A small-scale response of urban bat activity to tree cover

Urban Ecosystems - Bats in urban areas depend on trees, and bat activity increases with tree cover. To effectively manage bat habitat in cities, it is important to know the distance to which tree...     

Relationship between land cover and insectivorous bat activity in an urban landscape

Despite the clear importance of conserving biodiversity in urbanized areas, research on how bats are influenced by urbanization has is only recently catching up to the more established body of research for urban birds. Much of the extant research has been limited to urban parks and other natural areas. Here I present the results of an acoustic survey of bats throughout the agricultural/forest/suburban/urban mosaic of the Minneapolis-St. Paul metropolitan area. Activity indices by each of the six recorded species (Eptesicus fuscus, Lasiurus cinereus, Lasiurus borealis, Lasionycteris noctivagans, Myotis sp., and Perimyotis subflavus) were used as response variables with land cover variables in a series of statistical models. Because bats may perceive the landscape at different scales, candidate models included land cover variables within 100, 500 and 1,000?m of the sampling location. Activity of L. noctivagans was negatively related to the amount of impervious surface and open habitat in the immediate landscape. L. borealis activity was positively correlated with immediate tree cover and with impervious surface at the 1,000?m scale. Tree cover and proximity to water were positively related to activity levels of Myotis sp., L. cinereus and P. subflavus, but only the latter was influenced by the amount of surrounding impervious surface. These results suggest that a one-size fits all approach to bat conservation in human modified landscapes is not appropriate, but also that certain species appear to do well in urban environments provided that there is sufficient tree cover.     

Green remnants are hotspots for bat activity in a large Brazilian urban area

Urbanization tends to remove or isolate green areas into fragments or restrict them to narrow corridors inserted in a matrix of buildings. Nevertheless, urban green areas may act as refuges for fauna and bats are among the animals able to use such habitats. Using bioacoustics we investigated the influence of green areas on the activity of insectivorous bats in the metropolitan area of Recife, a conurbation of 4 million people in the Atlantic forest of Northeastern Brazil. Bat activity was statistically higher in green areas, based on calls (t?=?2.5298, p?=?0.0165), but not on feeding buzzes (t?=?1.8132, p?=?0.0817) or social calls (t?=??1.5551, p?=?0.1329). Several species were able to persist in an urban matrix and calls were classified into 16 sonotypes, belonging to five families (Emballonuridae, Molossidae, Noctilionidae, Phyllostomidae and Vespertilionidae). However, activity was significantly more associated with areas with vegetation, indicating that green remnants are hotspots for bat activity. Our results indicate that most insectivorous bats have a biased use of the urban landscape and the maintenance of urban green areas is essential to preserve them and the environmental services they provide.     

Contrasting strategies for tree species to cope with heat and dry conditions at urban sites

Street trees planted at tree pits with impermeable pavements are exposed to a high level of both, atmospheric and edaphic stress. For many species tree physiology, optimal growth, and consequently long-term vitality may be hampered under these harsh conditions. Therefore, maintaining the vitality and promoting the ecosystem services provided by urban trees, for example aesthetic values and microclimatic benefits, it is important to establish trees with a high tolerance to stressful urban environments. Measurements of leaf gas exchange, leaf water potential, leaf surface temperature and chlorophyll-fluorescence were used for identification of specific response of Corylus corluna L., Ginkgo biloba L., Liriodendron tulipifera L., and Tilia cordata Mill. ‘Greenspire’. The summer months in 2013 with a period of heat and drought over eight weeks only interrupted by two rainy days were appropriate to access tree’s strategies to cope with low water availability. During the measurement period, the influence of high temperatures, high values of vapor pressure deficit (VPD) and low soil water availability on stomatal conductance, water-use efficiency (WUE) and leaf water potential (Ψmin, Ψmax ) was highest for Liriodendron followed by Ginkgo. These species showed high reductions in WUE in case of higher air temperatures and high values of VPD. Results indicate an avoidance strategy under increasing heat and VPD. In contrast, Corylus and Tilia followed a tolerance strategy indicated by decreasing values of Ψmin and lower reductions of WUE. In conclusion, wide species-specific variation in response to high temperatures and high VPD indicates that substantial potential exists in the selection for dry and hot urban places.     

Patch or mosaic: bat activity responds to fine-scale urban heterogeneity in a medium-sized city in the United States

Many recent studies have suggested that cities are spatially heterogeneous. Only limited research has investigated whether urban heterogeneity influences the distribution of bats in a city. Between 2010 and 2012, we acoustically surveyed bats in Waco, Texas, a medium-sized city in the United States. Seven species were detected, five in adequate quantity for analyses. Three distinct distribution patterns were evident (Mexican free-tailed bats; red bats and evening bats; big brown bats and cave myotis), reflecting the distinct functional guilds of these species. Bayesian conditional autoregressive models indicated that tree-dwelling red bats and evening bats were influenced by variables describing heterogeneity of urban vegetation. Big brown bats and cave myotis were associated with variables related to water sources. Mexican free-tailed bat distribution could be explained well by variables related to urban buildings and other constructions. Our modeling also suggested that urban socioeconomic heterogeneity influenced bat distributions. Distributions of tree-dwelling bats corresponded to income level. Distributions of Mexican free-tailed bats, big brown bats, and cave myotis related to human density. These results support the idea that a city comprises a mosaic of habitats as perceived by various species of bats and likely by other species of wildlife in urban settings.     

Woody plant species richness,composition and structure in urban sacred sites,Grahamstown, South Africa

Sacred sites are important not only for their traditional, spiritual or religious significance, but may also potentially be valuable for biodiversity conservation in human transformed landscapes. Yet, there has been little consideration of sacred sites in urban areas in this respect. Consequently, to better understand the ecosystem service and conservation value of urban sacred sites, inventories of their floral communities are needed. We examined the richness, composition and structure of the trees and shrubs in 35 urban churchyards and cemeteries in the City of Saints (Grahamstown). The combined area of urban sacred sites (38.7 ha) represented 2.2% of the city area and 13.6% of the public green space area. Species richness of woody plants was high, albeit dominated by non-native species. Levels of similarity among sites were low, indicating the effects of individual management regimens. There was no relationship between age of the site and measured attributes of the vegetation, nor were there any significant differences in vegetation among different religious denominations. However, the basal area and number of woody plants was significantly related to site size. These results indicate the significant heterogeneity of urban sacred sites as green spaces within the urban matrix. The significance of this heterogeneity in providing ecosystem services to users of sacred sites and the broader urban communities requires further investigation.     

Improving confidence in tree species selection for challenging urban sites: a role for leaf turgor loss

High species diversity is argued to be the most important requisite for a resilient urban forest. In spite of this, there are many cities in the northern hemisphere that have very limited species diversity within their tree population. Consequently, there is an immense risk to urban canopy cover, if these over-used species succumb to serious pests or pathogens. Recognition of this should motivate the use of less commonly used species. Analysis of plant traits, such as the leaf water potential at turgor loss (Ψ_P0), can provide useful insights into a species’ capacity to grow in warm and dry urban environments. Therefore, the aim of this study was to evaluate Ψ_P0 of 45 tree species, the majority of which are rare in urban environments. To help evaluate the potential for using Ψ_P0 data to support future decision-making, a survey of professionals engaged with establishing trees in urban environments was also used to assess the relationship between the measured Ψ_P0 and the perceived drought tolerance of selected species. This study demonstrates that Ψ_P0 gives strong evidence for a species’ capacity to tolerate dry growing conditions and is a trait that varies substantially across species. Furthermore, Ψ_P0 was shown to closely relate to the experience of professionals involved in establishing trees in urban environments, thus providing evidence of its practical significance. Use of plant traits, such as Ψ_P0, should, therefore, give those specifying trees confidence to recommend non-traditional species for challenging urban environments.     

Plant species richness, vegetation structure and soil resources of urban brownfield sites linked to successional age

Brownfield sites contribute significantly to urban biodiversity due to their high spatio-temporal dynamics and their transient character. Plant species richness is, among other factors, contingent on vegetation structure. In this study, we examined plant species richness, vegetation height, vegetation density and soil parameters of a chronosequence of urban brownfield sites in Bremen and Berlin, Germany. These parameters were linked to successional age using single and multiple linear regression. Most biotic and abiotic variables differed significantly between sites with and without brick rubble in the soil, indicating a strong effect of site history on vegetation development. Soil parameters of the sites were not clearly linked to site age. Vegetation height and density increased significantly over time. Additionally, height and density increased with soil phosphorus content and water permeability of the soil, whilst plant available water only contributed to the model of vegetation density. Species richness increased with vegetation height but decreased with vegetation density. This indicates that species richness is maximised when a community comprises a mixture of early and mid-successional species. The results suggest that high plant species richness on sandy brownfield sites can be achieved by strong disturbances at an interval of 5 (±2) years. However, limiting soil resources can prolong this interval considerably. Management aiming to maximise plant species richness in urban brownfield sites should therefore take into account the interplay between soil resources and site age.     

Determining economic activity in a post-capitalist system

The main tendency of (both planned and market) post-capitalist system is cosidered to be the production of personal (and not only material) conditions of functioning of that system. That includes not only production of technical disposition to master things but also that of social disposition to master (or, at least, be superior to) other persons. These are as important organizing factors for an economic system producing its personal conditions as are value in exchange for the one producing its material conditions. Typical cases are cited when the economic activity is not determined by the price of the item produced by it, but, rather, by the social identity of the person producing it.     

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...     

Predicting tree species richness in urban forests

There has been an increasing interest in urban forests and the levels of biodiversity they contain. Currently there are no spatially explicit maps of tree species richness in urban areas. This research tests and identifies GIS and remote sensing metrics (climate, area, productivity, three-dimensional structure) hypothesized to be associated with species richness in native forests and identifies methods that can be applied to predict and map tree species richness in cities. We quantified tree species richness, floristic composition, and structure in 28 1-ha plots in the city of Los Angeles. Climate and remote sensing metrics from high-resolution aerial imagery (10 cm), QuickBird (60 cm), Landsat (30 m), MODIS (250 m), and airborne lidar (2 m) were collected for each plot. There were 1208 individual stems and 108 trees identified to species. Species richness ranged from 2 to 31 species per ha and averaged 17 species per ha. Tree canopy cover from QuickBird explained the highest portion of variance (54%) in tree species richness followed by NDVI from Landsat (42%). Tree species richness can be higher in residential urban forests than native forests in the United States. Spatially explicit species richness maps at 1 ha can be created and tested for cities in order to identify both hotspots and coldspots of tree species richness and changes in species richness over time.     

Methodological proceedings to evaluate the physical accessibility in urban historic sites

Historic urban sites are set by cultural and social diversities, generating multiple activities and use and access to these sites should be available to all people including those with disabilities. Taking into consideration that using the same methodology that was used in different historic sites researches with positive results facilitates replication, we aimed to develop methodological procedures that identify conditions of physical accessibility in open public spaces and access to public buildings in historic urban sites to support proposals about design requirements for improvements to the problems diagnosed and control inadequacies of the physical environment. The study methods and techniques from different areas of knowledge culminated in a proposal built with an emphasis on user participation that could be applied with low cost and in relatively short period of time.     

Rainfall interception capacity of tree species used in urban afforestation

Afforestation is inserted in the urban environment and interferes directly in the surface runoff. In order to quantify the rainfall interception by tree species, an experiment was carried out in the city of Uruaçu, Goiás, Brazil, with the four most common tree species in the urban afforestation of the region. The species chosen were the Mangifera indica (mango tree), the Caesalpinia peltophoroides (sibipiruna tree), the Pachira aquatica (munguba tree) and the Licania tomentosa (oiti). In order to register precipitation, ten pluviographs were used. They are capable of measuring precipitation over time in terms of duration, volume, and intensity. For events with a mean cumulative precipitation of 16.7 mm, the mean values of interception found in each species were: Mangifera indica - 8.0 mm; Pachira aquatica - 7.4 mm; Licania tomentosa - 7.2 mm; and Caesalpinia peltophoroides - 4.8 mm. The research confirms the importance of studies related to the identification of the species’ individual characteristics that interfere in the rainfall interception capacity and that can consequently contribute to urban drainage actions. In addition, it proves the existence of variations of rainfall interception in relation to rainfall events and during their occurrences and emphasizes the need for a careful definition of the species that will compose the urban afforestation.     

Determining the effect of urbanization on generalist butterfly species diversity in butterfly gardens

This study investigates the effects of urbanization on local butterfly populations and the role of butterfly gardens in preserving regional butterfly diversity. Data are from 135 butterfly gardens of varying size, location, and number of blooming plants in the Washington DC metropolitan area observed during 2001 and 2002. We investigated the species diversity for comparable gardens in rural, suburban, and urban locations to determine whether the landscape matrix surrounding otherwise suitable habitat affects the diversity found in the habitat. We hypothesized that, once factors such as garden size and number of blooming plant species were taken into account, butterfly diversity for 12 generalist species would decrease as urbanization increased. We found that there were systematic decreases (with one exception) in diversity from rural to suburban to urban gardens only for medium-sized gardens (0.10 to 0.20 ha) with one to ten types of blooming plants, and large gardens (>0.20 ha) with over 20 types of blooming plants. Gardens of other sizes or plant communities showed some decreases in diversity from rural to suburban to urban sites, but these differences were not consistent across the urban/rural gradient. Results of this study indicate that local butterfly diversity is negatively affected by increasing levels of human population, but that the matrix is just one factor determining generalist species diversity.     

Unwanted sexual activity among married women in urban China

This paper examines the prevalence, precursors, and consequences of unwanted marital sex activities in a national sample of 1,127 married urban Chinese women aged 20-64. During the lifetime of their current marriage, 32% reported ever experiencing unwanted spousal intercourse, with about one-fifth reporting that this unwanted intercourse ever involved force. Reports for the past year were 21% unwanted intercourse, 22% unwanted sex act(s), and 72% sex only to please the husband. The major risk factors for these activities were poor relationship quality (hitting, lack of daily intimacy and foreplay, and husband insensitivity to wife's sexual needs); a woman's negative attitudes towards sex, and weak bargaining position (low income share, husband's family of superior economic status, and no additional adults in home). In addition, unwanted activity was more common when women reported sexual dysfunctions (dryness, pain, low arousal, inorgasmia), were more educated, and had more permissive sex attitudes. Net of feedback effects, unwanted sexual activity diminished women's psychological well-being.     

Linking bird species traits to vegetation characteristics in a future urban development zone: implications for urban planning

Identifying the relationships between species traits and patch-scale vegetation characteristics in areas designated for urban development can improve our understanding of how animal communities may change with urbanization. We explored the implications of this premise to the urban planning process in a mixed-use landscape in Canberra (Australia), prior to its development into new suburbs. We used RLQ analysis to relate bird foraging, nesting and body size traits to patch-scale vegetation characteristics. Relationships between species traits and vegetation characteristics within the development zone suggest that species that forage and nest on the ground and in the understory strata, and smaller-bodied species will be most negatively affected by urbanization. Identifying the relationships between species traits and vegetation characteristics may be used by urban planners to (i) identify potentially critical habitat and species at risk from development, (ii) inform the choice of impact mitigation measures, and/or (iii) distinguish between high and low mitigation measures. Analyses conducted early in the planning process can then be used to allocate proposed land uses in an ecologically sensitive way, and to plan appropriate mitigation measures.     

Colonization and habitat selection of a declining farmland species in urban areas

Despite the accelerating global urbanization and its associated implications for wildlife and humans, we know little about the biology of urban ecosystems. Here, we investigated colonization and habitat selection of the European hare (Lepus europaeus), a declining farmland species, in urban areas in Denmark, using a combination of citizen science data and transect counts. Further, we estimated the population density of urban hares in Aarhus, Denmark’s second largest city. Our results provide the first evidence that hares have established populations in urban areas, potentially in response to decreasing habitat quality in rural areas due to agricultural intensification. The hare density in Aarhus was ca. 8 hares per km², which is comparable to or slightly higher than hare abundance estimates from various pastural areas in Europe, suggesting that urban areas provide suitable habitat for hares. Hare habitat selection was generally associated with areas consisting of large lawns, such as high buildings and parks, which potentially provide high-quality forage throughout the year. Considering the increasing expansion of urban areas and deteriorating habitat quality of agricultural areas, urban planning that incorporates habitat requirements for wildlife could help to support urban animal populations, especially for species of conservation concern.

     

Reducing management intensity and isolation as promising tools to enhance ground-dwelling arthropod diversity in urban grasslands

Urbanisation is a growing global phenomenon having multiple ecological consequences. However, the effects of urbanisation on biodiversity remain ambiguous, and some evidence exists that cities provide valuable secondary habitats for many species, possibly mitigating regional biodiversity loss. Therefore, the value of urban sites for biodiversity depends on local habitat conditions and the configuration of the surrounding landscape. We aimed to disentangle the effects of local habitat parameters (management, plant diversity) and urban matrix variables (urbanisation, isolation) on carabid beetle and spider diversity and traits in informal urban green spaces in Berlin, Germany. Habitat management and isolation were the most important influences on carabid beetle and spider species and trait compositions. Spider communities of irregular managed sites contained 2.5 times more species of conservation concern than extensive (regular) managed sites. Moreover, irregular managed sites contained larger species (both for carabid beetles and spiders) and affected the hunting mode of spiders. Isolated sites tended to have lower spider species richness and number of spider species of conservation concern. Moreover, isolated sites were characterised by small, mobile and herbivorous carabid beetles. In contrast, urbanisation and local plant diversity had no effect on carabid beetles and spiders. We conclude that urban grasslands within residential areas – even if not targeted for conservation plans – can provide important habitats for conserving biodiversity, including species of conservation concern. Reducing the intensity of habitat management and increasing the connectivity of urban grassland sites can promote diverse arthropod communities and should therefore be considered in urban planning.     

Determinants of species richness within and across taxonomic groups in urban green spaces

Urban green spaces provide habitat for numerous plant and animal species. However, currently we have little knowledge on which determinants drive the species richness within and across taxonomic groups. In this paper we investigate the determinants of total, native, and endangered species richness for vascular plants, birds, and mammals within and across taxonomic groups. We examined a stratified random sample of 32 urban green spaces in Hannover, Germany. Species inventories for plants and birds were generated on the basis of line transect surveys. Mammals were surveyed by means of point counts using camera traps. Using a principal component analysis and multiple regression models, we tested 10 explanatory variables for species-area effects, distance effects, and the effects of habitat structure of green spaces on species richness. When analyzing single explanatory variables, we determined that the species richness of all groups was significantly positively correlated to patch area, number of habitat types, and a short distance to the nearest green space. Testing combined effects of variables showed that patch area in combination with habitat heterogeneity was most important for plants (total, native, and endangered), birds (total and native), and overall species richness. This emphasizes the importance of the species-area effect and the effects of habitat structure on species richness in urban green spaces. We conclude that, in the context of urban planning, it is important to conserve large green spaces that include a high diversity of habitats to maintain high species richness.