Historical Changes Of Water Environment And Tamarix Ramosissima Stem Diameter Growth Response To Ecological Water In The Lower Reaches Of Tarim River

The characteristics of tree-ring width sequence of populus euphratica were studied through the interannual change analysis and the abrupt change examination. The research reappeared the change pattern of water environment of the lower reaches of Tarim river in the past 54 years; through the annual rings of Tamarix ramasissima in ten transporting water river banks in the lower reaches of Tarim River were measured and statistically analyzed, compared the water environmental change before emergency transporting water to after emergency transporting water .Through comparison the changes of annual stem diameter growth of Tamarix ramasissima and Populus euphratica,analysis the changed tendency of water environment condition after emergency transporting water. The results indicated:The best periods of water environmental conditions appeared in the 1960s and at the beginning of this century, and that the worst periods occurred mainly in the 1990s. The water environmental change of the ten sampling sites were various and complicated in the river downstream. The water environmental condition did not display completely that the nearer to the upper reaches(Daxihaizi reservoir) the site was, the better its water environmental condition was. These reflected degrees of ecology degeneration of the downstream ten sampling areas were different; The abrupt change examination indicated that the water environmental change of the downstream ten sampling areas had the obvious sudden change effect. The emergence time of every abrupt change point was later than corresponding hydrology event.After emergency transporting water in 2000,groundwater level in each section showed different changed regular pattern in the lower reaches of Tarim River on account of different transporting water in every year .The same section of Populus euphratica and Tamarix ramasissima changes in stem diameter growth trends similar to those .And changes in groundwater level are closely related ; Populus euphratica and Tamarix ramasissima changes in stem diameter growth reflect changes in the water environment Annual stem diameter growth of Tamarix ramasissima in different locations in the lower reaches of Tarim River shrink to approach year by year before emergency transporting water, and water environment condition of every locations nearly to be conformity and there was a tendency to aggravate year by year; as the difference to receiving the strength of water after emergency transporting water, annual stem diameter growth of Tamarix ramasissima in different locations had augmentations in different extents; the effective ecological significance of emergence transporting water to the stem diameter growth of Tamarix ramasissima was determined by coercing degree of drought before transporting water and the quantity of receiving water.