Getting closure: The role of urban forest canopy density in moderating summer surface temperatures in a large city

With a growing number of people living in urban areas, city residents are more frequently exposed to stresses related to the built environment including elevated summer surface temperatures contributing to the urban heat island (UHI) effect. This study examines the role of urban tree density in moderating surface temperature variation in a densely populated city (Toronto, Canada). By applying parallel aspatial (OLS) and spatial regression (GWR) approaches with satellite derived data describing tree canopy density and surface temperature, one dimension of tree canopy quality (i.e., canopy density) is shown to contribute directly to a reduction in the surface urban heat island (SUHI) effect at a local scale. Though the model fit differed between the two regression approaches, both exhibited moderately strong explanatory power and demonstrated that observed surface temperature decreases in locations with increasing high-density and closed tree canopy. Study findings provide an empirical basis to recommend that municipal urban forest strategies embrace canopy quality metrics, such as increasing the density of existing urban forest stands, as a part of tree planting objectives seeking to effectively deliver temperature moderation as a valuable ecosystem service.     

Floristic composition and richness of urban domestic gardens in three urban socioeconomic stratifications in the city Heredia,Costa Rica

The urban domestic gardens that are part of urban green areas have become a very important element due to their ecosystematic benefits and the poor information about them. Information regarding the floristic richness of three socioeconomic stratifications from the city of Heredia, Costa Rica is presented in this study. Research was conducted from October 2011 to May 2012. Information was collected using a semi-structured questionnaire, which was provided to 61 garden owners, including the owner’s personal data, time living in the dwelling, area of the property and the garden, variation of its size in time and the garden’s location on the property. In addition, a floristic inventory was conducted in each garden as well as a taxonomic identification of all plants. Vegetative forms and substrates were also noted. Characteristics of the gardens and their owners were then analyzed to determine the relationship of species richness between the three sites studied. The number of plant species recorded was 618, corresponding to 102 families (19 % exotic). Regarding geographical origin, 64, 4 % were exotic, 35,6 % native. Orchidaceae (93 spp.) and Araceae (39 spp.) were the most dominant families. The variables of garden area and location and owner's age determined the garden’s floristic richness. In addition, the garden’s area and vegetative forms varied among the sites studied probably due to socioeconomic differences among them. Diversity of pioneer plants increased with the garden’s area. In sum, this research provides important floristic information of domestic gardens, since, being private property, data about them is scarce and municipal management guidelines are nonexistent.     

Effects of land use on sediment composition in low-order tropical streams

The objective of this study was to evaluate the relative effects of watershed land-use on streambed substrate composition in eight low-order tropical streams. Data were collected at 24 sampling sites for eight wadeable streams in the Pirapó River Basin, southern Brazil. According to the percentage of impervious surfaces in the watershed, we defined the streams as either urban or rural. We estimate the percentages of the different streambed substrates, hydrological variables, and the rainfall intensity. The results showed that silt, sand and coarse particulate organic matter (CPOM) contributed to significant differences in streambed substrate composition between urban and rural streams. Silt, sand and CPOM were found in a higher mean proportion in the rural streams. Probably the urban streams have a greater bed load, promoted by precipitation and discharge, than rural streams, especially fine sediment. Rural streams have soft hydrographs, with stream flow slowly increasing during a rainstorm and subsequently decreasing over a long period after the rain event is over. These characteristics can provide the lixiviation of fine sediments into the stream channels due to land-surface clearance for agricultural activities and their accumulation in the streambed due to the moderate discharge regime.     

Influence of urbanization on the occurrence and activity of aerial insectivorous bats

Activity and species-specific responses of insectivorous bats in different urban-forest conditions provides a general perspective on the adaptability and vulnerability of bat species towards urbanization intensity. Here we evaluated species richness and activity patterns of aerial insectivorous bats across an urbanized landscape in the highlands of Chiapas, in Mexico. Acoustic monitoring of echolocation calls was conducted for 27 nights over a period of four months. Species richness and relative activity of insectivorous bats were estimated in a landscape with different conditions of urbanization intensity: urban areas, non-urban and forest areas. We identified a total of 14 bat species and three phonotypes. Bat species richness and relative activity was similar (X² = 0.568, gl = 2, p > 0.05), but species composition differed among conditions. We observed a significant higher occurrence of Bauerus dubiaquercus, Eptesicus brasiliensis and Myotis californicus in forest sites. Urban sites presented higher occurrence of Molossus rufus and phonotype Molossidae 2, while non-urban sites presented a higher occurrence of Eptesicus furinalis and phonotype Molossidae 2. We were able to identify bat species according to their relative activity in relation todifferent landscape conditions. Species of the Molossidae family presented the highest activity in urban sites, which was positively affected by the number of streetlights, while species of the Vespertilionidae presented the highest activity in forest sites, which was positively related totree density. While urbanization tends to diminish native biodiversity and alter faunal communities, our results show a similar richness and relative activity of aerial insectivorous bats along the urban ecosystem. The effect of urbanization intensity becomes more apparent in species-specific bat activity; the response of species towards particular habitat conditions depends on local habitat quality and characteristics (i.e., presence of streetlights, vegetation cover and tree density).     

Does education influence wildlife friendly landscaping preferences?

In sprawling metropolitan areas, residential landscaping is a major concern with respect to biodiversity conservation, and it could play a critical role in conserving wildlife habitat. In the United States, residential landscaping typically consists of maintained lawns with specimen plantings of non-native trees and shrubs; such designs provide poor habitat for urban wildlife species. We conducted a case study of Raleigh, North Carolina residents to determine how providing information about the benefits of native plant landscaping to bird species influenced urban residents’ landscaping preferences. We used Wilcoxon Signed Rank tests to determine if respondent preferences for 0, 50, 75 and 100 % native plant landscaping coverages changed after residents were informed about the benefits that native plants provide for birds. Initially, the 50 % native landscaping coverage was most preferred by residents; however, preferences for all four native plant landscaping coverage designs were significantly different after the informational treatment. Neutrality changed to opposition for the 0 % native plant coverage, while opposition changed to support and neutrality for the 75 and 100 % native plant coverage designs, respectively. After the informational treatment, the 50 and 75 % native plant landscaping coverage had the highest mean preference levels, although the 100 % design was ranked first more than any other design. Our findings suggest that residential support for native plant landscaping is higher than is reflected by typical residential landscaping practices, and that dissemination of information regarding the benefits of native plant landscaping to birds could alter public preferences for native plant landscaping.     

Life pattern of urban trees: A growth-modelling approach

Urban afforestation improves life quality in urban centers providing social and environmental benefits. Understanding growth of urban trees exposed to air pollution will support planning, managing and expanding urban areas. This approach intends to determine growth patterns of urban trees to support future urban planning. Non-destructive samples were collected from trees of Araucaria angustifolia (Bertol.) Kuntze in Araucaria city, Parana State, Brazil. Growth rings were related to pollutant concentrations and meteorological series. Growth reduction was observed except in the border areas of the city. Trees established during or after the period of industrialization incentives were most affected by air pollution, indicating that immature plants are more vulnerable. Sulphur dioxide and nitric oxide significantly affected growth of smaller trees. Those greater than 60 cm dbh did not demonstrate significant correlation with any identified pollutant. As the trees established before accentuated urbanization were less affected by air pollution, it is reinforced the importance of preserving remaining urban trees. We suggest that planning urban afforestation should precede industries placing. When urban planning is impossible, new planted trees should not be expected to grow as in free pollution areas, but they will still present satisfactory diameter increment, contributing to improve local urban environment.     

Elevated phosphorus: dynamics during four years of green roof development

Green roofs are emerging engineered ecosystems that provide multiple benefits, but many are constructed with nutrient-rich substrate and have been found to leach out high levels of phosphorus (P) in runoff. It is unclear, however, how long green roofs act as sources of P or what mechanisms are responsible for these net losses. We measured P concentrations in runoff water over 4 years from a 1–5 year old extensive green roof in Cincinnati, OH, USA, produced a model to predict runoff P levels into the future, and validated predictions using runoff from 2 nearby extensive green roofs. P concentrations in runoff from the focal green roof were on par with heavily fertilized agroecosystems and displayed strong seasonal dynamics and a rapid decline over the 4-year study. Runoff measurements and changes in substrate P content over a 2-year period were used to estimate a mass balance for green roof P. P loss from the substrate was substantial (4.55 ± 2.3 g P/m²/yr), but only a small portion of the loss was attributable to leaching of P in runoff (0.19–0.65 g P/m²/yr). Missing P may be attributed to a combination of plant uptake and altered P form and binding strength, but further research is needed to precisely identify the mechanisms of P depletion. Our results also suggest that these and similar extensive green roofs are likely to act as environmentally significant sources of P for 10 or more years following roof installation, highlighting the need for reductions in initial substrate P content.     

Bootstrap-calibrated empirical likelihood confidence intervals for the difference between two Gini indexes

Measuring the difference between two Gini indexes is important in comparing the inequality between two groups. This paper systematically provides confidence intervals for this difference. First, normal approximation- and bootstrap-based confidence intervals are provided for the difference. Second, empirical likelihood (EL)-based confidence intervals are proposed according to a ratio statistic that is proven to have a weighted Chi-squared distribution with one degree of freedom. Third, two calibration approaches are established to improve the undercoverage issue of the EL method; these two approaches are augmented EL and bootstrap-calibrated EL. Monte Carlo simulations show that bootstrap-calibrated EL generally outperforms other methods in constructing confidence intervals. In the simulations, these methods are compared with the permutation method to test the equality of two Gini indexes. Lastly, these methods are applied to real data.     

Who gets to look nice and who gets to play? Effects of child gender on household expenditures

We examine the relationship between a child’s gender and family expenditure using data from the Polish Household Budget Survey. Having a first-born daughter as compared with a first-born son increases the level of household expenditures on child and adult female clothing, and it reduces spending on games, toys and hobbies. This could be a reflection of a pure gender bias on behalf of the parents or a reflection of gender complementarities between parents’ and children’s expenditures. We find no robust evidence on gender differences in educational investment, measured by kindergarten expenditure. The analysed expenditure patterns suggest a so-far unexamined role of gender in child development. Parents in Poland seem to pay more attention to how girls look and favour boys with respect to activities and play, which could have consequences in adult life and contribute to sustaining gender inequalities and stereotypes.     

Child care and parent labor force participation: a review of the research literature

Early care and education (ECE) enables parental employment and provides a context for child development. Theory suggests that lower child care costs, through subsidized care or the provision of free or low-cost arrangements, would increase the use of ECE and parents’ employment and work hours. This paper reviews the research literature examining the effects of child care costs and availability on parental employment. In general, research suggests that reduced out-of-pocket costs for ECE and increased availability of public ECE increases ECE attendance among young children, and has positive impacts on mothers’ labor force participation and work hours. However, there is considerable heterogeneity in findings. Among U.S. studies that report the elasticity of employment to ECE price, estimates range from ?0.025 to ?1.1, with estimates clustering near 0.05–0.25. This indicates that a 10 % reduction in the price of child care would lead to a 0.25–11 % increase in maternal employment, likely near 0.5–2.5 %. In general, studies using more recent data or data from non-U.S. countries find smaller elasticities than those using U.S. data from the 1990s. These differences may be due to historical and cross-national differences in ECE attendance, labor force attachment, and educational attainment among mothers with young children, as well as heterogeneity in the methodological approaches and data used across studies. More research in the U.S. using contemporary data is needed, particularly given recent changes in U.S. ECE policy.