Water Consumption Characteristics Of Pinus Sylvestris Var.Mongolica,an Urban And Rural Greening Species,and Its Response Characteristics To Rainfall Reduction

In today's society,the problem of water shortage is increasing day by day.At the moment when our country vigorously advocates the construction of beautiful rural and urban-rural integration,landscaping construction and green space maintenance,as major water consumers,have attracted much attention for their water use.Pinus sylvestris var.mongolica Litv.is the main landscaping tree species,economic tree species and ecological tree species in Northeast China,it is extremely necessary to study its water consumption characteristics and its own physiological regulation ability.In the artificial Pinus sylvestris var.mongolica Litv.forest,there are two conditions for reducing the water volume by 30% and the normal water volume treatment,and useing TDP thermal diffusion technology and automatic weather monitoring tower to dynamically monitor the sap flow of Pinus sylvestris var.mongolica Litv.and environmental factors in the sample plot,and collect their data regularly.Research on the sap flow velocity,influencing factors and plant transpiration water consumption through data analysis,in order to reveal the water consumption characteristics and regulation mechanism of Pinus sylvestris var.mongolica Litv.,an urban and rural landscaping tree species,it provides a theoretical basis for establishing a rational irrigation system for urban and rural landscaping,improving the water use efficiency of urban and rural green spaces,and developing water-saving gardens.The research results are as follows:(1)The daily variation trend of sap flow velocity of Pinus sylvestris var.mongolica Litv.is a single-peak curve(the control group has a “narrow peak” curve,the water-reducing group has a “broad peak” curve)under sunny conditions,it is a bimodal curve under cloudy conditions,and it is an irregular and multi-peak curve under rainy conditions;The daily average value of sap flow velocity was the highest in sunny days,followed by cloudy days,and lowest in rainy days.The difference between the two groups of Pinus sylvestris var.mongolica Litv.is as follows: The daily average value of the water-reducing group was higher than that of the control group;The peak sap flow velocity(the first peak)of the water-reducing group appeared earlier than the control group under the three weather conditions.On a seasonal scale,the start time and peak arrival time of sap flow of Pinus sylvestris var.mongolica Litv.on a typical sunny day in spring are the earliest,and the autumn is the latest.(2)The time lag effects between the sap flow velocity of the two groups of Pinus sylvestris var.mongolica Litv.and various environmental factors have a certain unity.The relationship of lag time in different seasons: autumn > summer > spring,control group > water-reducing group.(3)At the beginning of the growing season(April),the correlation between the sap flow velocity of Pinus sylvestris var.mongolica Litv.in the control group and various environmental factors was not significant,and at the end of the growing season(October),the correlation was opposite to the overall trend.However,the reduced water group is highly consistent with the overall trend.(4)During the growing season,the control group had the highest water consumption in June and July,with a water consumption contribution rate of 33.49%,and the lowest water consumption in April,with a water consumption contribution rate of 11.02%;the water-reducing group had the highest water consumption in July and August,with a water consumption contribution rate of 40.99%,and the lowest in April,with a water consumption contribution rate of 7.28%.The daily water consumption of the water-reducing group was higher than the control group under the typical sunny weather in August.The water consumption of the water-reducing group increased earlier than the control group,but the water-reducing group reached the peak(first peak)time later than the control group.(5)In the peak growth season,the daily cumulative water consumption of the control group and the water-reducing group under different typical weather conditions were as follows: sunny > cloudy > rainy,July > August > September.(6)In the three seasons of spring,summer and autumn,water consumption at night is the highest in autumn,while water consumption during the day is the highest in summer.The difference in day and night water consumption of the two groups of Pinus sylvestris var.mongolica Litv.was the largest in summer,and the difference in water consumption between day and night in the three seasons of the water-reducing group was always higher than the control group.The average proportion of daytime water consumption was: the control group 72.53%,77.53% of the water-reducing group.