Alien plant species do have a clear preference for different land uses within urban environments

Since neophytes can become invasive in the future, untangling their ecological preferences is of paramount importance, especially in urban areas where they represent a substantial proportion of the local flora. Studies exploring alien species assemblages in urban environments are however scarce. This study aims to unravel alien plant species preferences for five urban land uses (densely built-up areas, open built-up areas, industrial areas, broadleaved urban forests, and agricultural areas and small landscape elements). We took the city of Brussels as a model, in which we recorded all vascular species growing spontaneously in grid cells of 1 km². We tested two different ways of classifying the 1-km² cells: (1) We simply associated each cell with its dominant land cover; (2) We used a fuzzy approach for which the degree of association of a given cell to a given land cover depended on the proportion of that land cover within the cell. For both classification methods, we calculated the indicator species of the resulting land cover types based on alien species only. The crisp and fuzzy classifications identified 33 and 49 species, respectively, with a clear preference for some urban land use types (from a total of 129 alien plant species analyzed). Results showed that urban land use types having apparently similar environmental conditions can actually harbor different neophyte assemblages. Fine-tuning the categorization of urban environments in future ecological studies is therefore important for understanding spatial patterns of alien species occurrence.     

Species richness in urban parks and its drivers: A review of empirical evidence

There is growing recognition of urban areas as hosts for innovative ways to conserve and promote biodiversity. Parks, as one specific type of urban green space, constitute particularly important biodiversity hotspots in the cityscape. We reviewed empirical findings on the species richness in urban parks across all species groups that have been studied. The aim was to assess and discuss the overall species richness of urban parks, its community attributes and drivers. Search and subsequent selection process resulted in 62 papers from 25 different countries. For all examined species groups, the findings consistently show that parks are among the most species rich types of urban green spaces, but also that exotics constitute large shares, especially of plant species. Key ecological theories like the gradient approach and the island habitat ecological theory, and fundamental ecological relationships such as the species-area relationship are valid despite the manipulated ‘nature’ of parks and the surrounding urban matrix. Most studies surveyed large number of parks and applied ‘multi-scale’ approaches in tests of confounding variables, providing methodological strength. While matrix effects are consistently found to affect species richness negatively, the diversity of habitats and microhabitat heterogeneity contained in urban parks appears as the most decisive factor for the overall species richness. However, a constraint of research to date is the limitation of individual studies to one or a few species groups, rarely bridging between flora and fauna. Adopting ‘multi-species group’ approaches in future research is needed to further advance the understanding of the overall biodiversity of urban parks, and its drivers.     

Lepidoptera-habitat relationships in urban parks

We examined the relationships among Lepidopteran species richness and relative abundance, field and park size, and herbaceous plant richness and cover in parks of New York, NY. Lepidopteran populations and habitats were quantified from 1 June–30 September 2002 in fields of 8 New York City (NYC) parks. We observed 42 species of Lepidoptera, with park size, field size, and plant species richness positively related to Lepidopteran abundance and species richness. Several plant species received heavy use and appeared to be important to Lepidoptera in this urban environment, particularly butterfly-bush (Buddleia davidii), mugwort (Artemisia vulgaris), knapweed (Centaurea maculosa), and clover (Trifolium spp.).     

Fungal community composition analysis of 24 different urban parks in Shanghai,China

Urban Ecosystems - Urban parks are an important constituent of cities; they harbour microbial diversity which plays a key role in soil ecosystem functioning. The bacterial diversity of many urban...     

A comparison of carbon and nitrogen stocks among land uses/covers in coastal Florida

Coastal areas are rapidly developing due to population growth and the appeal of coastlines. In order to gain insight into how land use/cover affects carbon (C) storage in a coastal context, we examined soil and vegetation C and soil nitrogen (N) across land uses near Apalachicola, FL. Forested wetlands had the greatest soil C and N storage, while natural pine forests and pine plantations had the least. In paired plots, urban lawns had significantly greater mineral soil N content compared to urban forest remnants. Total ecosystem C (soil + vegetation) was higher in forested wetlands than all other land uses/covers combined due to the high organic content of those wetland soils. Urban forest remnants and lawns had greater total ecosystem C than natural pine forests and pine plantations, which likely reflects the differential influence of prescribed fire and less frequent anthropogenic disturbances between the rural and urban areas, respectively. Projections of land use change in Franklin County, FL combined with these data suggest that increases in C storage are possible with continued urbanization along the Gulf Coast, if forest remnants are left and lawns are incorporated in built-up areas. However, this study does not account for C emissions during land conversion, or any emissions associated with maintaining urban built-up and residential areas. A better understanding of land use/cover influences on C pools has applications for planning and development, as well as ecological and environmental protection in the region.     

Size does matter: Passive sampling in urban parks of a regional bat assemblage

Urban Ecosystems - We studied the occurrence of bats in urban parks in the city of Madrid (Spain), and the resulting patterns were compared with bat occurrence in the surrounding region. In this...     

Relationships between urban green land cover and human health at different spatial resolutions

Relationships between landscape patterns and ecological processes can vary with changing resolution. Many studies in ecosystem services and human health rely on spatial-dependent data, yet the effects of changes in spatial resolution on the linkages between landscape and human health are underexplored. This study seeks to address the research gap by exploring the relationships of green land cover and pattern metrics at 1 m, 10 m, and 30 m with life expectancy in the City of Baltimore, Maryland, USA. Spearman’s rho correlation and stepwise and hierarchical regression models were applied. Results showed that the effects of resolution change did not emerge for percent green land cover but were evident in other pattern metrics. Multivariate relationships showed that metrics at 1 m explained the most variability of the relationships between green land cover and life expectancy after controlling for potential confounding factors (adjusted R²?=?0.776, and 0.752 at 10 m and 0.747 at 30 m). Edge density of coarse vegetation was significantly associated with life expectancy at 1 m (adjusted odds ratio [AOR]?=?1.012, 95%CI?=?1.004–1.024, p?<?0.01) and 10 m (AOR?=?1.018, 95%CI?=?1.009–1.027, p?<?0.001) but not at 30 m. Euclidean distance of fine vegetation had a strong positive association with greater life expectancy at 1 m (AOR?=?2.067, 95%CI?=?1.185–4.072, p?<?0.05) but not at 10 m and 30 m. These findings underscore the importance of acknowledging the effects of resolution on the interpretation of landscape-human health relationships and the need for caution when results are used in planning and management decisions.

     

Butterfly diversity,habitat and vegetation usage in Hong Kong urban parks

The conservation value of urban parks for butterfly communities remains poorly understood, particularly for tropical butterflies in Asia. We conducted point count and route transect butterfly surveys, and used them to sample four habitats located within 13 urban parks across Hong Kong. We found 1054 individuals and 58 species of butterflies recorded in 60 survey hours over 6 months. This represents approximately one quarter of the entire known Hong Kong butterfly species list. Over 30 % of the individuals counted were Catospilia sp. but six of the species identified are classified locally as rare or very rare. Tree-covered habitats and grasslands showed higher butterfly diversity than open areas. The most common butterfly behavior was “directed flight,” which we also found to be habitat-dependent and most common in ponds and open areas. We additionally observed the use of vegetation in urban parks, which included 40 species of nectar plant and four records of butterfly oviposition. The high butterfly diversity, presence of rare species and usage of vegetation (especially as a nectar resource) we documented in this study suggests that urban parks have some conservation value for Hong Kong. However, the use of pesticides and heavy vegetation clearing may limit significant butterfly reproduction and population growth. Altogether these results emphasize the diversity of uses of urban parks for butterflies in Hong Kong while also providing possible directions for improvement in habitat and vegetation management that could increase urban park value for biodiversity.     

Gray squirrel density,habitat suitability,and behavior in urban parks

Increased density, increased intraspecific aggression, and a reduced fear of humans have been suggested as the more observable and frequently described characteristics of wildlife species undergoing synurbization, the process of becoming urbanized. The relationship among these variables and how they may be related to environmental variables that change with urbanization is poorly understood. In this paper we explore the relationship between density, intraspecific aggression, and reduced fear of humans in urban populations of gray squirrel. In the summer and fall of 2003 and 2004, we studied a park with a documented high density of gray squirrels, Lafayette Park, Washington, DC, and six urban parks in Baltimore, MD with unknown squirrel densities. We used linear regression (SAS Institute, SAS/STAT user’s guide. SAS Institute, Cary, NC, 2005) to determine if there was a relationship (P < 0.05) between squirrel density and intraspecific aggression, squirrel density and reduced fear of humans (wariness), and squirrel density and habitat suitability. We found a positive association between density and intraspecific aggression (R ² = 0.81, P < 0.00). A negative relationship between density and wariness (, P < 0.00). However, no relationship was evident between habitat suitability and squirrel density (, P = 0.437).     

关于我国城市建设用地的冷思考

一、城市建设用地是更集约的用地 中国人口众多,土地稀缺,必须坚决贯彻执行保护耕地、节约用地的基本国策.但在指导思想上要明确,城市建设用地是更集约的用地.我国城市建设人均用地指标仅100平方米左右,而农村居民人均用地一般在150～200平方米,所以因农民进城而增加的城市用地要远远小于因农村人口减少而置换出来的居住用地.     

Estimates of above-ground tree carbon after projected land-use and land cover change in a subtropical urban watershed

Urban Ecosystems - This study investigates the effect of land-use and land cover (LULC) change on above-ground tree carbon (AGTC) in a subbasin of the Tampa Bay Watershed, Florida. LULC change was...     

Occurrence of breeding bird species in urban parks: Effects of park structure and broad-scale variables

Occurrences of breeding bird species in 54 urban parks were investigated in the city of Oulu in northern Finland. Park area, human activity, habitat, and landscape structure within a 9-ha square surrounding the study park were related to the bird species richness and occurrence of individual bird species. A total of 22 species was observed. The area of the park explained 39% of the variance of species richness. Seven species (wheatear [Oenanthe oenanthe], common rosefinch [Carpodacus erythrinus], garden warbler [Sylvia borin], lesser whitethroat [Sylvia curruca], linnet [Acanthis cannabina], redpoll [Carduelis flammea], and yellowhammer [Emberiza citrinella]) were not detected in parks of >0.75 ha. Species with lower area demands occurred closer to the town center than species with greater area requirements. Ground-nesting species were poor colonizers of urban parks, whereas high numbers of nest boxes in urban parks attracted many cavity-nesting species. The willow warbler (Phylloscopus trochilus) and the magpie (Pica pica) bred more often in unmanaged than in managed parks, probably because of the greater vegetation cover in unmanaged parks. Park structure variables were entered into models for 7 of the 12 most common bird species, whereas broad scale variables were entered into models for 6 of the 12 species. The number of adjacent buildings had a negative affect on three bird species (the willow warbler, hooded crow [Corvus corone cornix], and spotted flycatcher [Muscicapa striata]). The occurrence of breeding species in urban parks depends on the size of the park, park structure, and landscape structure outside the park.     

Tree diversity,distribution, history and change in urban parks: studies in Bangalore,India

Urban parks constitute critical biodiversity hotspots in crowded, concrete-dominated city environments. Despite the importance, they remain little researched. This paper assesses the biodiversity and distribution of trees in urban parks in the southern Indian city of Bangalore. 127 plots were used to survey tree distribution in parks across the city. The distribution is largely dominated by a few common species. The proportion of exotic species was very high, with 77% of trees belonging to introduced species. Park history had an impact on distribution. Old parks had fewer but larger trees, and greater species diversity compared to recently established parks. Old parks also differed in species composition, having a greater proportion of large canopy trees compared to young parks. Examination of size distributions revealed that large canopied species were gradually being phased out, and replaced by narrow and medium sized tree species which are easier to maintain, but which may not provide the same environmental and ecological benefits. Greater attention requires to be paid to the selection of trees in cities, not just with a view to easy maintenance as is currently the case, but to select an appropriate mix of trees that supports biodiversity and maximizes environmental and ecosystem services.     

从"城市建设用地平衡表"看城市建设用地存在的问题

在社会主义市场经济条件下,城市规划方案在很大程度上是规划委托方（地方政府）用地需求和城市空间发展战略意图的体现,因此城市规划的制定在很大程度上可以说是一种政府行为,但城市规划的编制也不能因此而随心所欲。     

Relationships between urban parks and bird diversity in the Bangkok metropolitan area,Thailand

An analysis of the birds in Bangkok’s urban parks and landscapes provided guidance in designing healthy urban ecosystems. This research studied the relationships between bird diversity, park size, distance to the nearest main park, and habitat compositions in 10 urban parks in the Bangkok metropolitan area between January and August in 2013. Thirty sampling points per park were used to observe the number and species of birds in each urban park. A total of 50 bird species were found. Phutthamonthon, the largest urban park (400 ha), contained the greatest number of species (39 species), followed by Suan Luang Rama IX (80 ha and 34 species) and Wachirabenchatat (60 ha and 29 species). Moreover, the diversity index (H′) was highest in Phuttamonthon (1.17), followed by Thawiwanarom (1.08), and Wachirabenchatat (1.04). Larger urban parks and parks closer to the largest urban park had higher species richness than smaller parks and parks further from the largest urban park. The large parks contain higher habitat compositions than small parks. These findings can be applied to future urban ecosystem planning to combine the importance of park size (island size, and its proximity to a large park) and its arrangement, including features such as wetland, forest, buildings and grassland; and provide basic advice for future urban park design, as well as re-design of current urban parks.

     

Biodiversity conservation in urban parks: a study of ground-dwelling ants (Hymenoptera: Formicidae) in Rio de Janeiro City

Urban Ecosystems - Urban green recreational spaces may provide habitat for animals and plants. We investigated the importance of urban public parks in the city of Rio de Janeiro with regard to the...     

The credit channel of monetary policy transmission: evidence from stock returns

This paper offers a novel test of the credit view of the monetary policy transmission mechanism using stock market returns. We identify Fed policy shocks using newspaper accounts and track daily stock prices immediately following the shocks. If the credit channel is important, then firms that are dependent on bank credit and internal funds should receive a relatively greater benefit (loss) from a Fed easing (tightening) than firms with access to nonbank credit at favorable terms. We identify ten policy shocks during the expansion of 1993-94 and the 'credit crunch' period of the 1990-91 recession and find little evidence supportive of an operative credit channel.     

Mangrove forests store high densities of carbon across the tropical urban landscape of Singapore

Tropical forested ecosystems provide multiple ecosystem services to rural and urban landscapes, with carbon storage gaining particular attention. Deforestation due to rural-urban transitions may lead to a reduction in carbon storage ability. Coastal mangrove forests are particularly at risk from deforestation due to their location in the rapidly urbanizing coastal zone, and the city state of Singapore is an extreme example, losing as much as 90 % of its original mangrove cover due to land reclamation and reservoir construction. Knowledge of mangrove ecosystem services may allow better conservation, restoration and incorporation of remaining mangrove patches into the urban landscape. Focusing on the regulating ecosystem service of carbon storage, mangrove carbon stocks have been estimated for Singapore using a combination of field and remote sensing techniques. Biomass carbon showed substantial spatial variation, with old, contiguous mangrove patches containing a higher density of biomass carbon than fragmented, river-fringing or restored mangroves. In total, national biomass carbon equated to 116,117.1 megagrams of carbon (Mg C), and a coarse estimate of the total carbon stock (including soil carbon) suggests that Singapore’s mangroves may store 450,571.7 Mg C. While lower than other regional estimates focused on natural, oceanic mangroves, this is a significant carbon stock for a disturbed, urban mangrove system, and may be equivalent to the average annual carbon emissions of 621,000 residents. This analysis, alongside a review of other urban forest studies, highlights the importance of forested ecosystems such as mangroves in providing a carbon storage ecosystem service to urban areas.     

Vegetative characteristics of urban land covers in metropolitan Tucson

In this study we developed a methodology that associated land cover categories to aerial photographs. We selected 4, 42-mile (10 km2) study sites within metropolitan Tucson, Arizona for our pilot study. Land uses within these sites covered the range of landscapes found within Pima County, Arizona, although not necessarily in proportions representative of the metropolitan area. We designated land cover categories within the pilot sites based on recent (March, 1990) aerial photographs and developed a geographical information system (GIS) database of these land cover categories. We measured vegetation attributes on randomly selected samples within each land cover category and classified vegetation occurring on specific land cover categories according to the Brown et al. (1979) system. Our land cover classification system was nominal with a hierarchical structure, facilitating organization and providing flexibility for adding new categories.Our results showed that although neighborhood parks contained the greatest vegetated areas within our four study plots, very low density housing (4 acres/house), rivers whose banks were partially stabilized, naturally occurring washes (with no bank stabilization), and natural open space contained the highest percentage of native vegetation. Within our four study sites, low density housing (4 acres/house), rivers with partially stabilized banks, naturally occurring washes (no bank stabilization), and natural open space land cover categories contained the most area that was covered with vegetation providing escape cover.