Joint effects of air PM2.5 and socioeconomic dimensions on posted emotions of urban green space visitors in cities experiencing population urbanization: A pilot study on 50 cities of East China.

People may perceive and expose negative sentiments in days with PM2.5 pollutions, but evidence is still insufficient about the joint effects of PM2.5 and socioeconomic factors on human sentiments. In this study, a total of 8032 facial photos of urban green space visitors were obtained from Sina Weibo in 50 cities of East China and rated for happy, sad, neutral scores and net positive emotion index (NPE; happy minus sad). Seasonal air PM2.5 concentrations were collected from days when people exposed faces in cities that were categorized to medium, large, outsize, and mega sizes according to resident populations (RPs). In summer, people posted lower sad score (11.28 %) than in winter (13.51 %; P = 0.0357) and higher NPE (35.86 %) than in autumn (30.92 %; P = 0.0009). Multivariate linear regression on natural logarithms revealed that factors of gross domestic product per capita (parameter estimate: 0.45), RP (0.59), non-production electricity consumption (0.34), and length of road transport (0.34) together generated positive contributions to posted happy score, while the total retail trade of consumer goods (-1.25) and PM2.5 (-0.50) were perceived as joint depressors on NPE. Overall, cities with more rich households and activated retail sales attracted more people who exposed smiles in weathers with PM2.5 compared to cities where local economy is reliable on heavy industry. The summertime in mega cities will be recommended to enjoy a higher frequency to perceive satisfaction due to exposure to low PM2.5.

Facial expressions of Asian people exposed to constructed urban forests: Accuracy validation and variation assessment.

An outcome of building sustainable urban forests is that people's well-being is improved when they are exposed to trees. Facial expressions directly represents one's inner emotions, and can be used to assess real-time perception. The emergence and change in the facial expressions of forest visitors are an implicit process. As such, the reserved character of Asians requires an instrument rating to accurately recognize expressions. In this study, a dataset was established with 2,886 randomly photographed faces from visitors at a constructed urban forest park and at a promenade during summertime in Shenyang City, Northeast China. Six experts were invited to choose 160 photos in total with 20 images representing one of eight typical expressions: angry, contempt, disgusted, happy, neutral, sad, scared, and surprised. The FireFACE ver. 3.0 software was used to test hit-ratio validation as an accuracy measurement (ac.) to match machine-recognized photos with those identified by experts. According to the Kruskal-Wallis test on the difference from averaged scores in 20 recently published papers, contempt (ac. = 0.40%, P = 0.0038) and scared (ac. = 25.23%, P = 0.0018) expressions do not pass the validation test. Both happy and sad expression scores were higher in forests than in promenades, but there were no difference in net positive response (happy minus sad) between locations. Men had a higher happy score but lower disgusted score in forests than in promenades. Men also had a higher angry score in forests. We conclude that FireFACE can be used for analyzing facial expressions in Asian people within urban forests. Women are encouraged to visit urban forests rather than promenades to elicit more positive emotions.

Gas Exchange, Water Use Efficiency, and Biomass Partitioning among Geographic Sources of Acer saccharum Subsp. saccharum and Subsp. nigrum Seedlings in Response to Water Stress.

Responses to water stress were measured for sugar maple (Acer saccharum subsp. saccharum Marshall) sources from Oklahoma (Caddo sugar maple), Missouri, Tennessee, Ontario, and a black maple (Acer saccharum subsp. nigrum F. Michx.) source from Iowa. Seedling sources were selected for differences in temperature and precipitation of their geographic origins. Seedlings were preconditioned through moist (watered daily) or dry (watered every 4-7 days) cycles and then exposed to prolonged water stress. As water stress increased, dry preconditioned 17-week-old sugar maple seedlings from Oklahoma, Missouri, and Tennessee, sources from warmer, and/or drier climates with greater restrained photosynthesis, stomatal conductance, and water use efficiency than those from cooler and moister climates. Under imposed water stress, the Ontario and Iowa sourced seedlings increased their root to shoot ratios and decreased their specific leaf area, mechanisms for drought avoidance. However, no corresponding changes in these values occurred for Oklahoma, Missouri, and Tennessee sources and for the variable of leaf wilting across all sources. Results from this study suggest greater tolerance of water stress in the Oklahoma, Missouri, and Tennessee ecotypes from the western and southern range of sugar maple resulted primarily with water use efficiency (WUE) rather than other water stress coping mechanisms. Findings from this study provide evidence to support selection of sugar maples sources for forestation.

Spectral effect of streetlamps on urban trees: A simulated study on tissue water, nitrogen, and carbohydrate contents in maple and oak.

Streetlamps enforce night lighting on urban forest trees, but scarce information is available concerning the ecophysiological performance of street trees under these conditions. In this study, maple (Acer truncatum Bunge) and oak (Quercus mongolica Fisch. ex Ledeb.) seedlings were cultured with simulated exposure to streetlamp spectra in white (red/green/blue, 7.7:1.0:2.2) and red plus blue (RB; red/green/blue, 4.6:0.0:1.0) lights with photosynthetic photon flux rate of 80 µmol m-2 s-1 in a 18-h photoperiod. Nitrogen (N) was loaded through 15 weekly applications to an amount of 80 mg N plant-1 to mimic the mineral N deposition to landscape trees. Variables of biomass, carbohydrate accumulation, N and water contents were rarely found difference between the two LED-spectra treatments for both species. Compared to the un-lighted control, the RB spectrum lowered N concentration in oak seedlings and water content in maple seedlings. The white light spectrum resulted in an increase of starch concentration. Carbohydrate concentration had a positive relationship with biomass and N content across two species but a negative relationship with water content in maple seedlings. Overall, streetlamp-lights imposed effects on tree growth by a prolonged photoperiod instead of specific spectrum. Maple had a strong response of water uptake to streetlamp lighting at the cost of carbohydrate consumption, but oak had scarce demand of water-use for growth.

Using morphological attributes for the fast assessment of nutritional responses of Buddhist pine (Podocarpus macrophyllus [Thunb.] D. Don) seedlings to exponential fertilization.

Culturing slowly growing tree seedlings is a potential approach for managing the conflict between the increasing demand for ornamental stock and the decreasing area of farmlands due to urbanization. In this study, Buddhist pine (Podocarpus macrophyllus [Thunb.] D. Don) seedlings were raised in multishelves with light-emitting diode lighting in the spectrum of 17:75:8 (red:green:blue) at 190-320 µmol m-2 s-1 with controlled temperature and relative humidity at 19.5°C and 60%, respectively. Seedlings were fed by exponential fertilization (EF) (nitrogen [N]-phosphorus [P]2O5-K2O, 10-7-9) at eight rates of 0 (control), 20 (E20), 40 (E40), 60 (E60), 80 (E80), 100 (E100), 120 (E120), and 140 (E140) mg N seedling-1 for four months through 16 fertilizer applications. The nutritional responses of Buddhist pine seedlings can be identified and classified into various stages in response to increasing doses, up to and over 120 N seedling-1. Morphological traits, i.e., the green color index and leaf area (LA) obtained by digital analysis and the fine root growth, all remained constant in response to doses that induced steady nutrient loading. LA had a positive relationship with most of the nutritional parameters. A dose range between 60 and 120 mg N seedling-1 was recommended for the culture of Buddhist pine seedlings. At this range of fertilizer doses, measuring the leaf area through digital scanning can easily and rapidly indicate the inherent nutrient status of the seedlings.

[Effects of controlled-release fertilizer and organic amendment on the construction of nutrients reserves in Larix olgensis container seedlings].

A 2 x 2 factorial experiment was conducted to study the effect of fertilization on Larix olgensis container seedlings. 36.36 or 18.18 mg controlled-release fertilizer (CRF) N and 0 or 1.82 g FM organic amendment (OA) per seedling were applied. There were no significant responses to fertilization in the seedling height, collar diameter, biomass, and potassium (K) uptake. Applying FM OA increased the number of first-order lateral roots with a length > 1 cm (P = 0.040), the tap root length (TRL) (P = 0.012), and the ratio of TRL to seedling height (P = 0.008). Comparing with low application rate CRF N, high application rate CRF N increased the N concentration in root (P = 0.035) as well as the N reserves in stem (P = 0.005), root (P = 0.037), and stem plus root (P = 0.030), and the P reserves in stem (P = 0.047). Applying 36.36 mg CRF N plus 1.82 g FM OA increased the N concentrations in leaf and in stem plus root by 137% (P = 0.040) and 21% (P = 0.013), respectively, and the N reserves in stem (P = 0.020), root (P = 0.017), and stem plus root (P = 0.013). Vector analysis revealed that high application rate of CRF N led to the excess of seedlings N and P, while applying FM OA alleviated the N and P deficiency but led to the K depletion. For nursing L. olgensis container seedlings, a solution of CRF 18 mg N combined with 1.82 g FM OA per seedling was recommended.