| Urban park green space is an important part of urban landscape construction,not only conducive to improving the urban ecological environment,to maintain the ecological balance of the city,enrich the city's biodiversity,but also to meet people's higher level of culture,entertainment,recreation and other activities needs.However,along with our country's urbanization advancement speeding up unceasingly,the construction of urban ecological environment lags behind all kinds of infrastructure construction,and the greenbelt structure is still an unreasonable problem in urban garden settings in many urban construction processes,which affecting the living and working environment of urban residents seriously.Therefore,it is an important subject to study the landscape structure and its environmental effects of urban green space,to plan and design the layout of urban green space and to improve the ability of urban green space to regulate urban climate.Domestic and foreign scholars have given extensive attention to this issue,however,the research on the ecological environment effect of urban green space is mainly concentrated in summer and autumn,spring is the season of recovery in all the year,it also is a relatively dry season in the northern city climate.It is undoubted that the studies on eco-environmental effect of green space at the sprouting and growing stages has important theoretical and practical significance.Based on the previous study,the author chose five representative park green spaces in Shijiazhuang city to monitor atmospheric humidity from the late February to the early May in 2015 and 2016.Reference to weeping willow growth period,divided the whole spring process into three phases: before sprouting,sprouting time and flourishing period.Study the different changing rules between time and space greenbelt humidity at different stages of plant growth in spring,analysis of various factors that may affect the humidity effect of park green spaces.The main conclusions are as follows:First,during the process of plant growth in spring,the atmospheric humidity of park green spaces showed a tendency to increase with the growth of plant foliage,and the diurnal variation of atmospheric humidity is negatively correlated with air temperature.Second,the atmospheric humidity of all green spaces has vertical stratification characteristics among the parks,and the humidity near the ground is much higher than 0.2 m to 1.8 m.Grow with the germination of new plant leaves,the vertical stratification is more complex.The results showed that the transpiration and evaporation of the ground cover plants had a great influence on the vertical variation of atmospheric humidity.Third,based on the vegetation types and the characteristics of plant assemblage structure,the atmospheric humidity of evergreen shrubs is highest before the germination of plants.With the gradual growth of the plants,the atmospheric humidity of the multiple layer structure green spaces are higher than other green spaces.The results indicating that plant characteristics,combination of plant structure and plant density,height,canopy density and other factors also have great influence on the atmospheric humidity.Fourth,the influence of park green spaces on the atmospheric humidity environment have a certain degree of extension,and with the growth of plants,the scope of its influence has been expanded.Before sprouting time in spring,the influence of the park green spaces on the atmospheric humidity of the surrounding environment is within 24 m.The influence period of the plant sprouting time is about 30 m,while the flourishing period could be extended to 35 m.Fifth,the average daily atmospheric humidity in parks with water is higher than the ones without water,which indicating water evaporation has a greater impact on the surrounding atmospheric humidity environment,but its effect is different at each monitoring stage.Before sprouting and during sprouting time,the effect of water evaporation on the surrounding atmospheric humidity is significant,while in the flourishing period,its effect in atmospheric humidity is weaker than that of vegetation transpiration on the overall change.Sixth,the humidification effect of all kinds of green spaces in the park gradually increases with the growth of plants in spring.During the daytime,the strongest period of humidity effect is about 14:00,and the weakest period is 8:00.Before sprouting time,the humidifying effect of evergreen shrub is the most significant,followed by arbor-grasses,herbs,arbor-shrub-grasses,arbors.With the gradual growth of the plants,the atmospheric humidity of the multiple layer structure green spaces are more and more obvious.During the sprouting time,the humidification effect of green spaces from strong to weak in turn is arbor-grasses,herbs,shrubs,arbor-shrub-grasses,arbors,while in the flourish period,the order is arbor-grasses,arbor-shrub-grasses,shrubs,herbs,arbors.Seventh,throughout the spring,the humidification effect in parks with water is stronger than the parks without water.However,with the continuous growth of plants,the difference of the two types of parks is decreased,which indicated that the influence of the evaporation of the park water on the atmospheric humidity gradually weakened in the process of growing plants,while the effect of plant transpiration was gradually enhanced.Eighth,before sprouting time,temperature,vegetation type,soil moisture and artificial waters in the park are the main factors that influence the humidity effect of green spaces.This study shows that the green spaces will increase humidity only the average temperature in the spring during the day to reach or exceed 4?;ground cover plants and soil moisture have important impacts on the spatial variation characteristics of greenbelts humidifying effect;the evaporation of artificial water can enhance the humidifying effect of green spaces within a certain distance.In addition to the above factors,in the germination period,the spatial combination structure of green spaces is beginning to gradually show its effect on the humidification effect of green spaces,that is also to say,the humidification effect of the compound green spaces is dominant,and the single layer structure of the green space is relatively weak.To the end of the spring season,the plant density,canopy density,shading degree of foliage and other factors on the humidifying effect is also extremely prominent.Last,the park water area and greenbelt area,vegetation coverage and the shape are the basic factors that affect the humidifying effect of park green space.The humidification effect of each park green space is completely weak before sprouting,and it's difficult to determine the role of the basic factors;in the period of plant germination and foliage,the proportion of water area and green area in the total area of the park on the moisturizing effect is quite obviously.No matter what the water area or green area accounted for more than 0.7,which can become an important factor affecting the humidification effect of park green space.In addition,vegetation coverage and greenbelt shape index also have some impact on the humidity effect of park green spaces,but the degree of influence is controlled by the greenbelt and water structure layout conditions in the park. |
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