| The sandstone is distributed in the Yellow River Basin,which is centered on the border area of Shanxi,Shaanxi and Inner Mongolia.It is the most serious area ofsoil erosion in China.Due to the severe soil erosion,the ecological environment in this area is seriously deteriorated.How to effectively use the water resources in the arid areas becomes increasingly The hot spot of today's research.In order to understand the water use characteristics of Pinus tabuliformis and Hippophae rhamnoides in the sandstone area and the water consumption rule under long-term scale,the soil and water conservation demonstration area of Zhungeer Banner in Erdos City,Inner Mongolia was selected as the sampling site.The soil samples and seedlings developed with the sandstone as the parent material were brought back to the greenhouse of Inner Mongolia Agricultural University.The sap flow rate,growth index and chlorophyll fluorescence kinetic parameters of Pinus tabulaeformis and Hippophae rhamnoides were determined from April to October 2018.At the same time,the environmental factors in the greenhouse are measured.The water consumption model of Pinus tabulaeformis and Hippophae rhamnoides was generally fitted and the scale was expanded.The research results not only provide data support for the relationship between plant water supply and demand in the sandstone area,but also provide a theoretical basis for the effective use of water in important plant resources in the sandstone area.Research indicates:(1)Changes in stem flow rate at different time scales of Pinus tabulaeformis and Hippophae rhamnoides L.The diurnal trends of stem flow rate of Pinus tabulaeformis and Hippophae rhamnoides were unimodal and bimodal.During the selected observation day,the daily stem flow of Pinus tabulaeformis started later than seabuckthorn,and the stem flow rate of Pinus tabulaeformis started daily from 6:00-7:00 and peaked from 13:00 to 14:00.Then began to fall and reached the trough at 19:00-20:00.The sap flow rate of seabuckthorn starts at 6:00-7:00 every day,reaches the first peak from 10:00-11:00,and then the sap flow rate starts to fluctuate in a small range until the sap flow rate reaches 13:00-14:00.The second peak of the day,the stem flow maintained a high value from around 10:00 to 14:00,began to decline around 15:00,reached the trough at 19:00-20:00,and maintained the night stem flow rate of the two species.A state that is stable and not zero.The seasonal variation of stem flow rate of both tree species is that the start time and peak time of stem flow in summer are earlier than spring and autumn,and the trough appears later than spring and autumn,that is,the peak of summer stem flow is longer than that of spring.In spring and autumn,the peak flow rate and average stem flow rate in summer were higher than those in spring and autumn.The chlorophyll fluorescence kinetic parameters of Pinus tabulaefomis and Hippophae rhamnoides were measured monthly.The initial fluorescence valuesof Pinus tabulaeformiis and Hippophae rhamnoides L.were similar,but the maximum fluorescence value and maximum photochemical efficiency of Hippophae rhamnoides L,were greater than that of Pinus tabulaeformis and Hippophae rhamnoides.The water consumption is higher than that of Pinus tabulaeformis.(2)Effects of environmental factors on stem flow rate of Pinus tabulaeformis and Hippophae rhamnoides L.Among the easily observed environmental factors,solar radiation intensity,atmospheric temperature and relative humidity of air have the most obvious effects on the stem flow rate of the two tree species.Correlation analysis between stem flow rate and environmental factors showed that the environmental factors with strong correlation with stem flow rate were solar radiation intensity,air temperature and relative humidity of air.Although the soil temperature was not significantly correlated with the spring stem flow rate of Pinus tabulaeformis.Correlation with stem flow rate of seabuckthorn in all seasons reached a significant level,but its correlation was weaker than other environmental factors.There was a linear regression relationship between stem flow rate and environmental factors,and the regression relationship was significant at 95%confidence.In the model of relationship between stem flow rate and environmental factors of two tree species,the average simulated error rate of Pinus tabulaeformis and Hippophae rhamnoides is less than 10%throughout the year,and the error rate is acceptable.Therefore,the established single-tree daily water consumption prediction model has certain application value.(3)Expansion of water consumption of single pine and sea buckthornTaking the stem cross-sectional area of Chinese pine and the leaf area of seabuckthorn as spatial scalar,the transpiration water consumption was scaled to obtain the stand water consumption model Y=0.1329X1.4402 and Y=1.1615X1.387,and the model prediction consumption The average error rate of water quantity and measured water consumption is within 10%. |
PDF Full Text Request