| In order to study the sap flow of the Hippophae rhamnoides stump and the growth law of stump sprouts in Mu Us Sandy Land,and to fully understand the response of the Hippophae rhamnoides stump sap flow to environmental factors,this experiment will be carried out in Mu Us Sandy Land,Wushen Banner,Ordos from May to October 2021,taking the Hippophae rhamnoides,the associated species of the Salix psammophila,as the main research object,selected the Hippophae rhamnoides with good growth in different diameter classes and used40-tooth,60-tooth,and 80-tooth circular saw blade brush cutter for stumping.Nine 60-tooth stumping the Hippophae rhamnoides stump were selected as the standard wood for the sap flow test in different diameter classes.And the EMS62sap flow meter based on the principle of thermal balance is used to continuously monitor the sap flow of the Hippophae rhamnoides stump,and the surrounding meteorological factors(air temperature Ta,air relative humidity RH,etc.)and soil factors(soil water potential SWP,etc.)for synchronous observation,and follow-up investigation on the status of the Hippophae rhamnoides stump sprout.By analyzing the diurnal variation of sap flow in stumps in different months and its relationship with environmental factors,and the growth of the Hippophae rhamnoides sprouts,obtaining the diurnal variation characteristics of stump sap flow,the difference between months,and the environmental factors that dominate the changes of sap flow,the growth law of sprouts.In order to provide basic data support and theoretical basis for understanding the relationship between stumping and associated species of sandy shrubbery in promoting germination and regeneration.The results of this experiment are as follows:(1)Before the sprouts of the Hippophae rhamnoides stump spread their leaves,the diurnal variation curve of the sap flow in the Hippophae rhamnoides stump was"U"-shaped.After the sprouts of the Hippophae rhamnoides stump were fully expanded,the diurnal dynamics of the sap flow of the Hippophae rhamnoides stump showed a"ji"-shaped change law.No matter it was sunny or rainy,the ratio of the accumulation of sap flow at night to the accumulation of sap flow in the whole day in May and June was greater than that in July.The diameter class of the Hippophae rhamnoides stump is different,and the sap flow rate is different.(2)On the daily scale,the main environmental factors affecting the sap flow of the Hippophae rhamnoides stump in sunny and rainy days were soil factors(SWP,ST).On the hourly scale,the sap flow rate of the Hippophae rhamnoides stump is mainly affected by meteorological factors.The sap flow rate of the Hippophae rhamnoides stump has a high correlation with air humidity in rainy days.The stepwise regression equation results show that the solar radiation Q_splays a leading role in the sap flow rate,and R~2is smaller.Instruments should be used for direct monitoring.The smaller the diameter class of the Hippophae rhamnoides stump,the more sensitive the response to meteorological factors.(3)The three stumping methods all had different degrees of influence on the growth of the Hippophae rhamnoides stump sprouts.40-tooth stumping had a greater impact on the length of the Hippophae rhamnoides stump sprouts.The average length of sprouts was 560 mm,and the unstumping the Hippophae rhamnoides stump sprouts were the shortest.The average length of sprouts was270 mm,and the effect of stumping on the diameter of sprouts of the Hippophae rhamnoides stump was not significant.(4)The sprout length and diameter of root tiller were larger than those of branch tiller and s stump tiller.The angle of branch tillering of branches>the angle of tillering of stump>the angle of branching of the Hippophae rhamnoides root system.Based on the analysis of the above test results,it can be seen that after the Hippophae rhamnoides stumping,the sap flow at night increases significantly,which changes the state of water loss,and most of the water is stored at the base of the stump and the root system,which can provide enough water for the stump to carry out sprouting renewal.The height of the stumping is the same.It is recommended to use a brush cutter with 40 teeth or a smaller number of teeth to stumping the Hippophae rhamnoides with a larger diameter,which is conducive to the stump to produce better branches. |
