Biodiversity of ant species along a disturbance gradient in residential environments of Puerto Rico

One of the most effective ways to describe the successional gradient of an environment is by using measures of biodiversity. We investigated the biodiversity of ant communities (known tramp/structure invaders) in an environment undergoing urban succession to characterize how ant communities changed along a disturbance gradient. Ant community dynamics were examined within three Puerto Rican housing developments of different ages. Within each development, we assessed the ant community using biodiversity measures of richness, abundance, diversity and evenness. We also studied changes in biodiversity within each development over time as well as how biodiversity related to food preferences within the ant communities. In general, the biodiversity measures increased as the age of the housing development increased. Monthly changes in biodiversity indicated that month was a better predictor of biodiversity in the most recently disturbed development, while the biodiversity in the older developments was less predictable from month to month. The biodiversity measures also suggested that the ant community in the youngest development was comprised mostly of generalist feeders. However, the older sites’ ant species appeared to have more specific feeding preferences. Based on the biodiversity measures of these ant communities, our findings suggest that the housing developments of different ages represented advancing stages of secondary succession. Furthermore, this study indicated that the succession of ant species occurs rapidly (<10 years) in urban environments, resulting in a relatively diverse ant community.     

Using housing growth to estimate habitat change: detecting Ovenbird response in a rapidly growing New England State

Numerous measures of human influence on the environment exist, but one that is of particular importance is houses as they can impact the environment from species through the landscape level. Furthermore, because the addition of houses represents an important component of landscape change, housing information could be used to assess ecological responses (e.g., decline in wildlife habitat) to that change. Recently developed housing density data represents a potential source of information to assess landscape and habitat change over long periods of time and at broad spatial extents, which is critically needed for conservation and management. Considering the potential value of housing data, our goal was to demonstrate how changes in the number of houses leads to changes in the amount of habitat across the landscape, and in-turn, how these habitat changes are likely to influence the distribution and abundance for a species of conservation concern, the Ovenbird (Seiurus aurocapillus). Using a relationship between Ovenbird abundance and housing density, we predict suitable habitat in the forests of Massachusetts (USA) from 1970 to 2030. Over this 60-year period, the number of houses was projected to increase from 1.84 to 3.32 million. This magnitude of housing growth translates into a 57 % decline in Ovenbird habitat (6,002 km² to 2,616 km²), a minimum decline of ~850,000 (48 %) Ovenbirds, and an increase in the number of subpopulations across the landscape. Overall, housing data provide important information to robustly measure landscape and habitat change, and hence predict population change of a species. We suggest that time series of housing data linked to ecological responses (e.g., Ovenbird abundance) offers a novel and underutilized approach to estimating long-term and spatially broad predictions of ecosystem response to landscape change, which in turn can inform conservation and management.     

Vegetation structure along urban ephemeral streams in southeastern Arizona

Riparian areas in Arizona are being encroached upon by urban developments. This study investigated the impacts of different urban housing densities on riparian vegetation structure along ephemeral streams. Nine sites representing three levels of housing density were selected within the town of Marana, located in southeast Arizona. The housing densities were categorized as high (7–8 houses ha^?1), moderate (2.5–4.5 houses ha^?1), and low (< 1.5 houses ha^?1). Each treatment had three replications. The urban developments were relatively young (less than 15 years). No significant differences were found among the treatments for the tree variables (density, height, mean canopy volume and total canopy volume) or the herbaceous vegetation variables (species richness, percentage of introduced species and percentage of ground cover). However, the shrub variables (mean density, mean height, mean canopy volume, total canopy volume and species richness) showed some significant differences. Shrub density and species richness was significantly greater adjacent to ephemeral channels than just three meters upland. In addition, whitethorn acacia shrubs were significantly taller and larger adjacent to the stream channels in the high and moderate housing density sites than in the low housing density sites. Creosote shrubs showed the opposite trend. Increased runoff in the more heavily urbanized streams may have promoted the growth of the facultative riparian species (whitethorn acacia) but not the non-riparian species (creosote). Overall, in these young developments, vegetation was resilient across the levels of urbanization explored in the study.     

Effects of residential density on sonoran desert nocturnal rodents

We compared nocturnal rodent distributions among residential developments and in adjacent undeveloped native habitat remnants in Tucson, Arizona during October 1994. We trapped rodents in 2 low density (0.5 houses/ha) developments, 2 medium density (7.5 houses/ha) developments, and in 4 adjacent blocks of undeveloped native habitat using trap lines of 50 snap traps spaced at 2 traps every 10 meters. We compared species abundance, species richness, and total abundance among the 4 site types in a contingency table using a 2-tailed Fisher's exact test, and used post-hoc tests where the null hypothesis of no difference among sites was rejected. We encountered 144 individuals representing 5 species of nocturnal rodents in 1200 trap nights. Of 4 native rodent species, none were captured in medium housing density sites. House mice (Mus musculus) were captured only in medium housing density sites. Total rodent abundance was lower in both the medium density residential and the adjacent undeveloped sites than in either low density or adjacent undeveloped sites. Low density housing must be included in the developing matrix if the full complement of native nocturnal rodents is to be retained in Tucson.     

Migration to less-popular rural areas in the Netherlands: Exploring the motivations

Migration into rural areas is often explained in terms of the rural idyll, the attraction of the countryside with its less hurried way of life in a quiet, spacious and green environment. However, this migration phenomenon has mostly been researched in attractive, amenity-rich, popular rural areas. This paper investigates the characteristics and motivations of migrants to less-popular rural areas using survey data (N = 664) for four municipalities in the North of the Netherlands. Our study shows a young group of in-migrants with relatively low incomes, but also a large proportion of working people and a considerable number of highly educated movers. Separating the motivations for choosing to live in a rural area in general from the motivations for choosing this specific rural area reveals that while the pull of the rural idyll is an important motivation for moving to a rural area in general, the reasons for choosing the specific rural area are a mixture of housing characteristics, the physical qualities of the environment, personal reasons and the low house prices in the area. Combining the motivations with the characteristics of the movers reveals the diversity within the movers group. Our analysis shows a group of movers motivated to live close to family and friends, consisting of return migrants, singles, the youngest and oldest age groups and also the lowest income group. The physical qualities of the environment attract a group of highly educated movers, people with high incomes and people aged between 35 and 64. The motivation of housing characteristics, referring in most cases to the availability of a specific house, is mentioned by a wide range of movers, but in particular by people moving from urban areas.     

不断完善住房制度,努力构建有中国特色的住房保障体系

我国住房保障体系主要解决老百姓＂住有所居＂的问题,关键要在不同时间段使老百姓的住房条件适应社会发展的要求。要达到这个目标,需要不断完善住房制度改革。总体上,低收入者要有社会保障,中、高收入者要走商品化道路,中等偏下这一块要有政府支持,如发展公共租赁房,在房价上涨较快的地区增加限价商品房供应,通过三个不同的层次来达到老百姓＂住有所居＂的目标,构建有中国特色的住房保障体系。     

Housing and building materials in low-income settlements in Dar es Salaam

Dar es Salaam (Tanzania) is one of the fastest growing cities in sub-Saharan Africa. As in other sub-Saharan cities, government housing programmes have reached only a tiny percentage of urban residents. The vast majority either build for themselves or live as tenants in swahili houses provided by others. This paper examines the process of house building in Dar es Salaam through a survey of 90 house-owners in nine low-income settlements in the city. It is shown that in the past decade the price of manufactured building materials has risen steeply following the implementation of liberalisation policies. Despite this, house owners still strive to build modern houses in concrete blocks, which offer higher standards of comfort and security as well as bringing in higher income from rents. Those who cannot afford to do so, are obliged either to rent one or more rooms in a house constructed by others or to build a modest house using traditional materials. Although these materials are available in the market, some housebuilders still collect their own. There is evidence of increasing distance from the source, the substitution of inferior species and declining quality, all of which indicate that resources are coming under pressure.     

RACIAL DIFFERENCES IN HOMEOWNERSHIP and HOUSING WEALTH, 1970–1986

Black couples are found to own a disproportionately low share of aggregate housing wealth in the United States because they are less likely than whites to be homeowners and because black-owned houses have lower market values than white-owned houses. Probability of ownership and house value equations (corrected for selectivity bias) are estimated with national data for 1970, 1980, and 1986. Trends in racial differences in homeownership and house value are identified and reasons for their existence are investigated.     

Housing,memory and everyday life in contemporary Britain

With specific reference to public policy and the housing market in post-Second World War Britain, this article explores the relationship between housing, memory and everyday life. It argues that the house owes its cultural and emotional power to its capacity to separate itself ideologically from what Marc Augé calls the ‘non-places’ of everyday life. The extent to which houses have come to be seen as refuges from the non-place requires a great deal of symbolic work to conceal their sameness and everydayness. The association of the house with nostalgia, in particular, represents a denial of what Henri Lefebvre sees as the ‘residuality’ of the everyday, its capacity to lag behind the more dramatic transformations of modernity. In order to explore these questions, the article focuses on different types of housing in contemporary Britain, which are all based on a serial repetition and collectivity that are often denied. It examines: how the demolished terraced house and the surviving slum reveal the broader structures of everyday life in a way that the refurbished middle-class town house, alternating between a commodified past and a self-promoting futurism, specifically conceals; how the high-rise estates represent the most visible manifestation of the residuality of the everyday; and how new suburban houses are built in ‘timeless’ vernacular styles and sold as well-equipped interiors for exclusively privatized use, in a way that obscures their links to systems of mass production and consumption. The article concludes that the cultural economy of houses denies the reality of uneven development, and the ways in which our carefully refurbished homes are achieved at the expense of other everyday spaces.     

Exotic trees can sustain native birds in urban woodlands

Native landscaping has been proposed as a means of increasing native bird diversity and abundance in urban landscapes. However residents’ preferences for vegetation are such that exotic plants are often preferred over natives. We investigated the extent to which native birds foraged in three common native and three exotic tree species in mixed urban woodland during four seasons. We predicted that native birds would spend more time foraging in native trees, and that food resources provided by deciduous exotic trees would be more seasonal than those provided by non-deciduous natives. Native birds spent a lot of time foraging in two of the native tree species, but very little time in native red beech (Nothofagus fusca). They used exotic oak (Quercus robur) throughout the year, and sycamore (Acer pseudoplatanus) seasonally. Oak and European beech (Fagus sylvatica) were used by the largest number of species overall, because they attracted both native and exotic birds. With the exception of tree fuchsia (Fuschia excorticata), which produces large volumes of nectar followed by fruits, all tree species were sources of invertebrates for insectivorous feeding. Seasonality of use was high only in sycamore, indicating limited support for our second prediction. We show that being native doesn’t necessarily entail being a good food source for native birds, and popular landscaping exotic species, such as oak, provide foraging opportunities across all seasons.     

DNA of the House

ABSTRACT

The article aims to illuminate the hidden path by which a symbolic dimension in a traditional society is transferred to the modern world. The modernization process in Seoul during the second half of the twentieth century was one of the most intense and radical. The traditional courtyard house, which had been the single form of dwelling in the city for centuries, was replaced by modern houses within a few decades. Apartment housing became the most dominant housing type, and this new spatial setting reshaped domestic lifestyles. At the surface level, there seems to be no connection between the old and new housing culture. A series of analyses reveals, however, that there exists a hidden dimension of “level distinction,” i.e. a conceptual differentiation between high- and low-level floors that has not only survived the radical change, but also guided the direction of contemporary housing development.     

Ant dominance in urban areas

A survey was conducted to determine the distribution of dominant ants and factors that may influence their dominance in New Zealand cities. A new method of active ant trapping combining aspects of pitfall trapping and attraction to food baits was used to capture a sample of all ant species that attended baits. Fifty eight percent of the ant species present in New Zealand were recovered from 2202 traps, with multiple species catches in 245 traps. There was a strong latitudinal relationship in the distribution of ant species, with the proportion of native to introduced species increasing in favour of the native species as latitude increased (south). The presence of Linepithema humile, the Argentine ant, a numerically dominant species was associated with a significant reduction in the number of other ant species captured. With increased urbanisation, providing refugia at times of cool temperatures for warm temperate-sub tropical introduced ant species, their range may extend into the higher latitudes, further displacing native ants from New Zealand cities.     

Seasonal comparisons of daily activity budgets of gray squirrels (Sciurus carolinensis) in urban areas

Gray squirrels (Sciurus carolinensis) use trees for various resource needs in urban and nonurban settings; particularly, mast producing trees which are the preferred and supplemental foods for the species. During periods of abundant mast availability, less time will be invested in foraging because of the higher success rate stemming from the increased ability to locate food items. Conversely, in periods of reduced mast availability, more time will be invested in foraging. However, correlations between food availability and foraging effort are only supported under the assumption that gray squirrels rely significantly on mast as a preferred or supplemental food source (Nixon et al, J Wildl Manag 39:1–25, 1975). Therefore, given the seasonal variation in the availability of mast, there should also be correlating seasonal variations in foraging effort. In this paper, we will examine daily and seasonal time-activity budgets of gray squirrels in urban areas. We studied the time-activity budgets of gray squirrels in six urban parks in Baltimore, MD. Seasonal frequencies of activities were expressed as percent occurrence and seasonal differences in activities were analyzed using a Tukey Studentized multiple range test for significance. We found that the activity with highest percent occurrence was forage (2003, summer: 23.8 %, fall: 25.9 %; 2004, summer: 23.1 %, fall: 25.2 %), followed by feed and store, all activities associated with food. Results of the Tukey Studentized multiple range test for seasonal differences of activities yielded significant results (P?P?=?0.003); fall 2003 and fall 2004 (P?=?0.048).     

Common factors influence bee foraging in urban and wildland landscapes

Bees are important flower-visiting insects that display differential occurrences at food resources throughout urban and wildland landscapes. This study examined the visitation rates and foraging patterns of eight taxonomic groups of bees that are common to California poppies, Eschscholzia californica, in both landscape types. Bee occurrence was documented in relation to floral resource characteristics (patch area, poppy coverage, and poppy density), local landscape characteristics (distance to the wildland-urban interface, distance to riparian areas, distance to green space, and land use), and regional landscape context (urban versus wildland). Similar abundance and richness measures were recorded at both urban and wildland poppy patches, but community composition varied in each landscape. Bumble bees were more abundant at poppies in the wildland whereas species in the family Halictidae (sweat bees) were more abundant at poppies within the urban landscape. Resource patch size and density consistently correlated with increased bee presence for all bee types foraging in the wildland. Individual patterns of occurrence in the urban landscape were somewhat divergent; the foraging dynamics of larger bodied-bees (Bombus vosnesenskii and Megachile species) correlated significantly with resource patch size and density, whereas smaller-bodied bees (family Halictidae and Andrena species) were influenced by landscape characteristics such as distance to the wildland-urban interface and distance to riparian areas. In summary, the surrounding landscape had an influence on community composition, but the magnitude of the floral resource present at a site and factors relating to foraging energetics were dominant drivers of local occurrence. These results suggest that management strategies that provide dense and abundant floral resources should be successful in attracting bees, irrespective of their location within the urban matrix.     

Globalization, de-industrialization and Hong Kong's private rental sector

A number of scholars have identified a changing role for private rental housing, as it becomes a more mainstream tenure to house the insecure rich and poor alike in globalizing cities. Hong Kong is an important global city and is experiencing rising rates of social polarization associated with globalization generally, its articulation with the Chinese economy specifically and the impact of the Asian Financial Crisis in 1997. Our empirical research suggests that Hong Kong's private rental sector has responded to and articulates with the city's specific globalization trajectory. It increasingly houses the highly paid, highly skilled but relatively insecure elite and the low paid, low skilled and very insecure underclass, for whom prospects of public housing or home ownership are diminishing. Private renters are younger, more mobile and house both top-end and bottom-end ethnic minorities. The traditional role of private renting and large scale obsolete inner-city housing stock, combined with the aggressive development of up-market and highly desirable private housing estates makes the sector particularly adept at meeting the needs of Hong Kong's hour glass shaped global society. We anticipate that the size of the private rental sector will increase, albeit from a low base and that its hour-glass shape will become more pronounced.     

Urban land cover decreases the occurrence of a wetland endemic mammal and its associated vegetation

Urbanization and other land cover changes have been particularly detrimental to wetlands throughout the planet. One wetland specialist that may be sensitive to land cover changes surrounding wetlands is the round-tailed muskrat (Neofiber alleni; hereafter RTM). The RTM is a wetland obligate rodent that appears to have declined over the last half century and is a species of concern in Florida, where it is a near endemic. To determine if urbanization or other land cover influenced the distribution of RTMs we took a multi-scaled approach to examine the occurrence of RTMs and their associated vegetation in North-Central Florida. We detected RTMs on 19 of 72 sample plots and used a Classification And Regression Tree (CART) to determine that dogfennel (Eupatorium capillifolium) was negatively associated with RTMs and maidencane (Panicum hemitomon) was positively associated with their occurrence on sampling plots. Examining the influence of landscape composition for 2 km surrounding our plots we found that RTM occurrence was negatively related to urban land cover. Further, we found that dogfennel increased and maidencane decreased as urbanization increased in the surrounding landscape. Our research suggests that conservation of RTMs and their associated vegetation should focus on limiting urban sprawl at least within 2 km of wetlands.     

Urbanisation factors impacting on ant (Hymenoptera: Formicidae) biodiversity in the Perth metropolitan area, Western Australia: Two case studies

Two synchronous projects undertaken in 2011 examined the likely impact of increasing urban densification on invertebrate populations within urban settlement in Perth, Western Australia. One project analysed the ant fauna found in 20 gardens and lawns in small to very small properties (these having a bungalow or duplex (semi-detached) as the main residential building, and a lawn or garden area of 43 m²–332 m²) east, south, north and west of the Central Business District (CBD). The other project examined the ant fauna at 14 sites, principally in native regrowth along the Kwinana Freeway, a major artery that runs north to south through Perth’s suburbs. The gardens and lawns produced a very depauperate fauna of 26 ant species, of which a maximum of 20 were native and at least six species were exotic. The ant fauna from regrowth adjacent to the Kwinana Freeway and at two additional sites (one a bush control) was more than twice as rich, the 56 species collected including only two exotics. In the garden project, ant richness, evenness and abundance were not significantly correlated with size of the garden area. The same applied even when the exotic Pheidole megacephala-dominated gardens were removed from the analysis. Ordination analysis combining the two sets of data revealed a distinct clustering of most of the regrowth sites, whereas the bush control stood alone and garden or lawn sites exhibited a much looser pattern of association. We suggest that increasing the density of Perth suburbs is resulting in drastic loss of native invertebrate fauna, of which ants are a useful bioindicator. However, native vegetation regrowth along major arterial roads could act as a reservoir for invertebrate species that might otherwise disappear entirely from the Perth metropolitan area.     

‘Why isn’t it solved?’: Factors affecting improvements in housing outcomes in remote Indigenous communities in Australia

A range of factors has affected the design and construction of Indigenous housing in remote areas of Australia in recent times, including: socio-demographic issues; culture and design; consultation processes; the costs of remoteness; and procurement and delivery processes. Their implications for appropriate design and construction of remote Indigenous housing are analysed in this paper. Most significantly, these factors cannot be separated from cost because the need to spread available funds broadly to build the largest number of houses at the best price affects design and construction quality, and these are often neglected in the short-term budgeting within this process.     

Hadedas in the hood: Hadeda Ibis activity in suburban neighbourhoods of Pietermaritzburg,KwaZulu-Natal,South Africa

Urban environments are a combination of green and grey spaces and although many species are unable to live in these transformed areas there are some that can use urban features to benefit their persistence here. The Hadeda Ibis (Bostrychia hagedash) is one such species and this study investigated the urban activities of these birds. Five suburbs of Pietermaritzburg in KwaZulu-Natal, South Africa were surveyed for Hadeda Ibis engaged in flying, foraging, perching and calling behaviours. Each suburb differed in the degree of urbanisation and we expected that their morning activity would differ accordingly. A difference in Hadeda Ibis calling, foraging and flying activity between summer and winter was also expected because of seasonal rainfall patterns. Although Hadeda Ibis were more common in suburbia than the city centre in Pietermaritzburg, they occurred throughout. More were observed calling in summer than in winter probably because of changes in distribution during the breeding season with more family groups of two or three individuals. There was no significant difference in Hadeda Ibis flock size when comparing foraging during summer with winter despite greater summer rainfall. Also there was no significant difference in flock size with flying activity for both seasons nor suburb although it was expected that Hadeda Ibis would need to travel further during winter and from suburbs with more grey space to access ideal foraging areas. Hadeda Ibis need moist soil to forage effectively and in an urban environment short grassed, well watered lawns provided an ideal foraging habitat regardless of season. Hadeda Ibis used urban structures like house roofs, poles, pylons, and fences for perching but continued to roost in trees so while they are able to use urban features, they still rely on a certain degree of green space for urban persistence.