STRUCTURE AND DYNAMIC OF POPULUS EUPHRATICA POPULATION ALONG TARIM RIVER

Populus euphratica Oliv. is a common tree species found along the Tarim River and is important for the development of the local economy. We did our study in the upper and lower reaches of the Tarim River during 2.5 months, from September to November. We used the static life table and survivor curve for our investigations, and population dynamics were predicted by time sequence model. According to our results, young individuals were dominant in the upper reaches of the P.euphratica population, with the survivor curve belonging to the Deevey C type category. The time sequence model demonstrated that the number of mid-aged individuals in the upper reaches of the river will increase in population over the next 20, 30, to 40 years, when there will be continuous development. In contrast, in the lower reaches, young individuals were rare, and mid-aged individuals comprised the largest proportion of the population. The time sequence model for this population demonstrated that the number of old individuals will increase and young individuals will decrease during the next 20, 30, to 40 years. The main cause of this difference between the upper and lower reaches of the Tarim River is connected mostly to the level of ground water, which played an important role in the determination of age structure. Therefore, the crucial factors for the natural regeneration and restoration of P.euphratica were the rising ground water level and improvement in their habitat.