The Research On The Growth And Water Physiological Characteristics Of Riparian Populus Euphratica Oliv. Forest

To study the growth and water physiological characteristics of dominant plant p. euphratical will provide a scientific basis for protect the Ejina oasis and distribute the water of eco-utilization properly. According the purpose of research we have chose the p. euphratica at 3 age period: the die-back tree, the mature tree and the small tree (small tree-1: all the type of leaf are narrow; small tree-2: the leaf type of under crown is narrow and the top crown is broad). The research (include the growth of new branch and leaf emergence ; the diurnal change of transpiration rate and the leaf and root water potential; the seasonal change of transpiration rate and the stem water potential, P-V curve)of p. euphratica has been conducted for two continuous vegetation growth period in Ejina oasis. Analyses the change of growth and water physiological characteristics of p. euphratica at the different age, different type of leaf (broad and narrow) and different water grads (From riverbank to Gobi 280m), Some conclusion have been draw as follow: 1)Compare the narrow leaf branch and broad leaf branch, the growth of new branch and the numbers of leaf emergence of narrow leaf branch is more big,and leaf emergence is late for 3 or 5 days. The growth of branch and numbers of leaf emergence of different age narrow leaf branch as follow: die-back tree>small tree-2>small-1. 2) From riverbank to desert the mature tree and small tree have the same trend, the growth of branch and the numbers of leaf emergence are decrease and the time of leaf emergence is late. 3) With the distance from riverbank to Gobi increasing the diurnal change and seasonal change of transpiration rate are decrease. The diurnal change of leaf water potential shows as: in the middle of forest is high and near the riverbank and Gobi is low. The change of root water potential is reverse. 4) At the different period of growth, the type of water transport of stem is different: before the canopy start to consume water in mass, the water potential of stem of 2cm and 9cm depths are decline, and from riverbank to Gobi the extent of changes of stem water potential is decrease. Near riverbank stem of the tree depends on the 9cm depth intensively to transport water, far from the riverbank for the 2cm depth. 5) The transpiration rate of narrow leaf is bigger than broad leaf; The transpiration rate of narrow leaf of different age are as follow: small tree-2>die-back tree>small tree-1. 6) The broad range of osmotic regulation is benefit for the growth of small tree; the low transpiration rate and osmotic potential for broad leaf shows the drought resistance is better.