More than a hundred hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of existing dams and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. We introduce a Dam Environmental Vulnerability Index to quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-reaching impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.

Magister Scientiae - MSc (Biodiversity and Conservation Biology) / In recent years, a global trend of increasing woody vegetation densities in semi-arid savanna habitats has been recorded, commonly described in South Africa as 'bush encroachment'. The shrubs and trees that do this (Increasers) have wrought significant economic and ecological impacts upon carrying capacities of large areas of savannas. This occurs, as suitable grazing areas are incrementally engulfed in shrubs and trees establishing new equilibria, from open savannas (essentially grasslands with scattered trees) into closed woodlands (treelands with scattered grasses). This thesis demonstrated a link between grass biomass, small mammal abundance and diversity, and their potential increaser seed/seedling predatory activities in the semi-arid Lowveld Savannas of South Africa. / South Africa

Coastline communities have experienced a marked increase in human populations over the last few decades. This increase in population places disproportionate pressure on coastal ecosystems to provide economic services to support local economies. At the same time, overuse of these services can aid in the destruction of the ecosystems responsible for them. Seagrass ecosystems are mainly found near coastlines, and are typically a chief provider of some of these economic goods and services. Many previous studies have documented the ecological functions of this seagrasses. Unfortunately, our increasing knowledge of seagrass structure and function has not been fully incorporated into economic models estimating their value. In this dissertation, I focus on the seagrass ecosystem in southern Biscayne Bay, and simultaneously study the ecological dynamics of the seagrass beds, and estimate its economic value. This value is based on recent ecological models in the literature as well as data I collected from the system. I focused on Biscayne Bay due to, 1) the relevance that this question had to the relationship between Biscayne Bay and the Miami metropolis, and 2) the lack of existing reliable models that explore this relationship in this area. More specifically, I became very interested in this question while working for Biscayne National Park, where such a model would have improved seagrass restoration work taking place there. I found that southern Biscayne Bay is dominated by Thalassia testudinum, with other seagrasses following a spatial pattern primarily determined by salinity and water column nutrient distribution. Syringodium filiforme was mostly found east of the islands, Halodule wrightii was mostly found near the shoreline, and Halophila engelmenii was spotted at only two of the 190 sites visited. T. testudinum distribution was largely unaffected by nutrient enrichment at all sites, but it appeared to induce severe herbivory further from the coastline. For the calendar year 2004, we deduced using a Total Ecosystems Valuation (TEV) model that seagrass ecosystems potentially contributed over $198 million US dollars to the local economy. We argue that a simultaneous understanding and use of both ecological and economic models is important for future conservation efforts of seagrass ecosystems.

L'émergence et la propagation des technologies de communication à travers le monde ont facilité l'accélération du rythme de l'innovation dans une multitude de domaines. Avec un accès quasi-continu aux flux de l'information, la façon dont les humains vivent a changé, et avec elle ont évolué la structure et la fonction des entreprises, des marchés et de leurs composants. Dans cette thèse, nous explorons la co-évolution des entreprises et des marchés et analysons la création d'une nouvelle architecture organisationnelle qui résulte de cette co-évolution.Dans le chapitre 1, nous explorions les nombreuses branches de la littérature sur la théorie de la firme et la confrontons au phénomène de platformization des marchés au travers de l'étude d'eBay. Suite à l'analyse détaillée de cette étude de cas, le chapitre 1 conclut que le concept de l'entreprise a subi une métamorphose et que ses contours se redéfinissent aujourd'hui au-delà des définitions traditionnelles et contemporaines de l'entreprise. Pour résoudre ce problème, nus proposons la notion d'équivalence firme / marché. Ce concept sera ensuite utilisé dans les trois autres chapitres de la thèse.Quand les économistes voient une défaillance de marché, les entrepreneurs voient une opportunité d'affaire. Les entreprises d'aujourd'hui sont un entrelacement complexe d'interactions qui répondent aux défaillances du marché. Dans ce chapitre 2, nous expliquons comment les entreprises adressent ces opportunités de marchés grâce à des stratégies d'intermédiation passant par la création de plates-formes. Non seulement les entreprises facilitent l'activité du marché en fournissant aux autres participants des ressources de base, mais elles prennent également un rôle de premier plan dans la régulation de l'ensemble des activités économiques ainsi générées. L'objectif du chapitre 2 est d'explorer le phénomène de la double fonction de l'entreprise (création de marchés et soutien du marché) grâce à la notion d'équivalence firme / marché. Nous expliquons le rôle des entreprises qui choisissent de se positionner comme intermédiaire et qui prennent à leur charge la construction, le fonctionnement et le support de la plate-forme. Dans la littérature, ces entreprises sont appelées entreprises centrales, keystones, catalyseurs, ou tout simplement plates-formes. Ces entreprises sont capables d'attirer à elles une multitude de partenaires qui forment ce qu'une partie de la littérature appelle des écosystèmes d'affaires.Le chapitre 3 propose un regard différent sur la stratégie de création d'une plate-forme. Alors que dans le chapitre 2 nous nous sommes concentrés sur les entreprises qui créent et soutiennent les plates-formes, dans ce troisième chapitre, nous examinons de plus près les autres participants. Nous abordons ces participants comme des entreprises-satellites en raison de leur tendance à graviter vers les créateurs et les opérateurs de plate-forme. Nous étudions le rôle de ces entreprises-satellites dans les écosystèmes à base de plate-forme et observons que certaines entreprises-satellites peuvent potentiellement faire peser des menaces sur les détenteurs de plate-forme. Nous discutons ensuite les questions des clusters et du multi-homing, ainsi que la façon dont ces phénomènes affectent les entreprises centrales et leurs écosystèmes d'affaires. Nous concluons que ces comportements sont une source de pression concurrentielle entre les détenteurs de plateforme. Le chapitre 4 traite de la dynamique de l'équivalence entreprise / marché. Idéalement, l'équivalence entreprise / marché présente deux dimensions : l'innovation et le développement commercial. Dans ce modèle, la plate-forme est un artefact socio-technique central qui soutient les stratégies d'ouverture par rapport à ces deux dimensions. Elle facilite le partage et les échanges entre les participants. Ces systèmes ne sont pas statiques. / Emergence and spread of telecommunication technologies throughout the world facilitated acceleration in the pace of innovationin multitude of domains. Having access to the ongoing stream of information, the way human live has changed, and with it evolved the appearance and function of firms, markets, and their constituents. In this thesis we explore the co-evolution of firms and markets and observe the creation of new organizational architecture that resultas from this co-evolution. In chapter 1 we explore the numerous branches of the theory of the firm lterature and confront it to the phenomenon of platformization of markets through the study of the eBay case. Following the detailed annalysis of this case study, chapter 1 concludes that the concept of firm has undergone metamorphosis and has been redefined beyond the traditional and contemporary definitions of the firm. To adress this, we hence propose the concept of film / market equivalency. This concept is thoroughly explained ans discussed in the three chapters that follow. What the economists call a market failure, the entrepreneurs call a market opportunity. Firms today are the intricate interlacing of interactons, which arise in response to market failures. In chapter 2 we describe how the market opportunities that emerge as a result are adressed by the firms through market support strategy, i.e through creation of platforms. Not only do the firms facilitate marketa ctivity by providing participants with basic ressources, firm also take up a leading role in the regulation of all of their creation's activities. The purpose of chapter 2 is to explore the phenomenon of concurrent double function of firm, market creation and market support, through the concept of film / market equivalency. We explain the role of firms that that choose to position themselves as intermediaries and take charge over platform construction, operation and support. In the literature, ssuch firms are referred to as central partners who form what the management calls business ecosystems. Chapter 3 discusses a different take on the platform creation strategy. Whereas in chapter 2 we focused on the types of firms that create and support the platforms,in the third chapter we take a closer look at the constituents of platforms : the small players. In text we adress these players as "firms-satellites" due to their tendency to gravitate toward creators and operators of platforms. We study the role of these firms-staellites in the platform-based ecosystems and identify that some of firms-satellites may potentially bear threats to the platform owners. We then discuss the issues of clustering and multi-homing as welle as how these issues affect central firms, their business ecosystems and whether or not these behaviors are a source of competitive pressure. Chapter 4 discusses the dynamics of firm / market equivalency. Ideally, firm / market equivalency has two dimensions : innovation and business development. In this model, the platfform is a central sociotechnical artefact that supports openness strategies in both dimensions. It facilitates sharing and exchanges among participants. Such systems are not static. They co-evolve with their constituents : the participants and the platform owner. This chapter explores the dynamics involved in firm / market equivalency models. For each stage of development (birth, expansion, leadership, renewal), we study the architecture of the platform, the behaviour of participants and the strategic responseof the platform owner. We conclude the thesis with discussion ofa ntitrust issues that do or may arise as the result of employment of amrket creation and support strategies.

Context: Since the beginnings of software engineering, metrics (such as SLOCs) and practices have been used in an attempt to measure and improve the features of software development projects, their process, or their contributors. Measuring and enhancing software ecosystem features brings a new complexity level because a software ecosystem comprises several interrelated software projects. Over the past two decades, software ecosystems have gained considerable attention, and researchers have proposed various metrics and practices to measure and improve software ecosystems' health. Objective: This thesis presents a systematic literature review that aims to build comprehensive taxonomies for software ecosystem health metrics and practices. These taxonomies synthesize the results of previous categorizations and update them with newer metrics and practices proposed since then. This study also aims to collect and synthesize all the definitions, metrics, and practices proposed to define, measure, and improve software ecosystem health in the literature. Method: I conducted a systematic literature review and identified 40 primary studies related to defining and measuring software ecosystem health. I extracted the definitions, metrics, and practices for software ecosystem health from the primary studies, and then I categorized the metrics and practices to build the taxonomies. Results: I identified a total of 7 different definitions for software ecosystem health, 142 different metrics, and 174 various practices for software ecosystem health. Our taxonomies for software ecosystem health metrics and practices have three categories (niche creation, productivity, and robustness). Each of these categories has several sub-categories of metrics and practices. Conclusion: Software ecosystems have a wide range of stakeholders that have different perspectives regarding software ecosystem health. To satisfy this spectrum, researchers have proposed various metrics and practices to measure and improve software ecosystems' health. To improve unifying contrasting opinions, I conducted this study. The metrics and practices proposed are diverse in both purpose and the data required to compute them. Some metrics are presented along with a method on how to compute them. In contrast, others are defined abstractly without an operational approach to calculate them, and some are mentioned without a clear rationale. Furthermore, the same metric or practice is often proposed in more than one publication using different names. This thesis addresses these alignment problems. / Graduate

The restoration of degraded tallgrass prairies can mitigate climate change due to the carbon accrued during the development of grasslands. The focal species, dominant grass Andropogon gerardii, can assist the recovery of grassland ecosystem functioning. Climate, local adaptation, and biodiversity have been found to impact the accrual of carbon in grasslands. This study examined the difference in ecosystem functioning between ecotypes along a dry to mesic precipitation scale. The study site for this project was at the Southern Illinois University Agriculture Research Center in Carbondale, Illinois. The field site was planted with seeds originating from dry to mesic ecotypes, and the resulting ecosystem functioning was analyzed. It was found that the Kansas non-local ecotypes had significantly higher biodiversity, while the local Illinois sites demonstrated local adaptation with A. gerardii. Aboveground plant biomass was higher in the local sites, but there was no difference in carbon accrual between any of the ecotypes. While ecotypic variation in a dominant species will usually differentially influence ecosystem functioning, in this case, high biodiversity and local adaptation result in similar carbon inputs in grassland soil. It is necessary to analyze the carbon content of the soil in the drier field sites in order to determine if major differences in rainfall leads to differences in carbon accrual. If the goal of restoring a tallgrass prairie in southern Illinois is to assist with climate change mitigation, then it does not make a significant difference if the dominant species is sourced locally or non-locally.

The process of internationalization may be more difficult for emerging markets' artificial intelligence startups (AI startups) due to several challenges. These challenges include weak institutions, limited financial support, political instability, lack of adequate local infrastructure. Significantly less research has being done on entrepreneurial ecosystems, especially in emerging markets. Therefore, this study aims to address the current state of the entrepreneurial ecosystem, in emerging markets and AI startups internationalization process. As a result, the study focuses on the challenges faced by AI startup within the Nigerian and South African entrepreneurial ecosystem, to address how the entrepreneurial ecosystem affects AI startups internationalisation process. To answer the research question, qualitative research was carried out using semi structure interviews with different case companies from South Africa and Nigeria. Although these countries are similar in nature, AI startups face various internal challenges in terms of government policies, institutions, and infrastructure. Based on the findings, it was noticed that there is a relationship between the entrepreneurial ecosystem and the growth and survival of AI startups. The elements of an Entrepreneurial ecosystem (social, cultural, and material elements) also influence the internationalisation of AI startups within an entrepreneurial ecosystem space. Entrepreneurial ecosystem challenges were identified which discourages or hinder the growth of AI startups within the Nigerian and South African markets. In conclusion, we noticed that African AI startups prefer to practice their business model in the home markets and flourish their confidence levels before seeking internationalization opportunities. Most of the case AI startups prefer to start internationalization from close psychic market before going distance international markets. However, these AI startups adopt network relationship approach through key business partners for international expansion.

Compounding evidence suggests a current or impending sixth mass extinction event and pollinator crisis. While several factors contribute to pollinator declines, the most notable driver is habitat loss and degradation. Agricultural grasslands provide crucial habitat for wild and domesticated fauna, regulate water and nutrient cycles, store carbon, and maintain soil stabilization. However, conventional tall fescue pastures, which dominate the southeastern United States, limit pollinator habitat, reduce ecosystem services, and diminish cattle productivity if infected with toxic endophytes. Establishing wildflowers (WFs) and native warm season grasses (NWSGs) into tall fescue pastures has the potential to boost both pollinator ecosystem services and cattle productivity. This study monitored the differences in honey bee colony health, productivity, and pollen foraging behavior between diversified and conventional grazing pastures in south west Virginia. Chapter 1 sought to evaluate the health and productivity of hives within NWSGW+ diversified and conventional grazing systems. Chapter 2 sought to 1) determine whether honey bees used sown wildflower species in diversified pastures as significant sources of pollen, 2) compare species composition and nutritive value of pollen collected from hives within diversified and conventional pasture systems, and 3) evaluate temporal trends in pollen collection. Floral surveys revealed diversified pastures had almost 4x greater mean bloom density than conventional pastures, with over half of all blooms recorded in diversified pastures belonging to unsown species. Results from this study suggest that colonies in diversified pasture systems may have a slight advantage in population resource acquisition, population growth, and winter survival following the first year of establishment, though further research is needed. Pollen DNA metabarcoding revealed that honey bees in both diversified and conventional pasture systems have similar diets, and that sown species were foraged upon primarily in the fall. Samples collected from diversified pasture systems yielded greater pollen weight, species richness, and protein content. In conjunction with previous research, these results indicate that diversified pastures could ultimately provide a more complex nutritional support system for pollinators in grazing agroecosystems. However, individual pasture renovation may not be large enough to yield statistically significant differences in honey bee colony success. / Master of Science / Many studies have suggested that we are currently experiencing or entering a sixth mass extinction event and pollinator crisis. While several factors contribute to pollinator declines, the most notable driver is habitat loss and degradation. Agricultural grasslands provide crucial habitat, regulate water and nutrient cycles, store carbon, and maintain soil stabilization. However, conventional tall fescue pastures, which dominate the southeastern United States, limit pollinator habitat, reduce ecosystem services, and can diminish cattle productivity. Establishing wildflowers (WFs) and native warm season grasses (NWSGs) into tall fescue pastures has the potential to boost both pollinator and cattle health and productivity. This study monitored the differences in honey bee colony health, productivity, and pollen foraging behavior between pastures diversified with WFs and NWSGs and conventional grazing pastures in south west Virginia. Chapter 1 evaluated the health and productivity of hives within diversified and conventional grazing systems. Chapter 2 sought to 1) determine whether honey bees used sown wildflower species in diversified pastures as significant sources of pollen, 2) compare species types and value of pollen collected from hives within diversified and conventional pasture systems, and 3) evaluate temporal trends in pollen collection. Floral surveys revealed diversified pastures had almost 4x greater mean bloom density than conventional pastures, with over half of all blooms recorded in diversified pastures belonging to species we didn't purposefully plant. Results from this study suggest that honey bee colonies in diversified pasture systems may have a slight advantage in resource acquisition, population growth, and winter survival following the first year of establishment, though further research is needed. A Pollen DNA analysis revealed that honey bees in both diversified and conventional pasture systems have similar diets, and that they collected pollen and nectar from the flowers we planted primarily in the fall. Honey bee colonies in diversified pastures collected more protein-rich pollen from a wider variety of flowers. These results indicate that diversified pastures could ultimately provide a more complex nutritional support system for pollinators in grazing agroecosystems. However, individual pasture renovation may not be large enough to yield large differences in honey bee colony success.

Ecosystems and their components (e.g., organisms, physicochemical variables) are dynamic in space and time. This dynamism makes ecological change notoriously difficult to study and manage. This thesis therefore aims to develop new ways of using spatiotemporal information for inference and prediction. Applying theoretical and statistical concepts to patterns of spatiotemporal variation in aquatic ecosystems led to three discoveries that show promise as ecological applications. First, I show that temporal variability of an ecosystem process can be inferred from its spatial variability. This application may be the first quantitative form of the widely-used method, space-for-time substitution. Its use is supported by an analytical framework giving the conditions under which space is a good surrogate for time. Second, I demonstrate the use of spatiotemporal patterns to predict responses of variables when ecosystem fragments are connected. Connection leads to large shifts in spatiotemporal pattern and other response metrics (e.g., temporal variability) for variables showing asynchrony and concentration gradients among sites (e.g., populations). Meanwhile, these changes are minimal if variables exhibit synchrony and homogeneity across space (e.g., energetic variables). A final discovery is that temporal attributes like stability are strong predictors of persistent spatial variation – a pattern that reflects how reliably resource concentrations occur in the same locations. This finding suggests the potential of time-for-space substitution, where one or few well-resolved time series could be used to infer landscape patterns. All but one of the tested approaches were data efficient and broadly-applicable across ecosystems and ecological processes. They thus contribute new possibilities for prediction when data are scarce, as well as new perspectives on dynamics in multi-variable landscapes. Research here shows that work at the intersection of spatial and temporal pattern can strengthen the interpretation of ecosystem dynamics and, more generally, foster synthesis from populations to landscapes. / Thesis / Doctor of Philosophy (PhD) / The physical and biological components of ecosystems are constantly in flux, varying in value among locations (spatially) and over time (temporally). This dynamism makes it difficult to predict current or future behaviours of ecological variables (e.g., population size). This thesis tests the potential of using spatial and temporal patterns to make inferences and predictions about changes in ecological systems. I tested three new theory-based tools in aquatic ecosystems, finding that: The size of temporal fluctuations in an ecosystem variable can be predicted from the size of value-differences among locations; spatial and temporal patterns can predict how a variable responds when isolated fragments of ecosystems are connected; and attributes of ecosystem variables (e.g., their stability) can indicate the likelihood of resources recurring in the same location. Findings show that new insight into spatial and temporal patterns can help prediction and management in complex landscapes.

<p dir="ltr">Physical traits and the hydrologic setting of lake and wetland environments strongly affect the biogeochemical signature of aquatic ecosystems and their structure and function in the landscape. Natural freshwater ecosystems have a high propensity for carbon capture and storage through aerobic production, sedimentation, and sequestration, yet differing physical characteristics including water depth, lake surface area, and watershed size likely influence the extent to which these processes occur. Anthropogenically modified ecosystems also demonstrate complex function regarding carbon cycles, where the influence of human disturbance heightens nutrients and carbon loads into aquatic systems and leads to unique biochemical regimes. Across Indiana, agricultural practices currently affect around 65 percent of the state’s landscape, while urban development and population growth are expected to expand throughout the state. This trend is modeled throughout the midwestern United States, where the impacts of urban development on aquatic environments is further heightened by expected changes in climate, as storm intensity strengthens, and rainfall increases during certain times of the year. While understudied, there is good reason to believe that Indiana’s lakes and wetlands have incredible variability in carbon processing and carbon quality within and between systems. This variation is influenced by the wide variety of drivers including hydrology, geomorphology, water chemistry, metabolic processes, and redox conditions. The interactive influence of each of these drivers, however, is poorly understood across wide scale gradients. Predicting ecosystem productivity and its relationship with carbon dynamics is therefore an important tool for understanding freshwater ecosystems’ contributions to global fluxes of carbon. The variability within and across midwestern ecosystems creates a challenging, yet critical paradigm to understand the complexities of carbon dynamics in aquatic ecosystems, emphasizing the importance for direct data collection across a stratified gradient of ecosystems. This research shows that 1) human-assigned classifications of system type, including lake, reservoir, and wetland, are useful tools in classifying the metabolic and nutrient regimes of lentic systems, and 2) morphological features including lake depth and watershed area influence the structure of carbon quality throughout the water column. Findings provide valuable information to watershed and lake managers on the importance of different physical drivers in determining water quality across a range of lentic systems.</p>