Impact of Street Built Environment on Human Thermal Comfort in Summer

With the continuous intensification of the global greenhouse effect,thermal comfort has become a highly concerned issue in the living environment.The study explores the influencing factors and improvement strategies of urban street thermal comfort.The urban heat island effect,environmental parameters,building layout,and green planting all have a significant impact on the thermal comfort of streets.Improvement strategies include optimizing cultivating pattern of plants,adjusting street layout,and improving paving materials of road.The multi-layer vegetation structure provides green shade,reduces local temperature,and humidifies the surrounding environment.It should adjust the street orientation and aspect ratio to provide sunlight and ventilation,and reduce ambient temperature.Paving materials with low reflectivity and light color and permeable underlying surface should be chosen to reduce heat absorption,increase shading and greenery,and improve thermal comfort.

橡胶与砂仁间作小气候特点初探

橡胶与砂仁间作小气候特点初探周再知，郑海水，杨曾奖，尹光天（中国林业科学院热带林业研究所，广州５１０５２０）ＲｅｓｅａｒｃｈｏｎＭｉｃｒｏｃｌｉｍａｔｉｃＣｈａｒａｃｔｅｒｉｓｔｉｃｉｎＰｌａｎｔａｔｉｏｎｏｆＲｕｂｂｅｒＩｎｔｅｒｃｒｏｐｐｅｄｗｉ...

Microclimate and Its Formation Mechanism in Cunninghamia lanceolata Hook. Plantation Ecosystems in the Subtropical Zone of China

Microclimate characteristics and related environmental energy mechanisms were examined based on the long term located observations in the mature, thinned and young Cunninghamia lanceolata plantation ecosystems in western Hunan Province, China. The results show that the mature plantation ecosystem can improve the microclimate significantly by regulating the amount and spatial distribution of environmental energy, which delineates the pattern of the microclimate in forest ecosystems in the process of ecological restoration. Compared with the young plantation, the mature plantation ecosystem decreased annual mean air temperature by 0 4℃. The maximum decrease in monthly mean air temperature was 2 3℃. The mature plantation ecosystem decreased annual mean ground temperature by 1 2℃ with a maximum decrease in monthly mean ground temperature of 2 3℃. Mainly due to the dense canopy, the mature forest ecosystem regulates the distribution of radiation energy, and expenditure ratios of heat budget and principal energy components to decrease temperature or make it even.

Effects of N Rates on Canopy Microclimate and Population Health in Irrigated Rice

Objective The aim was to elucidate the effects of N rates on rice canopy microclimate and community health so as to provide a sci- entific basis for studying the production potential in irrigated rice with healthy canopy. Method The effects of rice population structure traits under different N rates on rice canopy temperature, relative humidity （ RH）, light transmittance and sheath blight were studied by using Sunscan canopy analysis system and HOBO（ Pro Temp/RH IS logger）. Result The results showed that leaf area index, plant height and tiller number had significant effects on canopy cooling, RH enhancing and light reducing. Extremely significant multiple linear regression relationships existed among canopy day temperature, day RH, LAI and tiller number, and among light transmittance, tiller number and plant height. At flowering stage, per unit LAI could result in a day-maximum-temperature （Tmax） deceasing of 0.87℃ and a day-minimum-RH （RHmin） enhancing of 2.5% within canopy. Similarly, 100 plants per ms could respectively cause a Tmax deceasing of 1.23℃ and an RHmin enhancing of 3.3% in rice canopy. And per 10 cm plant height and 100 plants per m^2 could respectively reduce 9.3% and 7.8% of light in canopy. Conclusion Sheath blight disease index was significantly enhanced as the canopy day temperature decreased, day RH increased and light transmittance reduced. Bigger canopy from higher nitrogen level treatment leads to a more stable canopy microclimate with little changes in temperature and RH during day and night, which has the risk of worsening canopy health. Thus, moderately controlling the space development of canopy is the basis of constructing healthy canopy in rice.

Research Advance on Sod Culture in Peach Orchard

Sod culture in peach orchards is an advanced soil management. The significances of sod culture in peach orchard are introduced, as well as the sod ways. The effects of sod culture in a peach orchard on soil, microclimate and growth and development of peach tree, and disease, pest and weed are reviewed. The problems in sod culture in peach orchard in China are summarized. Sod culture could increase soil fertility, improve soil physical properties, relieve soil temperature change, increase soil microbial growth and soil enzyme activity, improve microclimate and fruit quality, reduce physiological disease, insect pests and weeds.

Sub-Canopy Temperature Dynamics of a Native Tree Plantation from a Lowland Tropical Rainforest in Costa Rica

With urbanization encroaching upon forestlands, characterizing microclimates in secondary forests will be important for the sustainable management of microclimates in agroforestry systems. We used micro-sensors to characterize changes in temperature at different heights in the sub-canopy of both secondary forest and 15-year-old agroforestry plots. Results show that while agroforestry plots had different temperature profiles from the secondary forest, the monoculture plot (consisting of Pentaclethra macroloba) had temperatures similar to the profile found in the secondary forest. This suggests that the replication of temperature profiles in a secondary forest may be independent of the number of tree species in a plot (e.g. polyculture), but may instead depend on the density of a given trees species. These findings further suggest that characterizing temperature microclimates in secondary forests can serve to improve the ecological sustainability of agro-forestry systems.

Biological Basis & Microclimate Effects of Intercropping in Jujube Field

Objective] This study aimed to explore the biological basis and microcli-mate effects in intercropping jujube orchard. [Method] From 2009 to 2011, jujube was intercroped with wheat, peanut, soybean, garlic, watermelon, vegetables etc. By fixed observation and simultaneous mobile observation, the field microclimate factors such as the air temperature, surface temperature, air relative humidity, wind speed, etc. were measured, with mono-crop farmland as the control. [Result] The competi-tion relationship existed between jujube trees and the intercropped plants for re-sources such as il umination, fertilizer, and water; however there were differences in phenological phases and the critical periods in needing for water, fertilizer and il u-mination between jujube and intercropped plants. Meanwhile, there was significant difference （P〈0.05） in the variation of agricultural microclimate environment in jujube field compared with that in control farmland. Compared with the control, the air tem-perature in intercropping jujube orchard was reduced by 0.2 to 0.7 ℃, the earth surface temperature reduction ranged from 2.1 to 2.5 ℃, the relative air humidity increased by 3.7% to 6.8% and the wind speed decreased by 0.2 to 0.4 m/s. [Conclusion] Al above results showed that intercropping in jujube orchard could be promoted in central China and northern China areas.

Microclimate regimes following gap formation in a montane secondary forest of eastern Liaoning Province, China

In order to improve the understanding of the role of a canopy opening/gap on the physical environments in a secondary forest in Northeastern China, a case study was conducted in and around a small irregular gap in a montane secondary forest. The secondary forest, which was severely disturbed by human beings about 50 years ago, was dominated by Quercus mongolica and Fraxinus rhynchophyllaan. Temporal variation in photosynthetic photon flux density （PPFD）, air temperature （TA） at 10 cm above the ground, soil temperature （Ts） and soil water content （SWC） at top-layer （0-15 cm） and sub-layer （15-30 cm） were measured from May to September after the second year since the formation of the small gap （the ratios of gap diameter to stand height were less than 0.5） in 2006 respectively. Results indicated that the highest value of PPFD occurred at the northern edge of the gap, particularly at the beginning of the growing season in May. On sunny days, the highest value of PPFD appeared earlier than that on overcast days. Maximum and mean values of TAwere higher in the northern part of the gap, and the minimum values of TAwere at the southern edge of the gap. Soil temperature varied obviously in the gap with the range from 1 to 8 ℃. Maximum values of Ts occurred at the northern part of the gap, which was significantly correlated with the maximum values of TA （R = 0.735, P〈0.05）. SWC was higher in the top-layer （0-15 cm） than that in sub-layer （15-30 cm）, but the difference of them was not significant （p〉0.05）, which might be attributed to the small gap size and the effects of aboveground vegetations. From these results, the maximum of PPFD in the study area occurred at the northern part of the gap, which was consistent with the results observed in north hemisphere, but the occurrence time varied with the differences of the latitudes. The highest values of air and soil temperatures also occurred in the northern part of the gap because they were affected by the radiation. However, the variation of temperature in July was different from other months due to the influence of gap size. And the values of soil water content were neither higher in the gap in the wet season nor lower in the dry season, which might be affected by the gap size and topography the gap located. The variations of light, soil and air temperatures, and soil moisture in this small irregular gap might be related to the effects of the micro-site, which affects the regeneration of plant species.

Effects of long-term warming on the aboveground biomass and species diversity in an alpine meadow on the Qinghai-Tibetan Plateau of China

Ecosystems in high-altitude regions are more sensitive and respond more rapidly than other ecosystems to global climate warming.The Qinghai-Tibet Plateau(QTP)of China is an ecologically fragile zone that is sensitive to global climate warming.It is of great importance to study the changes in aboveground biomass and species diversity of alpine meadows on the QTP under predicted future climate warming.In this study,we selected an alpine meadow on the QTP as the study object and used infrared radiators as the warming device for a simulation experiment over eight years(2011-2018).We then analyzed the dynamic changes in aboveground biomass and species diversity of the alpine meadow at different time scales,including an early stage of warming(2011-2013)and a late stage of warming(2016-2018),in order to explore the response of alpine meadows to short-term(three years)and long-term warming(eight years).The results showed that the short-term warming increased air temperature by 0.31℃and decreased relative humidity by 2.54%,resulting in the air being warmer and drier.The long-term warming increased air temperature and relative humidity by 0.19℃and 1.47%,respectively,and the air tended to be warmer and wetter.The short-term warming increased soil temperature by 2.44℃and decreased soil moisture by 12.47%,whereas the long-term warming increased soil temperature by 1.76℃and decreased soil moisture by 9.90%.This caused the shallow soil layer to become warmer and drier under both short-term and long-term warming.Furthermore,the degree of soil drought was alleviated with increased warming duration.Under the long-term warming,the importance value and aboveground biomass of plants in different families changed.The importance values of grasses and sedges decreased by 47.56%and 3.67%,respectively,while the importance value of weeds increased by 1.37%.Aboveground biomass of grasses decreased by 36.55%,while those of sedges and weeds increased by 8.09%and 15.24%,respectively.The increase in temperature had a non-significant effect on species diversity.The species diversity indices increased at the early stage of warming and decreased at the late stage of warming,but none of them reached significant levels(P>0.05).Species diversity had no significant correlation with soil temperature and soil moisture under both short-term and long-term warming.Soil temperature and aboveground biomass were positively correlated in the control plots(P=0.014),but negatively correlated under the long-term warming(P=0.013).Therefore,eight years of warming aggravated drought in the shallow soil layer,which is beneficial for the growth of weeds but not for the growth of grasses.Warming changed the structure of alpine meadow communities and had a certain impact on the community species diversity.Our studies have great significance for the protection and effective utilization of alpine vegetation,as well as for the prevention of grassland degradation or desertification in high-altitude regions.

Influencing Factors on Rice Sheath Blight Epidemics in Integrated Rice-Duck System

Sheath blight, a disease caused by the fungus Rhizoctonia solani Kuhn （anamorph）, has been the most economically significant disease of rice. It was frequently reported that the disease was well-controlled in integrated rice-duck system without the employment of fungicides. However, the effecting factors behind this phenomenon were rarely reported. In this research, experiment was carried out between two treatments, rice combined with ducks （RD） and conventional rice field without ducks rearing （CK） in early season rice paddy, to investigate the variations of sclerotia in floodwater and on rice plant, microclimate 10 cm above the waterline in rice paddy and activity of protective enzymes in rice plants. The results showed that the floating sclerotia in floodwater in RD was 86-91% lower than that in CK, and adhering sclerotia in rice plant in RD was 67-78% lower than that in CK. The relative humidity tested significantly lower and light intensity tested significantly higher in RD. The temperature in the early rice growth stages in RD was slightly lower than that in CK, but it was significantly higher （32.3-36.5~C） in the middle stage rice growth stages. The polyphenoloxidase （PPO） activity in RD were lower than that in CK, but the enhanced activity of phenylalanine ammonia-lyase （PAL）, peroxidase （POD） and Chitinase was observed in different stages of rice growth in RD, especially the Chitinase which showed higher activity in all investigating days.

Effects of Mulching Mode on Canopy Physiological, Ecological Characteristics and Yield of Upland Rice

The effects of mulching mode on population physiology and ecology of rice were studied using a combination P88S/1128 as the material under three mulching cultivation modes including plastic film mulching, straw mulching and liquid film mulching, as well as bare cultivation (control). The results indicated that mulching mode had significant effects on micro-meteorological factors and individual growth of rice, as shown by an increase of relative humidity, a better internal micro-meteorological environment of rice population, a significant reduction under the rice canopy temperature, especially during high-temperature periods. Rice plants under mulching cultivation conditions displayed a stronger transpiration and lower leaf temperature, thereby improving the ability of anti-high temperature stress and markedly increasing the photosynthetic rate. Furthermore, the yield components of rice were significantly optimized under mulching cultivation, of which with plastic film mulching displayed the highest grain number per panicle and seed-setting rate, and a yield increase of 16.81% compared with the control; and with straw mulching displayed an increase of effective panicle number and a 9.59% increase of total yield compared to the control.

Microclimatic characteristics of the Heihe oasis in the hyperarid zone of China

The microclimate of a desert oasis in hyperarid zone of China was monitored using micrometeorological methods and compared with those of areas adjacent to forested land. Differences in ground-level photosynthetically active radiation （PAR） on clear, cloudy and dust storm days and their subtending causes are analysed and discussed. Desert oases serve the ecological functions of altering solar radiation, adjusting near-ground and land surface temperatures, reducing soil temperature differences, lowering wind velocity, and increasing soil and atmospheric humidity. The total solar radiation in the interior of the oasis was roughly half of that outside a forest canopy. During the growing season, air temperatures in Populus euphratica Oliv. （poplar） and Tamarix ramosissima Ledeb. （tamarisk） forests were 1.62℃ and 0.83 ℃ lower respectively than those in the areas around the forests. Furthermore, the miler the forest cover, the greater the temperature drops; air temperatures in the upper storey were greater than those in the lower storey, i.e., air temperature rose with increasing height. Over the growing season, the relative humidities of the air in the poplar and tamarisk forests were 8.5% and 4.2% higher respectively than those in areas around the forests. Mean wind velocity in poplar-forested lands was 0.33 m·s^-1, 2.31 m·s^-1 lower than that in the surrounding area. During dust storm days the PAR was significantly lower than that on cloudy or clear days, when it was high and varied in an irregular manner.

Land surface temperature andcharacteristics for a raingarden insoil moisture distributionFitzroy Gardens, Melbourne

To better understand the cooling effect of raingarden in Fitzroy Gardens, Melbourne, as well as it benefits for an urban microclimate, two rounds of 36-h microclimate monitoring at the raingarden were conducted.Land surface temperature and soil moisture were analyzed according to monitoring data. The results showa clea raingarden cooling effect in summer. The largest difference o land surface temperatures inside and outside the raingarden can reach 23. 6 ℃, and the diurnal variation in temperature insid the raingarden was much less than that outside the raingarden.The soil moisture increased rapidly after irrigation, with th increase in the volumetric water content( VWC) of 2% to3. 6%. The soil moistures of adjacent irrigated garden bed and grass were higher than those inside the raingarden.Monitoring soil moisture helps guide raingarden irrigation.

CFD Based Study of Heterogeneous Microclimate in a Typical Chinese Greenhouse in Central China

Indoor microclimate is important for crop production and quality in greenhouse cultivation. This paper focuses on microclimate study based on a computational fluid dynamics （CFD） model of a typical plastic greenhouse （with a sector shape vertical cross-section） popularly used in central China. A radiation model is added into the CFD model so as to simulate coupling of convective transfers and radiative exchanges at the cover and the roof, instead of using the usual coupling approach based on energy balance. In addition, a fractal permeability model is innovatively adopted in the modeling of the crop canopy. Compared the numerical results with measured experimental data, the model simulation is proved with success. This model then is used to explore the microclimate variable distributions in the greenhouse. It shows that the airflow pattern, temperature and humidity profiles are different from those in a sawtooth Mediterranean- type greenhouse. The study suggests that this deliberately developed CFD model can be served as a useful tool in macroclimate research and greenhouse design investigating.

Effect of abiotic factors on understory community structures in moist deciduous forests of northern India

Understory vegetation controls, in a significant way, the regeneration of overstory trees, carbon sequestration and nutrient retention in tropical forests. Development and organization of understory vegetation depend on climate, edaphic and biotic factors which are not well correlated with plant community structures. This study aimed to explore the relationships between understory vegetation and abiotic factors in natural and planted forest ecosystems. A non-metric multidimensional scaling(NMS) ordination technique was applied to represent forest understory vegetation among five forest communities, i.e., a dry miscellaneous forest(DMF), a sal mixed forest(SMF), a teak plantation(TP), a low-land miscellaneous forest(LMF) and a savanna area(SAV) of the Katerniaghat Wildlife Sanctuary, located in northern India. Microclimatic variables, such as photosynthetically active radiation(PAR), air temperature(AT), soil temperature(ST), ambient atmospheric CO 2 concentration, absolute air humidity(AH), physical and chemical soil properties as well as biological properties were measured. Understory species were assessed via 100 random quadrats(5 m × 5 m) in each of the five forests in which a total of 75 species were recorded encompassing 67 genera from 37 families, consisting of 32 shrubs and 43 plant saplings. DMF was the most dense forest with 34,068 understory individuals per ha of different species, whereas the lowest understory population(13,900 per ha) was observed in the savanna. Ordination and correlation revealed that microclimate factors are most important in their effect compared to edaphic factors, on the development of understory vegetation in the various forest communities in the north of India.

Elevational patterns of bird species richness on the eastern slope of Mt.Gongga,Sichuan Province,China

Background:In biological systems,biological diversity often displays a rapid turn-over across elevations.This defining feature has made mountains classic systems for studying the spatial variation in diversity.Because patterns of elevational diversity can vary among lineages and mountain systems it remains difficult to extrapolate findings from one montane region to another,or among lineages.In this study,we assessed patterns and drivers of avian diversity along an elevational gradient on the eastern slope of Mt.Gongga,the highest peak in the Hengduan Mountain Range in central China,and a mountain where comprehensive studies of avian diversity are still lacking.Methods:We surveyed bird species in eight 400-m elevational bands from 1200 to 4400 m a.s.l.between 2012 and 2017.To test the relationship between bird species richness and environmental factors,we examined the relative importance of seven ecological variables on breeding season distribution patterns:land area(LA),mean daily temperature(MDT),seasonal temperature range(STR),the mid-domain effect(MDE),seasonal precipitation(SP),invertebrate biomass(IB) and enhanced vegetation index(EVI).Climate data were obtained from five local meteorological stations and three temperature/relative humidity smart sensors in 2016.Results:A total of 219 bird species were recorded in the field,of which 204 were recorded during the breeding season(April–August).Species richness curves(calculated separately for total species,large-ranged species,and smallranged species) were all hump-shaped.Large-ranged species contributed more to the total species richness pattern than small-ranged species.EVI and IB were positively correlated with total species richness and small-ranged species richness.LA and MDT were positively correlated with small-ranged species richness,while STR and SP were negatively correlated with small-ranged species richness.MDE was positively correlated with large-ranged species richness.When we considered the combination of candidate factors using multiple regression models and model-averaging,total species richness and large-ranged species richness were correlated with STR(negative) and MDE(positive),while small-ranged species richness was correlated with STR(negative) and IB(positive).Conclusions:Although no single key factor or suite of factors could explain patterns of diversity,we found that MDE,IB and STR play important but varying roles in shaping the elevational richness patterns of different bird species categories.Model-averaging indicates that small-ranged species appear to be mostly influenced by IB,as opposed to large-ranged species,which exhibit patterns more consistent with the MDE model.Our data also indicate that the species richness varied between seasons,offering a promising direction for future work.

Optimization of rhizosphere cooling airflow for microclimate regulation and its effects on lettuce growth in plant factory

In plant factories,the plant microclimate is affected by the control system,plant physiological activities and aerodynamic characteristics of leaves,which often leads to poor ventilation uniformity,suboptimal environmental conditions and inefficient air conditioning.In this study,interlayer cool airflow(ILCA)was used to introduce room air into plants’internal canopy through vent holes in cultivation boards and air layer between cultivation boards and nutrient solution surface(interlayer).By using optimal operating parameters at a room temperature of 28℃,the ILCA system achieved similar cooling effects in the absence of a conventional air conditioning system and achieved an energy saving of 50.8% while bringing about positive microclimate change in the interlayer and nutrient solution.This resulted in significantly reduced root growth by 41.7% without a negative influence on lettuce crop yield.Future development in this precise microclimate control method is predicted to replace the conventional cooling(air conditioning)systems for crop production in plant factories.

Photosynthetic Characteristics of Ash and Larch in Mixture and Pure stands

The photosynthesis of ash (Fraxinus mandshurica) and larch (Larlk gmelini) in pure and mixture plantation stands was measured and the influence of the microclimate on the photosynthesis was analyzed in this study. The result shows that the net photosynthetic rate (NPR) of ash is higher in mixed stand than in pure one, 61 .64% higher in the measuring day. The NPR of larch is approximately the same in the two stands. The microclimate in the mixed ash-larch stand is much different from that in the pure one. The temperature is moderate in the mixture stand, e.g., the maximum temperature in the mixture stand is lower and the minimum temperature is higher than that in the pure ash stand. The relative air moisture is higher in the mixture stand. The microclimate in the mixture stand benetits the photosynthesis of ash, considered as one of the important reasons that make the mixture stand more productive.

Improvement of Outdoor Microclimate Comfort of Rural Residence in Southwest Mountainous Area through Plant Application

Improvement of microclimate comfort is good to save energy,and create and improve communication space,and promote sustainable development of countryside.Wind is an important factor that influences outdoor microclimate and plant is an economic,high-efficiency and healthy choice to improve wind environment.This article discussed technical strategies of improving the microclimate comfort of rural residence in southwest mountainous areas,by taking use of native vegetations.The strategy is to set up the wind-guide or wind-break plant landscape system through site planting,courtyard planting and residence planting.

Analysis on Thermal Environment of Underlying Surface and PM2.5 Concentration in Community Park of Beijing in Winter

Community park is one of the most important landscape spaces for urban people to live outdoors,and people’s perception of environmental microclimate is a direct factor affecting the use frequency and experience of community parks.In this paper,Shijingshan Sculpture Park of Beijing was taken as experimental object.Using the method of fi eld measurement,9-d winter test for 3 months was conducted in three kinds of landscape architecture spaces,including waterfront plaza,open green space and square under the forest.Via regression analysis method,the measured air temperature(Ta),relative humidity of air(RH),particulate matter(PM2.5)were analyzed.It is found that winter sunshine is main infl uence factor of garden microclimate,and there is a negative correlation between local temperature and humidity;local temperature and humidity can regulate the local PM2.5 concentration,and temperature shows negative correlation with PM2.5 concentration,while humidity shows positive correlation with PM2.5 concentration.Meanwhile,via comparative analysis of temperature,humidity and PM2.5 concentration in different types of garden spaces,the infl uence of different space forms,planting forms and materials on thermal environment of underlying surface and PM2.5 concentration was summarized,and design strategy was optimized,to be as benefi cial reference of reconstruction design of community parks.