title: A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers

authors: Aronson, Myla F. J.

subjects: anthropogenic activities

abstract: Urbanization contributes to the loss of the world's biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the world's cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km2) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.

text: A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers Urbanization contributes to the loss of the world's biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the world's cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km2) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.

year: 2014

title: Range imager performance comparison in homodyne and heterodyne operating modes

authors: Conroy, Richard M.

subjects: three-dimensional

abstract: Range imaging cameras measure depth simultaneously for every pixel in a given field of view. In most implementations the basic operating principles are the same. A scene is illuminated with an intensity modulated light source and the reflected signal is sampled using a gain-modulated imager. Previously we presented a unique heterodyne range imaging system that employed a bulky and power hungry image intensifier as the high speed gain-modulation mechanism. In this paper we present a new range imager using an internally modulated image sensor that is designed to operate in heterodyne mode, but can also operate in homodyne mode. We discuss homodyne and heterodyne range imaging, and the merits of the various types of hardware used to implement these systems. Following this we describe in detail the hardware and firmware components of our new ranger. We experimentally compare the two operating modes and demonstrate that heterodyne operation is less sensitive to some of the limitations suffered in homodyne mode, resulting in better linearity and ranging precision characteristics. We conclude by showing various qualitative examples that demonstrate the system’s three-dimensional measurement performance.

text: Range imager performance comparison in homodyne and heterodyne operating modes Range imaging cameras measure depth simultaneously for every pixel in a given field of view. In most implementations the basic operating principles are the same. A scene is illuminated with an intensity modulated light source and the reflected signal is sampled using a gain-modulated imager. Previously we presented a unique heterodyne range imaging system that employed a bulky and power hungry image intensifier as the high speed gain-modulation mechanism. In this paper we present a new range imager using an internally modulated image sensor that is designed to operate in heterodyne mode, but can also operate in homodyne mode. We discuss homodyne and heterodyne range imaging, and the merits of the various types of hardware used to implement these systems. Following this we describe in detail the hardware and firmware components of our new ranger. We experimentally compare the two operating modes and demonstrate that heterodyne operation is less sensitive to some of the limitations suffered in homodyne mode, resulting in better linearity and ranging precision characteristics. We conclude by showing various qualitative examples that demonstrate the system’s three-dimensional measurement performance.

year: 2009

title: Joseph Harris Smallman

authors: Hart, Philip

abstract: Born to a mining agent and trained as a mining surveyor, in 1864, less than a year after the birth of his first child, Smallman left England for New Zealand to establish a ‘Mining business’, promising that his family would join him once it was successful. But they were never asked to join him, and after 1870 he ceased to write to his wife. 
The ‘Mining business’ never eventuated, but in 1865 he prospected at Thames, unsuccessfully seeking alluvial gold. Although criticized for living off Maori and doing little prospecting, with his partner he investigated several areas of the Hauraki Peninsula, again unsuccessfully. When the Thames goldfield was opened, with his encouragement, two years later, he mined there for some years, proving himself to be a competent miner but not making his fortune. After working elsewhere, by the mid-1870s he was living with another man’s ‘half-caste’ wife on her land near Te Aroha, having five children with her. Happy to be described as a Pakeha Maori and closely associated with the local hapu, he supported them over land dealings and the development of the district. Despite spending most of his time farming, he remained interested in prospecting, and made some explorations in districts closed to Pakeha. After gold was found at Te Aroha, for a short time he worked with Maori partners in unprofitable claims.
Either before or after his second wife had a child by another man in 1886, he left New Zealand to return to his English family; and remarkably, despite his first wife knowing that his liaison had produced children, she accepted him back after his long absence, and they remained together for the rest of their lives.

text: Joseph Harris Smallman Born to a mining agent and trained as a mining surveyor, in 1864, less than a year after the birth of his first child, Smallman left England for New Zealand to establish a ‘Mining business’, promising that his family would join him once it was successful. But they were never asked to join him, and after 1870 he ceased to write to his wife. 
The ‘Mining business’ never eventuated, but in 1865 he prospected at Thames, unsuccessfully seeking alluvial gold. Although criticized for living off Maori and doing little prospecting, with his partner he investigated several areas of the Hauraki Peninsula, again unsuccessfully. When the Thames goldfield was opened, with his encouragement, two years later, he mined there for some years, proving himself to be a competent miner but not making his fortune. After working elsewhere, by the mid-1870s he was living with another man’s ‘half-caste’ wife on her land near Te Aroha, having five children with her. Happy to be described as a Pakeha Maori and closely associated with the local hapu, he supported them over land dealings and the development of the district. Despite spending most of his time farming, he remained interested in prospecting, and made some explorations in districts closed to Pakeha. After gold was found at Te Aroha, for a short time he worked with Maori partners in unprofitable claims.
Either before or after his second wife had a child by another man in 1886, he left New Zealand to return to his English family; and remarkably, despite his first wife knowing that his liaison had produced children, she accepted him back after his long absence, and they remained together for the rest of their lives.

year: 2016