Simulation Research On The Microclimate Effect Of Plant Community In Ribbon Park Of Cold Region In Spring

Plant community is one of the important landscape elements that affect the microclimate characteristics of urban space.It is of great significance to know the regulatory effect of its spatial characteristics on microclimate factors in order to optimize the spatial design of climate adaptability of plant landscape and improve the thermal comfort of citizens in outdoor environment.At present,the researches on the microclimate characteristics of plant communities based on the field measurement methods have been gradually perfected.However,the numerical simulation methods have become another important tool for studying the urban microclimate characteristics due to its advantages of saving manpower and resources.In this paper,ten typical community units of Stalin Park in Harbin were used as samples to simulate the spatial and temporal variations of the virtual reality of three-dimensional plant communities with different spatial structures,layouts and morphological features using the ENVI-met three-dimensional micro-climate model.Firstly,the data of ENVI-met software is verified by field measurement combined with ENVI-met numerical simulation.The simulation object was further determined by the method of field sampling and scenario assumptions.Finally,numerical simulation experiments were conducted on May 12,2017 after the ENVI-met optimization of software parameters and the establishment of the plant three-dimensional space model were completed.Numerical simulation results show that:(1)In terms of space structure,the larger the LAD value of arbors,the higher the community richness,the more the planting rows are and the smaller the spacing is,the stronger the ability of the community to cool and humidify,and the stronger the ability to control the wind.The lower the height of tree branches,the weaker the ability of cooling and humidifying,but the ability of controlling the wind was significantly strengthened.The shrubs had a certain ability of humidifying,but the ability of cooling was weak,and the shrubs had higher wind resistance at 1.4m than arbors.The variation of line spacing has a great effect on wind speed and is related to the main wind direction of the site.(2)In terms of spatial layout,the integrity,evenness,confinement and opening characteristics of the community layout all have different regulating effects on the microclimate factors in the community.Evenly distributed plant community has better regulation of temperature and humidity,and the lower the wind speed is,the lower the wind speed is,the lower the wind speed is.The wind speed of community with high enclosing degree,compactness and perpendicular to the wind direction is lower,but the influence on temperature and humidity is different.The direction of opening and the number of openings of the community have little influence on the size and distribution of temperature and humidity inside the community,and have a significant impact on the wind speed.The wind speed inside the open windward community is larger,and the wind speed distribution at the community opening changes significantly.However,there is no clear relationship between the number of openings and the wind speed in the community.(3)In terms of space form,the changes of community height have significant effects on the values of temperature,humidity and wind speed,the changes of community width have significant effects on changes in the distribution of microclimate factors.The higher the community height,the lower the temperature,the greater the humidity and the greater the wind speed.The wider the width of the community,the smaller the variation of temperature and humidity values,wind speed decreased within the community,and the distribution changes significantly.The variation of community crown height has the strongest influence on the wind speed value and distribution,followed by the temperature and the weakest humidity.The distribution of wind speed with rich variation of crown line changed significantly,the value of wind speed is related to the wind direction of the site,and the average wind speed inside the community with low trees on the windward side is smaller.In this study,Through the numerical simulation of the plant community in the cold area,the spatial and temporal variations of microclimate factors in different spatial characteristics were compared,the regulatory mechanism of the spatial characteristics of the micro-climatic effects of plant communities were clarified,and the microclimate adaptability spatial design of plant community in ribbon park was discussed,and corresponding design guidelines were put forward.According to the climate characteristics of Harbin in spring,this paper summarized the improvement of wind,dryness and large temperature difference between day and night and other climatic conditions of the spatial pattern of plant communities.The conclusion can be used as the basis to optimize the spatial pattern of plant community in the cold-spring ribbon park and provide mathematical support for the design of the microclimate suitability space for plant community in the cold-drawn strip park.