438 research outputs found

    Super-resolution mapping of wetland inundation from remote sensing imagery based on integration of back-propagation neural network and genetic algorithm

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    Mapping the spatio-temporal characteristics of wetland inundation has an important significance to the study of wetland environment and associated flora and fauna. High temporal remote sensing imagery is widely used for this purpose with the limitations of relatively low spatial resolutions. In this study, a novel method based on integration of back-propagation neural network (BP) and genetic algorithm (GA), so-called IBPGA, is proposed for super-resolution mapping of wetland inundation (SMWI) from multispectral remote sensing imagery. The IBPGA-SMWI algorithm is developed, including the fitness function and integration search strategy. IBPGA-SMWI was evaluated using Landsat TM/ETM + imagery from the Poyanghu wetland in China and the Macquarie Marshes in Australia. Compared with traditional SMWI methods, IBPGA-SMWI consistently achieved more accurate super-resolution mapping results in terms of visual and quantitative evaluations. In comparison with GA-SMWI, IBPGA-SMWI not only improved the accuracy of SMWI, but also accelerated the convergence speed of the algorithm. The sensitivity analysis of IBPGA-SMWI in relation to standard crossover rate, BP crossover rate and mutation rate was also carried out to discuss the algorithm performance. It is hoped that the results of this study will enhance the application of median-low resolution remote sensing imagery in wetland inundation mapping and monitoring, and ultimately support the studies of wetland environment.This paper was supported by the National Natural Science Foundation of China (Grant No. 41371343 and Grant No. 41001255) and the scholarship provided by the China Scholarship Council (Grant No. 201308420290)

    Woody Plant Invasion into the Freshwater Marl Prairie Habitat of the Cape Sable Seaside Sparrow: Final Report

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    In the fall of 2005, U.S. Fish and Wildlife Services (USFWS) contracted with Florida International University (FIU) to study the physical and biological drivers underlying the distribution of woody plant species in the marl prairie habitat of the Cape Sable Seaside Sparrow (CSSS). This report presents what we have learned about woody plant encroachment based on studies carried out during the period 2006-2008. The freshwater marl prairie habitat currently occupied by the Cape Sable seaside sparrow (CSSS; Ammodramus maritimus mirabilis) is a dynamic mosaic comprised of species-rich grassland communities and tree islands of various sizes, densities and compositions. Landscape heterogeneity and the scale of vegetative components across the marl prairie is primarily determined by hydrologic conditions, biological factors (e.g. dispersal and growth morphology), and disturbances such as fire. The woody component of the marl prairie landscape is subject to expansion through multiple positive feedback mechanisms, which may be initiated by recent land use change (e.g. drainage). Because sparrows are known to avoid areas where the woody component is too extensive, a better understanding of invasion dynamics is needed to ensure proper management

    Multispectral remote sensing of wetlands in semi-arid and arid areas: A review on applications, challenges and possible future research directions

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    Wetlands are ranked as very diverse ecosystems, covering about 4–6% of the global land surface. They occupy the transition zones between aquatic and terrestrial environments, and share characteristics of both zones. Wetlands play critical roles in the hydrological cycle, sustaining livelihoods and aquatic life, and biodiversity. Poor management of wetlands results in the loss of critical ecosystems goods and services. Globally, wetlands are degrading at a fast rate due to global environmental change and anthropogenic activities. This requires holistic monitoring, assessment, and management of wetlands to prevent further degradation and losses. Remote-sensing data offer an opportunity to assess changes in the status of wetlands including their spatial coverage. So far, a number of studies have been conducted using remotely sensed data to assess and monitor wetland status in semi-arid and arid regions

    Urban Forests and Landscape Ecology

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    Urbanization is a dominant driver of landscape transformation across the world, with cities representing centers of economic and socio-cultural development. Today, more than 4.2 billion people live in urban areas, which represent ~3% of the Earth’s land area. By 2050, it is predicted this number will increase to 6.6 billion people (~70% of the predicted global population). As the human population grows, cities around the globe will continue to expand, increasing the demand for food and services. Within cities, urban forests provide multiple nature-based solutions, as well as other environmental services and socio-economic benefits, such as heat mitigation and social integration. Urban forests are also important for coping with psychological stress during events, such as the COVID-19 pandemic. Therefore, urban forests are a priority for basic and applied forest research because they are intimately connected with people’s physical, cultural, and economic well-being in the urban environment, and can also be important reservoirs of biodiversity. To promote a better understanding of urban forests and landscape ecology, this book in “Urban Forests and Landscape Ecology” compiled research set in urban forests and focused on some spatially explicit processes. Studies presented in this book are highly interdisciplinary and use a wide range of research approaches. This book present nine scientific publications from global urban forests demonstrating that these forests, as a nature-based solution, provide multiple environmental services and are crucial to improve urban livability and thereby the wellbeing of city dwellers

    The role of dispersal in range change in birds

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    Eurasian reed warbler Acrocephalus scirpaceus expanded its range in Great Britain in the late 20th and early 21st centuries. The role of dispersal in this range expansion was investigated. Inference of the mechanisms underlying the range dynamics drew on fieldwork, analysis of large observational datasets, and a simulation model; this model was run in a reedbed map of Britain, generated from satellite data using machine learning. Breeding season temperature sets up reed warbler’s range limit in Britain directly, by influencing occupancy in the current year, perhaps mediated through reed Phragmites australis phenology. Although components of productivity were positively related to temperature, these and adult survival did not decline to the range edge. There was therefore no evidence that demography plays a role in limiting reed warbler’s range in Britain; however, not all aspects of demography were investigated. Survival was negatively related to temperature, and simulations suggested that this may allow reed warbler to maintain a more northerly range limit than without such a relationship. Reed warbler’s range expansion can be explained by a gradual equilibration with climate space, enabled by long-distance dispersal: only rare long-distance dispersing individuals matched the rate of range expansion. Reed warbler’s range edge tracked climate change, but the bulk of the population lagged behind. This could be due to dispersal-limitation, or perhaps newly established populations grow too slowly to generate sufficient emigrants. Simulations suggested that reed warbler’s range size is more sensitive to demography than to dispersal. The number of fledglings per breeding attempt increased over time, probably due to climate warming, and could have increased emigration; if so, this may be the cause of a more rapid movement in the range centroid later in the study period. Emigration, transition and immigration may therefore play different roles in reed warbler’s range dynamics in space and time

    Science-based restoration monitoring of coastal habitats, Volume Two: Tools for monitoring coastal habitats

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    Healthy coastal habitats are not only important ecologically; they also support healthy coastal communities and improve the quality of people’s lives. Despite their many benefits and values, coastal habitats have been systematically modified, degraded, and destroyed throughout the United States and its protectorates beginning with European colonization in the 1600’s (Dahl 1990). As a result, many coastal habitats around the United States are in desperate need of restoration. The monitoring of restoration projects, the focus of this document, is necessary to ensure that restoration efforts are successful, to further the science, and to increase the efficiency of future restoration efforts

    Earth observation for water resource management in Africa

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    Inland Waters

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    Inland waters, lakes, rivers, and their connected wetlands are the most important and the most vulnerable sources of freshwater on the planet. The ecology of these systems includes biology as well as human populations and civilization. Inland waters and wetlands are highly susceptible to chemical and biological pollutants from natural or human sources, changes in watershed dynamics due to the establishment of dams and reservoirs, and land use changes from agriculture and industry. This book provides a comprehensive review of issues involving inland waters and discusses many worldwide inland water systems. The main topics of this text are water quality investigation, analyses of the ecology of inland water systems, remote sensing observation and numerical modeling methods, and biodiversity investigations

    Signals of nonlinear, multiscale and stochastic processes in coastal landscapes

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    Salt marshes are some of the most productive and valuable landscapes on earth, but they are vulnerable to the effects of sea-level rise, erosion and eutrophication. These processes act on a wide range of temporal and spatial scales, which complicate assessments of the health and stability of marsh ecosystems. High-frequency monitoring using in situ sensors captures the complete range of these dynamics, but extracting meaningful physical and ecological information from these signals requires process-based models coupled with statistical techniques. I develop and apply such methods to study two coastal landscapes, a coastal pine forest on the Eastern Shore of Virginia and a mesotidal salt marsh complex in the Plum Island Estuary, Massachusetts. Observations from groundwater wells in the Virginia pine forest indicate that storms are the dominant controls on the hydrology of the forest and that tidal influence is nonexistent. This forest exhibits a distinct spatial pattern in age structure in which young trees do not grow at low elevations. This pattern can be explained by a model that includes the interaction of sea-level rise, storms and the age-dependent variation in tree stress response, which predicts that the long-term evolution of the boundary is an ecological ratchet. Stresses due to sea-level rise slowly push the boundary at which young trees can survive upslope. Powerful storms then kill the mature, persistent forest at low elevations, which quickly pushes the forest boundary up to the regeneration boundary. Salt marshes need to accumulate sediment to replenish material lost as sea-level rises and creek banks erode. Fluxes of sediment can be monitored with simultaneous high-frequency observations of flow from acoustic Doppler current profilers and turbidity from optical backscattering sensors. I first investigate the relationship between water level and flow in marsh channels and develop predictive stage-discharge models to simplify the monitoring of fluxes. I then construct sediment budgets for eleven salt marshes in the Plum Island Estuary. The observed budgets depend strongly on the unique hydrodynamic conditions of each marsh channel. Variability in these conditions leads to the observed spatial and temporal variability in sediment fluxes from these marshes
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