Determinants of subjective outdoor thermal comfort in an urban historic and cultural heritage landscape in Xi'an, China.

In this study, we investigated factors related to subjective outdoor thermal comfort in the Ancient Ming Dynasty Walled City in Xi'an, China. Environmental data were collected from study sites by microclimate monitoring. Survey locations, demographics, psychological characteristics, thermal sensation vote (TSV), and thermal comfort vote (TCV) data were collected from 639 individuals in a questionnaire survey. Generalized linear regression analysis and path analysis were used to understand the associations between the TSV, environmental and psychological factors, and TCV. We found that green space locations, higher age, and greater subjective well-being and environmental satisfaction were associated with increased TCV. The universal thermal climate index was associated with TCV, and this association could have been affected by the individual's psychological state. Our findings suggest that environmental factors and psychological factors had non-negligible effects on the subjective thermal comfort of individuals located in an open urban area with historical and cultural significance.

Utilizing spiders for biomonitoring air pollution from road traffic: a novel approach and preliminary findings.

Polycyclic aromatic hydrocarbons (PAHs) are air pollutants generated mainly by fuel combustion, industry, and other anthropogenic sources. The level of these pollutants can be assessed by employing biomonitors, a cost-effective and less contaminating alternative than conventional methods. In the present study, we aimed to investigate whether spiders inhabiting areas around a major city like Córdoba, Argentina, adsorb and retain PAHs in their exoskeletons. Additionally, we aimed to determine if spiders' life traits influence their capacity to accumulate PAHs and explore potential relationships between PAH levels and the types of roads where they were collected. Specimens of a funnel-shaped web spider (Aglaoctenus lagotis) and an orb-weaver (Metepeira spp.) were collected from roadsides. Roads were classified into four categories based on their traffic intensity. Using high-performance liquid chromatography (HPLC), we identified 15 different PAHs. Both species exhibited varying concentrations of PAHs, although Metepeira spp. showed 15-18 times higher PAH levels compared to A. lagotis. Moreover, A. lagotis individuals living alongside highways accumulated up to six times more PAHs compared to those along other road types. These findings suggest that spiders' life traits may influence pollutant concentrations. Our study demonstrates that spiders near roads are exposed to and accumulate PAHs on their exoskeletons, likely sourced from petrogenic vehicular emissions, highlighting their value as biomonitors and emphasizing the need for mitigation measures to address air pollutants emitted from mobile sources.

Temporal and Spatial Variation Characteristics and Influencing Factors of Bacterial Community in Urban Landscape Lakes.

Urban landscape lakes are closely related to human activity, but there are limited studies on their bacterial community characteristics and risks to human health. In this study, four different types of urban landscape lakes in Xi'an were selected, and the bacterial community structures in different seasons were analyzed by Illumina Nova high-throughput sequencing technology. Seasonal variations in bacterial communities were analyzed by linear discriminant analysis, STAMP difference analysis, and nonmetric multidimensional scaling. Redundancy analysis was used to investigate the influencing factors. Furthermore, the metabolic functions of bacterial communities were predicted by Tax4Fun. There were clear seasonal differences in the α-diversity of bacteria, with bacterial diversity being higher in winter than in summer in the four urban landscape lakes, and the diversity of different water sources was different; the distributions of Proteobacteria, Actinobacteria, Chloroflexi, and Verrucomicrobia had significant seasonal differences; and the dominant bacteria at the genus level had obvious temporal and spatial differences. Furthermore, a variety of environmental factors had an impact on bacterial communities, and temperature, DO, and nitrogen were the primary factors affecting the seasonal variation in bacteria. There are also significant seasonal differences in the metabolic functions of bacterial communities. These results are helpful for understanding the current status of bacteria in the aquatic environments of such urban landscape lakes.

Assessment of street forest characteristics in four African cities using google street view measurement: Potentials and implications.

Accurate information on urban forests of tree sizes, health state, community structures, and spatial distribution is still limited in African cities. Using a Google Street View (GSV)-based tree-size measuring method developed by our team, this paper aims to evaluate street trees of four African metropolitan cities using GSV data. The study compiled a large dataset with 46,016 street trees in 3454 sites in Kampala, Nairobi, Bloemfontein, and Johannesburg. The data including tree size (diameter at breast height, DBH; tree height, TH; underbranch height, UBH; canopy size), tree floristic composition (apical dominance types, broadleaf-conifer-palm leaf, flowering or not), tree health (leaf color, diebacks, dead tree, and bracket-supporting percent), streetside development (lane number, roadside shops, parking vehicle, and pedestrian density), and geolocation (latitude, longitude). These data can be spatially visualized with the help of ArcGIS, and the large dataset favors reliable maps from the street-view level. Data statistics showed that four cities were dominated by broad-leaved, apical dominance, and flowering trees, with a low level of unhealthy leaves and a tiny percentage of dead. The arbor-shrubs-herb structure vegetation dominated all four cities. Kampala had the most slender trees (DBH = 23 cm, TH = 8.4 m), while Nairobi and Johannesburg had the thickest trees (DBH = 38 cm, TH = 8.5-8.6 m). Bare land rates were lowest at 23% in Bloemfontein and highest at 33% in Nairobi. Principal analysis and Pearson correlations showed that these tree variations were closely associated with street development and local land use configuration. By comparing the urban tree data in other regions of the world, we found that the trees in African cities are generally giant but have a lower density (the trees within a 100-m street segment). Our findings emphasized that GSV data is feasible enough for urban forest monitoring in Africa, and the database is helpful for urban landscape planning and management.

Distribution, source, risk and phytoremediation of polycyclic aromatic hydrocarbons (PAHs) in typical urban landscape waters recharged by reclaimed water.

A park that had used reclaimed water as the sole water supply for fourteen years, was selected to analyze the distribution, sources and risks of 16 priority polycyclic aromatic hydrocarbons (PAHs) in waters and sediments. The effects of phytoremediation were investigated in waterbodies classified as phytoremediation, transitional and non-phytoremediation areas. Diagnostic ratio (DR) and principal component analysis (PCA) were used to analyze the sources of PAHs, while risk quotient (RQ) was used as risk assessment tool. Results showed that ∑PAH concentrations in sediments ranged from 29.4 to 1245.6 ng‧g-1, with average of 354.3 ng‧g-1, corresponding to a moderate pollution level. The concentration of PAHs in water ranged from 10.6 to 326.3 ng‧L-1, with average of 147.2 ng‧L-1, corresponding to a low pollution level. The ∑PAHs in sediments showed a downward trend from northwest to southeast along with the water flow direction, with average values of 459.5, 362.9 and 246.1 ng‧L-1 in the upstream, midstream and downstream, respectively. In contrast, PAH concentrations in water were consistent with recreational activities in the urban park area. There were 95% of water samples and 72% of sediment samples obtaining the Ant/(Ant + Phe) > 0.1 and Flu/(Flu + Pyr) > 0.5, indicating that coal combustion was the major source of PAHs in both the water and sediment. The RQ∑PAH(NCs) values in water and sediment were all between 1 and 800, while RQ∑PAH(MPCs) reached equal to 0, suggesting that ∑PAHs presented a low ecological risk. Acenaphthene accounted for 28.4% of RQ(NCs), and became the most risk PAH in water column. Aquatic plants effectively removed high-ring PAHs from water and middle-ring PAHs from sediments, reducing the overall risks posed by PAHs.

Application of plant metabarcoding to identify diverse honeybee pollen forage along an urban-agricultural gradient.

Understanding animal foraging ecology requires large sample sizes spanning broad environmental and temporal gradients. For pollinators, this has been hampered by the laborious nature of morphologically identifying pollen. Identifying pollen from urban environments is particularly difficult due to the presence of diverse ornamental species associated with consumer horticulture. Metagenetic pollen analysis represents a potential solution to this issue. Building upon prior laboratory and bioinformatic methods, we applied quantitative multilocus metabarcoding to characterize the foraging ecology of honeybee colonies situated in urban, suburban, mixed suburban-agricultural and rural agricultural sites in central Ohio, USA. In cross-validating a subset of our metabarcoding results using microscopic palynology, we find strong concordance between the molecular and microscopic methods. Our results suggest that forage from the agricultural site exhibited decreased taxonomic diversity and temporal turnover relative to the urban and suburban sites, though the generalization of this observation will require replication across additional sites and cities. Our work demonstrates the power of honeybees as environmental samplers of floral community composition at large spatial scales, aiding in the distinction of taxa characteristically associated with urban or agricultural land use from those distributed ubiquitously across the sampled landscapes. Observed patterns of high forage diversity and compositional turnover in our more urban sites are likely reflective of the fine-grain heterogeneity and high beta diversity of urban floral landscapes at the scale of honeybee foraging. This provides guidance for future studies investigating how relationships between urbanization and measures of pollinator health are mediated by variation in floral resource dynamics across landscapes.

Green spaces, quality of life, and citizen perception in European cities.

Urban green spaces generate a number of perceived benefits toward human health and well-being, including an overall improvement in the quality of life. To date, processes underlying these benefits are mostly investigated at city level, while very little research has been conducted at a larger scale, such as the European level. Evidence is lacking on the association between green spaces and citizens' perceived benefits based on variations among cities with different socio-economic conditions. This study aims to disentangle the relationship between greenness, citizens' perceived quality of life, the environment, social inclusion and urban management in 51 European cities, as well as the role of per capita income in moderating the effects of greenness on overall perceived quality of life. Through structural equation modeling, the effect of greenness was tested on citizens' perceived overall quality of life (i.e., on the environment, social inclusion, and urban management). The role of metropolitan gross domestic product per capita in moderating the relationship between greenness and citizens' perceptions on overall quality of life was investigated. Our findings confirm the influence of greenness on citizens' quality of life. More importantly, the influence of greenness on the overall perception of quality of life was considerably more marked in lower-income cities. This study represents one of the first attempts at exploring the complex mechanisms underlying the association between green space and citizens' well-being at continent level. Practical implications for European urban planners and policy makers are discussed.

Simulation of the Urban Space Thermal Environment Based on Computational Fluid Dynamics: A Comprehensive Review.

Rapid urbanization has made urban space thermal environment (USTE) problems increasingly prominent. USTE research is important for improving urban ecological environment and building energy consumption. Most studies on USTE research progress have focused on meteorological observations and remote sensing methods, and few studies on USTE are based on computational fluid dynamics (CFD). During the past two decades, with the increasing applications of CFD in USTE research, comprehensively summarizing the phased results have become necessary tasks. This paper analyzes the current research status of CFD-based USTE simulation from six perspectives. First, we summarize the current research status of USTE simulation with CFD models that integrate ground observations and remote sensing technology. Second, we define and classify the spatial scope of CFD-based USTE simulations at different scales. Third, we systematically analyze the quantitative relationships among urban land type, the underlying surface structure, water bodies, green space and the corresponding changes in CFD-based USTE simulations. Fourth, we quantitatively analyze the impact of anthropogenic heat in CFD-based USTE simulations. Fifth, we summarize the corresponding USTE mitigation measures and methods based on the CFD simulation results. Finally, the outlooks and the existing problems in current research on CFD simulations of the USTE are analyzed.

Behavior and fate of fungicide chlorothalonil in urban landscape soils and associated environmental concern.

This novel study investigated the behavior and fate of chlorothalonil in terms of kinetics, sorption‒desorption and leaching potential in urban landscape soils using batch experiments. The pseudo-second-order model well described the sorption kinetics of chlorothalonil in urban soils. Consequently, chlorothalonil was partitioned into heterogeneous surfaces of soil following the Freundlich isotherm model. According to PCA, soil organic matter (OM), silt, clay, and oxides of Al and Fe exhibited a significant positive correlation (P < 0.05) with chlorothalonil Kd (P < 0.05), while sand content and soil pH showed a negative correlation at P < 0.05. In soils, decreased sorption of chlorothalonil was also due to the presence of undecomposed or partly decomposed OM, whereas increased sorption could be attributed to the combined effect of OM with C = O and C-H groups, silt, clay, Al and Fe oxides and hydrophobicity of the fungicide. Also, HI, GUS, LIX and Kd of four among nine urban soils indicated that chlorothalonil has a great potential for leaching into the groundwater from the soil surface, posing an unintended threat to non-target biota and food safety. Therefore, utmost care must be taken while applying chlorothalonil in urban landscapes, particularly on impervious surfaces, to minimize the impact on the ecosystem.

Horizontal and vertical gene transfer drive sediment antibiotic resistome in an urban lagoon system.

Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes (ARGs) in urban aquatic ecosystems. However, limited information is available concerning the ARG profiles and the forces responsible for their assembly in urban landscape lagoon systems. Here, we employed high-throughput quantitative PCR (HT-qPCR) to characterize the spatial variations of ARGs in surface and core sediments of Yundang Lagoon, China. The results indicated that the average richness and absolute abundance of ARGs were 11 and 53 times higher in the lagoon sediments as compared to pristine reference Tibetan lake sediments, highlighting the role of anthropogenic activities in ARG pollution. Co-occurrence network analysis indicated that various anaerobic prokaryotic genera belonging to Alpha-, Deltaproteobacteria, Bacteroidetes, Euryarchaeota, Firmicutes and Synergistetes were the potential hosts of ARGs. The partial least squares-path modeling (PLS-PM) analysis revealed positive and negative indirect effects of physicochemical factors and heavy metals on the lagoon ARG profiles, via biotic factors, respectively. The horizontal (mediated by mobile genetic elements) and vertical (mediated by prokaryotic communities) gene transfer may directly contribute the most to drive the abundance and composition of ARGs, respectively. Furthermore, the neutral community model demonstrated that the assembly of sediment ARG communities was jointly governed by deterministic and stochastic processes. Overall, this study provides novel insights into the diversity and distribution of ARGs in the benthic habitat of urban lagoon systems and underlying mechanisms for the spread and proliferation of ARGs.

Deep Learning to Unveil Correlations between Urban Landscape and Population Health.

The global healthcare landscape is continuously changing throughout the world as technology advances, leading to a gradual change in lifestyle. Several diseases such as asthma and cardiovascular conditions are becoming more diffuse, due to a rise in pollution exposure and a more sedentary lifestyle. Healthcare providers deal with increasing new challenges, and thanks to fast-developing big data technologies, they can be faced with systems that provide direct support to citizens. In this context, within the EU-funded Participatory Urban Living for Sustainable Environments (PULSE) project, we are implementing a data analytic platform designed to provide public health decision makers with advanced approaches, to jointly analyze maps and geospatial information with healthcare and air pollution data. In this paper we describe a component of such platforms, which couples deep learning analysis of urban geospatial images with healthcare indexes collected by the 500 Cities project. By applying a pre-learned deep Neural Network architecture, satellite images of New York City are analyzed and latent feature variables are extracted. These features are used to derive clusters, which are correlated with healthcare indicators by means of a multivariate classification model. Thanks to this pipeline, it is possible to show that, in New York City, health care indexes are significantly correlated to the urban landscape. This pipeline can serve as a basis to ease urban planning, since the same interventions can be organized on similar areas, even if geographically distant.

Integration of medicinal and aromatic plants in an urban landscape as a living heritage: an example in Malatya City (Turkey).

This paper aims to determine the potential for using medicinal aromatic plants, which have been considered living heritage since prehistoric times, in urban landscapes. The area of study covers Malatya City and its counties, which are found in Eastern Anatolia, a region of importance in terms of the endemic species in Turkey. Malatya is specifically selected as the study area, as the city's geomorphological, hydrological and climatic characteristics favour a high floral diversity. The methods used in this paper consist of five stages: floristic field works conducted in Battalgazi county (Malatya) in the scope of the Scientific and Technological Research Council of Turkey (TUBITAK) Project No. 217O290, the identification of the plants by a taxonomist, the determination of the medicinal and aromatic species in other counties of Malatya based on literature review, the establishment of criteria for the application potential of the identified species in landscape designs and the assessment of the use of the identified species in landscape architecture according to the parameters set in the criteria. Aromatic medicinal species were analysed to generate planting designs in landscape projects; the aesthetic properties (flower, leaf and fruit characteristics), sensory properties (scent and texture), seasonal change characteristics (flowering period and colour change) and use areas (flower parterres, solitary plantings, live fences and site coverings) of the plants were analysed. As a result of ethnobotanical and floristic studies carried out within the boundaries of the study area, a total of 189 medical aromatic species were identified. A total of 157 of these species were herbaceous plants. In conclusion, it was determined that 80 aromatic medicinal species conform to the planting design criteria and could be used in landscape designs in Malatya City.

Greenspace and Infant Mortality in Philadelphia, PA.

Despite mounting evidence that urban greenspace protects against mortality in adults, few studies have explored the relationship between greenspace and death among infants. Here, we describe results from an analysis of associations between greenness and infant mortality in Philadelphia, PA. We used images of the normalized difference vegetation index (NDVI), derived from processed satellite data, to estimate greenness density in each census tract. We linked these data with census tract level counts of total infant mortality cases (n = 963) and births (n = 113,610) in years 2010-2014, and used Bayesian spatial areal unit, conditional autoregressive models to estimate associations between greenness and infant mortality. The models included a set of random effects to account for spatial autocorrelation between neighboring census tracts. Infant mortality counts were modeled using a Poisson distribution, and the logarithm of total births in each census tract was specified as the offset term. The following variables were included as potential confounders and effect modifiers: percentage non-Hispanic black, percentage living below the poverty line, an indicator of housing quality, and population density. In adjusted models, the rate of infant mortality was 27% higher in less green compared to more green tracts (95% CI 1.02-1.59). These results contribute further evidence that greenspace may be a health promoting environmental asset.

Impact of window views on recovery-an example of post-cesarean section women.

OBJECTIVE: The objective of this study was to examine the impact of urban landscape from window views on quality of care for women who underwent Cesarean Section (C-section) in Taiwan. DESIGN: The participants were randomly assigned into 46 different hospital rooms to see the effects of various window views and daylight exposure on women's recovery from post C-section care. SETTING: We carried out this study in the obstetrics departments of three tertiary hospitals located in two major cities of Taiwan: Taipei City and New Taipei City. PARTICIPANTS: A total of 296 women who underwent C-sections and used patient-controlled analgesic (PCA) for pain control after their surgery during the 10-month data collection period were recruited for this study. INTERVENTION: The 46 different patient rooms provided diverse window views and different daylight exposure for the participants. MAIN OUTCOME MEASURES: Recovery for the women who underwent C-sections in this study was defined as PCA usage and perceived pain measured by Brief Pain Inventory (BFI). RESULTS: Higher satisfaction of window view significantly decreased analgesic usage (P = 0.057), reduced the scores of overall perceived pain (P = 0.046), pain severity (P = 0.004), and 'pain's interference with relations with others, enjoyment of life, and mood (REM).' (P = 0.095). CONCLUSIONS: To maximize benefit and well-being of patients recovering from surgery, health care architects should design patient rooms to create maximum satisfaction with visual impacts and optimize window views. By doing so, it may decrease the use of pain medication and substantially reduce healthcare costs.

Response of gas-exchange characteristics and chlorophyll fluorescence to acute sulfur dioxide exposure in landscape plants.

To explore the toxicity and action mechanism of acute sulfur dioxide (SO2) on urban landscape plants, a simulated SO2 stress environment by using fumigation chamber involving increasing SO2 concentration (0, 25, 50, 100, 200 mg m-3) was carried out among three species. After 72 h of exposure, SO2-induced oxidative damage indicated by electrolyte leakage increased with higher dose of SO2. Meanwhile, SO2 decreased the contents of chlorophyll a, chlorophyll b and carotenoid and increased the contents of sulfur. Net photosynthetic rate (Pn) decreased as a result of stomatal closure when SO2 dose was lower than 50 mg m-3, out of this range, non-stomatal limitation play a dominant role in the decline of Pn. Simultaneous measurements of chlorophyll fluorescence imaging (CFI) also revealed that the maximal quantum efficiency of PSII photochemistry in dark-adapted state (Fv/Fm) and the realized operating efficiency of PSII photochemistry (Fq'/Fm') was reduced by SO2 in a dose-dependent manner. In addition, the maximum quantum efficiency of PSII photochemistry in light-adapted state (Fv'/Fm') and the PSII efficiency factor (Fq'/Fv') decreased when exposure to SO2. These results implied that acute SO2 exposure induced photoinhibition of PSII reaction centers in landscape plants. Our study also indicated that different urban landscape plant species resist differently to SO2: Euonymus kiautschovicus > Ligustrum vicaryi > Syringa oblata according to gas-exchange characteristics and chlorophyll fluorescence responses.

Phosphorus retention along a typical urban landscape river with a series of rubber dams.

Small dams are widely constructed in urban rivers as landscape engineering practice, which increasingly cause eutrophication problems. Phosphorus retention in dammed rivers is a critical factor driving eutrophication, but it is little known in urban landscape river systems controlled by small dams. In this study, we investigated the retention of different phosphorus species along an urban landscape river with 30 rubber dams. We found that 42.5% (7.69 metric tons/yr) of the total phosphorus (TP) was trapped within dams, of which total particulate phosphorus (TPP) retention load accounted for 81.5%. From first river segment BBF-4# to the segments further downstream, the TP retention rate sharply decreased from 47.6% to -8.3%-9.2%, and phosphorus was mainly retained in the uppermost segment of the dammed river. The retention rate of dissolved reactive phosphorus (86.3%) was higher than that of TPP (40.3%) because of biological uptake. Further, with a retention rate of -11.3%, the dammed river was a net source of dissolved organic phosphorus. Different hydrological regimes, due to seasonal events and dam management, greatly influenced phosphorus retention within the dammed river, resulting in higher retention loads in the rainy season than in the dry season, and very low retention loads in the snowmelt season, with 1.48, 0.55 and 0.06 t/month, respectively. Our findings imply that management practices should focus on reducing the phosphorus export from the upper watershed and improving the hydrodynamic conditions of the dammed urban landscape river with regard to eutrophication.

Potential of combined Water Sensitive Urban Design systems for salinity treatment in urban environments.

Water sensitive urban design and similar concepts often recommend a 'treatment train' is employed to improve stormwater quality. In this study, the capability of a combined permeable pavement and bioretention basin was examined with a view to developing a permeable pavement reservoir that can supplement the irrigation needs of a bioretention system in semi-arid climates. Salinity was a key study parameter due to published data on salinity in permeable pavement storage, and the potential to harvest water contaminated with de-icing salts. To conduct experiments, roofwater was collected from a roof in Adelaide, South Australia. Water was amended with NaCl to produce a control runoff (no added salt), a medium (500 mg/l) and a high (1500 mg/l) salinity runoff. Water was then run through the pavement into the storage reservoir and used to irrigate the bioretention system. Samples were collected from the roof, the pavement reservoir and the bioretention system outflow to determine whether significant water quality impacts occurred. Results show that while salinity levels increased significantly as water passed through the pavement and through the bioretention system, the increase was beneficial for irrigation purposes as it was from Ca and Mg ions thus reducing the sodium absorption ratio to levels considered 'good' for irrigation in accordance with several guidelines. Permeable paving increased pH of water and this effect was prominent when the initial salt concentration increased. The study shows that permeable pavements with underlying storage can be used to provide supplementary irrigation for bioretention systems, but high initial salt concentrations may present constraints on beneficial use of stormwater.

Temporal Dynamics of the Driving Factors of Urban Landscape Change of Addis Ababa During the Past Three Decades.

Mapping and quantifying urban landscape dynamics and the underlying driving factors are crucial for devising appropriate policies, especially in cities of developing countries where the change is rapid. This study analyzed three decades (1984-2014) of land use land cover change of Addis Ababa using Landsat imagery and examined the underlying factors and their temporal dynamics through expert interview using Analytic Hierarchy Process (AHP). Classification results revealed that urban area increased by 50%, while agricultural land and forest decreased by 34 and 16%, respectively. The driving factors operated differently during the pre and post-1991 period. The year 1991 was chosen because it marked government change in the country resulting in policy change. Policy had the highest influence during the pre-1991 period. Land use change in this period was associated with the housing sector as policies and institutional setups were permissive to this sector. Population growth and in-migration were also important factors. Economic factors played significant role in the post-1991 period. The fact that urban land has a market value, the growth of private investment, and the speculated property market were among the economic factors. Policy reforms since 2003 were also influential to the change. Others such as accessibility, demography, and neighborhood factors were a response to economic factors. All the above-mentioned factors had vital role in shaping the urban pattern of the city. These findings can help planners and policymakers to better understand the dynamic relationship of urban land use and the driving factors to better manage the city.

Multi-scale heterogeneity in vegetation and soil carbon in exurban residential land of southeastern Michigan, USA.

Exurban residential land (one housing unit per 0.2-16.2 ha) is growing in importance as a human-dominated land use. Carbon storage in the soils and vegetation of exurban land is poorly known, as are the effects on C storage of choices made by developers and residents. We studied C storage in exurban yards in southeastern Michigan, USA, across a range of parcel sizes and different types of neighborhoods. We divided each residential parcel into ecological zones (EZ) characterized by vegetation, soil, and human behavior such as mowing, irrigation, and raking. We found a heterogeneous mixture of trees and shrubs, turfgrasses, mulched gardens, old-field vegetation, and impervious surfaces. The most extensive zone type was turfgrass with sparse woody vegetation (mean 26% of parcel area), followed by dense woody vegetation (mean 21% of parcel area). Areas of turfgrass with sparse woody vegetation had trees in larger size classes (> 50 cm dbh) than did areas of dense woody vegetation. Using aerial photointerpretation, we scaled up C storage to neighborhoods. Varying C storage by neighborhood type resulted from differences in impervious area (8-26% of parcel area) and area of dense woody vegetation (11-28%). Averaged and multiplied across areas in differing neighborhood types, exurban residential land contained 5240 ± 865 g C/m2 in vegetation, highly sensitive to large trees, and 13 800 ± 1290 g C/m2 in soils (based on a combined sampling and modeling approach). These contents are greater than for agricultural land in the region, but lower than for mature forest stands. Compared with mature forests, exurban land contained more shrubs and less downed woody debris and it had similar tree size-class distributions up to 40 cm dbh but far fewer trees in larger size classes. If the trees continue to grow, exurban residential land could sequester additional C for decades. Patterns and processes of C storage in exurban residential land were driven by land management practices that affect soil and vegetation, reflecting the choices of designers, developers, and residents. This study provides an example of human-mediated C storage in a coupled human-natural system.

Mycorrhizal detection of native and non-native truffles in a historic arboretum and the discovery of a new North American species, Tuber arnoldianum sp. nov.

During a study comparing the ectomycorrhizal root communities in a native forest with those at the Arnold Arboretum in Massachusetts (USA), the European species Tuber borchii was detected on the roots of a native red oak in the arboretum over two successive years. Since T. borchii is an economically important edible truffle native to Europe, we conducted a search of other roots in the arboretum to determine the extent of colonization. We also wanted to determine whether other non-native Tuber species had been inadvertently introduced into this 140-year-old Arboretum because many trees were imported into the site with intact soil and roots prior to the 1921 USDA ban on these horticultural practices in the USA. While T. borchii was not found on other trees, seven other native and exotic Tuber species were detected. Among the North American Tuber species detected from ectomycorrhizae, we also collected ascomata of a previously unknown species described here as Tuber arnoldianum. This new species was found colonizing both native and non-native tree roots. Other ectomycorrhizal taxa that were detected included basidiomycetes in the genera Amanita, Russula, Tomentella, and ascomycetes belonging to Pachyphlodes, Helvella, Genea, and Trichophaea. We clarify the phylogenetic relationships of each of the Tuber species detected in this study, and we discuss their distribution on both native and non-native host trees.