Corresponding Relationships Between Populus Euphratica Growth And Water-Soil Condition Changes Of Ejina Oasis In The Lower Reaches Of The Heihe River

This study object is aim at the riparian Populus euphratica forest as a dominating growth and widely distributing in Ejina Oasis in lower reaches of Heihe River. According to the relevant the informations in the tree-ring data for the P. euphratica tree growth and its environmental changes-and-affects in past, a great deal of the data in relation to the P. euphratica tree growth in the past different growth periods were extracted from the tree-ring data by the forest inventory method and the tree-ring analysis technique. Base on the analysis of corresponding correlation between these tree growth data and the field observation and monitoring data of regional climate, hydrology and soil condition dynamic changes in past years, revealing that corresponding correlativity between the P. euphratica tree growth and its environmental condition changes-and-affects. For example, according to field investigation and statistical analysis for the P. euphratica tree growth in different stand growth types (i.e. natural-, semi-natural- and planted stand), different water-soil condition, different growth phases and periods, analysis and demonstating that corresponding relationships between the different indices in the course of the P. euphratica tree growth in lower reaches of Heihe River; based on the application of the tree-ring analysis technique and a series of correlative models established between the different indices of P. euphratica tree growth, a great deal of basis informations of the P. euphratica tree growth in past different period extracted from the tree-ring data, such as diameter at breast height (DBH), total tree height (HT), aboveground accumulative tree volume (i.e. main stem volume and branch stem volume), accumulative biomass and its allocation (i.e. main stem biomass, branch stem biomass, root biomass and leaf biomass). Furthermore, analysis and revealing that the tree growth rule and dynamic changes with increasing tree-age; meanwhile, P. euphratica tree growth rule in different water-soil condition was revealed by the statistic analysis of correlation between the tree population dynamic changes and environmental influences. Additionally, addressing and explaining the corresponding relationships between the P. euphratica tree growth and various indices of the regional climate, surface runoff, groundwater and soil conditions, and relevant models were eatablished and validated, and then, P. euphratica tree growth level and its environemt quality were simply estimated and evaluated based on the relevant models. These finding would be helpful to improve and enhance for the evaluation system of the dynamic changes between oasis vegetation development and its environment evolvement in lower reaches of the Heihe River.This study results showed that it is quite close for the corresponding correlations between various indices of the P. euphratica tree growth in whole lifetime, among them, P. euphratica DBH, as an important estimating index for the tree growth, correlation between it and other growth indices are also quite close, and it is play an important pole in the aspects of the P. euphratica individual and population growth rule and dynamic changes revealed, and a larger growth potential implicated in different growth phases, as well as the tree growth sensitivity and variability exhibited response to its environmental changes-and-affects. This index investigated and relevant data obtained from field work of the forest inventories and monitoring environment changes would also be more simple and convenient. In addition, in the analysis of the correlation among annual mean DBH increment or annual aboveground biomass increment of the P. euphratica population in different study site and its environmental condition changes (i.e. microclimate, annual surface runoff, groundwater table dynamic changes and soil comditon changes), showed that it is quite remarkable in corresponding and correlation between the tree growth and its condition changes-and-affects, therefore, it is reasonable and feasible for these relation would be used for estimating relevant environemt dynamic changes and development in further research.In a word, aiming at a systemical analysis and all-sided study for the P. euphratica individual and population growth, P. euphratica tree growth rule in lower reaches of the Heihe River was not only revealed rationally and also relevant relationships between the oasis vegetation development and environment evolvement were further understood in a higher levels. This study provides a simple method and reliable scientific basis for the maintenance of the oasis ecosystem sustainable development, protection and reasonable using of natural resources (e.g. vegetation, water and soil, and so on) in arid area.