| With the rapid development of urbanization,environmental problems such as urban heat islands have been triggered.Urban park plant communities have improved the urban heat island and human comfort through self-regulation.In this study,36 typical plant communities in Qunli Clove Park of Harbin were used as sample plots to extract plant community structure types by field investigation and UAV recording.Temperature and humidity data were obtained by mobile measurement method to identify the effects of temperature and humidity dynamics.Factor,explore the regulation of its structure on the local cooling and humidification,and reveal the dynamic distribution characteristics of the temperature and humidity effect in different periods of the park,and propose the optimal structure of the temperature and humidity dynamics and comfort of the plant community.Provide mathematical support for the planning and design of plant communities in urban parks.Firstly,to understand the geographical and climatic characteristics of Harbin in the cold city,the temperature and humidity regulation effect is explained from four aspects:shading effect of plant community,plant transpiration and evaporation of underlying surface,regulation of carbon and oxygen balance in the environment and wind control.The principle of action is described,and the evaluation criteria for the comfort of temperature and humidity effects are explained.Secondly,the field survey of 36 plant communities in the Lilac Park was conducted.The measured time was selected in the summer with the most obvious effect of vegetation cooling and humidification(August 4th-August 6th,2018).Three days without clear wind or breeze.Record the temperature and humidity data of each sample point for each time,for 9:00-11:00,13:00-15:00,17:00-19:00 and 9:00-19:00 Data processing was performed,including temperature,humidity,and temperature-humidity discomfort index(DI)calculated from temperature and humidity data.Finally,the data processing is divided into three aspects:(1)by comparing the temperature and humidity data of the park and the control group in one day,describing the overall improvement of the environment in the park;(2)using SPSS software,from the canopy structure and composition of the community.Three aspects of structure and vegetation spatial layout,bivariate correlation and fitting analysis with temperature and humidity data at different time periods,explaining the optimal range of temperature and humidification of the structure at different time periods;(3)according to the sample temperature wet effect discomfort data,imported into Arcgis software to construct a comfortable dynamic map through spatial interpolation,to clarify the ideal and non-ideal venues for people to perform activities in the park at different times.The results show that:(1)The average air temperature and temperature drop in the park were all changed to the unimodal daily variation trend.Compared with the control group,the difference was at most 2.5?,with a minimum difference of 0.8?;the relative humidity and humidification inside the park.The effects showed a daily average trend of "U" type,which was up to 27.4%compared with the control group,with a minimum difference of 3.7%.(2)The effect of community structure on temperature and humidity regulation:canopy canopy closure is significantly higher than three-dimensional green density,and the three-dimensional green density is more significant than canopy closure.The vegetation combination method in the local cooling and humidification effect on the arbor.In the period of 17:00-19:00,three-dimensional green of the amount of density is better in the range of 0-2m3/m2;when the three-dimensional green density is above 3 m3/m2,the optimal humidification effect can be exerted,and the herb layer is an important moisturizing vegetation layer.When the ratio is in the range of 3-6,the effect of cooling and humidifying is better.In the spatial arrangement of the six plants,the compliant layout of the ring and the small diameter and the dominant wind direction are the same,and the local microclimate and human comfort are improved.It is better than the other.When the canopy closure is between 0.71 and 0.86,the local cooling and humidification effect is optimal.(3)During the period from 9:00 to 11:00,the temperature and humidity effect at the entrance to the southeastern part of the park and the southwest azimuth square is better than that of the northwest area.In the period from 13:00 to 15:00,all inside the park,The comfort value of the sample temperature and humidity effect is higher than that of the control group.The temperature and humidity effect comfort of the southern part of the park and the small part of the northeast area is better than that of the northern area.In the period of 17:00-19:00,the northwest area of the park The comfort of the temperature and humidity effect is better than that of the southeast region.In this study,the dynamic and wet dynamic effects of plant community structure in cold city parks were studied.The mechanism of cooling and humidification regulation of different plant community structures and the dynamic distribution of comfort and temperature of lilac park were clarified,and corresponding microclimate adaptation was proposed.The guidelines for the design of sexual space lay the theoretical and technical foundation for the construction and renovation of other urban parks,providing people with a safer and more comfortable outdoor environment,thus realizing the significance of sustainable development of the city. |
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