank abundance for number of ants caught during the sampling in Temengor Forest Reserve, Peninsular Malaysia in 2008 [Δ], 2009 [ο] and combined [■].Published as part of <i>Mustafa, Nur-Zati A., Salim, Hannah M. W., Fletcher, Christine, Kassim, Abd Rahman & Potts, Matthew D., 2011, Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia, pp. 181-194 in Raffles Bulletin of Zoology 59 (2)</i> on page 185, DOI: <a href="http://zenodo.org/record/10107188">10.5281/zenodo.10107188</a>
Fig. 2 in Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia
No full textFig. 2. Species accumulation curves with error bars for sampling in Temengor Forest Reserve, Peninsular Malaysia in 2008 [Δ], 2009 [ο] and combined [■].Published as part of <i>Mustafa, Nur-Zati A., Salim, Hannah M. W., Fletcher, Christine, Kassim, Abd Rahman & Potts, Matthew D., 2011, Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia, pp. 181-194 in Raffles Bulletin of Zoology 59 (2)</i> on page 184, DOI: <a href="http://zenodo.org/record/10107188">10.5281/zenodo.10107188</a>
Fig. 4 in Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia
No full textFig. 4. Number of species (bars) and number of individual (lines) of ants from different functional groups. C: Cryptic species; DD: Dominant Dolichoderinae, GM: Generalised Myrmicinae; TCS: Tropical Climate Specialists; O: Opportunists; SC: Subordinate Componitini; SP: Specialist Predators.Published as part of <i>Mustafa, Nur-Zati A., Salim, Hannah M. W., Fletcher, Christine, Kassim, Abd Rahman & Potts, Matthew D., 2011, Taxonomic And Functional Diversity Of Ants (Hymenoptera:Formicidae) In An Upper Hill Dipterocarp Forest In Peninsular Malaysia, pp. 181-194 in Raffles Bulletin of Zoology 59 (2)</i> on page 185, DOI: <a href="http://zenodo.org/record/10107188">10.5281/zenodo.10107188</a>
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The effects of anthropogenic disturbance and environmental change on multiple dimensions of microbial biodiversity
Full text linkDespite recent advances in microbial ecology, including the widespread use of high- throughput sequencing and micro-array technologies, microbial taxonomic, phylogenetic, and functional diversity remain understudied and poorly understood compared to our knowledge of macrofaunal diversity. In this dissertation, I work to close this gap by: (1) addressing the challenges of quantifying and comparing modern microbial data, (2) elucidating the changes to soil microbial diversity caused by widespread land-use change in tropical ecosystems, and (3) modeling the unique evolution of marine diatoms.The dissertation begins in Chapter 1 with a general overview of the three original research projects that were carried out. In Chapter 2, I explore the use of diversity profiles, which are a novel way to analyze microbial datasets. Diversity profiles may be better suited than traditional ecological indices for quantifying data spanning multiple domains of life and dimensions of diversity. I evaluate the use of diversity profiles for analyzing microbial assemblages in order to determine whether the inclusion of rarity and similarity information changes the interpretation of comparative studies of microbial community diversity.In Chapter 3, I assess the effects of anthropogenic land-use change, soil abiotic factors, and geographic distance on the taxonomic, phylogenetic, and functional gene diversity of soil microbes. I discover and quantify multiple dimensions of bacterial, archaeal, and fungal diversity in five different land-use types (Primary Forest, Secondary Forest, Oil Palm, Rubber, and Rice) throughout a dipterocarp forest landscape in Peninsular Malaysia. In Chapter 4, I identify major shifts in lineage diversification rates during diatom evolution by building a new diatom phylogenetic tree with significantly more environmental diatom sequences than previously published phylogenies.The dissertation concludes in Chapter 5 with a summary of key findings: Microbial diversity comparisons may vary when taxa rarity and similarity information are considered by diversity profiles. Incorporating this information can greatly alter our comparisons and conclusions of microbial diversity in multi-community studies (Chapter 2); conversion of Primary Forest to other land-use types led to the loss of rare microbial OTUs (Chapter 3); fungal diversity was more strongly affected by land-use type than bacterial and archaeal diversity (Chapter 3); functional gene diversity was most strongly linked to abiotic soil environment (Chapter 3); and analyses of the global diatom phylogenetic tree yield estimates of diversification rate shifts across the tree with all but one of the estimated shifts corresponding to net increases in diversification rates (Chapter 4)
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Forest carbon management in mangroves and monoculture plantations
Full text linkRestoring forest cover is a prominent strategy for offsetting emissions of greenhouse gases. When done appropriately, restoring forest cover can remove atmospheric carbon dioxide and confer non-carbon benefits such as biodiversity conservation, ecosystem service provisioning, or direct economic returns to local communities. Although a range of pathways exist for restoring forest cover, two prominent avenues have caught the attention of decision-makers and investors across the globe: blue carbon and plantations. The three chapters of my dissertation consequently examine the degree to which mangroves, a prominent blue carbon ecosystem, and monoculture plantations, the dominant approach for restoring forest cover, can meet our climate change goals. In the first chapter of my dissertation, I compare and critically assess estimates of carbon stocks in mangroves using i) empirical field data, and ii) outputs of predictive models at global scales. Global maps of carbon stocks are increasingly used to inform environmental management, policy, and decision-making, but may produce biased estimates of mangrove carbon stocks at local scales. My findings suggest that although global maps of mangrove carbon perform well at regional scales, comparison with empirical field data at local scales identifies statistically significant differences in carbon stocks. The results suggest that despite recent advances in computing power, compilation of global datasets, and remote sensing, empirical measurements of mangrove carbon stocks will remain key to informed decision-making at local scales.My second chapter examines a critical question for mangrove conservation and restoration policy-making: are the carbon stocks of deforested mangroves recoverable over time scales meaningful for mitigating climate change? Deforestation of mangroves induces massive carbon emissions from the soil organic carbon pool; however, the pace at which these soil organic carbon stocks are recovered following reforestation is unclear. Using high resolution spatial datasets of land cover and land use change over the last 20 years and models of carbon stock loss and gain in mangroves, I use scenario analysis to examine the net balance of carbon stocks associated with mangrove gain and loss within Thailand. My findings indicate that in areas where regenerating mangroves are commonly re-cleared, carbon stock losses may be four-fold greater than what net change in mangrove extent statistics would otherwise suggest.Finally, my third chapter turns to monoculture plantations, the dominant approach for restoring forest cover globally. Approximately two thirds (66%) of high-level commitments in the tropics for forest restoration involve planting and almost half (45%) involve the establishment of monoculture plantations. Despite the prominence of this approach, the science and policy communities lack systematic understanding of the degree to which monoculture plantations can meet climate change mitigation goals. Thus, my colleagues and I compiled a database of approximately 3,500 empirical estimates of aboveground carbon in monoculture plantations across the globe. I then used this database to examine variation in growth patterns as well as the key drivers that mediate this growth. I used nonlinear growth curves to more accurately model the accumulation of aboveground carbon stocks with time, which I found to vary substantially by genus of tree and plant functional type. Furthermore, I found factors such as genus, endemism, prior land use, and plant traits to strongly mediate carbon accumulation in monoculture plantations, whereas factors such as biome were found to have little effect.Taken comprehensively, the chapters of my dissertation critically assess the scientific datasets and approaches that are guiding actions and commitments within the reforestation space. The chapters employ data that have been collected through in situ forest inventories, predictive modeling, and government programs, as well as methodological approaches such as statistical modeling and data synthesis. The findings provide key insights such as i) improved understanding of a critical uncertainty (i.e., the recoverability of mangrove carbon stocks) for investors in reforestation of blue carbon ecosystems, as well as ii) improved understanding of carbon accumulation patterns in global monoculture plantations. I anticipate that these findings will facilitate improved environmental outcomes from reforestation efforts, which are rapidly scaling across the globe
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The Politics of Sociocultural Impacts in Mexico’s Ongoing Energy Transition
Full text linkGrounded in science and technology studies (STS) and political economy, this dissertation elucidates and analyzes the construction of Mexico’s controversy regarding the sociocultural impact of renewable energy technologies and their central role in the domestic politics of its ongoing energy transition (ET). Much attention has been devoted to the diffusion of policies and technologies of ETs and measures taken to strengthen their technical and economic viability. However, the opposition to policies and infrastructures of ETs has revealed that the implications of these transformations exceed the substitution of technologies and energy resources, having broad interplay with the social domain. This issue can be illustrated by Mexico’s controversy around the sociocultural impacts of renewables. From its local origin in an indigenous territory to its implications for international climate policy, this controversy is evidence of the complex interplay between the social arena and ETs and problematizes their compensations and contradictions.Research in political economy tends to underestimate the role of the sociotechnical arrangement of technological projects and their contextual meaning in the shaping of the agendas and visions of actors and social groups. In analyzing these issues, scholars frequently focus on later stages where the objective and subjective frame of actors' agendas have already been delineated. I focus on the earlier stages of these issues by investigating critical areas in the construction of Mexico's renewables controversy, specifically: i) its epistemological development, ii) the formation of the policy intended to address this issue, and iii) the subsequent implementation of these policy tools. In doing so, I argue, the design of the ET policy played a crucial role in defining the characteristics that shaped renewable energy projects in Mexico. In turn, the contours of the controversy over sociocultural impacts were shaped by the interaction of these projects with the particular vision of the territory hold by the indigenous Huave and Zapotec communities and their social organization. I also argue that among the diverse possibilities for addressing this controversy, the government response led to the design of policy tools that have limited scope for altering the interplay between projects' sociotechnical arrangements and local communities. As a result, the design of this political solution has prevented the closure of the controversy, leading to the current political instability.In Chapter 2, “Resisting renewables: The energy epistemics of social opposition in Mexico,” I examine the academic and technical research on social opposition to renewable energy (RE) in Mexico and the normative visions embedded in this body of knowledge. Previous research has examined the authoritative role of knowledge production in the shaping of ETs, yet non-economics social research has received less attention. I argue that social research plays a central role in some components of ETs, and when these areas concern an unequal dispute between different interests and visions, then the production of knowledge, its outcomes, and its use can have vast energy justice implications. In the Mexican case, researchers have addressed the opposition to renewables through different understandings of human interactions with projects and methodological choices, shaping critical aspects of knowledge-making, such as the voices and agendas of the included social groups. In their outcomes, these research practices have offered competing interpretations of the causes of social opposition and the alternatives to solutions, which propose different material and symbolic roles to communities (e.g., downstream policy fixes for addressing social externalities vs. communitarian involvement in the decisions, management, and benefits of projects). Through a subject of controversy characterized by the lack of domestic regulation and experience and limited institutional capacity, social research has exceeded the academic domain, providing critical insights into the activism, the policy formation, and the practices of governmental and private actors. In Chapter 3, “The social and material shaping of Mexico’s energy transition,” I analyze the formation of Mexico’s Law on the Use of Renewable Energies and Financing of the Energy Transition (LAERFTE-2008) and social impact assessment (2014), tracing the translation of this controversy back to the sector’s institutions and the process of policy formation. I argue that although climate mitigation and the social opposition of renewables have promoted destabilizing changes in the political regime of Mexico's energy sector, the existing sociotechnical arrangement of this system has meant that entrenched industrial interests and values, as well as bureaucratic decision-making norms, have persisted in the way that institutions process these agendas and in the design of policies and regulations. Mexico's position in the international politics of climate change and the limitations that the national regulatory framework to the development of renewables played a crucial role in the design of LAERFTE. The solutions that this Law established to the investment and cost-effectiveness of renewables and their intermittency and transmission frame the particular arrangement of the projects took in Mexico - wind, large-scale, private, for the consumption of large corporations - and their concentration in Tehuantepec. The local effect of these projects and their interaction with the vision and organization of the indigenous Huave and Zapotec communities that inhabit this region defined the emergence of opposition groups with a discourse focused on sociocultural revindication. The centralism and top-down management that have characterized energy institutions and policies and the dispute between the political left and right regarding private participation in this sector framed the institutional translation of this controversy and the design trajectory of the SIAs and associated policy tools. In Chapter 4, “The effectiveness of the social impact assessment (SIA) in energy transition management: Stakeholders' insights from renewable energy projects in Mexico,” I analyze the performance of this policy tool in Mexico’s renewable sector. Social opposition to renewable energy projects has become a significant issue both for the deployment of RE technologies and its social justice implications, yet the policy tools oriented to address this issue have received little research attention, particularly in the Global South. Since its introduction in 2014, the SIA has generated some favorable changes in the sector’s social management. Yet, its effectiveness is constrained by diverse issues related to its institutional and regulatory design, government implementation, practices of companies and consultants, and restricted social involvement. Moreover, the sector’s sociotechnical arrangement (priorities, organization, experience, and policies) strongly influences the performance of SIAs and accounts for the lack of consideration of social aspects in project design and planning. Thus, I argue that without a substantial internalization of the social dimension in the priorities, policy, and planning of RE, the SIA would be limited to a problem-fixing role, which would constrain the effective management of social impacts.This dissertation builds on and extends STS scholarship on energy transitions in three distinct ways i) research in social sciences, showing the justice implications that may stem from research practices ii) the formation of policies and regulations, revealing the role played by social and material factors and iii) the management of social impacts and relations, demonstrating the crucial role of these areas in the construction of energy futures. By tracing and deconstructing these arenas, my findings show that the practices of knowing, governing, managing, and contesting renewable energy projects have been intimately intertwined: From international climate negotiations to Mexico's adoption of energy transition (ET) policies and the emergence of local opposition groups to the formation of policy tools for addressing social impacts, to the current uncertainty facing Mexico's climate policy. The interplay among research production, political agendas, and regulatory rules have influenced each other at the international, national, and local domains, co-producing Mexico's particular energy transition pathway, regional geographies of energy development, social movements, actors' practices, and societal views. Taken collectively, my findings uncover existing alternatives that can help think about, design, and govern a fair ET system in Mexico, and reveal the political and social risks of driving top-down ETs without a substantive involvement of the communities
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Assessing Forest Cover and Livelihood Dynamics in Central America from Household to Multi-National Scales
Full text linkDeveloping countries face the challenging and seemingly contradictory task of preserving or expanding their forests and natural ecosystems while lifting their populations out of poverty. Global change, or anthropogenic shifts in climate and ecosystems, is putting increasing strain on human and natural systems and threatens to dramatically undermine these efforts. Smallholder farms, which are the source of most food calories across many developing nations, are especially vulnerable to climate-related events like drought. These impacts can disrupt farmer livelihood strategies and land use arrangements in complex ways. Investigating how disruptors like drought affect land use and livelihoods, and how governments and local contexts mediate these impacts, is crucial to building adaptive capacity in smallholder systems in the face of global change. In this dissertation, I explore global change dynamics in smallholder-dominated systems, focusing on drought and land use change. I investigate multinational changes in forest and crop cover due to livelihood shocks, the impact of national forestry payment programs, and farmers' relationships with drought in Zacapa Department, Guatemala. My analysis takes a land use systems approach, considering underlying drivers, dynamics, and scales in assessing change in smallholder-dominated regions. The three chapters that comprise the body of this dissertation address global change questions at increasingly smaller scales. Chapter 2 provides a multinational assessment of how livelihood shocks affect land use in the developing world. Chapter 3 examines the impact of Guatemala’s long-running national payment for ecosystem services on forest cover, considering different program contexts. Chapter 4 focuses on Zacapa Department, Guatemala, analyzing how households in this part of the Central American Dry Corridor experience droughts. This research stitches together the interplay of drought, conflict, and forestry on land cover and livelihoods to reveal key dynamics that are shaping these systems. My findings provide critical insights such as i) theoretically-backed links between livelihoods shocks and land use change; ii) improved understanding of how government-backed forestry incentives improve forest cover; and iii) regionally-specific measures of drought exposure and drivers of vulnerability. Using a scaled approach that analyzes data at the multinational, national, and local levels allows for a comprehensive and a more nuanced understanding of global change in smallholder-dominated systems. My research in Chapter 2 investigates the impact of food insecurity shocks on human land use. Existing literature largely describes the extent, patterns and drivers of food insecurity or land cover change separately, but the interplay between the two remains understudied. I use data from USAID to track food insecurity events and their resulting impacts on land use and population in 25 low- and middle-income countries. To isolate impacts on forest area, cropland, and population dynamics in the wake of food insecurity events, I use matching with difference-in-differences and two-stage least squares to disentangle the impacts of major food insecurity drivers. I find that spikes in regional food insecurity lead to forest recovery and a loss of cropland and population. When I parse the underlying drivers of food insecurity, I show that drought-driven shocks most impact land cover, whereas conflict-driven shocks most impact population, suggesting that changes to land productivity are most predictive of subsequent land use change. Chapter 3 evaluates the effectiveness of two long-running forestry incentive programs in Guatemala which aim to expand forest cover and improve rural livelihoods. These programs underlie Guatemala’s ambitious forest restoration goals, but have yet to be critically evaluated at a national scale. I use a synthetic control counterfactual to evaluate the impacts of over 16,000 individual Payment for Ecosystem Services projects on forest extent and loss. A program for smallholders resulted in lower rates of forest loss, while a program for industrial timber owners led to greater gains in forest cover. Across policies, I found dramatically higher forest cover increases from restoration projects compared to plantation and agroforestry projects. Overall, my analysis found forest cover increases to be under 10% of total enrolled area, although positive local spillovers suggest this is an underestimate.In Chapter 4, I combine ethnographic research with remotely sensed data to characterize the climate vulnerability of smallholder farmers in Zacapa, Guatemala. This region of the Central American Dry Corridor has been one of the hardest hit by drought in recent decades, with the World Food Programme estimating that up to 70% of the corn crop was lost in recent years. I investigate the experiences of farmers through historic and recent droughts using ethnographic interviews across two smallholder communities. I further evaluate crop water stress within vegetation groups and agricultural fields using remotely sensed imagery. Integrating these datasets identified a socio-ecologically relevant measure of water stress that allows for better evaluation of drought exposure and also reveals how shifting land tenure may be driving drought vulnerability through limiting farmers’ access to high-elevation forests. These findings can inform policies aiding smallholder-dominated systems, targeting points of vulnerability and supporting interventions with the best socio-ecological outcomes. They also support future research via the application of findings across scales, to either zoom in on how important global drivers are mediated within local contexts or to apply a flexible but locally-relevant framework to multinational studies. I further suggest that better measurements of change drivers can improve our understanding of the mechanisms and impacts of global change, leading to more applicable and forward-thinking research findings in this field
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Fate, Luck or Destiny? Regeneration of Tropical Rainforest in Singapore
Full text linkTo date, our understanding of the long-term recovery of secondary forests in the tropics is based on surprisingly little empirical data. In my dissertation, I examined some of the stochastic (dispersal events) as well as deterministic factors (environmental filtering) that are important to community dynamics and thus the on-going regeneration of older tropical secondary forests in Singapore. These secondary forests underwent intensive agricultural activities from the late 1800 to early 1900, and have today, recovered differently after at least 56 years of regeneration. Chapter 1 provided a synopsis of how my research is situated within the larger theoretical framework of tropical forest succession, along with rationale for the focus on older secondary forests in Southeast Asia. In Chapter 2, I compared the floristic composition and structure of a two hectare secondary forest to an adjacent two hectare primary forest in Bukit Timah Nature Reserve, and also examined the extent to which dispersal limitations was limiting forest recovery. In Chapter 3, using nine secondary and three primary forest plots in the Central Catchment Nature Reserve, I determined the effect that changing environmental variables and distance to the nearest mature forest had on seedlings' abundance, diversity as well as the distribution of four broad functional groups. In Chapter 4, using the same twelve research plots, I investigated the linkages between the regenerating environment and functional traits of seedlings and adult trees, as well as analyzed their relative influence on forest recovery. Results from Chapter 2 and 3 demonstrate that forest recovery in Singapore, in terms of species composition, species richness and stand structure, is very slow compared to other old secondary forests elsewhere in the tropics. I found that local Ultisol soils have inherently low nutrients, even when compared to other Dipterocarp forests, and decades of intensive agricultural activities has further resulted in soils whose high aluminum saturation, soil C:N ratio and low available phosphorus inhibit forest regeneration. Overall, forest succession in Singapore is characterized by plant species whose nutrient conserving traits allowed them to specialize on degraded soil, along with the changing light environment, as the forest regrow. The longevity of these plants on degraded land, their ability to slow nutrient returns as well as the strong dispersal limitation in these fragmented forest reserves are important factors that explain the overall slow recovery
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