Carbon sequestration of four urban parks in Rome

Urban parks form the largest proportion of public green spaces contributing to both physical and mental well-being of people living in urban areas. CO₂ sequestration capability of the vegetation developing in parks of four historical residences (Villa Pamphjli, Villa Ada Savoia, Villa Borghese and Villa Torlonia) in Rome and its economic value were analyzed. Villa Pamphjli and Villa Ada Savoia having a larger vegetation extension (165.04 ha and 134.33 ha, respectively), also had a larger total yearly CO₂ sequestration per hectare (CS) (780 MgCO₂ ha⁻¹ year⁻¹ and 998 MgCO₂ ha⁻¹ year⁻¹, respectively) than Villa Borghese (664 MgCO₂ ha⁻¹ year⁻¹) and Villa Torlonia (755 MgCO₂ ha⁻¹ year⁻¹), which had a lower vegetation extension (56.72 ha and 9.70 ha, respectively). CS was significantly correlated with leaf area index (LAI). The calculated CS for the four parks (3197 MgCO₂ ha⁻¹ year⁻¹), corresponding to 3.6% of the total greenhouse gas emissions of Rome for 2010, resulted in an annual economic value of $ 23537 /ha.     

Density,diversity and richness of woody plants in urban green spaces: A case study in Chennai metropolitan city

A tree diversity inventory was carried out in urban green spaces (UGSs) of Chennai metropolitan city, India. This inventory aims to study the diversity, density and richness of trees in UGSs of Chennai. A total of one hundred 10 m × 10 m (total 1 ha) plots were laid to reveal tree diversity and richness of UGSs. Trees with ≥10 cm girths at breast height (gbh) were inventoried. We recorded 45 species in 42 genera and 21 families. Caesalpiniaceae and Fabaceae each with 6 species dominated the study area followed by Arecaceae (3). Density and stand basal area of the present study were 500 stems ha^?1 and 64.16 m², respectively. Most of the inventoried trees were native (31 species) and deciduous (28 species). Fabaceae and Caesalpiniaceae dominated the present study area in terms of stand basal area and density. The Shannon diversity index and evenness of study area were 2.79 and 0.73, respectively. The most important species and families based on species important value index (IVI) and family important value index were Albizia saman, Polyalthia longifolia and Azadirachta indica; Fabaceae, Caesalpiniaceae and Annonaceae respectively. We find Chennai's urban forest is relatively superior to many urban forests of the world in terms of stand basal area and species richness. Results emphasize the importance of enhancement of urban green spaces in Chennai metropolitan city.     

Estimation of broad-leaved canopy growth in the urban forested area using multi-temporal airborne LiDAR datasets

Inter-annual canopy growth is one of the key indicators for assessing forest conditions, but the measurements require laborious field surveys. Up-to-date LiDAR remote sensing provides sufficient three-dimensional morphological information of the ground to monitor canopy heights on a broad scale. Thus, we attempted to use multi-temporal airborne LiDAR datasets in the estimation of vertical canopy growth, across various types of broad-leaved trees in a large urban park.The growth of broad-leaved canopies in the EXPO '70 urban forest in Osaka, Japan was assessed with 19 plots at the stand level and 39 selected trees at the individual-tree level. Airborne LiDAR campaigns repeatedly observed the park in the summers of 2004, 2008, and 2010. We acquired canopy height models (CHMs) for each year from the height values of the uppermost laser returns at every 0.5 m grid. The annual canopy growth was calculated by the differences in CHMs and validated with the annual changes in field-measured basal areas and tree heights.LiDAR estimations revealed that the average annual canopy growth from 2004 to 2010 was 0.26 ± 0.11 m m⁻² yr⁻¹ at the plot level and 0.26 ± 0.10 m m⁻² yr⁻¹ at the individual-tree level. This result showed that growing trends were consistent at different scales through 2004 to 2010 despite uncertainty in estimating short-term growth for small crown areas at the individual-tree level. This LiDAR-estimated canopy growth shows a moderate relation to field-measured increase of basal areas and average heights. The estimation uncertainties seem to result from the complex canopy structure and irregular crown shape of broad-leaved trees. Challenges still remain on how to incorporate the growth of understory trees, growth in the lateral direction, and gap dynamics inside the canopy, particularly in applying multi-temporal LiDAR datasets to the large-scale growth assessment.     

The influence of small green space type and structure at the street level on urban heat island mitigation

The purpose of this study was to determine the types and structures of small green spaces (SGs) that effectively reduce air temperature in urban blocks. Six highly developed blocks in Seoul, South Korea served as the research sites for this study. Air temperature was measured at the street level with mobile loggers on clear summer days from August to September in 2012. The measurements were repeated three times a day for three days. By analyzing the spatial characteristics, SGs within the six blocks were categorized into the four major types: polygonal, linear, single, and mixed. The result revealed that the polygonal and mixed types of SGs showed simple linear regression at a significant level (p < 0.01). It indicated that the blocks’ urban heat island (UHI) mitigation (ΔT_Rmn) increased in a linear fashion when the area and volume of these two types of green spaces increased. The area and volume of a polygonal SG with mixed vegetation, over 300 m² and 2300 m³, respectively, lowered the ΔT_Rmn by 1 °C; SG with an area and volume of larger than 650 m² and 5000 m³, respectively, lowered the ΔT_Rmn by 2 °C. The results of this study will be useful to urban planners and designers for determine the types and structures of urban green spaces to optimize the cooling effect, as well as how such green spaces should be designed and distributed.     

In situ emission of BVOCs by three urban woody species

Controlling and monitoring air quality in cities requires understanding anthropogenic sources, but also natural sources must be considered. This is because beneficial Biogenic Volatile Organic Compounds (BVOCs) can exacerbate air pollution by reacting with anthropogenic pollutants. Although these compounds help trees survive, they may have negative effect on human life in polluted cities. In this study we measured terpenoid emissions of urban trees early and late in the growing season, using Solid Phase Micro-extraction (SPME) in a branch enclosure system. Results showed that Robinia pseudoacacia and Platanus orientalis emitted significant amounts of isoprene throughout the season. Isoprene emission early in the season was roughly the same for both species. Late in the season, the standardized emission rate increased to 17.8 and 45 μg g⁻¹ dw h⁻¹ for R. pseudoacacia and P. orientalis, respectively. Furthermore, all trees emitted significant amounts of 2-ethylhexanol late in the season (7.3, 7.9, and 9.2 μg g⁻¹ dw h⁻¹ for Fraxinus rotundifolia, R. pseudoacacia, and P. orientalis, respectively). In conclusion, trees that are typically planted in urban Tehran, emit significant amounts of isoprene. Planting more F. rotundifolia and fewer P. orientalis trees would help improve air quality in Tehran and the cities like Tehran.     

Responses of four hornet species to levels of urban greenness in Nagoya city,Japan: Implications for ecosystem disservices of urban green spaces

Although there is a common trend towards increasing green space in modern cities, urban green spaces provide not only ecosystem services but also disservices for urban dwellers. However, the relationship between urban greenness and ecosystem disservices has been poorly examined. We aimed to understand the effect of greenness level on the abundance and species composition of hornets – critical pests in Japan and to identify the best spatial scale for estimating their abundance with reference to greenness levels. We used a dataset that contained eight years of abundance data for four hornet species at 11 sites in Nagoya city. The levels of greenness around the hornet sampling points were measured using averages from the Normalized Difference Vegetation Index (NDVI) with radiuses of 0.1–10.0 km. We analysed the relationship between abundance and species composition of hornets and NDVI at different spatial scales using generalized linear mixed models. Higher NDVI values positively affected the abundance of all the hornet species except Vespa analis. The abundances were estimated most effectively using the NDVI average with a 1–2 km radius for all species. The species composition of hornets drastically changed along the gradient of NDVI values; V. mandarinia was dominant in greener areas (over 0.2–0.3 NDVI average with a 2 km radius) and V. analis in less green areas (below 0.2–0.3 NDVI average). Our study showed that the abundance and species composition of hornets were both strongly associated with the level of urban greenness. This suggests that increases in the greenness of urban areas can increase hornet abundance and alter the species composition of hornets; a more aggressive species, V. mandarinia, may also increase in urban areas, although V. analis is currently the most critical species according to regional consultants. Balancing ecosystem services and disservices has become crucial for the planning and management of green spaces, particularly when urban green space increases. We also demonstrate how human tolerance towards wildlife may have to be improved in order to live in greener environment where wildlife can be expected.     

Normalized difference vegetation index (NDVI) as a marker of surrounding greenness in epidemiological studies: The case of Barcelona city

The normalized difference vegetation index (NDVI) is often used as a marker of surrounding greenness in epidemiological studies aiming to evaluate the health effects of green space in urban settings. However, it is not clear the relationship between built environment characteristics, including green space, and NDVI. We aimed to evaluate the relationship between built environment characteristics, based on land-use and land-cover maps, and NDVI as a marker of surrounding greenness in the city of Barcelona. We used data from an already existing cohort of pregnant women in Barcelona (N = 8402). NDVI was derived and averaged within buffers of 100 m and 300 m for each participant, and categories of the built environment (m²) were derived from land-use and land-cover maps of Barcelona. We conducted ANOVA models to calculate the contribution (R²) of each land-use (or land-cover) category. The variability in NDVI in Barcelona was mainly explained by urban green (R² between 0.32 and 0.53) and natural green areas (R² between 0.19 and 0.52), although for the latter less than 4% of the participants were exposed to this. Both land-use and land-cover maps explained NDVI at 300 m better (full models explaining 76% and 78%, respectively) than at 100 m buffers (full models explaining 55% and 54%, respectively). Results of the present study indicate that NDVI can be a useful greenness metric depending on the hypothesis and area of study. However, for certain sizes of study areas (buffers smaller than 100 m), NDVI might have a lower predictive value. Results of the present study should be replicated in studies from other cities with different urban characteristics and climate conditions.     

Ozone forming potential of tropical plant species of the Vidarbha region of Maharashtra state of India

Volatile organic compounds (VOC) are emitted by many plants. In this study, sixty common plant species of the Vidarbha region of Maharashtra, India were examined for VOC (isoprene and monoterpene) emissions. Plant species VOC emission rates ranged from undetectable to 75.2 μg g^?1 h^?1. Dalbergia sissoo exhibited a maximum VOC emission rate of 75.2 μg g^?1 h^?1. Ozone forming potentials (OFP) of the sixty plant species were also estimated using the method of Benjamin and Winer (1998). Maximum ozone forming potential of 77 g O₃ (tree)^?1 d^?1 was observed in the case of Mangifera indica. Out of 60 species, 26 species (43.3%) had low OFP (less than 1 g O₃ (tree)^?1 d^?1), 18 species (30%) had medium OFP (less than 1–10 g O₃ (tree)^?1 d^?1) and 16 species (26.7%) had high OFP (more than 10 g O₃ (tree)^?1 d^?1).     

Investigation of plant growth and flower performance on a semi-extensive green roof

Understanding of plant growth and flower performance is crucial for appropriate planting design. This study was aimed to understand characteristics of growth pattern and flower performance in green roof plants and how plant species diversity effect these characteristics. A semi-extensive green roof was installed in 2005 and 54 species plant species were planted in 10 cm and 20 cm of the substrate in Rotherham, UK. Thirty-two quadrats (50 cm × 50 cm) were set up through the combinations of plant species diversity (high and low), planting density (high and low). Percentage of coverage and height of each species were recorded at every month from February to November 2006 in these 32 quadrates. Flowering time of each species was studied every two weeks from February to November 2006. Flowering time was various from plants; some showed a very long flowering time, over five months whereas some finished flowering within two weeks. The growth characteristics of individual plant species over time were categorized into six patterns of coverage and vertical growth pattern. Spread of individual plants was larger in high diversity of plants than those in low diversity of plants. Number of flowering was higher and overall flowering term was longer in the quadrats of higher plant species diversity than those of lower plant diversity. However, these tendencies were affected strongly by the combination of species used. Therefore, it is important to be aware of individual plant growth characteristics such as plant size, growth pattern and flower performance for planting design.     

Private residential urban forest structure and carbon storage in a moderate-sized urban area in the Midwest,United States

In conjunction with urbanization and its importance as a major driver of land-use change, increased efforts have been placed on understanding urban forests and the provisioning of ecosystem services. However, very little research has been conducted on private property and little is known about the structure and function of privately owned urban forests. This research examines the structure of and carbon storage services provided by private residential urban forests in a moderate-sized Midwestern city. The primary research questions are as follows: What is the structure of private urban forests, and how does it vary across parcels? How much carbon is stored in tree and soil pools of private urban forests, and how does carbon vary across parcels? Ecological inventories were conducted on 100 residential parcels within 14 Neighborhood and Homeowners Associations of varying size and development age. Tree species richness, diversity, density, and diameter distribution were determined on a per parcel basis and for the entire tree population sampled. Further, tree and soil carbon storage were determined for each parcel. Results of this research demonstrated large variability in per-parcel tree metrics. Twelve of the parcels sampled had two or fewer trees, while eleven had greater than 50 trees. Further, tree carbon storage ranged from no carbon to 11.22 kg C m^?2. Alternatively, soil carbon storage was less variable and averaged 4.7 kg C m^?2, approximately 1.9 times higher than the average carbon stored in trees (2.5 kg C m^?2). Management efforts aimed at maintaining or enhancing carbon storage and other ecosystem services should focus on both soil protection and maximizing services in living biomass. Our results demonstrate that sustaining tree-produced ecosystem services requires maintenance of large old trees and species diversity, not only in terms of relative abundance, but also relative dominance, and in combination, species–specific size distributions.     

Mapping leaf area of urban greenery using aerial LiDAR and ground-based measurements in Gothenburg,Sweden

Leaf area of urban vegetation is an important ecological characteristic, influencing urban climate through shading and transpiration cooling and air quality through air pollutant deposition. Accurate estimates of leaf area over large areas are fundamental to model such processes. The aim of this study was to explore if an aerial LiDAR dataset acquired to create a high resolution digital terrain model could be used to map effective leaf area index (L_e) and to assess the L_e variation in a high latitude urban area, here represented by the city of Gothenburg, Sweden. L_e was estimated from LiDAR data using a Beer-Lambert law based approach and compared to ground-based measurements with hemispherical photography and the Plant Canopy Analyser LAI-2200. Even though the LiDAR dataset was not optimized for L_e mapping, the comparison with hemispherical photography showed good agreement (r² = 0.72, RMSE = 0.97) for urban parks and woodlands. Leaf area density of single trees, estimated from LiDAR and LAI-2200, did not show as good agreement (r² = 0.53, RMSE = 0.49). L_e in 10 m resolution covering most of Gothenburg municipality ranged from 0 to 14 (0.3% of the values >7) with an average L_e of 3.5 in deciduous forests and 1.2 in urban built-up areas. When L_e was averaged over larger scales there was a high correlation with canopy cover (r² = 0.97 in 1 × 1 km² scale) implying that at this scale L_e is rather homogenous. However, when L_e was averaged only over the vegetated parts, differences in L_e became clear. Detailed study of L_e in seven urban green areas with different amount and type of greenery showed a large variation in L_e, ranging from average L_e of 0.9 in a residential area to 4.1 in an urban woodland. The use of LiDAR data has the potential to considerably increase information of forest structure in the urban environment.     

Micro-scale heterogeneity in urban forest soils affects fine root foraging by ornamental seedlings of Buddhist pine and Northeast yew

Urban soils are frequently characterized by a strong heterogeneity caused by intense anthropogenic activity and land use changes. Soil heterogeneity is commonly known to affect tree root development, but little has been detected concerning root foraging by ornamental trees in heterogeneous urban soils at micro-scale. In this study, Buddhist pine [Podocarpus macrophyllus (Thunb.) D. Don] and Northeast yew (Taxus cuspidata S. et Z.) were selected as ornamental tree species for a two-year study. In the first-year, seedlings were cultured under contrasting photoperiods to generate different morphologies. In the second year, seedlings were transplanted to pots filled with soils collected from an urban forest. Controlled-release fertilizers (N-P₂O₅-K₂O, 14-13-13) were evenly broadcasted to a half patch of the pot (heterogeneity) or to both halves (homogeneity) on the surface 5 cm beneath the pot-top at the rate of 0.135 g N seedling⁻¹. In the fertilized heterogeneous patch, larger Buddhist pine seedlings had greater dry weight, length, surface area, volume, number of tips, and morphological foraging-precision in fine roots. Compared to Northeast yew seedlings under natural photoperiod in the first year, those under the extended photoperiod had larger size, greater fine root biomass, and length but lower foraging-precision in the second year. N and P concentrations in second-year fine roots mainly increased with the availability of patches generated by fertilization for both species. In conclusion, the ability to forage for nutrients by ornamental tree seedlings in heterogeneous urban forest soils was species-specific. Buddhist pine seedlings had higher foraging precision in heterogeneous urban soils than Northeast yew seedlings due to their response to the extended photoperiod during culture.     

The impact of photoperiod and irradiance on flowering of several herbaceous ornamentals

Forty-one herbaceous species were grown under short-days (8 h photoperiod, ambient irradiance averaged 12–13.2 and 6.4–8.3 mol m⁻² day⁻¹ for Experiments I and II, respectively) with or without supplemental high-pressure sodium lighting (+50, 100, or 150 μmol m⁻² s⁻¹); or under long-days delivered using natural day lengths and irradiance with night interruption lighting (2200–0200 h at 2 μmol m⁻² s⁻¹ from incandescent lamps) or under ambient daylight plus supplemental irradiance during the day and as a day extension to 18 h (0800–0200 h) with supplemental high pressure sodium lighting (+50, 100, or 150 μmol m⁻² s⁻¹) to identify the impact of photoperiod and irradiance on flowering of each species. Days to first open flower, leaf number below first flower, and mean dry weight gain per day (MDWG) were measured when the first flower opened. Twenty-seven species were photoperiodic with examples of five photoperiodic response groups represented: obligate short-day (2), facultative short-day (5), obligate long-day (16), facultative long-day (4); 13 were day neutral (no photoperiod response in flowering). One species, Salvia sclarea L., did not flower. A facultative irradiance response was observed with 10 species; 28 species were irradiance indifferent; 2 had delayed flowering as irradiance increased. Photoperiod affected MDWG of 30 species. Increasing irradiance affected MDWG with 14 species. Photoperiod interacted with irradiance to affect MDWG of 11 species. Cobaea scandens had the greatest MDWG (0.40 g day⁻¹) while Amaranthus hybridus had the least MDWG (0.01 g day⁻¹) across photoperiod and irradiance levels.     

Variations of urban greenness across urban structural units in Beijing,China

Urban structural units (USUs) are work (or similar) units in urbanized areas. In this study, USUs based on urban land use and land cover were used to explain and compare urban ecological conditions within Beijing. This study focused on the spatial pattern of land use for different USUs in urban areas. The results showed that 453 USUs belong to 12 primary USUs and to 38 different secondary USUs. The percentage of built-up area was highest in those regions with hotels, and lowest in areas with cemeteries. The percentage of woodland area was highest in primary and middle schools, and the lowest in entertainment plazas. The percentage of grassland area was highest in farmland or orchards, and lowest in Siheyuan (courtyards). The percentage of green space is highest in lands dedicated to middle and primary schools, and lowest in areas with museums. There is no significant linear relationship between construction period and green space percentage in Colleges/Universities (R = 0.045, p = 0.806 > 0.05) and Parks (R = 0.13, p = 0.43 > 0.05). However, there was an inverted-U curve relationship with the relevant housing price in the residential area, a relationship that can be described by the equation: f = 17736.45 + 348.21x ? 4.15 x², p = 0.0022 < 0.05. This relationship implied that the socio-economic factors like housing prices may be a factor in determining the green space pattern of urban ecosystems in Beijing.     

Bird song diversity influences young people's appreciation of urban landscapes

Increased losses of green areas in cities reduce people's experience of flora and fauna. Earlier studies have shown that biodiversity has benefits for urban inhabitants but the influence of animal sounds on people's experience of green space is poorly known. A sample of young urban people (N = 227) rated their reactions – positive or negative – to three bird song combinations: House Sparrow (Passer domesticus), Willow Warbler (Phylloscopus trochilus), 7 spp. i.e. Willow Warbler, Chaffinch (Fringilla coelebs), Blue Tit (Cyanistes caeruleus), Great Tit (Parus major), European Robin (Erithacus rubecula), Common Blackbird (Turdus merula), Great Spotted Woodpecker (Dendrocopos major), three urban settings (residential areas with varying amount of greenery) and nine combinations of song and setting. Bird song was generally considered positive and singing by several species was more highly rated than singing by a single species. On average, urban settings combined with bird song were more highly appreciated than the settings alone and even more so where there was singing by several species rather than just one. We conclude that our data support the idea that bird song contributes to positive values associated with urban green space. Urban planners should consider preserving a variety of habitats in cities for hosting a diversity of birds and thereby boost conservation of songbird diversity and recreational experiences for urban people.     

Energy use and greenhouse gas emissions from turf management of two Swedish golf courses

Turf management on golf courses entails frequent maintenance activities, such as mowing, irrigation and fertilisation, and relies on purchased inputs for optimal performance and aesthetic quality. Using life cycle assessment (LCA) methodology, this study evaluated energy use and greenhouse gas (GHG) emissions from management of two Swedish golf courses, divided into green, tee, fairway and rough, and identified options for improved management. Energy use and GHG emissions per unit area were highest for greens, followed by tees, fairways and roughs. However, when considering the entire golf course, both energy use and GHG emissions were mainly related to fairway and rough maintenance due to their larger area. Emissions of GHG for the two golf courses were 1.0 and 1.6 Mg CO₂e ha⁻¹ year⁻¹ as an area-weighted average, while the energy use was 14 and 19 GJ ha⁻¹ year⁻¹. Mowing was the most energy-consuming activity, contributing 21 and 27% of the primary energy use for the two golf courses. In addition, irrigation and manufacturing of mineral fertiliser and machinery resulted in considerable energy use. Mowing and emissions associated with fertilisation (manufacturing of N fertiliser and soil emissions of N₂O occurring after application) contributed most to GHG emissions. Including the estimated mean annual soil C sequestration rate for fairway and rough in the assessment considerably reduced the carbon footprint for fairway and turned the rough into a sink for GHG. Emissions of N₂O from decomposition of grass clippings may be a potential hotspot for GHG emissions, but the high spatial and temporal variability of values reported in the literature makes it difficult to estimate these emissions for specific management regimes. Lowering the application rate of N mineral fertiliser, particularly on fairways, should be a high priority for golf courses trying to reduce their carbon footprint. However, measures must be adapted to the prevailing conditions at the specific golf course and the requirements set by golfers.     

The impact of greenspace size on the extent of local nocturnal air temperature cooling in London

Urban greenspaces can provide a significant cooling service, which extends beyond the greenspace boundaries. Consequently, greenspaces are recognised for their ability to locally reduce the urban heat island, a phenomenon that has negative implications for the thermal comfort and health of urban citizens. However, the amount of cooling provided by a greenspace and the distance over which that cooling extends depend on factors such as greenspace size and characteristics. Based on data collected in and around eight London greenspaces, with areas ranging from 0.2 to 12.1 ha, this work models the distance and magnitude of cooling provided by each greenspace and defines the relationships between cooling extent and the size of greenspace or the areas of tree canopy and grass. Such data, illustrating the value of expanding the area of urban greenspaces and explaining how cooling relates to greenspace size/coverage characteristics, will be of use to urban planners and climatologists concerned with finding solutions to the urban heat island. Modelling was statistically valid on calm warm nights (with mean air temperatures ≥10 °C and wind speed ≤3 m s⁻¹). On those nights, cooling distance increased linearly with increasing area of greenspace, tree canopy and grass, but the relationship between those factors and the amount of cooling was non-linear. Cooling distance was most strongly related with tree canopy whereas the amount of cooling was most strongly linked to the grass coverage. Our results suggest that a comprehensive cooling service on calm warm nights within cities with similar climate/characteristics to London may come from greenspaces with 3–5 ha, situated 100–150 m apart.     

Assessment of light adequacy for vertical farming in a tropical city

The pursuit of urban agriculture as part of a city’s green infrastructure is often a challenge, particularly within compact cities, where there is a limited amount of space between buildings for urban farming and gardening. Instead, such high-rise urban developments present often under-utilized spaces on the vertical surfaces of buildings. A key unknown is the adequacy of light for plant growth. Many leafy vegetables that require high amounts of light form a significant proportion of the staple diet in many Asian countries. We report on the assessment of sunlight adequacy for growing leafy vegetables in a compact tropical city, based on the high-rise and high-density residential environment of Singapore. Leaf physiological traits of seven leafy vegetables were assessed and used to estimate plant light requirements. A survey of photosynthetically active radiation (PAR) along exposed corridors showed that the daily light integral (DLI) value ranged from 2 to 35 mol m⁻² d⁻¹ under relatively ideal weather conditions during days with abundant solar insolation, and façades that experienced a minimum of half-day direct insolation matched the light requirements of vegetables within the moderate to very high-light categories. With regard to the building form, PAR increased gradually with height, but remains highly influenced by façade orientation and configuration. Owing to the annual north–south oscillation of the sun’s path, reduced annual PAR variability and higher total annual PAR at façades, buildings with an east–west orientation will better support continuous vegetable cultivation, especially for basic building typologies without self-shading configurations. However, excessive PAR and temperatures during mid-day hours may hinder plant growth. By highlighting such patterns in levels of PAR, this study confirms the potential for high-rise and high-density conditions in the tropics to support farming using typically under-utilized vertical spaces of residential buildings.     

Effects of roads on fruit crop and removal rate from rowanberry trees (Sorbus aucuparia) by birds in urban areas of Finland

Roads destroy natural habitats. To reduce erosion, support wildlife and decorate surroundings, ornamental trees are planted near the roadside. However, it is inadequately understood how roads influence fruit production of trees and birds that consume their fruits, within urban landscapes. During the autumn and winter of 2012–2013, we studied the extent to which birds used the fruit from rowanberry trees (Sorbus aucuparia), in two cities along a 700 km latitudinal gradient in Finland. In matched pair design (total of 35 pairs), we compared roadside trees (approximately 8 m from main roads) with trees grown away from roads (control trees; approximately >80 m from the roads). During the autumn, each rowanberry tree pair was photographed, and frugivorous birds were surveyed twice per month until all of the rowanberry fruit-crop was consumed. There was no difference in fruit crop size between roadside trees and control trees. A total of eight frugivorous bird species and 960 individuals were observed foraging in roadside trees. The three most abundant species were Bohemian waxwing (Bombycilla garrulus, 56.4%), Pine Grosbeak (Pinicola enucleator, 28.9%) and Fieldfare (Turdus pilaris, 10.5%). Total abundance and species richness of frugivorous birds were lower around roadside trees than control trees during most of the study period. Fruits were consumed later from roadside trees than from control trees, probably due to human-caused disturbance. Therefore, roadside rowanberry trees extended the period when frugivorous birds stayed in urban habitats. Later consumption of fruits in northern areas than in southern areas was related to earlier peak abundance of frugivorous birds in south than in north. Our results indicated that rowanberry is a suitable ornamental tree for urban and roadside landscaping and may additionally benefit birds and other frugivorous wildlife.     

Relationships between bole and crown size for young urban trees in the northeastern USA

Knowledge of allometric equations can enable urban forest managers to meet desired economic, social, and ecological goals. However, there remains limited regional data on young tree growth within the urban landscape. The objective of this study is to address this research gap and examine interactions between age, bole size and crown dimensions of young urban trees in New Haven, CT, USA to identify allometric relationships and generate predictive growth equations useful for the region. This study examines the 10 most common species from a census of 1474 community planted trees (ages 4–16). Regressions were applied to relate diameter at breast height (dbh), age (years since transplanting), tree height, crown diameter and crown volume. Across all ten species each allometric relationship was statistically (p < 0.001) significant at an α-level of 0.05. Consistently, shade trees demonstrated stronger relationships than ornamental trees. Crown diameter and dbh displayed the strongest fit with eight of the ten species having an R² > 0.70. Crown volume exhibited a good fit for each of the shade tree species (R² > 0.85), while the coefficients of determination for the ornamentals varied (0.38 < R² < 0.73). In the model predicting height from dbh, ornamentals displayed the lowest R² (0.33 < R² < 0.55) while shade trees represented a much better fit (R² > 0.66). Allometric relationships can be used to develop spacing guidelines for commonly planted urban trees. These correlations will better equip forest managers to predict the growth of urban trees, thereby improving the management and maintenance of New England's urban forests.