Analysis Of Stem Sap Flow Of Populus.euphratica In Middle Reaches Of The Tarim River

The forest is a huge water consuming ecosystem which stores water through rain,reduces surface runoff, increase the water use efficiency. Populus euphratica is one ofthe important trees in arid areas, which has sophisticated root system, mainly relies ongroundwater. In minimal precipitation, extreme dry climate of northwestern region,water resources are scarce, water evaporation is fast. In the process of afforestationand vegetation restoration, estimating water consumption of Populus Euphratica treeby trunk stem flow in Iminqak that could save water and offer a way to effective useof water resources in the Tarim River. Using thermal diffusion technology to estimatewater use by a tree is a hot topic in current research. In this study p. euphratica of twotransect sites in middle reaches of Tarim River are chosen, continual stem flowmeasurement of populus euphratica tree trunk was done from march to August, inorder to investigate the daily, monthly and seasonal stem flow change and analyzeflow change rule and the stem flow volume and related environmental factors. Aim ofthis study to find out the daily, monthly and seasonal stem flow change of populuseuphratica tree trunk, and biggest factors which influencse of populus euphratica treetrunk stem flow, establish the regression equation between the stem flow rate andenvironmental factors and model the water condition and the rational use of waterresources by populus euphratica in Tarim River middle reaches to provide theoreticalfoundation and reference. The results show that:1)There are similarities in populus euphratica tree trunk stem change in two sites,but there are some differences in stem flow. And this is due to differences inunderground water level and geographic location of two sites. Plant stem flow rate notonly affected by their physiological impacts, but also by the surrounding environment.2)Daily variation regularity of populus euphratica tree trunk stem flow showsobvious diurnal variation. Through correlation analysis, populus euphratica tree trunk stem the diurnal variation of the flow rate and the solar radiation, air temperature wassignificantly positive correlation, air humidity was significantly negatively correlatedand air, and wind speed and soil moisture content has no obvious correlation. Thesolar radiation is the dominant factor that results in the change of stem flow. Populuseuphratica tree trunk stem the diurnal variation of the flow and there is no obviouscorrelation with soil water content, possibly the diurnal variation of the soil moisturecontent is less volatile, impacts to stem flow lag behind.3）Regression analysis to daily average stem flow and shows that there aredifferences correlation in monthly average stem flow and its environmental factors, insome months sun radiation has played leading role and some months temperature hasplayed leading role. However, among correlation of monthly average value and itsenvironmental factor during the flood season, soil moisture has leading role, Augustaverage stem flow of populus.euphratica and its environmental factor regressionanalysis shows that daily average stem flow of populus.euphratica and soil moisturehas the highest correlation in each month, slightly lower correlation with sun radiation,air temperature and air humidity. Wind speed has no correlation with stem flow.4）Form monthly average stem flow of populus.euphratica and its environmentalFactor regression analysis, we have discovered that seasonal change of stem flowof populus.euphratica has no apparent correlation with sun radiation, air temperatureand air humidity, soil moisture content is the biggest driver for seasonal change ofpopulus.euphratica stem flow.