1,721,029 research outputs found
Co-limitation toward lower latitudes shapes global forest diversity gradients
No full textThe latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers.EEA Santa CruzFil: liang, Jingjing. Purdue University. Department of Forestry and Natural resources. Forest Advanced computing and Artificial Intelligence Laboratory (FAcAI); Estados UnidosFil: Gamarra, Javier G. P. Food and Agriculture Organization of the United Nations. Forestry Division; Italia.Fil: Picard, Nicolas. GIP ECOFOr; FranciaFil: Zhou, Mo. Purdue University. Department of Forestry and Natural resources. Forest Advanced computing and Artificial Intelligence Laboratory (FAcAI); Estados UnidosFil: Pijanowski, Bryan. Purdue University. Department of Forestry and Natural resources; Estados UnidosFil: Jacobs, Douglass F. Purdue University. Department of Forestry and Natural resources; Estados UnidosFil: Reich, Peter B. University of Michigan. Institute for Global change biology. School for environment and Sustainability; Estados UnidosFil: Reich, Peter B. University of Minnesota. Department of Forest resources; Estados UnidosFil: Reich, Peter B. Western Sydney University. Hawkesbury Institute for the environment; Australia.Fil: Crowther, Thomas W. Institute of Integrative biology. Crowther Lab. Department of environmental Systems Science; SuizaFil: Nabuurs , Gert-Jan. Wageningen University and research. Wageningen environmental research; Países BajosFil: Nabuurs , Gert-Jan. Wageningen University and research. Forest ecology and Forest Management Group; Países BajosFil: de-Miguel, Sergio. University of Lleida. Department of crop and Forest Sciences; EspañaFil: de-Miguel, Sergio. Joint research Unit CTFC. Agrotecnio cercA; EspañaFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Hui, Cang. Stellenbosch University. Department of Mathematical Sciences. Centre for Invasion biology; SudáfricaFil: Hui, Cang. African Institute for Mathematical Sciences; Sudáfric
The Impact of Refuse on the Kelp Gull (Larus Dominicanus) in the Río de la Plata Estuary, Uruguay
No full textModern economic activities, like industry and agriculture, as well as household activities, generate an important amount of refuse. The way we collect, transport, and dispose it will determine the level of environmental contamination. May animals exploit refuse as a food source (i.e., anthropogenic food subsidy) and gulls are the most important group. Refuse subsidizes energetically gull populations, which impacts on their acquisition and allocation of resources, as well as on the environment, with ecological and evolutionary consequences are not well understood. In this dissertation we evaluated potential impacts of refuse on gulls by doing a literature review as well as empirical research on the Kelp Gull (Larus dominicanus) in the Rio de la Plata Estuary in South America. Direct and indirect impacts of refuse on gull species and the environment have been observed during the review process. We have detected positive impacts of refuse on body size, chick growth, fecundity, reproductive success, and population dynamics. However, negative impacts were also found focusing on fecundity, reproductive success, and population dynamics. Indirect negative impacts on other species, water bodies, and airport security were also found. Refuse produces numerous impacts on gulls at the individual, population, and species levels, with indirect negative consequences on ecosystems. There is a need to reduce the access of gulls to sources of refuse to mitigate the existing and potential conflicts with human activities and other species, especially those that are threatened and endangered. During our empirical research we found that refuse was ingested and assimilated by Kelp Gull chicks during the chick rearing period and that the ecological niche width increased with the age of the chick. We propose that parents incorporate isotopically unique food sources to nestling’s diet during their growth, increasing isotopic diversity of nestlings. Additionally, we found that refuse could affect foraging decisions of females during the pre-incubation period, which could positively affect future fecundity and negatively impact reproductive success. We found also that refuse consumption on fecundity and reproductive success of gulls is generally studied at the colony level, using conventional diet techniques, but not much has been done using stable isotopes at the individual level, making comparisons among studies and conclusions difficult to address. We encourage other researchers to continue incorporating the isotopic ecology perspective to study the effect of food subsidies on gulls. Additionally, we found that Kelp Gull on the coast of the Rio de la Plata Estuary ingest plastic debris. We conclude that plastic bags and plastic films might be the most important source of contaminants for the Kelp Gull on the coast of the estuary. Main findings of this dissertation suggests the need for an improvement of waste management practices and a regulation of plastic production and use in Uruguay to reduce plastic ingestion by gulls. Finally, next steps for research are provided in this important area of environmental science and natural resource management
Assessing changes and drivers of crop rotation patterns and their implications for nitrogen loading in the United States
No full textThe purpose of this study was to assess the changes and drivers of crop rotation patterns in the United States and their implications to nitrogen loading using principally the Cropland Data Layers (CDL) produced by the United States Department of Agriculture (USDA). We determined the temporal changes for different crops in the United States using different time periods from 2003 to 2011. Annual, biannual, and four-year rotation patterns were quantified and the trends of monocultural cropping practices were analyzed. The price of crops, changes in policies and expansion of ethanol production were found to contribute to the observed shift in crop rotation strategies. The impact of ethanol plants on corn monoculture was analyzed using different sized buffers and a continuous distance raster. We found that the closer to an ethanol plant, the higher likelihood that corn is planted continuously. The results also showed the direct effect of policy changes as well as changes in crop prices. With the increase in corn monoculture there is an increase in the required amount of applied nitrogen fertilizer to attain desired yields. We developed a model based on the corn yield potential of different soils combined with the recommended amount of applied nitrogen for different corn rotation practices at a national scale from 2009 to 2011. Our results were within 1 percent of National Agricultural Statistic Services (NASS) estimated nitrogen use for corn in 2009 and 2010. The model allowed us to spatially determine the distribution of nitrogen used for corn growth as well as to create scenarios to simulate the potential changes to nitrogen loading if all corn was grown in rotation or if all corn was grown in monoculture. We found that changes in crop rotations can have as much if not greater impact on the total amount of recommended nitrogen applied for corn production as the increased nitrogen from the yearly growth in corn production. Using the nitrogen model, we developed a user interface that allows a land manager or farmer to select their area of interest. The interface calculates the contribution to the total applied nitrogen within each intersected 12 digit hydrologic unit from a selected area of interest and the desired rotation practice. The interface then determines how much nitrogen would be used if the manager changes their rotation practices
Assessing sustainable land-use practices using geographic information systems
No full textMany prominent scientists have claimed that we need to develop environmentally sustainable practices otherwise societies may collapse. The use of Geographic Information Systems allows detailed studies that can cross disciplinary boundaries and lead to quantifiable statements as to the change of land use practices that took place in the past and those that may occur in the future. This dissertation focuses on two research topics. One that attempts to quantify the environmental consequences of parking lots located in the Midwest, USA. The other research topic focuses on the land area needed to support ethanol in the United States. In Tippecanoe County, Indiana, it was determined that parking lots occupied approximately 6.6% of the urban areas, that the area devoted to parking lots exceeded the area devoted to urban parks by a factor of 3, and that these parking lots contributed to increased runoff of pollutants. The parking lots of Tippecanoe County were estimated to be responsible for 46.5 thousand pounds of oil and grease released annually in runoff, as well as an increase of 240.6 thousand pounds of suspended solids, and 65.7 pounds of lead released when compared to pre-development conditions. A method that scales up the county wide study was also developed to determine the areal footprint of parking lots with the states of Illinois, Indiana, Michigan and Wisconsin. It was estimated that these four states allocate approximately 1260 square km of their land to parking lots and that this accounts for 4.97% of urban land use and over 43 million parking spaces, whereas the number of individuals in age of driving (adults over 18 years old) amounted to just over 25 million. Within the four states studied, states where urban sprawl was considered more prevalent were also states that had a higher proportion of their urban land devoted to parking lots. The second dissertation topic focused on using GIS to locate suitable sites for corn or cellulosic based ethanol production facilities. Since a valuable byproduct of corn ethanol production is Distiller’s Grain Solubles (DGS), siting of ethanol plants was considered with regard to both corn production by county within the conterminous United States and head of cattle available to use this output as feed. We found that many counties outside the Midwest could sustain smaller sized ethanol plants, especially when considering that most large production facilities need to redistribute their DGS in dried form sometimes as far as California which has negative impacts on the Net Energy Value of corn based ethanol. The future of ethanol expansion however lies with cellulosic feedstock which is bulkier and thus more costly to transport than corn. Our results indicate that cellulosic ethanol plants should be smaller in capacity, especially when compared to corn ethanol plants where 100 million gallons a year (mgy) plants are more the norm. Only 7 out of 3109 counties in the conterminous United States contain enough wood, switchgrass or crop residue feedstock to sustain plants that produce greater than 40 mgy of biofuel, meaning that larger plants would need to import feedstock from considerable distances and thus incur greater feedstock transport costs. The last section explored co-location options for siting lignocellulosic ethanol plant production facilities
The role of local institutions in shaping household responses to climate change and variability: A case study along the slopes of Mt. Kenya
No full textRural households in Kenya are, and will continue to be challenged by climate variability and change. The ways in which diverse institutions shape local responses to climate change and variability, however, have not been sufficiently explored. In order to help remedy this situation, this work examines the role of local institutions in shaping household responses to climate change and variability on Mt. Kenya. In both conducting the field research and composing the current dissertation, I have posed and responded to the two following research questions: (1) How do local informal institutions, broadly defined as sets of rules and norms, shape individuals’ responses to climate change and variability in rural Kenya? (2) How can classic and innovative research methods be combined to study and understand intricate institutional arrangements? Through an examination of data on rural Kenya during both the colonial period and the past two and a half decades of governmental disengagement from rural areas, this research demonstrates that informal local institutions shape individuals’ responses to climate variability and are likely to frame future adaptations to climate change. In the colonial period, local clans promoted informal institutions such as mutual help groups and seasonal migration in response to climatic extreme events. Since the mid-1980’s, local organizations commonly classified as Local Rural Institutions (LRIs) have promoted new informal rules and norms such as institutional innovativeness and the development of non-climate-dependent sources of income. A significantly large number of households on three study sites in the Mt. Kenya area have adopted these livelihood strategies and, as this dissertation argues, these rules and norms have played an important role in reducing their overall vulnerability to climate variability. Examining another informal local institution upon which the people of Mt. Kenya have relied to cope with climate variability and develop adaptive capacity, this dissertation also analyzes the use of local social capital in one specific village in the semi-arid area of the mountain. Complementary social networks diffusing information related to farming and other income generating activities have continued to shape local adaptive capacity in Kambita. Looking towards the future, this work provides evidence that LRIs and social networks will shape future adaptation to climate change on Mt. Kenya by fostering increased institutional innovativeness and further disconnecting income from climate conditions. In order to understand the influence of intricate informal institutional arrangements on the shape of coping and adaptation strategies in the Mt. Kenya area, this research has demonstrated the value of combining relatively classic methods and relatively innovative methods. First, after conducting and gathering information from a role-playing game on land-use decision-making, I built a qualitative decision-making matrix, a neural network model, and a multi-criteria evaluation model and then compared their relative explanatory power. In fact, this research found that due to the specific complementarities, tradeoffs, and synergistic dynamics that exist between them, these separate methods can be used together to better analyze local institutional frameworks in contexts where informal institutions are dominant. Second, through a qualitative analysis of life-stories interviews, I studied the evolution of informal institutional arrangements over several decades and obtained in-depth knowledge of coping strategies for climate variability, including mutual help groups and seasonal migration. Third, I performed a statistical analysis and a social network analysis on data collected in three village-wide, household surveys and then contextualized and increased the validity of those quantitatively meaningful results with key informant interviews. Finally, I conducted a number of role-playing games in which players made livelihood decisions in simulated conditions of climatic change. By collecting and analyzing the players’ simulated adaptation strategies, this research improves upon works that base predictions for future adaptation to climate change solely on past coping strategies and provides new insight into the dynamic processes of adaptation
Ecosystem tipping points in the Laurentian Great Lakes
No full textThe effects of human land use change are ubiquitous and pervasive. Anthropogenic changes to landscapes around the world have impacted terrestrial ecosystems in numerous ways. Because what human activities occur on the land often affects water, management of the use of the land becomes tantamount to preserving a precious natural resource, water. The overarching focus of this thesis is to examine how increased human land use affects the integrity of surrounding freshwater systems. The terrestrial and aquatic components characterizing these interactions are complex, adaptive, and dynamic, and as such, possess qualities of emergence and nonlinear behaviors, including characteristics of what some call \u27tipping points\u27. Unfortunately the term \u27tipping point\u27, as used in the ecological literature, is poorly defined and is a topic of considerable debate. To address this concern, and clarify what is meant by the term \u27tipping point\u27, a conceptual framework for tipping points is presented in this thesis. In order to apply the theoretical framework of tipping points to real-world occurrences, data on stream-insect response to agricultural and urban land uses from the Great Lakes states of IL, WI, and MI are analyzed using the conceptual framework developed in Chapter 2. The application of tipping points in management is rather rare due to deficits in long-term monitoring capabilities, and reliable early warning signal measures or useful indicators. We are also unable to account for or predict emergent, unexpected properties, which may have large consequences on system dynamics and generate tipping points if they are of high magnitude. However, recognizing that the study of tipping points strictly related to the natural sciences is still in its infancy, there is currently ample opportunity for breakthrough developments in tipping point predictability, which in turn may yield valuable information about coupled natural human systems
Using Soundscapes to Measure Biodiversity, Habitat Condition, and Environmental Change in Aquatic Ecosystems
No full textBiodiversity loss is the silent crisis of the 21st century. Human activities are drastically altering the diversity of life on Earth, yet the extent of this transformation is shrouded by our limited information on biodiversity and how it is changing. Emerging technologies may be suited to fill this information gap, and as a result increase our capacity to measure and manage natural systems. Acoustic monitoring is a remote sensing technique that is rapidly reshaping the temporal and spatial scales with which we can assess animal biodiversity. Through recording and analyzing soundscapes—the collection of sounds occurring at a given place and time—we can assess biodiversity, habitat condition, and environmental change. However, the relationships between soundscapes and these three ecological dimensions are still in the early phases of categorization, especially in aquatic systems.This dissertation investigates how soundscapes can be used to measure biodiversity, habitat condition, and environmental change in aquatic habitats. It addresses several knowledge gaps: First, I develop a framework for classifying unknown sounds within a soundscape, which I use to measure the acoustic diversity and dynamics within a tropical freshwater wetland. Second, I demonstrate that soundscapes can reflect the resilience of animal communities following disturbance events. Altered soundscapes revealed that Hurricane Maria, which swept through Puerto Rico in September 2017, impacted dry forest animal communities more than adjacent coral reef communities. Third, in kelp forest habitats off the coast of California, USA, I showed that soundscape variables correlated with ecological variables associated with regime shift in kelp forests, including urchin density, kelp cover, and fish diversity. Overall, this dissertation demonstrates that soundscape recording and analysis is a promising way to assess the ecological conditions of aquatic systems
Theory and application of soundscape conservation and management: Lessons learned from the U.S. National Park Service
No full textSoundscapes, or the acoustic environment of a given area, are being impacted by the growing threat of human generated sounds. The knowledge about the effects of noise on humans and wildlife is building, but in the United States there is no national policy related to noise mitigation. Soundscape management is emerging as an approach to protect soundscapes and their associated values. In an effort to inform this new approach, the goal of this dissertation is to improve the understanding and management of soundscapes. This goal is addressed through three objectives: (1) Identify the characteristics of and values ascribed to soundscapes, (2) Explore the challenges of soundscape management implementation within the context of the U.S. National Park Service (NPS), and (3) Determine the role of park managers\u27 perceptions regarding soundscape management. The research in this dissertation distinguishes soundscapes as a resource by identifying the values ascribed to them. The social and ecological values of soundscapes that are identified include human and wildlife wellbeing, sense of place, landscape interactions, and ecological integrity. A typology of soundscapes representing significant values is proposed to guide conservation. Soundscapes also possess characteristics that align them with common-pool resources: there are multiple users of soundscapes, soundscapes can experience subtractability and degradation, and it is difficult to exclude users from accessing soundscapes. This dissertation then explores the challenges of soundscape management implementation within the context of the U.S. National Park Service (NPS). NPS formally adopted soundscape management in 2000, but there is little research on the implementation of soundscape management within individual park units. A mixed methods approach was used to gain an in-depth understanding of soundscape management. An NPS-wide survey of park unit managers was analyzed providing a comprehensive depiction of soundscape management in park units. The survey results indicate that motorized transportation noise, primarily from roads and aircraft, are widespread. These and numerous other noise sources are being addressed with a number of different soundscape management actions or not at all. To understand the differences in soundscape management implementation across park units, NPS managers from parks representing different levels of implementation were interviewed. Guided by the Theories of Reasoned Action Approach and Diffusion of Innovations, the role of managers\u27 attitudes, subjective norms, and perceived behavioral control were investigated. Five categories of soundscape implementation emerged ranging from Innovative/Early Adopting to Nonadopting. Two primary challenges managers identified were lack of control to manage noise sources that are outside park unit boundaries (perceived behavioral control) and the perception that soundscapes are not a priority in the park or NPS-wide (descriptive norms). From this research three overarching findings are presented: (1) Soundscape management is consistent with conservation biology principles, in particular utilizing significant values to prioritize management, (2) Recognizing the common-pool resource characteristics can help to craft management strategies, and (3) Managers\u27 perceptions are important considerations to overcome barriers to implementing soundscape management
Using Computational Musicological Approaches and Informatics to Characterize Soundscapes in Diverse Natural and Human-dominated Ecosystems
Full text linkThe overarching objective of my dissertation research is to use computational musicology and informatics methods to characterize soundscapes in myriad ecosystems across different disturbance gradients. Three questions guided my research: (1) Can my methods place sound signals into three major sound source bins (classes) better than current approaches? (2) How can traditional metrics quantify disturbance and temporal periods within a time-dependent structure? (3) Can a multi-labeling approach allow for content discovery in a soundscape ecology database?To address these questions, I organized the dissertation into three research chapters.The second chapter, “Spectral timbral analysis for discrimination of soundscape components,” explores sound beyond traditional acoustic metrics and utilizes spectral features as described in MIR systems as a novel approach to classify dominant soundscape compositions. Current soundscape analyses consider the acoustic properties of frequency and amplitude resulting in varied metrics, but rarely focus on the discrimination of soundscape components. Computational musicologists, however, ingest similar data but consider a third acoustic property, timbre. We used recording samples from three different ecosystems from the soundscape library at the Center for Global Soundscape to demonstrate the efficacy of timbre in distinguishing among dominant soundscape components.The third chapter, “A rapid assessment monitoring framework to characterize a loud sound event stressor on a vocalizing bird community in a US Midwestern prairie,” addresses the two research questions that broach traditional metrics to quantify disturbance in an ecosystem to a rapid assessment approach in a coupled-human natural system. This chapter is the result of two years of field experience at a restored prairie in a US Midwestern prairie. We investigate how a proposed stressor-response monitoring framework could be used to quantify changes in a vocalizing community’s response to a loud sound event (LSE) at an urban historical park. The framework utilizes time-dependent data to assess an LSE stressor using a passive acoustic recorder network.The fourth chapter, “Data mining for soundscape content using a multi-label kNN approach presents a case study for rapid assessment of disturbance in a temperate forest. The multi-label approach combines practice of knowledge discovery with music information retrieval systems using recordings from a long-term study on climate change in Tippecanoe County, Indiana. The aim was to see if soundscape content analysis using a supervised clustering method could contribute to a system that assesses the impact of altered soundscapes on wildlife communities and human systems. We propose a soundscape content analysis framework for improved knowledge outcome with assistance of the multi-label (ML) concept.Finally, the fifth chapter provides summary remarks about each chapter and the future of the field
Habitat contributions to biodiversity trends at a subcontinental extent
No full textThe extent to which humanity\u27s metabolism of natural resources has impacted the biosphere is significant. After discussing the global state of biodiversity, I use the 1992 National Land Cover Dataset and the North American Breeding Bird Survey to examine how avian species richness responds to habitat-level factors across the conterminous United States, and find a significant relationship between land-cover and species richness. I then use BBS data to examine whether species richness changes over time by examining trends in species richness on 554 routes surveyed continuously between 1990 and 2006. A linear regression analysis indicates a slight increase in species richness over this interval, but the spatial and frequency distributions of this change suggest the possibility that species richness attains a level of dynamic equilibrium in the absence of human disturbances. These two studies reinforce the need for integrative approaches to the measurement of multiple dimensions of biodiversity simultaneously, leading to a discussion of the role that the biophony, as a measure of biotic activity in the soundscape, could play as a multidimensional measure of biodiversity. In addition to facilitating transitions across spatial and temporal scales in biodiversity studies, the biophony of different habitats may offer unique information about the physiology, intraspecific communication, interspecific interactions, and responses of groups of organisms to anthropogenic disturbances. This information could foster a deeper understanding of the spatio-temporal dynamics of biodiversity, and could facilitate a perceptual shift that re-couples human and biophysical systems
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