| Bioecology characteristics of Populus euphratica is drought resistant to salt water,like light,is against the sand,curb desertification in the tarim basin ecosystem,maintaining regional ecological balance,protecting biodiversity and ensure the important barrier of oasis agriculture production,the survival of Populus euphratica mainly depends on the annual river flood and groundwater after melting,In recent years due to the rapidly increasing agriculture water consumption of middle and lower reaches of tarim river,and man-made destruction,the status of the current in iminqak is older trees many more of,less young trees,disease,less robust,distributed sparsely in iminqak,distribution less dense,more as a result,the reasonable irrigation measures has important significance for Populus euphratica the renewal of the young forest tending.This test in the middle and lower reaches of tarim river watershed typical location,through artificial simulated before and after water flooding irrigation research of Populus euphratica sapling forest,soil water potential and content,electrical conductivity,net photosynthetic rate,transpiration rate,stomatal conductance and intercellular CO2concentration change,analysis of different water treatment on the influence of physical growth index of Populus euphratica sapling forest,In order to provide reasonable irrigation basis for improving the growth environment of Populus euphratica forests,and to provide technical support for the renewal and tending of Populus euphratica forests in the reaches of Tarim River.The results are as follows:（1）Effects of difpopulus ferent irrigation amount on leaf water potential and soil water potential of Populus euphratica（1）Multiple irrigation significantly promoted the growth of Populus euphratica trees in arid areas.The leaf water potential and soil water potential of Populus euphratica trees under different irrigation amounts were significantly higher than those of the control,and the greater the irrigation amount was,the greater the water potential was.The diurnal variation of leaf water potential and soil water potential was 60L/m~2<40L/m~2<20L/m~22）,WUE（Water use efficiency）all produced different results,indicating that the amount of irrigation had different effects on the photosynthetic characteristics of Populus euphratica.（2）Under different irrigation rates,the diurnal variation of Pn value of 3-year-old Populus euphratica saplings showed a unimodal curve,peaking between 12:00-14:00,and Pn reached the maximum under 60L/m~2treatment.（3）The Tr values of three-year-old Populus euphratica seedlings showed unimodal curve:the WUE value of each plot reached the maximum value of 8:00,and the daily average value of WUE of 20L/m~2irrigation amount was the largest,indicating that the 20L/m~2treatment was more conducive to the survival of Populus euphratica saplings,and is more conducive to the regeneration and forest formation of Habitat influence（3）Ecological characteristics of Populus euphratica under different habitat influence（1）The soil conductivity,ammonium nitrogen,available phosphorus and available potassium of Populus euphratica saplings increased with the increase of irrigation amount,and the older the saplings,the more obvious.（2）Water has a very important influence on the growth and development of Populus euphratica saplings.The tree height,DBH and ground diameter of Populus euphratica saplings show an increasing trend with the increase of irrigation amount,and the growth status of Populus euphratica saplings also tends to be good.However,the unirrigated Populus euphratica saplings showed a tendency of poor growth conditions such as yellow branches and leaves due to lack of water and high soil salinity. |
